K2500 6.5 TurboDiesel with troubles.

[Platina Cruiser]

Hello to all.

I own a 1996 K2500 Silverado with a 6.5 TurboDiesel engine. My father purchased the truck new in 1996. The reason he bought this pick-up was that he needed something big and strong to haul trailers. It has done great and it proved to be a very though truck.

The problem of owning an American pick-up in Belgium (Europe) is that almost nobody knows what the weak points are on these diesels. We have found out the hard way that the PMD is weak point.

When the truck had about 60.000km (37.000 miles) it had became unreliable. Problem was that it would stall when driving. We contacted the importer and official Chevrolet dealers. They said the fuel pump needed to be changed along with the electronics. We had this done and it was llike new again.

Untill around 3 years ago. We had occasional troubles with it. Usually it would start again when you waited 5 minutes. This went from bad to worse to completly broken. Again the fuel pump and electronics were changed. My father had searched the internet to find out what was causing the problems. He found out that heat was the enemy. The solutions was to relocate the PMD as away from the valley of the engine as the original wiring would allow. The PMD was mounted on flat solid block of aluminium.

It again ran fine. My father was very happy to apparently have found the solution. Unfortunatly he passed away in 2007. Because the truck has lots of emotional value to me and my mother we have kept the truck. From then on I have been the driver of the pick-up.

About 2 months ago the troubles started again. It would sometimes stall about 30 seconds after the engine fired up. Again I began searching for answers. Recently I have found a dealer who claims to know what the trouble is with the PMD. He told me that heat indeed is the enemy. He also to me to see if there was a calibration resistor inside the PMD. There isn't one. This lack of resistor causes the engine to go in emergency procedure resulting in higher engine bay temperatures. The lift pump that is mounted in the chassis is good.

Now, to fix the problem I think I need:
1) a new PMD. I have searched the net and have found that Stanadyne makes a new PMD. The new and improved one is grey instead of black like our old one. Problem is that it has a new connector.
2) a calibration resistor.
3) a kind of cool fin to keep the PMD as cool as possible.

I have also read some about the oil pressure switch. But I do not understand how this is related to the fuel pump. Could somebody tell me if this is part of the trouble?

When it comes to getting the new parts I have a couple of options:
- by a PMD form Stanadyne and a calibration resistor from GM here in Belgium. But then I have to make some kind of cooling device. I have understood that the aluminium block we have now isn't good as it holds heath to long. If it is a grey PMD I have the trouble that the old wiring won't fit with the new connector.
- by a kit from accuratediesel (http://www.accuratediesel.com/shop/8.html) or by a kit from ********* (http://www.*********.com/pdc_pmd_fsd_pump_driver_cooler.htm)

Now my questions are:
- have I got it wright this time? Or are there others ting that need to be done first?
- where should I get my parts from? Are there places besides accurate or a1 where I can get my parts?

this is how my engine bay looks currently:
http://i68.photobucket.com/albums/i5/PtCruiser_05/PICT0811.jpg
http://i68.photobucket.com/albums/i5/PtCruiser_05/PICT0812.jpg

and here is a picture of the pick-up:
http://i68.photobucket.com/albums/i5/PtCruiser_05/PICT0318.jpg

Thank you all.

[suburbanK-2500HD]

Hi

And welcome

You can get all you need here: http://www.kennedydiesel.com/
http://www.kennedydiesel.com/detail.cfm?ID=31
ore at some of the others in the advertiser section.

""I have also read some about the oil pressure switch. But I do not understand how this is related to the fuel pump. Could somebody tell me if this is part of the trouble?""

The OPS controlls the lift pump also, when you get oil pressure it starts.

[Platina Cruiser]

Thank you for the link and welcoming.

I see that at Kennedy it is the black PMD. Is it good or should I try to get a newer grey one?

I was thinking about relocating the PMD. Would it be a good idea to put it inside the box of the air cleaner? I think it would cool very good in there because cold air gets sucked over it there.

[DaveNY]

Another option is Heath Diesel remote PMD which mounts behind the bumper on the splash pan. I have used this and have had good results. Bill Heath also offers a 7 year replacement warranty on his unit. Comes with everything you need.
Good Luck Dave

[Platina Cruiser]

I have looked at the pictures of the system offered by heath. It looks like a convenient kit. But I'm afraid the lack of cooling fins will pose problems in the future. Or is there sufficient cooling because of the mounting on the skid plate? I also fear that it is a bit too wet there. Won't that be a problem?

Looking into the matter further I have seen that a lot of you have pyrometers. What is the purpose of this device and do you really need it?

Are there other things I need to improve to my truck?

About the calibration resistors. I see that most PMD cooler kits come with a resistor 9. I find this a bit weird as I have read that most 6.5's originally have a 4 or 5. Is there any reason to go from a 5 to a 9? Does it really make a difference in power?

[DaveBr]

The new grey Stanadyne PMD is something that has yet to proven to be worth a second look. Most people prefer D-TECH which is deemed more reliable. I am almost sure Kennedy sells heat sincs for PMD's as well as extension harnesses. If you check out his Tech tips for 6.5's you will find a good location for your new PMD. Also try pmdcable.com The #9 resistor will cause more fuel to be put into use generating more power along with more heat.

[DaveNY]

I have looked at the pictures of the system offered by heath. It looks like a convenient kit. But I'm afraid the lack of cooling fins will pose problems in the future. Or is there sufficient cooling because of the mounting on the skid plate? I also fear that it is a bit too wet there. Won't that be a problem?

I have had the Heath Unit in that location for 5yrs, with no weather related problems.

I am not a salesman for Bill Heath but can tell you the PMD started acting up last year and he shipped me an entire assembly with return shipping lable No Questions asked.The new one came with the D-TECH.

I have a boost gauge and pyrometer to monitor exhaust temperature.Prudent practice with diesel engines.

[Platina Cruiser]

Could you explain me why it is so important to know your exhaust temperature?

[Robyn]

The DTECH PMD along with a remote mount and a wiring extension will solve most of the issues.

I like to moun t the PMD on the inside of the skid pan that folds down right below the radiator.

The coolers and extension cables are available from the vendors here at the page and online at such places as Ebay
(Look under 6.5 diesel)

Be sure to order a #5 resistor with the new PMD
The resistor goes into the plug cavity on the PMD and it will be evident how it fits.

Push the resistor to the bottom of the cavity over the pins and then its ready to go.

Be sure you use some heat sink compound between the new PMD and the cooler.

Many of the good coolers come with this white paste in a small tube.

The oil pressure switch is not as critical on the 96 as the lift pump power is controled via the ECM and a relay.

Just be sure that when the truck is running that you have fuel flow to the drain line up front.

With engine running, open the drain (with the hose into a can) you should get a nice flow from the hose.

If the engine stalls or no fuel flows there is an issue with the lift pump.

Normally if the SES light is not coming on then the stalling issue is the PMD.

***** Carry a spare PMD in the glove box*****

The DTECH units have shown to be very good.

With the truck the way you bought it from the dealer the addition of an exhaust gas temp gauge (Pyrometer) and also a Boost gauge is not really needed.

Most of us diesel nut cases have added larger exhaust and special computer chips to allow the engine to produce MORE POWER
With these aftermarket computer chips come modifications that eliminate some of the built in fuel controls.

The driver then must watch the Exhaust gas temperature and boost more closely as the computer no longer controls it, the driver does by backing out of the throttle on hard pull when the temps get up to around 1000F

Your factory stock rig will do fine as it is.

As far as the PMD goes, I use the DTECH only. For years Stanadyne knew they had issues with the PMD and never fixed the issue.
Now after all this time they come up with a new design, but only after someone else made a better one (DTECH)

Use the DTECH and it works with your original wiring.

I see you have a cooler on the manifold. Get a 5-6 FOOT extension cable and mount that cooler down under the front as I described above.

Keep us posted

Robyn

[Platina Cruiser]

Hello once again.

I have an update.

Yesterday my trusted mechanic gave the guys from Stanadyne a call. They said that the problem isn't the heat. They say that problem is that the connectors 'corrode' away and that you get a bad contact like so. They also said that with the new grey box problems are solved because of gold plated connectors.

What a load of crap. I am no mechanic but everybody knows that a hot place isn't a good location for electronics. You can't even touch the module because of the heath.



The annoying thing to me is that Ido not live in the US. So it very hard for me to get something other then what is offered by Stanadyne. I know that a lot of company's are willing to ship to my place. But that has some disadvantages like shipping costs (least annoying), delay in delivery, added cost by customs authorities, warranty issues, ...

I think I have no other option then to buy the new grey module from Stanadyne and mount it on the same location as the black one now. I think this could be a good place because:
- there is a gap between manifold an alumium block allowing hot air to go between. Thus preventing the build up of heat on the underside.
- it is the module that creates the heat. It isn't the engine that is heating up the module in that specific place.
- fan moves a little air over that place.

However; I will certainly make some improvements.
1) On the alumium block that is present now I want to a add a big cooling fin / heat sink. Can I just add it on this alu block or would that be a problem. I would like to use the biggest cooler I can fit on it.
2) I would like to mount a small ventilator on it to suck air over it so that it can cool beter.

Regarding the new grey module. I have seen that there are different connectors between old and new. Does anybody know if the kit includes some sort of conversion adapter?

Thanks

[Robyn]

Many of the vendors here will likely ship to you.

Ebay normally will have listings for the DTECH PMDs as well as finned coolers and extension cables.

Many ebay sellers will ship worldwide to your door.

Give these a look.

The PMD needs to be out from under the hood and on a finned cooler that can disipate the heat.

Robyn

[WelderSki]

While I'm fairly new here, and only been aware of 6.5 turbo diesel Injector pump & PMD problems since obtaining my '94 Chevy Suburban, this past August. I made the effort, like every 6.5 turbo engine owner, to understand the workings of their trucks. I did so the first night after driving it home, and getting on the computer to learn as much as I could, even before the PMD started acting up, and I had stalling problems weeks later too.

First let me say, that's a pretty nice Chevy you have there. I'm glad you held on to it, I would of done like wise if it had been my Dad's also.

From your pictures, of the remotely mounted PMD, I would suggest, taking the Aluminum block (heatsink) off, and take it to a local Machine Shop, and have the mill, in 1/4" wide slots, 1-1/8" deep, on the top side between the PMD bolt holes, cut from front to rear, leaving .125" thick fins for cooling, I'm basing that from the picture, and guess of an 1-1/2" thick aluminum block used, would leave a thickness of 3/8" to bolt the PMD to.
From what I've learned about the PMD's online, all the after market producers of relocation kits, say to use grade 5 bolts, torqued to 23 in. lbs, this leads me to the fact that a #10-32 requires 23 in. lbs. and is not a grade 5 machine screw.
I also learned that the owner of SSDiesel, was first to produce a relocation heatsink for the PMD/FSD's and all the others followed suite.

Some diesel machanics, even produced kits to mount the PMD's behind the front bumper, using a 65" to 76" long wiring harness, which adds to the resistance of the current from the ECM, which affects the transistors in the PMD even more, the two 500 watt transistors in the PMD, were by design of Stanadyne's Engineers, choosen for two functions, one to increase the weak signal from the ECM, to a voltage the solenoid needed to actuate the plunger in three positions within the function of the Injector pump. and secondly to heat the side (heavy boss/wall [heatsink] on the side of the pump, to pre-heat the diesel fuel for cold starts. ( One of the threads in this forum, someone found a web site that offered an Army Tech manual, on the 6.5 turbo diesel engins, that had complete tear down and rebuid of the IP, plus Testing and Calibration of same.) I down loaded it, it's a good read! And I learned a little more, than I knew two months ago. One thing was, during calibration after a rebuild, a pump being bolted to the test stand, and all fuel lines bled and connected, the pump was run at 2200 rpms for twenty minutes to warm the fuel, before any adjustments were made. The heat being provided only from the PMD's transistors.

Well son of a gun! Maybe the Engineers at Stanadyne designed it that way, only half the power of the PMD's transistors are required to boost the current for the solenoid to work. Let's think about this for a moment, when the trucks were new in 1994, there were no PMD problems at first, maybe around 50,000 miles, one would go bad!

Or did it? How many times when a truck is serviced, are the four screws to the PMD checked for tightness? Once loosened from 2500 rpms of engine vibrations, will the thermal compound grease be displaced? And not replaced by the service mechanic, because he just did the normal checks, or was hunting down a rattle you heard, after he changed the oil. ??
What about them GM quick-disconnects electrical plugs? How many times have you seen a mechanic, plug and un-plug one to brighten up the connections. ( Stanadyne's new Bullet Proof one has gold pins!) Even they may need to be checked now and again!
I remember a time before the quick-disconnects, when I was about 16 years old, my Dad a master mechanic at the time, was working on our car, checking wires to find a problem, when he pulled a connection full of corrosion and had me run into the house for three or four books of matches, I could not figure out why he wanted them, only to see him tear off the striker strip, and use them to brighten up the brass connectors, attach them and the car started right up, he then wrapped the connection in friction tape ! Who sells that any more?

Whats the Oil pressure switch got to do with the IP or PMD? Well it's in the electrical circuit with the frame fuel lift pump, connected to the lift pump relay, so when and if the engine lost or was low on oil, it would shut off the lift pump, stopping the flow of cooling fuel in the Injector pump that cools the PMD, whereby the PMD overheats and shuts off the IP solenoid, which informs the ECM of low fuel pressure, and the ECM, sends a signal to the Fuel Shut Off solenoid and the engine stalls to prevent a high RPM hunting condition.

One other thing to consider, is since 1997 the U.S. EPA, had determined that we are polluting the atmosphere, and ordered all sulfer be removed from Diesel Fuel, that same Sulfer kept the Optical sensor and internals of the Injector pump working better by the lubrication factor of sulfer, so use a fuel additive with every top off of the fuel tank. Why wait to an eighth of a tank to top off, when under the right climate conditions, water droplets form inside the fuel tank, just waiting to be sucked up and stop a Diesel in it's tracks.

When Stanadyne first produced the DB-4 (DS-4) IP, they told GM's engineers, the IP would work better if not in the engine valley, but a little higher up on the engine, GM needed the service work then, how they needed a bail-out is beyond my understanding, my Grandkids and their children will be paying for that for a long time, after I'm gone.

Which reminds me, my Suburban must be done at the Chevy Dealer, I gotta give them a call to see how much it's going to cost me now!

See Ya All later!

Semper Fi !
Ski
;)

[Platina Cruiser]

... ( One of the threads in this forum, someone found a web site that offered an Army Tech manual, on the 6.5 turbo diesel engins, that had complete tear down and rebuid of the IP, plus Testing and Calibration of same.) I down loaded it, it's a good read! ...

I am going to search the website for this manual.

Thank you for your explanation.

If I understand the part about relocation of the PMD behind the front bumper, then this too isn't a good choice for relocation? Seeing that the extra length of cables gives more resistance resulting in more heat. Or am I wrong in this deduction?

Where have you put your PMD?

I am also going to search the forum for engine bay pictures. Maybe you could post one of yours?

[Platina Cruiser]

I have just come across this link: http://www.dieselplace.com/forum/showthread.php?t=39436

The thing that worries me is:
"Locations best to worst:
1. Remote mount out of engine bay heat
2. Leave it on the pump
3. Mount over the intake on a heat sink.

Notice that #3 is last place, with #2 ahead of it. Pump mounting gives you liquid cooling. The point of failure there, is off-cycle, no liquid is cooling it.
"

Here it is suggested that the PMD mounted on the IP gets cooled from passing diesel fuel.

I haven't got a clue anymore.

Is mounting the PMD inside the engine bay with a cooler a sufficient measure or does it really have to go outside of the engine bay? What is the most common practice?

[More Power]

I also learned that the owner of SSDiesel, was first to produce a relocation heatsink for the PMD/FSD's and all the others followed suite.;)

Actually, Walt at SS was one of the very last vendors to offer these PMD relocation kits. He learned and followed what others had done. He was once a subscriber here at The Diesel Page, so he learned more about the 6.5 from our published product reviews and technical articles.

Heath and a few GM dealer diesel mechanics I spoke with were perhaps the first to remote mount the PMD sometime before 2000, but BETA was the very first vendor to offer a commercial PMD relocation kit (called the "FSD Cooler") in early 2000. We (The Diesel Page) discussed PMD relocation in the late 1990's and we produced a product review for the BETA kit in early 2000. We've also reviewed the Heath unit in years past. ;)

Jim

[a5150nut]

Hello once again.



I think I have no other option then to buy the new grey module from Stanadyne and mount it on the same location as the black one now. I think this could be a good place because:
- there is a gap between manifold an alumium block allowing hot air to go between. Thus preventing the build up of heat on the underside.
- it is the module that creates the heat. It isn't the engine that is heating up the module in that specific place.
- fan moves a little air over that place.

However; I will certainly make some improvements.
1) On the alumium block that is present now I want to a add a big cooling fin / heat sink. Can I just add it on this alu block or would that be a problem. I would like to use the biggest cooler I can fit on it.
2) I would like to mount a small ventilator on it to suck air over it so that it can cool beter.

Regarding the new grey module. I have seen that there are different connectors between old and new. Does anybody know if the kit includes some sort of conversion adapter?

Thanks

While the engine is running it is hot air flowing over everything. It is when you stop, "Heat Soak". All that radiant heat trapped under the hood. You need to get it out from where it is.

You can make the cable your self. Solder the connections and use heat shrink tubing to seal. Match wire size. Some like mounting on the skid plate, I have mine in front of the left battery. There is a hole in the panel that lets fresh air in and the battery shields it from most of the radiant heat.

Good luck

[Platina Cruiser]

@ a5150nut:

Do you still have a heat sink on your PMD? Or do you not need it there?

Do you have a picture of it?

[a5150nut]

Yes I have a heat sink. I will see if I can get a picture this evening.

[bwonderlich]

@ a5150nut:

Do you still have a heat sink on your PMD? Or do you not need it there?

Do you have a picture of it?


With heat sinks surface area is more important than mass.
In other words a light weight finned heatsink would be better than the big block of aluminum.
If you want to scrounge around you might be able to find discarded electronics equipment with heat sinks you could re-purpose.
Things like computer power supplies, high power car or home stereo equipment are examples that might have heat sinks you could adapt.
Also if you can mount it such that natural convection will help airflow across the fins that would be desirable as well.
If you can find the white thermal conductive grease to put between the PMD and the heatsink that couldn't hurt either.

[DmaxMaverick]

If you need a heatsink, you didn't look very far.....We have a member GIVING them away in the Class Ad Forum (http://www.thedieselpageforums.com/tdpforum/showthread.php?t=35512). Better speak up before they are gone.....

[Yesterday]

Regarding the new gray PMD from Stanadyne, mine came with the new
cable required to connect.

Hope this helps..

Duane

[Platina Cruiser]

If you need a heatsink, you didn't look very far.....We have a member GIVING them away in the Class Ad Forum (http://www.thedieselpageforums.com/tdpforum/showthread.php?t=35512). Better speak up before they are gone.....
Thank you for the link. I've contacted him.

Regarding the new gray PMD from Stanadyne, mine came with the new
cable required to connect.

Hope this helps..

Duane
Ok, that is usefull help.

[Dimsdale]

I last replaced my FSD about 4.5 years ago and nearly 100K miles traveled. After several of the typical FSD failures, including relocating on the FSD Cooler on the intake manifold, I bought and extension cable and relocated the FSD/Cooler combination on a homemade bracket behind the front air dam.

I haven't had to think about it once since then. As it should be.

[Platina Cruiser]

Thanks for the input I've received here.

So far I have put a heat sink on the aluminium block. A new PMD is ordered.

I'm also thinking about removing the insulation from the underside of the hood. Would that be any good? How is it fixed? Glue or just the little plastic things you can see?

[a5150nut]

I'm also thinking about removing the insulation from the underside of the hood. Would that be any good? How is it fixed? Glue or just the little plastic things you can see?

It will be a lot noisier! That insulation is more for sound than heat.

[Platina Cruiser]

I forgot to mention that last week (or has it been 2 weeks already?) I have cleared out the codes of the truck. Today I have scanned for new codes,and found this one: DTC 78 - Turbo Wastegate Solenoid. What does this mean?

I scanned for codes using the tech tip from KennedyDiesel.

[Robyn]

Wastegate solenoids can and do fail.

I would check the connections first and retry but I would bet a new solenoid (little device with a wire hookup and vacuum hoses on the LH VC towards the rear of the engine) will solve the troubles.

These little critters fail and cause the 78

Make sure your vacuum pump is working 26" HG at the pump and about 20"HG at the wategate actuator (on the turbo)

Keep us posted

Missy

[Platina Cruiser]

thanks for your reply.

Could you explain me what the wastegate is?

And one more noob-questions. Where can I find the vacuum pump?

THX