Help...Oil cooler Blowing UP

[chiromed0]

Problem with my 77 2.7s motor. Engine mounted oil cooler is splitting...I'm on my second used one (you know how expensive they are). Situation arises when driving (1st time) and at idle (2nd time). Engine was running fine and did'nt notice oil pressure being up high ( I don't recall what it was). Both times sprang a leak and dropped all the oil out in my driveway. Whats the deal? Shouldn't there be a pressure relief valve or something to prevent this? I'm considering just using the mounting plate and have some fittings installed so I can run some hose to an aftermarket cooler away from the engine (thought this was a crappy design anyway...oil "cooler" right next to a hot p/c/motor with no fan on it. Help.

[RoninLB]

I understand your dilemma. My '77 got a rebuild after 100,000 mi and no way was I going to use the orig. or another used oil cooler. $800 did cause me to think. " Do I want to wear old greasey jeans and sneakers for a year or buy a new oil cooler?" Sometimes the best throw of the dice is to throw them away.

[ChrisBennet]

I'm coming to believe that many 911 oil coolers leak or at least won't pass a pressure test. I think the one I I have now leaks and the one I sent in to be cleaned before it was found to leak as well. My next one will be new.
BTW: The engine oil cooler has air forced through it. That grey plastic duct on the top of the motor brings air from the fan to the top of the cooler and the air exhausts throught the bottom of the cooler.
Chris

[RoninLB]

Chris...IMHO the oil cooler is reliable for about 100,000 miles, may be less. Not an expert opinion given.

[Early_S_Man]

I think you should check the two pressure-relief valves to see if they are stuck in their bores. Their primary purpose is to protect the oil cooler from pressure surges when the oil is cold, so the fact that you hav had two leaking coolers seems suspicious!

Special 1/2"drive slotted bits are needed to remove the plugs ... and the fit needs to be very tight and precise! If need be, get a 'Drag-link Bit' and grind/file it to fit the plugs.

One plug is oriented vertically in the right case half, and the other is horizontal in the left case half ... both are circled in the following oil system diagram:

[cstreit]

Check the pressure relief valves as mentioned. Hit the pistons with some emory paper to clean them up.

Aditionally, if your oil thermostat isn't working properly, cold oil is thick and could overpressure the cooler...

Start the motor, if you can hear oil in the cooler lines early, the thermostat is stuck open. er wait, you said the engine cooler...

GANG, is there a thermostat on the engine mounted oil cooler?

[Dave Bouzaglou]

check the thermostat as well- pull it out, clean it, and throw it in a pan of water- heat it over the stove- you will see the piston slide at boiling point. If not, replace it- these are normally very reliable, but every now and then...