venetian928

just joined the site! i have a 87 928 that has a problem. when i was driving home the car overheated and the upper hose blew. there was oil mixed with the antifreeze. the next morning i checked the oil level and it was down 2-3 qrts. i took it to my dealer and they pulled the heads and determined that the head gaskets were bad. the heads were not sent out and were determined to be true and not cracked, visually. i left the dealership and within 10 minutes the car was overheating. i brought it back and they checked it and said that the block must be cracked. they said the oil cooler was ok. does my car have an internal oil cooler? there is a skinny external cooler in front of the radiator. two lines goe into the driver's side of the radiator and are they part of the oil cooler? my car is a 5 speed,and was made june of 1987.vin is 862375. any help would be appreciated.when the car overheated originally i drove it only 1 minute back to my house. it just seems that it is leaking oil at a very fast rate to be a cracked block. thanks for any help. jeff in n.j.

Mrmerlin

you can run a test remove the top oil line from the radiator then with a pressure tester pressurize the coolant bottle if coolant comes out of the oil hose hole then the internal tank has sprung a leak.

NOTE I took it to my dealer and they pulled the heads is an awful lot of work to not have any work done to the heads to check for cracks.
Is it possible the waterpump has also failed??

venetian928

so those are oil lines. someone told me that porsche around 87 made the oil coolers external so i guess i have the early one. i don't think it's the waterpump because it's leaking oil into the coolant.

Mrmerlin

a failed water pump will quickly overheat the engine.
IIRC the external oil coolers were fitted after 1990

Note the oil cooler lines are on the driver side of the radiator,
the ATF cooler lines are on the passenger side

venetian928

thanks mrmerlin, i will pressure the radiator and see if oil and antifreeze come out. when the head gaskets were done, they did not replace the waterpump.

Mrmerlin

the thermostat could also be bad as could the rear thermostat seal, i hope that you only have a damaged oil cooler and then just a need to flush to lines out ,
if you have oil in the coolant then adding tide and regular water and running then flushing the whole system will clean it out .

also you should replace all of the rubber hoses after cleaning as they will all be soft from the oil

venetian928

how much tide and what about cleaning of the heater core? run the heat and then flush. should i do it a few times? drain it from the radiator or is there plugs on the side of the block?

Mrmerlin

about 3 table spoons and fill with water, keep the heater open.

Note there are 2 block drains one under each EX manifold 3 and 7 ,
each block drain will hold back about 1 and 1/2 gallons of liquid

venetian928

well, i pressure tested the system with the top oil line off and no coolant came out but all the pressure is coming out of the line, i put my finger over the hole and it stops the air pressure. so gurus, do you guys think that my oil cooler is bad? there should be no pressure loss with the top oil line disconnected, correct?

blown 87

My guess is that was your problem all along.

mark kibort

my side tanks were leaking water into the oil and oil in to the water. drip drip drip over night, is about a quart into the oil. then, under pressure, the oil seeps into the water. this is a side tank problem in my case, (or was anyway).

Mrmerlin

Ahh lets get this straight, you removed the top oil line from the cooler and pressurized the coolant tank.

Now there is air pressure coming out of the
oil line or
the oil cooler??

Big difference

venetian928

the air was leaking ouy of the oil cooler end in the radiator. air was also leaking out of the small overflow hose on top of the radiator. i tightened it but air is leaking out of the oil line fitting in tank. is there any way to definitely narrow down if the oil cooler is bad. i was hoping all this antifreeze would come out.

Mrmerlin

if you want to see coolant come out of the cooler remove the lower oil cooler line and fill the coolant tank then pressurize it

Dave928S

I'm not waiting for mine to do that ... I'm removing it and fitting an external cooler only. Oil and auto fluid radiator heat exchangers are a big design fail in my opinion.