Oil leak above the oil filter, rear oil cooler head? what do I need to know before I start taking it apart?

[Farm Truck Bob]

Merry Christmas and Happy New Year to all!

I need some advice! I have a 1990, Ford PU, F250, automatic, 4X4, 7.3 idi, non turbo. Occasional driver, so being down for a while isn't an issue and I have the time to do it right.

I've developed an oil leak an inch or 2 above where the oil filter spins on. When the engine is running, I get a constant, approximate 1/8th inch stream of oil squirting out the back (rear axle side of the truck). Shut the motor off it slows and stops, so it's under pressure only. I downloaded engine diagram and think it's coming from the back head of the rear oil cooler head but I need a better look to tell if it's a gasket failure, crack or some kind of port. I plan to power wash the gunk off, start it up (I'm only about 1 qt low so I can do some diagnostics with out running dry) and try to get a better look at it. I'll upload pictures this weekend when I clean it up if needed.

My experience, lots of general repair and replacement on gas vehicles but this is my 1st diesel.

What do I need to know before I dive in? Is there any ports on the back side of the back cooler head that could be my issue? It doesn't seem like it's up against the block so I don't think it's a gasket but I haven't cleaned it up and inspected it close enough to be sure?

If it's a head crack, are they available anywhere. It didn't seem like a listed part in any site like RockAuto when I was looking for diagrams.

I've downloaded a video on replacing the cooler unit and other than getting everything out of the way it seems pretty strait forward, famous last words.

Thanks for any and all counsel!

Bob

 

[Old Goat]

"Happy New Year"
If it is your Oil Cooler Header end Cap leaking, what a great way to start off the New Year out in the cold.
I had to remove my OC 4 years ago next month in between Snow Storms.

There is a paper gasket on each end of the OC where it mates to the Block, and 4 bolts on ea end.
You will have to raise the engine on the drivers side a couple inches to remove the OC to the rear.
If you do have to remove it and that deep into it, might as well replace the 4 "O" Rings, 2 on ea end.

Goat

 

[franklin2]

That has to be one of the worst jobs I have ever done on a vehicle. No matter how well you drain it, coolant AND oil goes everywhere and all over you too. And then the thing won't come out without loosening the mount and jacking up the engine a little bit. And then getting the new o-rings in place and pressing it all back together is no fun either.

 

[Farmer Rock]

Yup, it ain't a fun job to do at all, but shouldn't take more than a days work to get done. The hardest part is trying to get the oil cooler out from under the engine, and back in later. It is really shoehorned in there. All the bolts are actually pretty easy to get to. I would recommend removing all the bolts before lifting the engine so you don't have to risk braking your hands. I came real close, so just passing that on. Also, I am sure you know this already, but you should loosen the transmission mounts as well to get more lift.Be sure you grease/oil the o rings in the oil cooler before replacing them.


Rock

 

[quickster]

I pulled off the wheel, the rubber shroud or inner wheel well cover thing first. Undid the motor mount bolts. Jack the motor up, and you can see the cooler bolts. And remember to drain the antifreeze first.

 

[IDIBRONCO]

Bob, I think you're on the right track, but definitely see if you can tell exactly where the leak is coming from before ordering any parts or tearing it apart.

 

[Old Goat]

I pulled off the wheel, the rubber shroud or inner wheel well cover thing first. Undid the motor mount bolts. Jack the motor up, and you can see the cooler bolts. And remember to drain the antifreeze first.

That`s the way I did it also. It is a few more steps to go through, but easiest way to get to the 4 front bolts.
Also removing the Battery, Coolant Bottle etc... then the inner fender, it gave me the chance to remove the dirty oil soaked Fiberglass Insulation off the Fender.

Also gives you direct access to get to the rubber fuel line to the Factory Water Separator.

Diesel Hub mention`s to remove the power Steering Pump to get to the front bolts. I did that, but still couldn`t easily get to them.

6.9L & 7.3L IDI Oil Cooler Rebuild & O-ring Replacement Guide

How to remove and rebuild the oil cooler on a 6.9L or 7.3L IDI diesel engine without lifting the engine. The oil cooler assembly on the IDI diesel is sealed by a series of o-rings which become brittle and fail over time. Removing the oil cooler is quite a task, but our step-by-step tutorial will...

www.dieselhub.com

Here is a thread I wrote up on FTE when I went through this.

Blown Head Gasket....OH Goodie... - Ford Truck Enthusiasts Forums

Pre-Power Stroke Diesel (7.3L IDI & 6.9L) - Blown Head Gasket....OH Goodie... - Blown Oil Cooler. Replaced Oil Cooler with remanufactured Ford cooler and gaskets and O Rings. Three cooling system flushes, and no new oil is getting into the system...so far. Probably do a few more flushes, and...

www.ford-trucks.com

Goat

 

[Old Goat]

Yup, it ain't a fun job to do at all, but shouldn't take more than a days work to get done. The hardest part is trying to get the oil cooler out from under the engine, and back in later. It is really shoehorned in there. All the bolts are actually pretty easy to get to. I would recommend removing all the bolts before lifting the engine so you don't have to risk braking your hands. I came real close, so just passing that on. Also, I am sure you know this already, but you should loosen the transmission mounts as well to get more lift.Be sure you grease/oil the o rings in the oil cooler before replacing them.


Rock

When you lift the engine, place a piece of 2 x 4 between it and the mount. This will keep you from getting flattened Pinkies...
You will have plenty of space to slide the Cooler to the rear.

Thinking about doing the Job, then looking at what has to be done, looks over wellming .
Once you are done...it was a piece of Cake.


Goat

 

[drewr13NJ]

I just pulled the oil cooler off my '92 on the 23rd. I had a turbo oil cooler cleaned up and ready to press together from a junk truck I bought to rob the turbo off of. I was dreading doing it, but I had low oil pressure issues and after investigating, there is no doubt the oil pressure regulating valve was sticking open. I checked the turbo oil cooler oil regulating valve and it always returns shut, so I'm confident I won't have the same problem again. I did it just like Diesel Hub says, and it wasn't too bad. And yes, you will probably get a bath of coolant and/or oil. My helper was exposed to COVID over Christmas, so currently waiting on that. It is tight, so I doubt I can get it on by myself without bumping the gaskets. Good luck and hopefully pulling the cooler will shed some light on the problem!

 

[testlight]

Be real gentle with a ratchet strap putting the cooler together. The O-rings can get damaged.

Consider re-using the old oil for the leak test. I poured mine thru clean tee shirt material.
(Oil is expensive, you can always change it again)

 

[franklin2]

I used a press to push mine together, it's pretty tight. You might be able to stand it up on top of a floor jack and put it under the frame of the truck and press it together.

 

[testlight]

I remember it being pretty simple but very very messy.

I bought a drip pan that goes underneath washing machines or water heaters to help catch all the drips and runs.

 

[Old Goat]

Here is a video Gensriptor did on pressing the Cooler together.

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when I pressed mine together, I used my 20 ton Hyd Press.
I pushed one end on at a time. one end pressed right on, the other end wanted to fight me....I won. Be sure to be square when pressing down.
I used Syl-Glide for the lube.


Goat

 

[Big Bart]

Some other tips.

1) Use some lube on the rubber o-rings to help them slide and seat. I use a Dow’s Molykote 111.

Dow Molykote 111 O-Ring Silicone Lubricant - 5.3 Oz. Tube

The DuPont Molykote compound is used in many different applications such as lubrication for control and pressure plug valves, water softener and faucet valves. Sealant for vacuum and pressure systems and outdoor equipment (also shipboard) subject to washing and harsh environmental exposure, such...

www.freshwatersystems.com

2) Use gasket sealer to stick the paper gaskets onto the block or oil cooler. Then you do not have to try to line them up. I put the gaskets on the block and was careful when mating the cooler up. I use Permatex high tack. Having a helper top side during re-install is very helpful but not mandatory.

https://www.autozone.com/sealants-glues-adhesives-and-tape/sealant/p/permatex-high-tack-gasket-sealant-4-oz/554063_0_0?cmpid=LIA:US:EN:AD:NL:1000000:GEN:10574827360&gclid=EAIaIQobChMIv7udydaV9QIVoCCtBh1l5ASXEAQYBCABEgJ_pfD_BwE&gclsrc=aw.ds

3) Clean the oil cooler heads really well. But don’t use something that will put deep scratches in the o-ring mating surfaces. Think steel wool or 220 grit sanding sponge but not a rough grit (80 grit) sand paper.

4) I used a shop press, it went together without issue, you could tell when each oil cooler head/end was all the way on. Try to press the assembly together as straight as possible. As I recall the ends are not flat. O-ring lube really helped out here.

5) Drain your radiator to limit the mess. I used this job as a reason to flush the coolant system and put in new coolant and hoses. I used Fleet Charge which has sca’s in it. O’Rielly’s can order it in. I feel you should change your coolant every 5 years.

6) You will need to take the oil filter off so order up a new one and some oil for a oil change or to top off. As TNBrett mentions if you do not get it right it is likely to put oil in your coolant or coolant in your oil. So topping off and testing is not a bad idea if you want to save some money. Personally I was confident I did it right and just did a oil change and new filter.

7) I lay a big cardboard box down, use a ********* cement mixing bin from Home Depot, and a couple 5 gallon buckets. (One for oil and one for coolant.) when I do jobs like this. Helps to keep the driveway or garage floor clean. Also keeps the knees happy and warmer than laying down on a cold concrete floor in the winter.

As these trucks age they all will need this done every so often.(O-rings harden and crack over time.) It is a very common IDI repair. Many members have done it. It is not as hard as some suggest. Take your time, mark your bolts, clean everything really well, lube the o-rings, and press carefully. You will get it done right! I did not have to lift my engine, I just had to loosen my brake line junction and move it a little. But my truck is a 88 NA 2wd C6 auto. So 4wd and turbo’s likely complicate things.

 

[Big Bart]

Guess you can’t say blaack on this site. So the cement bin is blaack.

Plasgad 20.9-Gal Black Large PVC Concrete Mixing Tub 887102C - The Home Depot

This multi-purpose Large Concrete Mixing Tub features a heavy-duty PVC material. The material allows it to withstand mixing of heavy materials such as concrete, grout or mortar for masonry. It has a large

www.homedepot.com