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Help?! Fuel Leaking from Valve Cover

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15K views 9 replies 7 participants last post by  JMJNet  
#1 · (Edited)
Did a search and couldn't find much.

I have fuel leaking from the drivers side valve cover gasket. I filled out the diagnostic checklist to the best of my knowlege. I've owned this truck for a little over a year. I believe the air filter setup isn't stock, but that's all I know about as far as modifications.

I use the truck to tow my race car. I have a race in about a month which I still have to prepare for (don't store the car at home). I'm trying to decide if I should try to tackle this myself or take it to the dealer down the street. They have surprisingly decent rates and are the best diesel mechanics I've had experience with in this area. I'm also not the most mechanically knowledgeable person.

1. Describe the problem you are having in detail: Fuel is leaking from the D.S. valve cover gasket. It's coming out at the lower rear corner.

2. Year of truck/engine. 1996
3. Odometer reading (indicate miles or kilometers). 159,200
4. Indicate the model number on the Injection pump (starts DS4 or DB2......). ???
5. Indicate if you know if it’s a 1500, 2500, 2500HD, 3500, 3500HD. C2500 2WD
6. Do you have an EGR on the engine? (An F or an S engine code 8th VIN digit) F
7. Air Filter condition (visual check). Good
8. Fuel filter condition (freshly changed, mileage since changed). No idea
9. Location of PMD/FSD? (ex. on pump/remote over intake, behind bumper). ???
9a. If remote mounted, describe wiring harness (homemade or purchased from which vendor). ???
9b. Indicate the location and condition of the FSD/IP grounding wire. ???
10. Outside Temperature (C or F). __70_ °

11. Service Engine Light while running?- on/off/intermittent
11a. Service Engine light does glow during start/cranking/bulb check: Yes/No
12.Have you scanned for engine codes? Yes/No
12a. List exact results on engine codes.

13. Condition of Battery terminals (removed, cleaned and tightened).
14. Known condition and age of Batteries. <5 years old
14a. Are batteries a matched set of same age? Probably
15. Condition of Major Grounds (removed, cleaned and tightened)

16. Does engine crank, or "turn over"? Yes
16a. Does engine start and run? Yes
17. If engine does not start- Crack injector line: do you have fuel? Yes/No
18. Does your Wait To Start light come on? Yes
18a.Number of seconds WTS light is lit. On and off for 20 seconds
19. Engine Cranking speed (if you have an accurate tachometer). ~500rpm

20. Are you experiencing Stalling? No
20a. Describe the event (upon startup only, down the road, hit a bump, etc...) Fuel leaks while engine is running
20b. Do you notice loss of dash or instruments? No
21. Check turbo inlet and air filter for obstructions.
22. In a no-hot start, pour a bottle of room-temp water on the injection pump. Does it start now?
23. Lift pump test - Describe results.

24. Upon cold start, does the radiator hose get hard quickly? Yes/No
25. Upon cold start, do you have excessive white smoke? Yes/No
26. Do you have excessive cranking time before the engine starts? Yes/No, when the air temp is below 50 degrees F, otherwise no
27. Have you used the block heater? Does it affect engine starting? (only try for starting problems). I have not
28. Are all glow plugs in proper working order?

29. During hard acceleration, do you have excessive black smoke? Yes/No
30. Do you have any unusual exhaust smoke issues? White smoke upon startup, regardless of outside temperature
31. Turbo check out - Pass/Fail
32. Indicate fuel that you are using: Bio-Diesel, #2 Diesel, SVO/WVO, other Pump diesel fuel
32a. If running Veggie Oil fuel setup, indicate details of your conversion (homemade or packaged system).
33. Are you using any fuel additives? If so, please list. No
34. Upon unscrewing fuel cap, do you have a large vacuum formed in the tank? Yes/No
35. Do you have any service history available that might pertain to the problem you are having? Unfortunately not
36. Please indicate any modifications to the vehicle that might help us diagnose better. ???
 
#2 ·
Check the small bleed return lines that run from injector to injector for leaks. An injector could also be leaking & spraying the fuel onto the valve cover.

The other candidate is the fuel filter housing is dripping from the heater or water in fuel sensor running under the intake manifold & appearing like it's coming from the valve cover
 
#5 ·
Check the small bleed return lines that run from injector to injector for leaks.
This would be where I'd put my vote. These little return lines dry out and crack with age and a leak...quite a quantity, at that, if the hole is big enough.

A small hole may allow a pinhole sized stream to spray up onto the valve covers which then drips back down.
 
#3 ·
It is not coming from inside the cover, if it is fuel. Chances are it drips in that direction.

In addition to Crankme suggestion, check the fuel filter bowl, there are 3 hoses and 2 o-ring that can cause a big leak. Problem is they are buried under and behind the manifold.
 
#4 ·
I've read one or two members have forgotten to tighten the injector lines down tight causing them to seep. I had that problem with the O ring being dry rotted from sitting.
 
#7 ·
Hey guys, thanks for the advice. I ended up bringing it to the dealer because I was in a time crunch and didn't have the time to mess around. It turned out to be one of the fuel return lines. As I and ya'll suspected, it wasn't coming from the valve cover (fuel doesn't leak from a valve cover). The fuel was leaking onto the valve cover and the exhaust manifold, making it appear that the fuel was coming from the under the cover. Hopefully this helps someone else in the future.
 
#10 ·
That is a very logical explanation. That rubber lines may leak overtime. Another popular fuel leak place is the o-ring for fuel heater under the filter housing and the fuel hoses under the intake.
 
#8 ·
I recommend that you pick up 3-4 feet of Tygon 5/32" hose (the stuff specifically for diesel and gasoline). I replaced all of my return lines with that hose. Much more durable, and easy to identify if they are leaking. It doesn't take but 30 minutes to run new return lines.

~Will Courtier~
 
#9 · (Edited)
Drew,

Where in CT are you?

If you ever need your truck looked at I'm in the south-eastern area of CT, and while I'm not one to blow my own horn, i will offer what tools and knowledge i have when it comes to the 6.2 and 6.5.