2002 Volvo S40 oil cooler leak rare

I walked out to my car one day and noticed a white oily substance on the driveway. I feared the worst.  I opened my hood and noticed my coolant reservoir full of white stuff. I cracked it open and a little more came out.

I first think oh crap, I have a crack or something in my engine block or head that has allowed coolant into my engine oil. I take off the oil cap and turn it over and holy moley it's white. I'm doomed now right?  I take a deep breath and decide to really look over the situation.

Stained paint all around the reservior from the oil and coolant cream sitting on the inner frame of the car all night. Could it be anything else. I just changed the thermostat last month.

Dealer says, never heard of this. Volvo forums, can't find this problem anywhere.

Okay, so hey I'll do first things first. I'll clean out the oil and sludge and coolant. I flush the radiotor about fifteen times (really), the engine block about ten times (really) and the reservoir about forty times (really). Basically here are the steps

1. Change oil and filter, to get white crap out. (I only did this once and then a second time later, read on)  I keep checking the dipstick and oil cap periodically.

2. Took out the thermostat so that I could get water flow through the engine. I did this after getting the initial crap out of the system. The thermostat helps to heat up the engine to loosen the crap.

3. I fed the reservoir hose water while slightly cracking the radiotor drain plug. This helped me overflow the reservoir so oil/coolant would come out the top and so the radiator would get some flushing too.

4. I unscrewed the drain bolt near the rear of the engine facing the firewall. This is to drain some crap from the block.

5. Also, I put everything back (except thermostat) tight and pulled out little red air screw on radiator hole and watch tons of crap come out of that for over 3-5 minutes.

6. I play games like leave the heater on full blast and run the hose out of the reservoir when the engine is warmer.

(i will get crap from car people about this, but I even used a commercial grease cutting all purpose cleaner, which help tremendously inside the engine cooling system.)


I repeated the steps above (except oil change) often. I'd drive the car up the street and back and do it again.

Morning, noon, and night I would do it. Quick errand to a store, come back do it. You get the point.

Finally when only water was coming out of my cooling system, nice clean water no more oil floating around, I decided it was time to fill the car with coolant, distilled water and change the oil and filter one more time to get anything out.

NOTE: Engine always ran, and runs great. No sluggish feeling etc. This is what made it tough to think it was an engine head gasket leak or anything else. So I ruled this out temporarily. 

Well geez, no water buildup in my engine through all that cleaning. Little drives to the store. 10 minute idle session. Great it must have been a fluke, just a one time thing. Right?
It must not be common I think to myself. No one else with the same problem.

So I'm driving the car daily for over a month checking the radiator cap every day. I'm getting used to my car again. One day, a month later I see white stuff on the ground, this time even more. I'm pissed off. All that work all that cleaning.

So I start the process again, determined to find where it's coming from no matter what. Then one day I wake up and have an epiphany, it's the oil cooler. Makes sense the water and oil meet here, it's outside the engine.

So I buy special tools and remove this thing. I look at it closely. Never been hit by anything. I look in it. Cant see anything it's too dark. So I pressure test it, checks out ok, but hey it should it's designed to flow not hold pressure. PICTURE BELOW show oil cooler with two black hoses going into it. I bought my tools at harbor freight. Need narrow shaft extensions otherwise you cant get the hex on there, because there is no clearance.

So I call the dealership. They want $250 for one. Now its worth it if it's the problem. But I don't know for sure. So I put it back on and clean out the system again. Not as good this time because I've lost some hope. But I watch the car closely for days. And yep it does it again but way less because I'm checking it very often. I did this to buy time. The recycler near my house wanted $230 for it used. So I waited until someone on Craigslist was posting an s40 for parts. Boom, got one for $60. Put it in, and have never had a problem since.  Cleaned up everything and back on the road.

SIDE NOTES: I had actually gone to the volvo recycler. new used engine was $800 bucks with 40K on the clock. Also, I did make a call to a local independent volvo dealer and he was telling me how the volvo engines with the way they form the blocks now using much better metals then they did 10 years ago, that the chance of the block cracking were far from non. Even with cold water from a hose running through it. He said, MAYBE if you were flooring it on the freeway, just go off, opened the hood and stuck cold water in the engine you could have a problem.

Thanks to that guy.

This is a rare leak hope it helps someone. If so say thanks. It's nice to hear.