I have a customers car here who has oil leaking/accumulating into the cooling system.

Scott (twisted) from New England did a cylinder head gasket on the car in hopes of fixing it, which I myself would have done. He seems to be well established in what he does so I feel the head gasket was done right and this is not the problem. The problem still persists.

I have disconnected the coolant hoses from the factory oil cooler, the see if oil under pressure was entering the pipes...no dice. The cooler is not the cause of the issue.

I remember reading a long time ago of some rare cases or pourous blocks and/or cylinder heads. Can anyone shed any light on this issue?

Car is 2001 with 37,000 miles and is not driven hard.

 

This isn't the first time I've heard of potential porosity problems. Apparently, Honda had a bad run in their castings which suffered form the porosity issues. I've heard about these problems a lot, but have only seen it documented once, here:

http://forums.clubrsx.com/showthread.php?t=735752

Start looking through the last few pages and you'll see the issue and pictures.

 

All of the Honda casting porosity issues I've seen seep oil externally, and non have been on S2000's. Usually getting all of the oil out of the cooling system has been the most time consuming, and the oil cooler has been the cause. How many times have you flushed the cooling system?

 

I havent flushed it. when scott did the head gasket, he even replaced all the hoses.

I guess I could try a flush, but the system was so clean after the head gasket job and a considerable amount of oil has returned.

 

Chris have you seen a factory cooler push oil out into the cooling system? How did you determine it?

I took the coolant hoses off the cooler and hooked them to another s2k cooler and let it just hang under the hood. This way I could run the engine, and watch inside the coolant pipes for oil to appear. After a long idle, nothing.

Perhaps I'll take it out and get the oil red hot and under pressure and see if it forces into the cooler.

Glad to see YOU in my thread man

 

Think I will take the car on an extended drive tomorrow and see if the cooler weeps oil from the oil side to the coolant side.

 

I've seen several other Honda oil coolers (A few Nissans too ) I'd say over the past decade plus less than 3 total. The have been on more pedestrian models such as Accords and Legends. The coolers are built the same. You'd be hard pressed to pick out the S2000 cooler from a Legend.

Multiple flushes to clear the system with the cooler bypassed. Run fresh H20 through the cooler with the engine running, if oil shows up it's the cooler.

If this car had a ported head I'd be suspicious of the port work being to close to a water jacket like the K24 posted in the link earlier.

I've never seen a real Honda (Passports are the exception) with a cracked head and coolant/oil cross contamination. After touring the Lincoln engine plant and seeing the high pressure casting I'm not surprised.

 

I would also flush the coolant system. I use the hydrocarbon degreaser ( the one that turns white when mixed with water) in a 1/3 strength mix. Drive it around for a while then flush with fresh hot water till it runs clean.

The only blocks I've seen leak are from the water jackets to the outside world. You can see a seam/line in the side of the block where molten material flowed from two directions and didn't fuse where they met.

There arent a lot of places high pressure oil can get into the water jackets. First is from the main oil gallery which runs long the bottom of the bores just above the bore squirters. I would look for possible inclusions in this area as cracks in the block could leak up into the water jackets or down into the crankcase. The latter would result in oil into the water but not the other way.

Next opportunites would be in the flow past the head bolt into the head. Once it gets to the rocker assembly there are no more opportunites to get through to water.

You could get a leak through the head gasket into a water jacket. Was the head skimmed? was the block surface checked for flatness around the oil supply hole? A gross overhead can result in depressed areas on the deck.

Most likely opportunity is the oil cooler which Bill is already investigating.

Only way to really tell is a full disassembly and crack test with die penetrant. I would do all the easly stuff first.

Chris

 

Thnaks guys...I wont rest on this case till I find out the cause 100% and post it up.

 

did you find out what was the problem?
i had the same issue. and i also change the head gasket cause i was worried

if i use an external oil cooler, can i bypass the oem one?