So a couple months ago my car started over heating. I checked the coolant level in the overflow tank and it was empty. I had no exterior leaks so i pulled the dipstick and found that the water was going escaping into the oil. Oil looked like chocolate milkshake. So I proceded to remove the head. Got a new head gasket and took the head to a machine shop to get resurfaced. Asked the man there to check for cracks cause its a common problem for MINI's. He said it was ok and I put the head back on. I started the car up finally about a week ago and my coolant again has magically disappered and was over heating again. Same issue!!!

So what I want to know is it safe to assume that the head is cracked and I need a new head?

Is there anyother way for water to get into the oil? I know about the heat exchanger in the back of engine next to the oil filter can this be the culprit?

If it is the head I found a cooper head a non s head but can't seem to find and s head. I was told it was told that the head was the same with different Valve train.

Can I change the valvetrain at home? Or is this the work for a machine shop?

 

I believe the difference between the two valvetrains is the material of the valve stems. Valve head diameter, CC volume and shape, cam, and porting are the same. If the valve stem diameter is the same (don't see why it wouldn't be), you could in theory, simply switch all the valves. And if you are savvy enough to R&R the head, that will be no problem. My issue with this is that the valves have been running in those guides for the lives of both motors. Each valve should stay with it's guide. You can't really change the guides, since they are reamed after installation because variances in the heads can change the internal shape of the guide. Then the valves will need (at a minimum) to be lapped into their "new" seats. Before doing all of this, I would sooner run the R50 head as-is. I think it might hold up better than a hodge-podge of mismatched used parts. The differing material is to account for a more volatile forced-induction environment. But since you don't actually own the head already, hold out and get the right one. There has to be some good low-mile heads left over from JCW kits, or other custom tuned motors. Unless, of course, it turns out to be the heat exchanger. Good luck.

 

When you had the cylinder head off, did the head gasket have any signs of failure?

If the machine shop said there are no cracks, then there are no cracks. They pressure test cylinder heads.

The only other options for coolant entering the oil are from the heat exchanger or a cracked engine block. If you are not getting white smoke under load, or at any time, then I highly suspect that it is the heat exchanger.


Unnecessary now but...
You could swap out the valve train, but the machine shop would have to regrind the valve faces, touch-up the valve seats, and either drill out or press out/in new valve guides. Aluminum heads have pressed in steel guides, and steel heads have cast/machined guides. Cast must be drilled out and steel inserts can be pressed out, or drilled if they used green sleeve retainer during assembly. We did this type of valve job in my automotive machining course at school.

 

Did you ask the machine shop to check that the head was indeed flat and not warped, or did you just have them check for cracks? I would also suspect the heat exchanger.

 

Ok so im going to try to replace the heat exchanger to see if that is truly the cause. When I took it to the machine shop they pressure tested and checked for warpage. There was very minimal warpage but the head was resurfaced to mate with the new head. There was never and smoke out of the exhaust. Water is not getting into the combustion chamber but into my oil. Im going to try and replace the heat exchanger before I proceed to take the head off all over again.

 

Oh and is there anyway I can test the heat exchanger before replacing it at all.

 

was the heat exchanger the problem? i am having the exact same issues as well... my head/block face looked sound gasket showed no signs of failure, replaced all the gaskets and orings involed with pulling off the head and im still losing coolant and getting milky oil. please let me know if the heat exchanger solved your issue, i just ordered one and im really hoping its going to solve my problem!!

 

Did either of you ever figure this out? I have the same problem with a 2003 R53. Replaced head gasket and totally bypassed heat exchanger (temporarily), still losing coolant, no external leaks.