Ive got a 1989 F350, 6.9L with a 1992 7.3L (don't ask) fuel/water separator/filter.It was leaking out of the top at the heater connection, so I took it off and replaced the two o-rings, but don't think I have the right sizes as it still weeps out of that connection a little bit.
Does anyone know of the *correct* sizes that we are supposed to use?
Actually thats a better water separator setup than the 6.9 had. Nothing wrong with your setup.
Only thing to do is swap the O rings around with different sizes until you get one that holds. Next time you have it apart, take a magnifier glass to the sealing surface of the O ring and look for any signs of a scratch or dirt that might be preventing a proper seal.
Other option is to take it a part, clean everything, and re install with a bit of oil resistant RTV sealant (permatex ultra black for example). Has to be perfectly clean and dry of fuel and solvent the sealant won't bond though.
I had a leak at the filter change prong on mine (which I don't use) and ended up just sealing it off with some RTV. That was a couple years ago and its still holding.
1986 F250HD Ex cab Fresh built up 6.9L diesel, Lariat AC leather seats power everything w/full cluster, sterling rear 3.08LS gears, E4OD trans, ram intake ATS 088 turbo
1986 F150 Ex cab Lariat rollercam 5.0L on LPG AOD trans 3.55 gears 390 000Ks
yeah, I did some reading around on the forum last night and it seems like a couple of guys just disconnected the heater wire and sealed off the connection. I went to Auotzone and bought a box of o-rings and am going to take a shot at it one more time. If I cant get it sealed up, I may just plug it up like you say, as I live in Arizona, and I never even bothered to fix the cab heat in my other truck since Ive been here
I think I finally solved the problem. I found a couple of o-rings that I put on the heater, I had trouble trying to locate the bottom bowl part of it (the drain part was bad on the original one), so I went to NAPA and bought a one piece unit, filter with drain and sensor hookup on bottom. Solved the problem, but kinda spendy. Anyhow it started up this morning, didn't leak, I let it sit all day, and it started up again woo-woo!
This is my first diesel, and while I am respectably knowledgeable about gas engines, diesel, not so much.
The truck originally had a 7.3L in it, and the guy I bought it from had a rebuilt 6.9L put in it, or so he thinks, and that is what a tag on one of the valve covers says. Are there any discernible outward differences between the two engines?
I Have An 88 F-250 Ext. Cab 4x4 With The 7.3L IDI Diesel And I Have The Exact Same Problem Its Leaking Out Where The Fuel Heater Connection Is. I Am Going To Try Seal It Up With A New O Ring. I Priced Out A New Assembly Today And Its $324(Can. Dollars). I Hope A New O Ring Fits Because Up Here Winter Gets Down Sometimes To -30 Dergees Celcius So I Need It. If You Find The Proper Size O Ring Please Let Me Know! Thanks
As for the o-rings, for the larger one I used a 5/8"I.D x 3/4"O.D, 1/16" wide. On the smaller one I used a 1/2"I.D x 11/16"O.D, 3/32" wide; this one I trimmed off the O.D a little, as it was probably too fat, a 1/16" wide might work here also.
-30... brrrr, I feel your pain. I was born and raised in Chicago, in Arizona now, wild horses couldn't drag me back there!
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