View Full Version : Fuel Leak 6.5 TD HELP
Hey Guys,
I am new to this site as well as Diesels in general so I am hoping for some help. I bought a 6.5 TD a few months back from an asphalting company that had it sitting for the past 2 years. It has 171,xxx miles. Now i put in a new batteries, new glow plugs and glow plug relay. I had it running but I noticed a lot of oil on the Turbo. So I put in a refurbished turbo in and then it wouldn't start. Fuel started to leak somewhere out of the rear block. took off the intake and there was no fuel sitting in the valley. There is also no fuel to the injectors. I swapped out the fuel filter and still the same issue. Please help!! I do not know what else to do.
Yukon6.2
07-02-2019, 09:56
Hi
The first thing you need to tell everyone is what truck you have.
Year,trans,model and any modifications done.
What he said, and, look for two short rubber hoses at the rear of the valley where the fuel lines duck down behind the firewall along the top of the bell housing.
jggiedeman
07-02-2019, 20:18
I just pulled those two short pieces off. They were definitely not made for diesel fuel. I made some brass barbs to install in short pieces of the cloth covered hose and viola - no more leaks.
Seems the rubber that was used did not hold up past a year. The small clamps actually cut into the rubber.
Wow I am an idiot. Sorry, I have a 1998 GMC c3500 with the 6.5 TD. I have not done any mods because I am still trying to get it to a dependable state. I do not know what trans. However, I have already checked those two rubber hoses and it does not seem like they are in bad shape
Run your hand down under the fuel filter/manager
My bet is it will be wet with fuel.
There is a drain hole in the rear of the valley...fuel will run out and then out on the ground.
The fuel managers are notorious for rotting out from having water in them.
I like the Racor 230R2 filter.
Has a water bowl you can see wasssssup and a drain.
2 micron filter...will keep the DS4 happy and pass plenty of fuel.
Easily mounted up front by the ABS unit on a custom L bracket.....Use a barb and connect the hoses to extend them up front....secure well to AVOID chafing.
Remove old filter and toss it...go find it and toss farther..
Remove the water drain hose that lays in the valley.
Check it out and let us know what you find...
The other possibility is a leaking Plug on one of the rear injectors (Rubber cap plug on the end nipple of the rear two injectors) these usually spray fuel all over if they leak..
Run your hand down under the fuel filter/manager
My bet is it will be wet with fuel.
There is a drain hole in the rear of the valley...fuel will run out and then out on the ground.
The fuel managers are notorious for rotting out from having water in them.
I like the Racor 230R2 filter.
Has a water bowl you can see wasssssup and a drain.
2 micron filter...will keep the DS4 happy and pass plenty of fuel.
Easily mounted up front by the ABS unit on a custom L bracket.....Use a barb and connect the hoses to extend them up front....secure well to AVOID chafing.
Remove old filter and toss it...go find it and toss farther..
Remove the water drain hose that lays in the valley.
Check it out and let us know what you find...
The other possibility is a leaking Plug on one of the rear injectors (Rubber cap plug on the end nipple of the rear two injectors) these usually spray fuel all over if they leak..
I do not believe any of the injectors are leaking. It is a slow leak straight to the floor that only happens after i introduce pressure into the system (Turn the key).
I do not know what you mean by water drain hose as I have only seen 2 rubber hoses in the valley connecting the filter to the IP.
Lastly, when you say custom L bracket, is it easy to make? Or is there already one out there?
Thank you! This does sound like the issue especially since this truck was sitting so long, would have been easy for any sitting water to rot it away.
DmaxMaverick
07-03-2019, 09:36
I do not believe any of the injectors are leaking. It is a slow leak straight to the floor that only happens after i introduce pressure into the system (Turn the key).
I do not know what you mean by water drain hose as I have only seen 2 rubber hoses in the valley connecting the filter to the IP.
2 hoses. One to the IP inlet. One to the thermostat housing, which is the T-valve, fuel filter water drain (from the bottom end of the filter manager).
Lastly, when you say custom L bracket, is it easy to make? Or is there already one out there?
Thank you! This does sound like the issue especially since this truck was sitting so long, would have been easy for any sitting water to rot it away.
Simple bracket, used to mount the filter assy to a vertical or horizontal mounting surface (or anywhere in between). Dozens of options likely available from your filter assy source, ebay, etc. It only has to fit the filter assy, and go between the assy and the mounting surface of your choosing. Use heavy duty lines, preferably with nylon braided covering (these prevent external damage and abrasion, which causes leaks).
The filter manager can deteriorate in a couple ways, one is the heater element potting, or the metal around it. Of course, rubber hoses and barbs are always suspect. The filter manager is just as likely to leak from failure inside out, as outside in. New or like-new FM100 assys (the OEM) are available, as are aftermarket filter assys, as Robyn said, and costs are similar. No adjustment needed for fitment. Jury's still out as to which is actually best. Racor makes good stuff. A visible water separator is a better option than the (unreliable) water sensors, IMO. A heated filter assy is important, so don't try to save money omitting that, even if you don't think you need one.
Ok I replaced the FM as well as the hoses that go to it. I put everything else back together besides the intake on top and it is still leaking! Any other suggestions?
Where does the fuel seem to be coming from ???
With the intake off you should be able to spot the leak right off.
It is somewhere around the back of the block. I cannot see it because there is only a few inches between the block and the cab. If I could see it I wouldnt have posted lol
Has to be the pressure fuel line coming up the rear of the engine (Across the top of the bell housing) and to the filter housing.
That line from the filter is metal part of the way and then rubber to the filter.
These can and do go bad.
trbankii
07-26-2019, 03:17
I just replaced these lines (supply and return) last year from the fuel manager back to the tank on my '93. Pulling them out, I'm surprised that I was getting any fuel at all for as long as I did - the literally crumbled in my hands.
The downside is getting to them. I did it without dropping the transmission, but it was a bear and a half!
The last one I did I replaced the lines from the electric pump up to the engine bay.
I rerouted the lines forward on the frame rail (Drivers side) and up into the engine bay.
I installed the aforementioned RACOR FILTER up by the ABS module and ran the fuel lines along the inner fender behind the ABS
The return line I ran across the firewall and to the engines return line. (Hard line on RH side that terminates by the factory filter.
The factory lines have a clamp that holds them to one of the stud top bolts in the top of the bell housing.
On that rig getting the lines out were a beotch... but after getting the old filter out I was able to remove the nut holding the clamp and then with some brute force, rip the old lines out.
I used the old metal portion of the line near the pump and added a ferrule fitting to it to provide a good retainer for the heavy duty fuel line and clamped the hose behind the ferrule.
Just leave the ferrule nut after tightening it to crimp... remove the fitting and your golden.
Be sure to fasten the new hose well along the frame rail and in the engine bay.
Jump the fuel feed hose across from the new filter to the Inlet on the IP
All the other old hoses are no longer needed (Ones in the valley)
A good fix..
The engineers gave zero thought to the PITA that replacing the lines is after the body is on the truck.
So I have rerouted the fuel lines, changed out the fuel manager, and I still have a leak! It is still coming down the passenger side down the starter. I am about to just throw this truck out in the yard with a for sale sign on it. Any other ideas?
Hi
YOU LIKELY have a leak at the rear injector on the little rubber plug that caps the rear injectors rear most nipple...
Or one of the rubber lines that daisychains the injectors together to feed return fuel back up the the return line up top.
Not at all a biggy.
You can get a complete hose kit for the injector return lines...
Not at all a spendy item.
ebay has the kits..."6.5 diesel injector fuel return hose kits"
Thank you! I will take a look when I get out of work and let you know!
DmaxMaverick
09-23-2019, 12:01
It has to be something simple you're missing. The only thing (in OEM trim) that can leak fuel down the block and onto the starter, is the rear injector(s). If it isn't missing, it isn't likely a fuel injector line. That leaves the return lines, and the termination cap on the rear injector. The location of the turbo and heat shield makes the area one of the most neglected on the truck. Oftentimes, a glow plug service will omit #6 and #8, just to save time and knuckle hide. It's also possible a return line under there was dislodged or damaged during the turbo replacement. It wouldn't be a first.
Stupid question, but are you SURE it is fuel that's leaking? The tranny dipstick tube is right there, and it wouldn't be the first time if ATF were to leak from it. Perhaps a pinhole near the mounting tab weld or corrosion? A minor leak of ATF along the block is almost indistinguishable from fuel. Catch some drops on a white paper towel and check the color. If you're running red or off-highway fuel, or blue ATF, only a smell or lab test may show the difference.
Lastly, and certainly the most common, may be valve cover leakage at the rear corner. Again, be absolutely sure of the fluid leaking. Get that wrong, and you'll be talking to the wrong end of the horse all day.
DmaxMaverick
09-23-2019, 12:03
Hi
YOU LIKELY have a leak at the rear injector on the little rubber plug that caps the rear injectors rear most nipple...
Once again, great minds......:D
Been there DONE THAT.
What sucks is when the plug leaks enough to catch fire..
THE FAN HOWLING AWAY MAKES FOR A VERY VERY INTERESTING TIME AND HOT DOG ROAST
:eek::eek:
Get in there and remove the sheet metal cover over the injectors.
Start the engine and my bet is it will be very obvious whats leaking.
one of the hoses or the rear injector nipple cap.
JUST AN FYI
Jack up the rig
Remove RIGHT FRONT TIRE/WHEEL
Block rig
Remove inner rubber fender splash shield
All the glow plugs accept #8 are easily accessed
Starter support hook and wires are easily accessed to.
Sit on your butt on a bucket and work on the stuff.
Okay guys, I looked at the nipples and the return lines and nothing! I'm going insane! I have attached a photo of the leak and the best I could do about the color. Maybe this helps because if not, I'm taking it to a shop
DmaxMaverick
09-23-2019, 19:59
Holey socks! That's not just a leak. You have a fuel line rupture, somewhere. Likely a line that crosses over the bell housing before it gets to the engine valley area. They can corrode or rub through. The wet starter is a casualty due to the sheer volume, but not where it's coming from. That much fuel flow shouldn't be at all difficult to run down. It's gushing out of somewhere.
As Maverick mentioned.."Fuel feed line"
The fuel line comes up the Drivers side frame rail to the lift pump.... then jumps over to the top of the bell housing and snakes up to the FILTER MANAGER UNIT.
The lines are steel part way and then have a rubber section that connects to the filter unit.
Either the rubber part has ruptured or the steel line has rotted through
What ever the case the line is the pressure line from the lift pump that's leaking that much fuel.
Trying to get a new factory steel/rubber line in there is a nasty job due to the close proximity of the tranny in the body tunnel.
Get the Filter off the engine and out of the way...
Plug the rubber hose that feed it (Fuel delivery) and then run the pump..
Get some serious light into the area so you can see where the leak is.
If the rubber has a hole close to the filter nipple area you may be able to simply cut it off and add an extension with a double barb and a fresh piece of hose..
If the leak is farther down then the easiest plan is to abandon the old line and run a good heavy duty hose from the lift pump up into the engine bay and then to the filter unit...
Cut off the line about 4 inches in front of the lift pump and then using a brass ferrule type fitting ....attach the fitting and tighten it well.
Remove the fitting leaving the ferrule in place... Slide the rubber fuel line over the ferrule and clamp with a stainless clamp.
Tie the new line off well as it ascends up the frame into the engine bay. (Use zip ties)
Make sure the line does not rub on sharp things or touch the exhaust manifold.
Once you get the new line connected to the filter... remove the fuel line from the top of the IP and then activate the lift pump.
Allow fuel pump to purge all air from the line until fuel is air free at the IP fitting (Catch in a coke cup/can or ??)
Connect and secure line.... good to go....
Starting should be easy and NO LEAK.
Ok so I know it has been a few weeks but I am looking at redoing the supply line. However, I am having trouble finding it. The drivers side rail has three lines. Obviously one is for the brakes but there are 2 others. Which one is the supply that I need to snip and reroute?
DmaxMaverick
10-12-2019, 11:35
The line that connects to the fuel lift pump is the supply. The other fuel line is the return to the tank.
Alright I did the line swap and.... the leak is still there!
DieselDavy
10-14-2019, 04:14
Don't give up. This will give you great satisfaction when you do find it. You'll also know a lot more about your truck by the time you find it. Is there a possibility there is a leak in the filter housing and it's finding a way to the back of the valley? I don't know. Robyn, DMax? Any more ideas? Hang in there Bully!
d
trbankii
10-18-2019, 03:13
You swapped the supply line from the tank to the fuel filter? Or swapped another line? What general location are you having a leak?
I swapped the fuel supply line from the lift pump to the Fuel Filter housing. I have also already replaced the Filter Housing with a brand new one. There is no viable leaks on the side around the return lines nor from the top along the back that I can see. It is somewhere over the bell housing. I don't know if there is any sort of gasket or anything back there but I have no idea anymore. I have checked everything that youtubers suggest as well.
Have you replaced the rubber water drain line that goes from the filter housing forward to the water drain valve near the front top of the engine.
That fuel looks to be coming out of the bell housing drain hole.
If you replaced the fuel delivery hose up from the lift pump on the frame...that takes care of the delivery side.
What about the fuel hose from the filter to the top of the injection pump ?????
That much fuel is a huge leak....and there are only a few places that can leak that much.
Check the drain line to the front and the delivery line to the IP...
Either one of these hoses can leak into the valley and then run out the weep hole in the rear of the valley...then it drains out on the ground.
Also check the fuel shut off solenoid on top of the IP...these can leak as well.
All 3 lines going to the fuel filter housing have been replaced. I am able to pick up the housing when it's running and no fuel is leaking from it and it also doesnt look like it's running through the valley wherever it is
One last line.
On the Passenger side under intake is the fuel return line.
This line runs the full length of the engine.
The return lines from the injectors and the IP fuel return connect to this line (Steel)
This is the main fuel return line to the tank
The steel line connects to a rubber hose that then connects to steel above the bell housing (Much the same as the fuel delivery line you replaced already)
The fuel return moves a lot of fuel...hence the large leak
The connection is right behind the oil pump drive unit.
Likely the hose is cracked.
There is a hose clamp that holds the hose to the steel tube..
Never seen one of these leak...very low pressure.
The steel tube is fastened to the rear intake bolt with a tab...If the hose is not the issue the tab may have broken off the tube...
See picture
I'm a little puzzled as to how this problem can drag out so long. If it's not leaking in the valley then it pretty much has to be one of the two lines running up over the bell housing. Doesn't it?
He showed a piccy with the fuel drizzling down over the starter..
Has to be the return line.
Easy fix...
3 1/2 months and 35 posts later...
DieselDavy
10-22-2019, 08:00
This is probably not a vehicle he needs to get by. I know I only get around to working on my "extra" vehicles when all other required jobs are complete. Yea, it's a long time, but I get it! Been there!
Dave
DieselDavy is right. This is not my primary vehicle so it hasnt been that important to fix.
Along with the fuel leak issue, I have been replacing the entire suspension, removing the bed to grind frame and rust proof it, redoing the entire interior, and I just started grinding under the cab.
35 posts yes, but a lot of them are saying the same thing twice or that they agree with someone, a few of me saying "still leaking" after trying a suggestion, and me saying I already tried it. Plus, the leak isn't visible except by the puddles underneath it so ive been blindly trying fixes.
Yes it seems simple, but this is the 9th thing to try along with the other projects within this truck.
I really appreciate everyone's help and all of the good ideas to try. The weekends are really the only time I get to try and get stuff done on it so I will let you know if it fixes it when I get a chance. THANK YOU ALL!
If it's not leaking in the valley then it can only be one of the two lines leading up over the bell housing. Anywhere else is plainly visible, and wouldn't drip off the bell housing. There are two short rubber lines right where the bell housing mates to the engine block. That is where I would look first. If they have already been replaced, then it must be in the hard lines leading up to them.
I posted the picture of the steel return line where it makes the 90 degree turn at the rear of the engine aft of the intake.
The rubber return line comes off the steel line that also comes up the bell housing.
Your leak has to be from that line.
Either the rubber hose portion or the line itself.
That is the only line we have not explored
From the factory both the lines that come up the rear of the engine pass through a sheet metal clip that fastens to one of the top bell housing bolts.
This bolt is a stud top with a locking type nut that holds the hoses secure.
Many times over the passing years the tranny gets yanked out/engine removed.....and depending on the mechanics tending to details the hose retainer gets left off..
These can be/are A PITA to deal with and are often left off.
Left loose these hoses can and will chafe on the bell housing...
Heat and time will also result in the hoses cracking and degrading....hence the leak...
We were wrong! It is not fuel! So I replaced all of the lines and it changed nothing. So I said screw it and continued the restoring efforts of the truck. As I was in the process of upgrading the cooling system, I had to take off the radiator. As soon as I took off the first hose, the leak started all on its own. As in me taking off the hose introduced air into the system and let it leak out! Now to trace those lines and see what is going on. Sorry it has been so long, I have had a tough time finding time to work on the truck.
DieselDavy
03-11-2020, 11:38
Bully,
Thanks for filling us in!
Dave
Since it was red antifreeze, it looked the same color as the fuel. And with it running down from wherever it is coming from, there really isn't a smell to it even though you would think it was easy to tell the difference. Now I think it is one of the steel lines but am still unsure. I took off all of the coolers and the main bracket that supports all of them on the front of the truck and still cant quite see. I am going to try and fill some of the lines tonight and see if any of them make it leak more to narrow down which line.
phantom309
03-15-2020, 08:26
It sure is difficult to diagnose a leak if you don't get some on your fingers and smell it and taste it
Diesel and coolant sure look and smell and taste way different,.
Lotta good experienced people here more than willing to help but only as good as the person being instructed to check and replace parts.
But sometimes its a "magic" leak which can be traced back to not doing basics,..
Apology needed in this case from OP inmho.
Na, it's all my fault. When he posted this picture and said it had no smell, I should have known it was coolant. (too much surface tension for fuel)
Well ya could have fooled me....
My diesel is green. I thought it was atf.
Red fuel is off road fuel.
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