So I finally got around to pulling the oil cooler on my '90 today and was surprised at how much grit was in the cooling system. The radiator wouldn't even drain from the petcock so I had to just release the lower hose. After draining the block I pulled the cooler and it looks Ok for the most part, however, on the ends of the bundle, not the headers, next to where the smaller o-ring seats there is some VERY crusty buildup. The area where the o-rings seat is still smooth and clean though. I tried going at it with a "Fine" sanding block and some 1000 grit sandpaper but not much luck. Since it wasn't leaking at the o-rings before I pulled the cooler I am tempted to just run it as is but I sure would prefer to clean things up some more but I do not want to create a separate problem by scratching the surfaces. The small o-ring was still quite supple when I removed it but the larger o-ring had just started to crack so i am glad I caught it before it failed.
So, is there any safe way to attack the crusty buildup? Lower grit sandpaper? Other?

 

I had that same crusty crystallized buildup in my headers. I used Fluid-Film applied to the crust which softened the buildup. I used a fine wired wire brush to remove the softened buildup.

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These brushes have the tuft on the ends and that portion used on an angle cleared my headers. Like having a handful of mini chisels. The Fluid-Film was very good at helping to soften the buildup. I used the brass brush on the header interior o-ring surfaces and the steel one with gasket remover on the gasket surfaces.

 

I used the Permatex o-ring lubricant in the 1 oz. Tube for o-ring lubricant. I also applied a small bead of lubricant on the surfaces that the o-rings bear on. The tiny hole in the tube made it easy to apply the bead in the freshly cleaned up corners of the bundle and header o-ring surfaces. One one ounce tube was adequate for that application plus a liberal coating on the o-rings themselves.

 

I hadn't thought to try fluid film. Luckily I just bought a can.
After finding so much grit in the system now my oil cooler R&R has turned into new radiator, water pump, and thermostat. And of course although this has been a dry winter where I live now there is a ton of rain in the forecast this week and I don't have a covered place to work.

I did manage to remove the oil cooler by just removing the one 10mm bolt holding the steering shaft to to steering gear and the cooler dropped right out between the pan and driveshaft--we'll see if I can get it to go back in the same way. I'm considering pulling the shock bracket for more access and I have new shocks to install anyway.

 

Mine would have dropped out as you say but on my 86 6.9, I have the brake proportional valve in the way. I had to unbolt the bracket and using a wood wedge was able to move it back and out enough to get the cooler by. Removing the shock tower support would definitely make access better, but I was able to get in there without doing that. Removal of the tire is a good idea too unless you're skinny.

 

I used Fluid-Film applied to the crust inside the header tubes as well as the o-ring surfaces. Since it's aluminum it has a different electro chemistry than most of my cooling system. So after the softening, and cleaning of the header I left a thin coating of Fluid-Film in there. Surely the warm coolant will wash it away over time but probably a very thin layer will still be left behind as a corrosion inhibitor.

 

Well I'm not skinny so I definitely removed the tire and also the shock mount. At least on my truck I don't see the value in removing the power steering pump but I would have appreciated the room gained from removing the steering gear and hoses. I had hoped to try and remove it in pieces from under the truck but just couldn't see a good way to do it despite reading accounts fro others who claimed it was much easier and faster to pry out the rear header and then deal with the front as a separate unit. Removing the shock mount made a huge difference, plus I have fused right wrist that sometimes makes it difficult to get the right position on some repairs.

 

In hindsight I can see that if you go in from the side, remove the steering shaft and the shock tower you probably don't need to remove the power steering pump. I removed mine completely which required sucking out the fluid. Next time I'll go in from the fender and then if needed detach the PS pump from the bracket and move it out of the way while still attached to the hoses. Last time I was following the diesel hub article and looking at the work from the top at first. That article didn't mention coming in from the side which is definitely the way to go. Better access to the bolts too, which I removed from the top and the bottom, following the cook book. Once there I will probably leave the shock and tower in place. I think you could extract and replace the cooler through the side if you do remove the shock and tower.

 

It's a pretty tight fit on my '90 trying to go in from the side and I didn't want to force anything and mess up the header orientation in terms of having them clocked just right to mate up cleanly with the block. Honestly if I ever have to do this again I am going to buy the appropriate all-thread and cut pieces so i can use them as temporary studs to hold the assembly in place while I then replace the all-thread with the actual bolts. I had a helluva time getting one bolt in the front header and then holding it steady while I got underneath so I could thread in a couple bolts in the rear header. I guess the 1-2 inch lift on my '92 made just enough extra room to maneuver my arm into position while doing everything from the side. It really is funny how many different ways people come up with to do the oil cooler job. I can't imagine having to pull the exhaust manifold or jack up the engine like some folks do.

 

One or two pieces of all thread is all you'd need. I used a wood dowel to help guide the cooler on the rear header while I got a bolt in the front header. Yes getting that first bolt in was a pita. But all the others went in easy. Two all thread studs would be perfect. One for the front and one for the rear. They are different diameter? I know the bolt heads were different and the torque specs. With the two all thread pieces in you can hang the cooler on them. That would be COOL indeed!

 

I had the classic oil in the radiator and coolant bottle one morning.
It was the Oil Cooler puking the oil...
I read all the classic ways to R&R the damn thing.
Read the Diesel Hub way to remove the power Steering Pump etc...
Stand on your head and bow to the east etc....
Sprinkle Fairy Dust on the Engine etc....

Jacked up the L/F removed the wheel.
Removed the Battery, Coolant & Washer Bottle.
Then the inner Plastic fender.
Removed the left side Engine Bolt.
Raise Engine, place a small 2 x 4 Block under it.
Then the 4 front Bolts are looking right at you, easy to get to you.
Remover the 4 rear Bolts and slide the unit to the rear and out.

Popped off the end Caps. Polished the insides with wet/dry 1000/2000 grit.
Came across a remanufactured Motor Craft OIL Cooler off Part`s Geek.
Used Syl-Glide to lube the O Rings and my 20 ton Hyd press to push the Caps on.
Do one end at a time.

Clean up the mating surface on the engine, put some stickum on the on the caps
and place the paper Gasket on. Keeps it in place. One side has the red rubbery seal
placed it to the engine side.
Had my Wife get one bolt to the back end I got one on the front end to hold it, and
then tightened it all down.
Remove 2 x 4 Block and replace Engine mount bolt.

With the Inner fender out makes it simple to get to the rubber Fuel Hose to the Water
fuel filter. (I deep six`d mine with a better filter)
Also removed the Fiberglass insulation with 20+ years of grit, grime & oil mess.
If you have a Pressure Washer, good time to blast it clean, I have a Hotsy, so have the
Hot water option.
Although, I did mine in January with snow, and had truck on under patio cover with a
Torpedo heater to keep warm.

If you just have a leaky Cooler vs having oil inside the engine you are lucky.
Other wise you have the fun of flushing out the cooling system to get all the oil out.
Replacing all the hoses and that fun stuff.

No right way to do it, just the way I did it.

Charlie

 

There's more than one way to skin a cat they say. Well done!

 

Yeah, as much fun as it is doing the oil cooler it seems like less fun than having to flush everything, replace all coolant hoses, and then still rebuild the oil cooler.
The one method I wanted to try but just couldn't see it being a lot easier was to remove the oil cooler in pieces by prying on the rear header and then reassembling it on the truck. I cam across a few posts of people claiming it worked great but when i got under there and started sizing things up it seemed like it would be a PITA too and the idea of blindly prying the bundle into the front header did not sit well with me.

 

If the orientation of the end caps is off, they will rotate and not damage the "O" Rings.
Set the Cooler on a flat surface to square them up.
Removing the Shock and Shock Tower is a new one, haven`t read that on any Forums.
Or the PV Valve. I guess removing the Cooler through the wheel opening might need
to do it that way.
Iam trying to picture in my mind leaving the Cap on the engine, and trying to push the
Cooler into it. They don`t easily slide together. it would kind of suck, not replacing the
paper Gasket, and then it would start to leak.

I read one thread where the guy used his Floor Jack, and pushed the Cooler up against
his rear Bumper.

When I did mine, gave me the excuse to finally buy the 20 ton Press.

Charlie

 

I didn't plan on removing the shock and tower but it gave me much better access and allowed more room to move my arms while supporting the assembly. My '92 is lifted about 1-2 inches in front and it was soooo much easier than my '90 which has the stock front leafs which are very flat--maybe they have flattened out a a bit more due to age and mileage? I also have a fused wrist that limits the angles I can use. If I have to R&R the oil cooler again i am definitely going to consider installing a stud for each header or at least using some all-thread as a temporary helping hand.
I still abide by the notion that if everything is cleaned properly and well lubricated you should be able to press the headers on without needing a ton of force. I weigh a bit over 200 and brace header against my flatbed while pressing against the other with body weight and it does take some effort but so far so good