I have a 2020 F56 JCW with 37k miles on it. I dropped my car off at Dinan (they were going to use it to develop a tune for 2020+ JCWs). A couple of days later I get an email saying that my car failed the initial health inspection, and although I shouldn't notice any drivability issues they can't use it for development. They said the following: The Mini received an engine health check that consisted of a visual check of the cylinders walls, piston and cylinder head with a video borescope. It was noted that in a few cylinders there was high carbon deposits on the piston face and around the crown of the piston. This could be due to worn piston rings, PCV issues or worn valve guides or seals. Fresh oil was seen leaking down from the valves indicating a worn valve guides/seals. This correlates with the high carbon deposits in the cylinders.

A Compression and leak down was performed and the results match the visual inspection. Compression test showed Cyls. 1, 2 and 4 are with in 6% of each other. Cyl. 3 was low and more that 25% off. A leak down test reiterated and showed there is more than 25% leak down. The leak down test showed that the majority of the leak was moving past the piston rings. We have seen this could be from worn rings, ring lands clogged with carbon and not allowing the rings to move and seal or The rings could lost tension due to high heat in the cylinder.

I completely understand why Dinan rejected my car, and I appreciate them bringing these issues to my attention. My question is, what should I do about these issues? My factory warranty expires in 6 weeks, and there are these signs of a serious problem coming. I talked to the mini dealership and they said since there has been no CEL it probably won't be covered under warranty. Does anyone have knowledge about what amount of compression loss is required to trigger a fix under warranty?

 

Drive the car extra hard for the next few month to try and exaggerate the issue to get warranty coverage?

 

Couple of things...

Fresh oil leaking into the cylinders from the valves is quite something. The valve stems and their seals are not submerged in oil with the engine off or running.

A cylinder with compression down by 25% I'm surprised there is not a CEL due to misfires.

Has the engine been manifesting any untoward behavior? Using oil? Smoking? Down on power?

I think given the conditions the inspection found are rather bad but with no CEL or other signs (at least you mentioned none) of a sick engine I think a 2nd opinion is called for.

 

that's horrible. a new engine should be really really really easy to get from BMW. That engine, with a few forged parts, is so ubiquitous to BMW. Plus, Mini makes them the most profit per work unit in their lineup, we should get fantastic warranty service.

 

They're have been no other issues. No burning oil, it runs great, the CEL has never been on.

 

The mini is at the dealership now for a compression test. I'm just waiting to hear what they have to say.

 

Compression test came back #1 - 210psi, #2 - 200psi, #3 - 180psi, #4 - 200psi. I do not want the car to have a problem, but if it does, I wanted it to be significant enough show up and get it done under warranty. I talked to the service manager to see how off the numbers had to be, to be a warranty issue, and he said the numbers did not matter at all. He said that even if #3 had 0psi, until the CEL comes on it won't be covered by the warranty.

 

That seems like a response (dealer's response) from an unqualified service manager. At least you have verified premature wear.

 

No MINI experience (thank goodness) and my experience with other brands of cars is 2nd hand -- what I gathered from talking to the techs -- but pretty much no CEL or no clearly untoward engine behavior no problem. That's not the tech's decision but what the factory requires before a possible warranty claim can be filed.

With the compression down on #3 I wonder if the misfire readiness monitor test is complete? Or even if there is any pending error codes...

 

Not true all the time, there are instances where a engine can be low on compression, exhibit rough running, but not set a CEL. Give them the complaint the engine runs rougher than normal, and they cannot ignore the reason why.

 

They absolutely did ignore it.