Oil Cooler Issue

Kputz · #1 (**permalink**) 08-14-2002, 04:10 PM

I'm running a standard Mocal oil cooler and have developed a leak. Oil blows back from the cooler fins under speed, resulting in oil loss and subsequent loss of pressure. The fittings are tight and it appears the the leak is in the core near the top fitting, although there is no damage to any of the cooling fins. My questions are as follows: Assuming I can remove and pressurize the cooler and determine that the leak is indeed in the core, what could be done to mend the break? Aluminum is tricky stuff and I hate to scrap a $140 cooler or ruin the unit attempting a fix that won't work. Anybody had a similar problem? Anybody have a suggestion as to a fix?

ERA535 · #2 (**permalink**) 08-14-2002, 04:18 PM

Well if it is leaking anyway you can't ruin it by trying to fix it - right?

I have always replaced oil coolers that leak - probably because they have always leaked as a result of a collision. I've never had one just leak.

To see where it is leaking from exactly, make up a mixture of thinner (or something really thin) and put some dye from a leak detector in it. Black light it and you will know exactly where it is leaking from.

I know I am not answering your question.

Pat

427sharpe · #3 (**permalink**) 08-14-2002, 04:35 PM

You can fix an oil cooler just like a radiator, find the leak and solder it shut. To avoid future leaks, try not to blip the throttle @ startup, as this creates a very high pressure spike that can create a leak. I found this out from Earl's, when I sent my first oil cooler back for warranty after it developed a leak. I added a bypass thermostat, but Earls makes a check valve that will shut off flow at very high pressure loads. Try www.amstreetrod.com for an quote.

Back in Black · #4 (**permalink**) 08-14-2002, 05:31 PM

Is to humanely shoot it, and buy a new one.

Kputz · #5 (**permalink**) 08-14-2002, 09:32 PM

You could be right about the pressure spike causing the leak, but then it is a small leak indeed. No puddling under the cooler when parked, but rather only oil loss at speed and then in a fine mist. Is an acid bath necessary before the solder attempt? (For the cooler you moron, not me....I shower). Anybody attempted such a fix?? Successful??

Bob Putnam · #6 (**permalink**) 08-15-2002, 05:20 AM

I wouldn't risk an expensive engine to save the cooler. Fins are thin and difficult to weld, and you may weaken the adjacent area in the welding process. As a desperation move - say the cooler started leaking 1000 miles from home - I would clean it and pack the area with epoxy.

Then throw it away when I got home.

ERA535 · #7 (**permalink**) 08-15-2002, 08:31 AM

If you have to avoid blipping the throttle when the engine is cold in order to try to keep the oil cooler from leaking, you need to find a better brand of oil cooler or replace the piece of junk you have on the car now.

They are rated for way higher pressures then your engine will see under any kind of normal use - even revving cold.

To restate the obvious -one should always avoid blipping a cold engine - for many different reasons.

Roscoe · #8 (**permalink**) 08-15-2002, 08:48 AM

Car must be taken when installing. This is the disclaimer from Pegasus Auto Racing regarding their Mocal Coolers:

"All oil coolers are relatively fragile. Care must be taken to avoid stressing the fittings when tightening connections (always use a backup wrench on the cooler fitting.) The cooler must be mounted in a manner that will minimize vibration. "

Roscoe

Mr.Fixit · #9 (**permalink**) 08-15-2002, 09:05 AM

I have seen several oil coolers (mocal and seetrab) leak at the flare of the fittings. Mark the tapered flare on the fittings attached to the cooler with a magic marker. Tighten up hose fittings to the cooler. Remove hose fittings and inspect contact pattern on the cooler fittings. I have seen this problem a number of times, irregular contact at the flare. The aluminum crush washers that fit in the flare "contact cone" can solve this leak. To find the leak for sure, pressurize the cooler with compressed air and spray simple green or formula 409 all over and look for the air bubbles coming out.

427sharpe · #10 (**permalink**) 08-15-2002, 01:45 PM

Actually, blipping a cold motor can cause MOMENTARY spikes of oil pressure FAR exceeding the rated capacity of any of the coolers, which in turn can cause leaks. Aeroquip among others recommend use a check valve or a thermostat (which basically in this case serve the same purpose) with an oil cooler. Such check systems are also integral in most power steering systems to avoid the same type of problem, but from prople holding the wheel at full crank and hence full pressure. Name or brand has very little to do with it. Certainly Earl's has a pretty good idea of what they suggest having dealt with AN hardware for over 40 years.
Now, to get back to the original point, an acid bath would not be required as long as you clean the spot of failure very well by itself. In reality, is $150 worth the hassle and/or the loss of peace of mind?