View Full Version : 6.5TD Slapping Noise - Extensive documentation.
Thanks in advance for any help. I/we have searched this and many other forums for a couple months now trying to identify and solve this. Hopefully I have been plenty detailed in the issue and symptoms and someone and lend a hand! Thanks.
Vehicle: 95 suburban K2500 w/6.5TD
Videos of noise: Located on YouTube Profile: LongRangeSuburban http://www.youtube.com/watch?v=EOCvckLzqBA
History: I bought the truck from someone that had replaced the whole motor. The truck itself has 179,000 on the odometer. He states that the 6.5TD motor in it originally was “bad” and replaced it with another 6.5TD motor from a rollover Suburban with 106,000.
Motor Identification: The chassis is an “F” I have confirmation that the replacement motor came from an “F” chassis of the same year. The computer was not swapped. But the entire engine was. On the valve cover of the motor is the following YDX 6.5 Liter SGM6.5C6DAAW and a bar code with the digits 81YDX above it. Advertised HP 190@ 3400RPM Fuel Rate at Adver. HP 61.25MM/Stroke @3400RPM
Modifications: Best I can tell, the only thing done to the motor was an FSD heatsink added and the PMD/FSD (SSDieselSupply) Ser No: 3722 was moved. This was done by the rollover owner as confirmed by the owner that did the swap. There is a chip inside the PMD/FSD and it is a “9”
Prior owner stated that he had trouble keeping the oil cooler lines on and it had dumped the oil a couple times and he was tired of dealing with it. He also stated he thought he heard a bearing in the bottom end going bad. No other info. It ran, had good and fast oil pressure. I bought the truck.
Work done: Replaced oil cooler lines and fittings on block. Oil change with Rotella (cut open filter found extremely small and not much fleck in oil, after oil change have constantly monitored condition of oil, no metal at all), new fuel filter, repair leak in return fuel line near tank, pulled oil pan and inspected bottom end by pulling each bearing. All bearings looked good, very very slight wear, crank looked smooth and clean. Replaced bearings because they are cheap and already off the crank. Inspected flywheel for cracks. Checked torque convertor bolts. Replaced all glow plugs. Truck was low on fuel, put in Diesel KLEEN w/injector cleaner and filled tank.
Starts and drives great. Transmission could not be smoother. No hesitation, excellent throttle response. No smoke. Thought it was down on power. Cut out the Cat and replaced with a pipe, it was plugged, gained power. Felt normal.
Problem: It is LOUD. Very loud. http://www.youtube.com/watch?v=EOCvckLzqBA The sound is equal to the ear from either side of the motor. We first thought the injectors were dirty as it does so well otherwise and put a hundred miles or so on it with the cleaner in it. The noise did not reduce. Still runs great and performs but the noise is out of place. We have a Tech1 and my friend is a former GM mechanic but has little experience with the 6.5. The local GM dealer does not have a diesel mechanic on staff.
Attempts at diagnosis and solution:
Injector Test - Used the Tech1 to turn on and off injectors. All created the same conditions. Reduction from an idle of 563 down 20RPM. The noise did not go away but the engine did run rough missing one cylinder.
Lift Pump - Confirmed proper operation of Lift Pump.
Serpentine Belt - removed belt so no accessories were moving and the noise was still there.
Timing - Have adjusted the timing to within factory specs with Tech1.
Optical Sensor – heard the optical sensor could be an issue. Took off the intake plenum, took off the plate and removed sensor. Had no way to test it but things inside looked super clean.
“Ear to the screwdriver on the injector and valve cover” test - Under the valve cover everything sounds normal. All the injectors sound very similar except for 6&8. I identify 6&8 as facing the truck the back two cylinders on the right (drivers side) of engine. #8 sounds loud thru the screwdriver but when the injector is turned off with the Tech1 the noise in question does not change. #6 has a similar sound to #8 but not as pronounced.
Questions:
Valve springs – could a broken valve spring (suggestion from someone) cause the noise yet the engine still run well? We pulled the driver’s side valve cover. Remove the rocker arms and inspected all good condition. Pulled push rods, checked for wear and not bent. Visually inspected springs. Is there a way to tell if the springs are ok?
Collapsed Lifter?
Injectors – could the #8 injector be creating the noise even though it responds to being turned off and on without the noise changing but while listening to that injector with the screwdriver it sounds louder than the others?
Injector Pump – Could there be a bad pump? But it runs great, not sluggish, good throttle response, its just really loud
Timing – could the pump timing be making this thing sound like piston slap? Yet it runs (aside from the noise) very smooth with fast throttle response.
Current State:
Driver’s valve cover is still off. We are planning to put the rocker arms back on, connect the injector lines and start it. Maybe move #8 injector to the front.
Any ideas, thoughts, theories, myths as to the slap/noise would be greatly appreciated!
Excellent information! Only one question, does the noise follow the rpms? Or does it stay constant?
It could be a loose flexplate.
Just my .02ยข worth.:)
Thanks KallyI.
This is the video with a higher RPM http://www.youtube.com/watch?v=3MGD1_jExao
The pitch remains the same but the sound gets louder. Not louder like things are getting worse just louder.
I'm thinking about taking a gamble and replacing all the injectors. People have commented that they need to be replaced or rebuilt after 100k.
We checked the bolts on the flywheel and rotated it looking for cracks as well. Everything looked good. Aside from the basic maintenance we did to bring it to specs (glow plugs, oil lines, etc) everything else we check seems to be in spec and does not look worn. We keep thinking injectors or pump but it runs smooth and the throttle response is like a gas motor. It's just louder than it should be. Like you can hear the usual diesel noise in the background with this slap on top of it.
Thanks again for your suggestion. :)
DmaxMaverick
03-12-2011, 21:34
By the sound of your video, I would suspect a combustion related problem. The sound isn't random, but is rhythmic with the engine speed. If it isn't the injector (don't rely on the Tech tool), then it's mechanical. I'd start with the rocker retainers (buttons) in the area of the noise.
A better test (than the Tech tool) of cylinder response is actually loosening the injector line nut. It can be a little messy (fuel should leak from the fitting), but is absolute. Loosen/tighten one at a time.
Also have a close look at the harmonic balancer and pulley. Pull the glow plugs and verify they are intact (a missing tip can embed in the piston crown and hammer the head).
Not sure what it would sound like if injector lines got crossed, but is that a possiblity? The second video almost sounded like a gas motor with a bad cylinder (plug, plug wire). Just making some easier suggestions :confused:
By the sound of your video, I would suspect a combustion related problem. The sound isn't random, but is rhythmic with the engine speed. If it isn't the injector (don't rely on the Tech tool), then it's mechanical. I'd start with the rocker retainers (buttons) in the area of the noise.
A better test (than the Tech tool) of cylinder response is actually loosening the injector line nut. It can be a little messy (fuel should leak from the fitting), but is absolute. Loosen/tighten one at a time.
Also have a close look at the harmonic balancer and pulley. Pull the glow plugs and verify they are intact (a missing tip can embed in the piston crown and hammer the head).
We are leaning towards combustion as well. The rocker retainers and everything under the valve cover on the drivers side all look normal and pulled out the rods to make sure they were straight. Haven't taken apart the passenger side.
Looked at the balancer and pulley. We had taken off the serpentine belt so the accessories were not contributing to it and inspection of the balancer seemed ok. - any specific test/inspection to do there?
We also have brand new glow plugs installed.
We had read about loosening the injector line nut. I don't really care about the mess but thanks for the heads up on it. We were starting to think if the injectors, being over 100k were simply not closing all the way the Tech1 would show the 20rpm drop when it should be 40rpm or whatever. And the nut loosening would answer that. But our thought was since all the injectors being turned off individually EQUALLY reduced the rpm, that the injectors were functioning normally, however, if they are all fouled they would act the same as well.
BUT, if they are all fouled to some extent as they are all over 100k then they would draw it down less. Anyone know how much an off injector SHOULD draw down the RPM?
Maverick, would you think that it sounds like it needs a new set of injectors?
Many thanks ..
Not sure what it would sound like if injector lines got crossed, but is that a possiblity? The second video almost sounded like a gas motor with a bad cylinder (plug, plug wire). Just making some easier suggestions :confused:
The lines are hard piped to each location, I don't see how they could have gotten crossed and it seems to start fine. Though a second or two longer than it seems like it should. Which could lead back to Mavericks injector issue. Injectors not closing all the way and extra fuel slowing start and making noise.
Thanks for the thought! I'm trying to get this thing rigged out to be my yearly runner to Canada for the walleye and Beer! Note the Capital "B" that means it is an important word!
The sound is definately running at crank speed and not cam speed.
This rules out the valve train.
With your having inspected the lower end the suspicions head to the pistons possibly and there is a chance that this noise could be from a failed serpentine crank pulley.
Remove the serp belt and check the drive pulley on the crank,
The pulley is mounted on a bearing that also has a rubber dampener.
If the dampener comes loose the pulley can slap back and forth against the built in stops and it will make a lot of noise.
If the crank pulley is ok then we need to check elsewhere.
Remove the glow plugs and disable to IP (Unplug the fuel shutoff)
Spin the engine on the starter and see if there is any unusual noise as the engine spins.
The other possibility is a failed wristpin or as Maverick mentioned, something embeded in a piston top.
If there is anything in the top of a piston, it will make noise when you roll the engine free on the starter.
A failed wrist pin is going to entail pulling the engine apart, or at least part way down.
A cracked or broken piston skirt, although not common on these engines can happen.
Check the crank pulley first, then move on to removing the glow plugs and spinning the engine.
Good luck and keep us posted.
Great video, sound is wonderful.
Missy
You definitely deserve the Missy Good Wench err Wrench moniker. Identifying the sound relation to the crank vs. the cam is a huge clue!
The valve cover is still off the drivers side (no gaskets on hand till Monday) so we are going to bolt on the rocker sets and injector lines with the cover off and do the crack injector line test and the start spin with no fuel to listen to mechanicals. A bit of oil spraying but hopefully the open cover won't add too much noise.
The serpentine belt was removed prior and the engine run with no accessories and the noise persisted. Pulling and prodding the balancer and it seems to be rock solid. But we have the belt off now so I double checked.
If the noise goes away while cracking injectors then we need injectors. They do have over 100k. And people have said replace/rebuild at that time. BUT could they all have the same sound reduction when cracking them and therefore not identify them as the culprit?
We will also do a starter only crank with fuel off and listen for a glow plug tip. That is a good test too. If there is a tip, embedded in the piston head, what then? Yikes! When the plugs were changed, there is faint recollection that one on the drivers side had a missing tip but since they were all so worn, we just thought it had burned off. Do they eventually burn out of the cylinder? We put a hundred miles or so on it as is, thought it would have been gone if it was there.
Many thanks again to everyone!
Just did the crank it over no fuel test. The motor sounded great, no noise. Here is the video. http://www.youtube.com/watch?v=1xKUg092xuA&feature=mfu_in_order&list=UL
Hopefully that means there is nothing mechanical going on.
That leaves the injector test. I'm ok with a set of injectors but if its the pump... "For Sale"
Sounds like this guy's http://www.youtube.com/watch?v=6Fcxnp0LC1U and he said his was "Turns out that I had a metal shard in the cylinder. Its tapping the head. Looks to be a compressor wheel shard."
I can't get to the crack injector line test today. It will be in the AM. Up until this video, all things were pointing towards injectors. I hope the "spin no fuel" test and not hearing anything tapping (like a metal part) keep pointing towards injectors.
If things quiet down with cracking the injectors I am going to order a set. I have heard a couple bad things bout SSDieselSupply and their injectors, anyone have other suggestions?
DmaxMaverick
03-13-2011, 11:29
We are leaning towards combustion as well. The rocker retainers and everything under the valve cover on the drivers side all look normal and pulled out the rods to make sure they were straight. Haven't taken apart the passenger side.
Looked at the balancer and pulley. We had taken off the serpentine belt so the accessories were not contributing to it and inspection of the balancer seemed ok. - any specific test/inspection to do there?
We also have brand new glow plugs installed.
We had read about loosening the injector line nut. I don't really care about the mess but thanks for the heads up on it. We were starting to think if the injectors, being over 100k were simply not closing all the way the Tech1 would show the 20rpm drop when it should be 40rpm or whatever. And the nut loosening would answer that. But our thought was since all the injectors being turned off individually EQUALLY reduced the rpm, that the injectors were functioning normally, however, if they are all fouled they would act the same as well.
BUT, if they are all fouled to some extent as they are all over 100k then they would draw it down less. Anyone know how much an off injector SHOULD draw down the RPM?
Maverick, would you think that it sounds like it needs a new set of injectors?
Many thanks ..
The miles alone indicate the likely need for injectors.
If the injector lines have been removed from the pump since the noise wasn't present, crossing 2 lines is possible. On an otherwise healthy engine, it doesn't significantly affect starting, and there isn't much power/performance loss. There will, however, be a fuel knock (similar to what you are now hearing). If the lines have not been removed (since it ran normal), discount this as a possibility.
I disagree with Robyn (which is rare). It sounded to me like the noise is combustion-timed. Meaning, it is timed with the cam (combustion stroke). A crank-timed noise should sound significantly faster. It isn't difficult to detect this by ear at standard idle.
Also, if you suspect the noise is coming from cylinder #6-8 area, you'll have to pull the passenger side (U.S.) valve cover. #8 is the rear most on the passenger side, and #6 is just in front of it on the same side.
suburbanK-2500HD
03-13-2011, 13:38
I have heard a couple bad things bout SSDieselSupply and their injectors, anyone have other suggestions?
[/QUOTE]
I and a friend have the SSD Marine injectors, havent had any problems so far, had them for 2 years
Maverick,
Thanks for the reply and info.
We were mistaken with the #6 and #8 locations. The area we thought while holding a screwdriver on the injector was #5 and #7 on the drivers side (US) We mixed up the firing order. #7 sounded louder than #5 and #5 was louder than the others. I'll update my first post to indicate proper location.
Leaning in on both sides of the motor, the noise is equal side to side. The other person's video that I last referenced sounded EXACTLY like mine. You can't tell the difference in a blind "listen test".
Regarding the location of the lines and if they have been moved (good initial call Kally) I can only go by the previous owner. He said he did not make changes to the engine when he bought it. He pulled it complete out of the Suburban that had been rolled over and put in in this one not changing anything. What it plumbed wrong before? I don't know. I'll pull off the upper plenum and try to figure out what is supposed to be where and see if that is an issue. I would think it would cause a miss and a code if things were backwards though. But I am far from an expert.
On another note. After the lines were off to inspect under the driver's valve cover and reinstalled. Upon startup, the sound was quieter than before and increased as each cylinder caught and fired. Again, I think, reinforcing an injector or plumbing or IP issue rather than mechanical.
Monday we are putting the drivers side valve cover back on and cracking injectors in that side, also going to do the same on the passenger side. Guess you have to install and uninstall the turbo a couple times there.
I'll also remove the upper plenum and try to determine proper plumbing.
So you think that all the injectors should be replaced at this mileage anyway correct? Do you think that the prior rollover could have dislodged crud and helped to foul the injectors or cause other issues?
[/color]
I and a friend have the SSD Marine injectors, havent had any problems so far, had them for 2 years[/quote]
I thought about going with the marine if I needed them. Did you notice a significant HP increase? And what about mileage? Increase? Decrease?
I had called them before to ask a couple questions about their product and it sounded like one guy that his mood depended on your service as opposed to it being run move like a business. And hearing a couple other people on other forums have issue made me question. One person stated they had the same noise using SSD injectors. Pulled their injectors and put in a set they had and the noise went away. Do higher performance injectors make more noise?
There is no benefit whatsoever with marine injectors on your engine since the fuel is controlled by the IP vs the injectors-stock rebuilds with bosch or delphi nozzles is all that is required.
A pop pressure test is mandatory for rebuilds to get them set evenly and to spec.
I am unsure if you stated that you ran the truck with the valve cover off,but if an injector line was hitting the valve cover you could be getting a noise from its pulsation when firing on that cylinder.
I am leaning toward bad injectors as well but keep checking everything.
My meaning was that it was not valve train noise such as a lifter, rocker or other stuff in the valve train.
If there is any ???? about the fuel lines its easy to check the layout with a little chart thats available here at TDP.
Now if there are lines crossed, the engine will have two cylinders that will be missing.
The engine seemed to run very smooth in the video.
Crossed lines with cause the engine to shake a LOT.
I have seen this done once and it was very obvious that there were issues.
Try the lossen the line trick and see what shakes out.
If you find that one injector when loose kills the noise, then you have likely found the gremlin.
An injector with a nasty spray pattern or that is peeing off into a corner will cause a nasty noise. or at least it can.
Injectors with 100K plus are suspect for sure.
If loosening the lines doe not bring a solution, then I am suspect of a bad piston/wrist pin.
Missy
Thanks Racer.
I did run it with the driver's side valve cover off. No change in noise though. I'll see if the passenger side lines could be hitting the cover. I'll look at that also.
Regarding Injectors, if I need them, I'm going with these people unless I hear reliable feedback otherwise. http://www.accuratediesel.com/shop/124.html They are are $235 a set of new ones.
Missy,
I will crack the injectors in the morning. If more than one are fouled and I loosen one at a time, will the noise change be significantly enough to be noticed over the other injector(s) having problems? My concern is that I have 8 questionable injectors due to miles, a rollover, maybe dirty fuel and turning off one at a time won't reduce the noise enough to pinpoint any one injector and therefore I'll bypass that as an issue and continue to look at possibilities.
And yes, it idles smooth and has great throttle response so I wouldn't think crossed lines but while I am in the hole I'll look. I'll find the chart on the site here and go from there.
Thanks EVERYONE! I'll keep updating and be sure to post a final video once resolved.
85-m1028
03-13-2011, 16:33
If the timing had slipped out then there would be some serious white smoke and it would prob continue to slip out and get worse and worse as you run it. Timing wise, if a sensor was throwing off timing then you would get a code and smoke.
Why not swap out the injector to the other side of the engine somewhere and see if it follows the injector?
Thanks Racer.
I did run it with the driver's side valve cover off. No change in noise though. I'll see if the passenger side lines could be hitting the cover. I'll look at that also.
Regarding Injectors, if I need them, I'm going with these people unless I hear reliable feedback otherwise. http://www.accuratediesel.com/shop/124.html They are are $235 a set of new ones.
Call to confirm that they are bosch or delphi nozzles in those injectiors-if so they will be fine,I would also ask that they be pop tested before delivery so they can be adjusted if nessasry.
Thanks Racer, just sent accurate an email asking that.
Also, I'm not sure they they carry them but I have two Stanadyne dealers close by. Anyone like their stuff? I gather they are the OEM people?
85-m thanks for the input on the timing, no smoke at all, burns clean. Monday is injector test day so we will be sure to to that in addition to cracking them if we can identify a single one or two as the problem.
The noise is so consistent all around that it makes me think they are all messed up!
All injectors are not created equal. this from Tim at Accurate. Cudos on a Sunday email reply!
We carry three different lines of injector for your truck.
1. Complete new Medallion injectors - $235
2. Remanufactured injectors (with US Diesel tips) - $240 + $80 core charge
3. Complete new Stanadyne injectors. - $425
Well Medallion website says they have been in North America for 5 years. This makes me think Asia.
USDiesel is in Texas and says they have been in the diesel injection business since 1984. They also SELL industrial fuel injection test equipment. Kinda high end stuff there. Makes me think if they arte rebuilding them, they have the equipment to properly test them.
I don't want to hijack my own post since I want to stay on topic of the noise but I do need to have an injector source ready as I need to buy them monday to make the schedule.
A little birdy just told me that Medallion is kinda quiet about where their injectors are made and are probably from that country that makes the umbrellas for your drinks.
Bosch used to be their premium injector formerly made in Germany but they moved to India for manufacturing. And Stanadyne (OEM for the fuel pump) has their injectors made in Italy home of many international diesel manufacturers.
I'm torn.
I would just have the local stanadyne dealers rebuild the ones you have now-do the entire set.
I would just have the local stanadyne dealers rebuild the ones you have now-do the entire set.
Brilliant! I hadn't thought of that. When its right in front of you.....
Specify that they use OEM nozzles.
Good luck on checking the squirts.
I always use a local Stanadyne certified shop to do my injectors.
The last set cost me $268
When you open the line on an injector that has issues the change in the sound will be unmistakeable.
All the info on the injectors is right spot on, stay with the "GOOD STUFF"
IMHO stay away from internet stuff, other than vendors that have a good reputation.
If you can get your squirts rebuilt locally with good parts and the POP set equal your better off me thinks.
I set the POP on my DS injected 6.5's at 2000 PSI with a used pump.
The pump will like it and the rattle will be a tad less than if the pressures are run right up to the top of the spec.
Keep us posted
Missy
Update:
Still waiting on valve cover gasket set. Cracked injectors on the driver's (easiest) side. Didn't notice a significant change in the sound. My wrench friend thought the sound was now more on the passenger side at this point.
I pulled the #1 injector Bosch 468-5 Orange Band
0430211097 973
Going to find a way to access the passenger side now. Maybe thru the wheel well.
1891
Here it is. I'm thinking I go ahead and put in a set of injectors anyway. Can anyone tell something from how this looks?
DmaxMaverick
03-14-2011, 10:37
Update:
Still waiting on valve cover gasket set. Cracked injectors on the driver's (easiest) side. Didn't notice a significant change in the sound. My wrench friend thought the sound was now more on the passenger side at this point.
I pulled the #1 injector Bosch 468-5 Orange Band
0430211097 973
Going to find a way to access the passenger side now. Maybe thru the wheel well.
Don't wait. Gaskets leak. Always, eventually. Use Permatex or "The Right Stuff".
That injector is "used up".
Quick update for everyone. I had to leave to Steubenville OH using my Tahoe (258k) as a tow vehicle to pick up a Hudson equipment trailer in Charlotte, then to OH to check and purchase a 65MPG tri wheel car to sell here in the Outer Banks. Trailer does not like not having a forklift on the back. There is no tongue weight on this 1800lb trailer. It had me in non stop tank slappers from 50mph plus. Manufacturer said lift the tongue to add tongue weight by removing the weight off the front axle. I couldn't get it high enough. So I put 6 bags (480lbs) of concrete in the tool box. Drove like a dream. Through lots of mountains and windy roads the old Tahoe did good. Got the car , heading back, and now I am stuck in Fayetteville, WV with parts rattling around inside the Tahoe motor in a random fashion as opposed to a proper and organized manner. Time for a new motor.
So the LongRanger (that's what I call my Burb) will be A#1 priority if I ever get back and I promise to update you and provide before and after video of the fix. I ordered a set of injectors and those are going in asap. Hopefully that is the issue.
Stay tuned!
It is a little late for the OP as far as hauling an empty tandem trailer,but for stability a good way to haul is with the front wheels/tires removed when hauling empty on the trailer.
That's a good solution. The LongRanger, once properly rigged, will have onboard air to run tools so that will make for quick tire removal.
I had never had that problem before hauling empty with a tandem. But this is a 12,000lb trailer with the axles centered under the deck for the forklift and little to no tongue weight. The manufacturers yard man hooked it up for me so I never even got a feel for it from shoving it on the ball. I definitely learned from it. And it was bad timing for my Tahoe. Hmmm do I hear a 4BT calling?
Finally got around to cracking the injectors on the passenger side. Couldn't notice a difference the the slapping sound, just expected RPM reduction.
However, did notice that on #5? (2nd from firewall on passenger side) rather than having diesel flowing out, it had foam/bubbles in the fuel. A leak in a return line? I expect the feed line would have fuel spewing elsewhere if indeed it was the supply.
I'm going to change the drivers side injectors and return lines then start it to listen before changing the pass side.
Feedback on the foam/bubbles?
DmaxMaverick
03-21-2011, 12:25
Either you have an air leak (suction side of the lift pump), or that injector/line is airlocked. When airlocked, the air bubble "cushion" in the line will prevent the injector from popping. Not a return line problem.
Status Update:
Changed the injectors on the drivers side, fired it up. No noticeable overall difference. But the sound seems to be primarily from the passenger side now. Before we seemed to think it was all over the motor. But overall still loud. i thought about posting a video but I didn't think you could hear a difference.
Below are the injectors from both sides, I had them in order but since they all looked the same and had knocked them out of line with tools I thought I would just show you the bunch.
18921893
Changed the injectors on the passenger side. We did NOT remove the turbo, but made a thin wall minimum length 30mm socket to clear the turbo oil drain line. Besides, the turbo seemed to be well attached!
1894
Please note the "welds" were done with eyes closed. It is a 30mm thin wall socket, cut off and welded to a 28mm socket that is a short as possible yet big enough to clear the return line nipples. The slots are not necessary, they were in the upper half for a prior "project".
Got the passenger side injectors in and fired it up. No change. :mad:
So tomorrow the plan it to crack the injector that had the foam/bubbles to make sure that the air issue is gone. Then adjust the timing again. THEN, pull the valve cover on the passenger side. Not planning to mess with the turbo, but pull the AC compressor.
By the way, I went with AccurateDiesel for my injectors. They have three versions. The China route which are Medallion around $230 for the set no core charge, the Remans for around $240 plus core charge. I went with the Reman, they are Bosch with US Diesel tips. US Diesel looks like a major injection player, they repair and sell injection testing equipment as well. For $25 you also get the install kit which includes the push on no clamp return lines, upper plenum gasket, and I assume the other gasket was for the turbo if you have to pull it. I chose Accurate because my questions sent on a Sunday were all answered on a Sunday (I sent 4 or 5 back and forth emails) and that to me indicated a company, though small, interested in good customer service by being available on a weekend.
Ok, we will see what happens tomorrow. Any feedback or other thoughts are always welcome.
Pulled the passenger side valve cover. Noise is definitely on that side.
Pulled rocker assemblies, no excessive wear.
Looked at springs, no obvious breaks.
Started, pushed down on rockers, all seemed to respond equally.
Did notice what seemed like excessive "blow-by" on the rear two cylinders. More exhaust leaking out there than the forward two cylinders. A clue?
Video below will show a little of the leak but the purpose of it was to show how easy this thing starts. And the glow plugs are not connected (ground disconnected to ease removal of valve cover.
http://www.youtube.com/watch?v=y6Xj9I3W4HQ
There is a particular little rattle sound in there that is not combustion related and seems to follow as the engine is shut off and spools down.
Not sure but my suspicions are, possibly a loose wrist pin bushing.
This can cause the type of noise you are hearing.
Using a bar on the crank, rock the engine back and forth moving the crank through at least 4 revolutions a little at a time.
(Glow plugs in) rocking the engine back and forth, if you can hear the little clack clack clack or anything similar when rocking the thing back and forth.
The noise I am hearing does not sound like injector missfire or other combustion related noises.
This may be to the point that the next logical step is to yank that engine out and get it apart.
My gut feeling says that the noise is mechanical and likely related to the rotating assembly.
Could even be a cracked piston skirt.
Good luck and keep us posted
Missy
Robyn,
That is beyond my means. How many hours are we talking about to R&R that motor? And how many to pull it apart to get to it? I know there are items that should be replaced while it is out but my plan was to only keep this thing for a year until I could put a 12V cummins in it. Something without the wires and idiosyncrasies of a 6.5.
As it sits, with the miles on it 106k, what do you think it is worth?
94 GMC 6.5
03-27-2011, 23:44
Hi, I feel your pain all too well. I have had almost all the listed problems you can have with the 6.5 including the mystery engine noise. I replaced the pump, injectors, pulleys blahh blahh blahh. The reality is the 6.2/6.5 is really a good solid engine, its the BS that is attached to it that has ruined its reputation.
As for the noise, try and have the injection pump timed by a professional. The tech1 or other scan tools dont really tell the whole story. The 95 falls with in the years of having computer control injection but not having the on-board timing adjustment as with the newer trucks. It needs to be Dynamically timed, this includes a luminosity probe that goes in the glow plug hole and a pick-up that mounts to the crank damper.
NOT all shops can do this. In fact most will tell you they can but really have no clue what they are talking about. This is because the elect. 6.5 is not a popular motor in the Cummins, PS, and Duramax era. The equipment to do this is quite expensive so you will have to find a shop that has one that the basically carried over from the "old" days. They should be able to tell you if the timing chain is out of tolerance too. Which may actually be the problem.
Will it help? It made a difference with mine. Think of it this way, on a gas engine if you advance the timing or retard, the sound is affected greatly, pre-ignition, loping, back firing. The same concept with the diesel, if the timing is off just a little the fuel delivery going to be wrong causing all kinds of funny noises and fits. Its about 100.00-150.00 to have it timed right about the same as a hour of psyco. therapy which most of us need after working on the 6.5
Another old school trick if you still think it could be internal 'mechanical' . Try changing the oil to some really thick stuff like a 30w. Remember though its diesel and turbo so running too thick may make it sound better but may ruin it in the end. Its just a simple "test" not meant to solve problem.
I can yank one of these engines by myself in a day (10am to maybe 6pm)
Steam clean the little critter to get the crap off.
Yank the heads and the pan and snoop it out.
If you can figure out which cylinder it is you could just pull that head and the pan then pull the one rod/piston assembly and fix it.
Just replace the rod with a good used one, same with the piston, if thats it.
I personally yank both heads and the pan and check it out.
Two head gaskets, Head bolt set and a few incidentals.]
This is not that bad of a job.
Once you get the crap off the engine it will come out easily.
As mentioned, these are pretty good engines.
I have seen the 12V cummins in the Chevy rigs but was never impressed with the overall results.
Keep us posted
Missy
As mentioned, pull the 6.5 engine out and check it out before going the Cummins route. They're not all that bad to pull out and very likely there is not that much wrong with it. I do pull the hood off so that I have easy access with the engine puller. The Cummins 6BT is an excellent engine but the rest of the truck was not designed for it. The IFS suspension is not designed to handle that kind of weight and it would be a constant battle to keep the automatic transmission alive with the massive amounts of low RPM torque this engine develops. You can get around all these deficiencies but it takes time and expense.
I think this weekend I am going to do the rotate and pull the head on that side. Maybe it will be an easy fix. :cool: I'll be sure to take photos of the insides.
Not to get off on a tangent, but the 4L80 in the 2500 is a burly trans. I'm only looking to turn the 6BT up to about 300hp. It takes up less room, needs no wires, the people around here hate the old 6.5 because it is so quirky and it doesn't seem to make real power without wondering if something is going to let loose or crack. If I lived near Missy and she was my wrench it might be another story having someone that knows these things inside and out. But around here you can see the fear when someone uses the words six and five in a sentence separated by the word point.
A local fellow did the 4 BT swap into a Burb with the 4L80E and they had issues getting the tranny to work and hold up.
They finally used a Mopar tranny with T case.
Using the hydraulic managed Mopar tranny is a far better way to go.
Using a stand alone controller can help with the installation, but the 4L80 does not really like this set up.
I have seen two 4BT swaps and both ended up using the Mopar tranny.
This is the 47 RH I believe and is a 4 speed with all hydraulic controls.
After the guys installed the Mopar tranny the rig was just super.
Just some observations
Missy
Finally, got the passenger side head off. It looks beautiful. The head looks fresh, tight, no carbon build up. Valves all look really good. The block side looks good too. No glow plug tip embedded in a piston. Tops are all clean and no dings from an object previously there either. There is even the cross hatching in the cylinder walls still. Very little wear and very clean.
1919
1920
So now I am down to seeing if there is a wrist-pin or piston skirt and need to figure out how best to diagnose that. There has to be something there or I am totally lost.
More Power
05-13-2011, 12:33
Run each piston in turn up to TDC, then try rocking the piston on the wrist pin. Even a perfect piston will rock just a little. After doing a few you'll be able to identify any that are outside the norm.
Jim
You may also find that there is a wrist pin with issues.
To check this do as follows.
Roll the engine by hand until each piston reaches TDC and then just starts down. Allow the piston to drop in the cylinder about 1/2 inch then stop turning the crank.
With your hand (thumbs) press down on the dome of the piston, if the piston moves down and then stops abruptly you have a worn out wristpin Bushing most likely.
The top of the rods are bronze bushed and do wear out.
This little technique can help diagnose a bad bushing.
A bad bushing will make a Helluva racket as the piston is drug back down on the intake stroke.
On the compression stroke and the power stroke ( no affiliation with FOMOCO) :D the wrist pin is loaded with the pin towards the bottom of the bushing.
This condition will continue through the power stroke, then the exhaust stroke (going back up) then as the piston rolls over TDC and starts to drop on the intake stroke the pin will slam into the top side of the bushing.
As the piston rolls through BDC on the intake stroke and enters the compression stroke the pin will again change sides of the bushing.
A whole lotta bangin a going on. :eek:
Missy
Missy, I know all about the bangin and the power stroking. I just didn't know how it pertained to my engine. You are very knowledgeable as is everyone here. Thanks for all the input.
Great description and that must be the problem. Wrist or bushing. The engine is pristine otherwise and it starts very fast, clean, smooth, sans bangin, and I am anxious to get this problem fixed.
I have a full tank of fuel at the old price and I am anxious to burn it out. As always, I'll keep everyone up to date with what I find.
Many thanks
Dave
john8662
05-14-2011, 21:30
A compression test would tell the tale on a bad wrist pin bushing. The compression would be less in the hole with the bad pin.
Since you got the head off, you might as well pull all the lifters and inspect them and the rollers.
The sound I was hearing in the video is hard to tell what it is other than it's really loud.
phantom309
05-20-2011, 19:12
did any one mention the vacuum pump at all?
nick
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