Hey All,

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?

Thanks in advance for any and all help!

Skip

 

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.

 

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

 

skiprrdog,
Welcome to FTE and the IDI diesel forum.

89 and 93 filter/seperator's are the same.

87 thru 94 used the new style filters with the water seperator in the filter.
83 thru 86 used seperate units, and the water seperator was the biggest source for air intrusion on the truck.

 

Thanks Dave,

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?

Thanks!
skip

 

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

 

Rowdy_Cowboy_73,
Welcome to FTE and the IDI diesel forum.

 

rowdy_cowboy, there is a pretty good set of images of a dis assembly/repair of one of these on this site here:

https://www.ford-trucks.com/forums/8...ml#post7610155.

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!

Good luck,
Skip