Greetings R53 owners... I went to pull my supercharger today (time to get it rebuilt) and found my coolant looked like a milkshake. I drained my oil and don't see any signs of coolant in it. Anyone know the the steps to diagnose this? I know the oil cooler and head gasket can cause this... I've replaced both a few years ago. Head gasket is a lot of labor and oil cooler is an expensive part. Would like to get a solid diagnosis before throwing time and money at it. I'm sure this has been discussed many times here and spent some time searching but couldn't find any good info... Any help would be greatly appreciated

- Justin

 

Is there a way to bench test the oil cooler to see if that is the issue? I currently have the supercharger off... wondering if I should just change the head gasket while I have it apart?

 

You can do a simple bench pressure test to the oil cooler.
but...
Unfortunately it won't tell you anything about the gaskets (large O Rings) which can go flat and lose their seal from all the heat. Which is normally the cause of most cooler/oil issues.

While not definitive, common sense says that if it were a head gasket, there would be other signs, for example...
-How are the plugs? If they're super clean? (a sign of them being steamed by coolant mixing in the combustion chamber.)
-Did the car overheat, it's unusual for a head gasket to go without overheating issues first, which could also mean a warped head. (These engines are notorious for Overheating... Warping a head... Losing head gasket seal... In That Order)
if you do decide to do a head gasket, do yourself a favor and have the head checked for true, better that doing the job twice.

Good luck

 

There has not been any recent history of overheating.. I replaced the head gasket 4 years ago after overheating. There was coolant in the oil that time. Took the head to a machine shop and had it checked out and had them do a valve job. I'm leaning towards replacing the oil cooler and gasket/O-rings. Fingers crossed because the head gasket was a job.

 

Milkshake most of the time is that oil cooler. I have my fingers cross for you also.

https://www.northamericanmotoring.co...n-coolant.html

 

Just following up to see how this one turned out (if it has yet). How many miles are on the car / motor?

Full disclosure: considering preemptive oil cooler replacement to avoid this situation in the future. Seems to happen often enough.

 

Ok... Got my new oil cooler.. I'm having a hard time getting the old one off... is there a trick getting to the lower front Bolt? Cant even see it.

 

If you're talking about the oil filter housing bolts, have to remove the two heat shields first. Also would think draining oil, removing the oil filter cover dome (with the 36mm special socket) might allow some additional access to reach down and around from above.

Mod MINI goes over how to detach the oil filter housing to change out the gasket but he doesn't remove the filter. Always wondered why he didn't.

Then on reinstallation he uses several extensions to come up from behind the splash shield area for that bottom bolt:

 

Thanks for posting this topic link. My nest question was going to be how to flush the system. Looks like it can take a while to get all the gunk out. fingers crossed this solved the issue.

 

Yes, you want to get all the residual coolant with its oil out of the system.

With oil in the cooling system think you need to consider using a coolant flushing chemical. You might check with the local MINI dealer parts department to see what it carries or ask what the techs use. And you might have to flush the system at least 2 times using the flushing chemical then flush with just water once then again and this time drain into a clean pan to look for any signs of oil sheen on the water.