Will Feather

This may be a stupid question but here it goes. If the oil cooler gasket is leaking, would oil leak from the housing, or coolant? It is my understanding that the cooler housing fills with coolant to be cooled by the "radiator" in which oil is traveling. Am I correct?

I ask because I have a big oil leak passenger side from the cooler area. Looks like the cooler leaks after testing, but it could also be traveling down from the BS housing or the OPRV. So I just wanted to clarify.

Thanks.

86 951 Driver

I have the same issue as well. I am interested to hear what people respond with. I heard some people when the BS housing is leaking they just put some RTV or similar on the outside to stop it from leaking.

River

www.clarks-garage.com

is your best friend.

I'd check the oil unit sensor first.

How bad is the leak? Take pics/video.

You don't have a 'mixing' do you? (oil in coolant/coolant in oil)

Will Feather

I am no stranger to clarks. Oil sender is not a problem, and no oil mixing.

Thanks for the input but that relates to nothing I asked.

VirginiaF1

Just finished this job this weekend... not terribly hard and I'm a novice.
Learned so much seeing in 3 dimensions.

Unless I'm way off, the coolant flows within the housing and enshrouds the oil cooler... Really allows us to run the car at high rpm's for hours with manageable oil temps. With the n/a engine having the housing right under the hot headers makes me wish I had the Turbo's external mounted cooler.


My oil leak was passenger side and drenched my sway bar bushings, control arm bushings and power steering boot. Driver side bushings are nice and dry.
Dripped oil from the oil cooler housing gasket right above the OPRV.
Verified same by degreasing & hosing the undercarriage; idling for 5 mins and looking for drip path. No milkshake but I was darn close by the looks of the seals. Another month and the oil nozzle o-ring would've failed thus introducing oil in to the cooling system. I'd assume the much higher oil pressures vs coolant pressures would result in far greater oil intrusion than vice versa.

Anyway, used Clark's and 944Foot2the floor... yes, terrific both.

1. We left ON the headers but removed the heat shield; removed PS pump and hose. Drained oil and coolant.
2. Bought the Pelican Oil Cooler seal kit for $36 and had everything needed.
3. Tested the oil cooler itself for cracks/leaks... tight. Installed a new Oil Pressure sender.
4. Thoroughly cleaned the 24-year old gasket gum/varnish off the block and the housing rim. Cleaned and tested the OPRV for 10 LBs actuation.

5. Changed the included gaskets and o-rings. Re-installed the Rubik's cube of the oil cooler & housing up onto the block. Slowly tourqued then inserted OPRV slowly. Re-installed heat shield. I have the '88 one-piece OPRV... and had to tap&die the threads due to a quarter century of heat cycling.

6. Loaded 2 gallons of distilled water and 4ounces of SHOUT to coolant system.
7. Loaded 5.9 quarts of 5W-30 to idle engine and prime oil pump. OC142.
8. Ran engine for 5 minutes with coolant bleeder open till fluid emerged.
9. Flushed oil and laundry fluid. Opened the coolant block nut to expel all fluid from block. Flushed another 2 gallons of distilled water to clear SHOUT and any oil from radiator system. Installed a 2nd OC142.

10. Reloaded with 15W-40 Rotella and 2 gallons of Zerex G-05 50%.
11. Enjoying no drips, nicenon-bouncing oil pressure and no milkshake fears.

Total net time: 6 hours... and yes we had a lift.
Thanks to Mark for his guidance and awesome set of tools.
Good luck!

River

Maybe I miss-read that.

Thing is why I asked if you are leaking oil or coolant in there, it'll be present in your coolant tank.

So, if not...then the leak could come from the sender. Or the cam tower (usually the rear and drips down everywhere). Or the cam tower itself.

The outer seal for the oil cooler is holding in coolant. Oil is in the middle part (hence, if that inside seal breaks, you get the mix).

Also, double check your oil filter. It happens.

Double check that all bolts are torqued to spec too. (I had a weird leak at the water pump till I noticed a couple bolts the p.o. didn't tighten down).

xsboost90

usually when the seals leak on the cooler they mix inside- if the outer seal is leaking coolant would drip. You prob. have a leak from the front seals on the cambox between the housing and the belt housing, dripping down to the oil cooler area.

andys-944

Your correct the oil runs through the heat exchanger surrounded by water, but there are oil passages and seals outside of the water passage so the housing could leak either (or both) oil and water. It can leak oil from around the pressure release valve, oil filter joint etc.
With all that said its normally seems to be the o rings on the heat exchanger that fail first.

Will Feather

Thanks for the responses.

Rear cam tower gasket is good, if that was leaking it would not make it to the control arm area, it would leak down the back of the motor and look like a RMS issue. Front seals weep a bit but not enough to produce this leak.

Andys, thanks thats what I was looking for. Thank you for confirming my suspicions.

M758

The stock NA cooler is an oil cooler trapped in bath of engine coolant. So if the outside of the housing leaks it will be water/coolant. If the oil cooler itself leaks or the 2 O-rings leak it will put oil in the water.

Also the oil as at higher pressure than coolant so small leaks always put oil in the cooling water first. This not the worst problem in that it can be fixed, but just hard to clean. If water gets in the oil this very bad as it can damage the crank. Most times you will see alot of oil in the water before it water gets in the oil.

If you have an external oil leak is not from cooler part, but either from the oil filter or oil pressure relief valve opening. Or from higher up on the motor that is leaking down an collecting on housing.

nasty9er

my oil cooler gasket went bad on me and i ended up redoing the top end thinking it was a head gasket and then found it was the cooler when replacing the gaskets half way threw the build

but a few month ago i was getting rid of my power steer and going to manual i thought my pump/reservoir was leaking i had fluid all over the sway bar bushing my A-arm ect... but after doing the swap i found out it was the oil pressure sender was loose all it needed was a half a turn and now i am leak free

and yes getting rid of the banana smoothie in the oil is a pain in the *** i recommend dropping the oil pan and also sucking out every oil passage and coolant jacket

M758

I suggest an all new rod and main bearings if you get severe water in the oil. I had motor back in 2003 that had really bad mixing. Could have been from oil cooler or head gasket. I did not because it came in parts car. Anyway even sitting for multiple years I was able to clean it and rebult the motor and it worked great. However it needed alot of cleaning.

pkt1213

I don't have the shop manual in front of me but does coolant flow out of the block and into the housing and then back in to the block?

andys-944

Here's some pics of the layout of the cooler and block with cooler removed.

KlineS147

I have the same issue i think mine is coming from the front camshaft seal, i'm going to replace them with my belt job next week