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Thread: Fuel Leak 6.5 TD HELP

  1. #1
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    Default 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.

  2. #2
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    Hi
    The first thing you need to tell everyone is what truck you have.
    Year,trans,model and any modifications done.
    90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews

  3. #3
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    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.
    The Constitution needs to be re-read, not re-written!

    If you can't handle Dr. Seuss, how will you handle real life?

    Current oil burners: MB GLK250 BlueTEC, John Deere X758
    New ride: MB GLS450 - most stately
    Gone but not forgotten: '87 F350 7.3, '93 C2500 6.5, '95 K2500 6.5, '06 K2500HD 6.6, '90 MB 350SDL, Kubota 7510

  4. #4
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    Default Same issue here

    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.
    1994 K2500 ext cab. Recently repowered with; Non-cracked 599 block, factory compression, used old DSG girdle for main caps. Factory for what remains. Changed diffs to 3.42. Fuel economy Hwy 22.5 mpg US, in town without lcokup in 2nd/3rd - 18 mpg US.
    1994 K3500 CC LB Silverado. Next project. Built for endurance, power and gearing. Plan on opened up intake and exhaust sytem, best cooling mods, 4.11 gearing 4L80E, followed by Gear Vendors OD. Need to be able to split all gears and have lockup in 2nd/3rd/4th. Tan interior cloth, Bad ass dark blue (coming) aluminum wheels and air ride (coming)

  5. #5
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    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

  6. #6
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    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..
    Last edited by Robyn; 07-03-2019 at 07:52.
    (1) 1995 Suburban 2500 4x4
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  7. #7
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    Quote Originally Posted by Robyn View Post
    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.

  8. #8
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    Quote Originally Posted by Bully44 View Post
    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.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  9. #9
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    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?

  10. #10
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    Where does the fuel seem to be coming from ???

    With the intake off you should be able to spot the leak right off.
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
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  11. #11
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    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

  12. #12
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    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.
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  13. #13
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    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!
    '94 GMC 6.5TD K1500 4L80E 2-Door Yukon SLE 221K
    '93 Chevrolet 6.5TD K2500HD NV4500 Std. Cab Longbed 187K
    '85 Toyota 22R RN60 4x4 Std. Cab Shortbed 178K (Currently retired for rebuild)
    Diesel Page Member #2423

  14. #14
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    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.
    (1) 1995 Suburban 2500 4x4
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  15. #15
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    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?

  16. #16
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    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"
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
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    THIS IS BOW TIE COUNTRY

  17. #17
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    Thank you! I will take a look when I get out of work and let you know!

  18. #18
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    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.
    1985 Blazer 6.2
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  19. #19
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    Quote Originally Posted by Robyn View Post
    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......
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  20. #20
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    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


    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.
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

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