# F250 7.3L diesel leak (under hood)



## cabosandinh (Jun 7, 2007)

I have a diesel leak somewhere inside my motor compartment but I can't 
seem to locate it. I did change the fuel filter recently (from Autozone) ,
this filter has the integrated black cap and separate O-ring, I suspect
this might be the problem. I did see a small puddle of diesel on top of
the engine and wet spots under the vehicle after I park the truck.
If you have ran into this problem before or have some pointers I'd like
to hear them. Thanks.


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## skypoke (Jul 14, 2005)

Cabo, 

Most likely it's the o-rings in the drain valve on the filter. This problem typically shows up during cold weather. Try working the valve open and closed a couple times for a temp fix. Ford sells a o-ring kit to address this very problem, it's around 40.00. You can also buy the viton o-rings for about a buck if you know the right size. That info is on dieselstop.com

Chuck


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## bwguardian (Aug 30, 2005)

That drain valve is kind of a pain to get to. You can take the four torque set screws out and flip the two o-rings over for a quick fix. I bought some o-rings at Home Depot to fix mine for about 25 cents 4 years ago and they are still holding up...even with the bio diesel I have been running in it for the last 3 years. I also got a big heavy duty o-ring for the fuel filter cap 3 years ago that gets reused upon filter change and have no problems...I hate those little o-rings they give you and when your cap warps, they just will not seal.


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## jeffsfishin (Jan 27, 2008)

*Diesel leak*

If the diesel is collecting on the back of the intake manifold and dripping to the ground from there, there is a good chance that the upper fuel pump is leaking from the weep hole, indicating a bad fuel pump.


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## bwguardian (Aug 30, 2005)

jeffsfishin said:


> If the diesel is collecting on the back of the intake manifold and dripping to the ground from there, there is a good chance that the upper fuel pump is leaking from the weep hole, indicating a bad fuel pump.


You bring up a good point...what you indicate happens on the old body style 1994-1998 and what everyone else (including myself) is giving reccomendations on is a Superduty 1999-2003...greenie to you for that.


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## bwguardian (Aug 30, 2005)

cabosandinh said:


> I have a diesel leak somewhere inside my motor compartment but I can't
> seem to locate it. I did change the fuel filter recently (from Autozone) ,
> this filter has the integrated black cap and separate O-ring, I suspect
> this might be the problem. I did see a small puddle of diesel on top of
> ...


What year is the truck?


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## cabosandinh (Jun 7, 2007)

bwguardian,

truck is an 02 Crew 4x4

Skypoke, I think you're on to something, I went ahead
and ordered 10prs of o-rings from amazon

o-ring size: #202, polyurethane
1/4" ID x 1/2" OD x 1/8" W

if replacing o-rings won't fix then I know to look at the pump
like jeffs said

thank you , guys!


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## Team S.A. Blue (Sep 8, 2004)

I changed my fuel filter once and there was a wire that kept getting under the back of the filter cover causing the o-ring not to seat right. I took the cap off 6 times before i found the problem.


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## bwguardian (Aug 30, 2005)

cabosandinh said:


> bwguardian,
> 
> truck is an 02 Crew 4x4
> 
> ...


If it is an 02 you do not have the lift (fuel) pump like jeffs says...what he is suggesting is for an old body style like I stated above. Your fuel pump is electrical, not mechanical and located under the drivers side front seat on the inside of the frame rail.


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## Bull Fish (Nov 15, 2006)

Some of the early 02's did have the "low volume high pressurepumps" I do not know the exact date or S/N that they stoped useing them but I changed one for my a coworkers FIL a few Months ago on his 02. I could be mistaken on the year but I belive it was an 02. Just look under the Turbo if there is a pump attached to the filter houseing that has a line that runs around to the rear of both heads than that very well could be the problem. If you are going to replace the o-rings on the drain I would strongly suggest that you pull the canister and replace all of them while you are at it. Because trust me you won't want to do it more than once.

Also if you have it out, remove the center plastic post in the housing ( 7/8 left handed thread) and inspect the botton of the housong. If you have had any kind of water (even if the light didn't gcome on) sit in the bottom mixed with fuel it will create sulfuric acid that will eat small wholes in the houseing. ( That is what happened to mine) If there are any holes in the housong find someone that works ina maintinance shop and get some Belzona. Fill the pitts and coat the inside. It will save you around $600 versus a new housing. Pm me if you have any questions


bwguardian said:


> If it is an 02 you do not have the lift (fuel) pump like jeffs says...what he is suggesting is for an old body style like I stated above. Your fuel pump is electrical, not mechanical and located under the drivers side front seat on the inside of the frame rail.


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## bwguardian (Aug 30, 2005)

Bull Fish said:


> Some of the early 02's did have the "low volume high pressurepumps" I do not know the exact date or S/N that they stoped useing them but I changed one for my a coworkers FIL a few Months ago on his 02. I could be mistaken on the year but I belive it was an 02. Just look under the Turbo if there is a pump attached to the filter houseing that has a line that runs around to the rear of both heads than that very well could be the problem.


You are thinking of the early 99's...the engines were the same from late 99 to early 03.


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## cabosandinh (Jun 7, 2007)

It took me 2.5 hrs this morning to replace the O-rings but it was
worth it.
Most of the time spent was moving wires and harnesses out of 
the way, which was neccessary to get the torx bit in the tight
space.
No really good way to do this so I placed a bunch of old towels
on top of battery, alternator etc... and just sat on top of 'stuff'
The old o-rings were flat and had hair line cracks in one of them.

thanks for the info gentlemen!


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## CaptainJMB (Nov 28, 2008)

Theres a little yellow pet-cock on the bottom side of the fuel filter housing, I used to drain the filter before I changed it and have forgotten to close that all the way ....maybe not what it is but something to check for in the future


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## Clark08 (Mar 4, 2008)

I had a leak just like that and it was after i changed my filter.What had happened was the o ring had gotten crimped,my thought it was too dry when it was installed.so i got a new o-ring and put it on myself..It still leaked an then figured out it wasn't tight enough..the trick is there is a place on top that you can use a tool for leaverage and you have to tighten the **** out of it.It feels like you are gonna break it but the way the plastic is designed it can take it.Hope that solves it!


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