hello guys/gals, you have helped me with my heater grid and hope you can help me again.

i have a slight feul leak at the top of the fuel filter. i replaced the filter and the oring, but it still leaks.

when i replace the filter, the all-thread stud came out with the filter. is there an oring that goes betw the all thread stud and the block?

 

Well there is also a very small O ring that goes between the fuel heater and the block. I don't know if this was an option item, but my 89 had the center fitting come out and the heater came out too. Then I found out that the small o-ring got pinched on the heater when I re-assembled. Pull it down and see if you can see the o-ring for the heater and install it with the stud, tight, before you put on the filter.

I honestly have not looked at my 93 that close as just the filter comes off.

Hope this helps..

J-eh

 

On my 92 when I take the fuel filter off the mounting stud stays on the housing. The fuel filters for the 92 come with two O rings, one the larger one (not square cut) goes on the bottom of the filter, the other one is slightly smaller and is square cut and goes on the mounting stud. From your description it would appear that the early first gen's may be a little different.
---
Al

 

Re reading my post makes it unclear as to what I want to say... >

Well on my 89, there was a fuel heater mounted above the filter, held to the block by the threaded mount for the filter. On the block side of the heater is a very thin (not small) O ring about the diameter of the filter can. It sealed the heater to the block mount. Then the threaded stud held the heater to the block. ALK is right about the two o rings for the filter, but the inner seal wouldn't cause an external leak, but would allow some fuel to bypass the filter.

I am going to have go look now to see what this thing has.. :-

 

my truck is a 91 and the heater element does not come out with the filter stud, at least it hasnt yet.

all i know is that fuel is leaking from atop the filter.

i think that i am just missing a oring. and i know i have both orings properly installed that come with filter.

there has to be another oring on the top side of the filter stud.

 

Just so happens that I saw a fuel mounting stud laying loose on one of the benches in the shop yesterday...
The upper threaded section has a fairly thick, square cut o-ring on it that would engage/seal the stud when it is threaded into the filter mount.
This square cut o-ring is rougly 5/32" thick perhaps a 1/32 more or so and is the exact diameter of the upper threaded portion of the mounting stud....

Does that help ????

Bob.

 

okay, im back, after several weeks of not being able to post for some odd reason. today my truck died and i was more determined to get back to posting so here i am! thanks for everyone's replies. i still have the fuel leak at the filter, its just a drip drip drip thing while the motor is running.

my first idea about another oring being on the upper side of the threaded stud was the wrong idea, because the big oring that comes attached to fuel filter from the manufactor would still keep it from leaking, thanks lil dog for helping see that. it just took it awhile to sink in.

so it must be above the peice that filter seals too, right?

when i get my truck home, i'll look into now that i understand what your trying to say. thanks, oh and check my other post and see if you have any idea's there as well, please! thanks

 

Are you sure it isnt simply the banjo bolt washers leaking and getting air into the system? The first gens have 2 banjo bolts. One ties into the filter block on the firewall side of the filter, the other ties into the outlet side of the filter in front.

Just a FYI....all 12v had the fuel heater mentioned and all will come unthreaded if the filter is put on too tight. The result is when you take it off the next time you will actually uncrew the nipple portion that seals the heater.

 

ok, stupid question, whats a banjo bolt?

your second para is prolly what happened to me, i screwed the filter on too tight and then the next time i took it off the threaded stud came off too.

whats the nipple portion that seals the heater?

 

A banjo bolt is a fluid pass thru bolt. This connects the fuel line to the filter block. There will be a special washer on each side of the bolt. (the washers look like an expansion valve washer) The top three bolts in the picture I have attached show what yours will look like.

The nipple portion that seals the heater is actually the threaded nipple that the fuel filter screw onto.

 

The Cummins part number for the sealing washers off the fuel block: 3963983. You will need 2 per banjo bolt, about .52 each.

Jim

 

monty, thanks for the FYI statement. after reading it, i went outside and took off the fuel filter, removed the threaded stud, and yep, your right the black plastic peice (im guessing is the fuel heater, but i dont know...) came right off.

i think its leaking around the top of it, but i dont know for sure. the top of it is wet.

anyway, i tightened the one banjo bolt that is facing you as you look at the fuel filter, and it seemed to be less than proper torque, but after tightening it i still had a leak. i looked for another line, but its dark outside and i cant see one.

however, i know now that if you say its there, IT HAS TO BE!! so i'll keep looking!

thanks for you help! wish i had my digi cam, i would take some pics rather than describe everything.

tell me more about those sealing washers. does that mean that torque doesnt matter, i have to have new sealing washers for proper seal?

 

Be careful tightening those banjo bolts. Since they are hollow..they can break very easily. Just snug it down and you should be fine. Basically the washers are a steel washer with a teflon coating and seal. Usually you can reuse them unless you have taken them off a couple of times.

Describing the way the fuel heater was loose and how it is wet on top...I betcha a coke its the fuel heater o ring or it isnt as tight as it needs to be.