Morning all,
So I have a 2012 R58 JCW with about 80,000 miles on it. Bought the car used with plenty of issues and been working through them. A few weeks ago it decided to not start. As I was headed out of town I dropped it off at shop in town to deal with it while I was out. They found VERY low compression in all cylinders and performed a leak down test and said it failed on all 4 with it leaking through the exhaust. They want $4,000 just to pull the head and inspect, so it is coming home and I will tear it apart over the next few months. I am not sure why it would be running one day and then not the next with these type of results. Had no engine codes before hand. The shop believes it to be a head issue. So if the head has to come off, I am guessing I should go ahead do a timing chain.
My question to all of you :
1) what do you think of these results from the shop?
2) any idea why such a sudden failure?
3) If I am pulling the head for inspection/cleaning or rebuild-- what else should I go ahead and do while it is apart? Timing chain and guide and ????????
CYLINDER NO. 1 - 16 PSI
CYLINDER NO. 2 - 12 PSI
CYLINDER NO. 3 - 0 PSI
CYLINDER NO. 4 - 21 PSI

LEAKDOWN TEST RESULTS
CYLINDER NO. 1 - 95% LEAKAGE
CYLINDER NO. 2 - 74% LEAKAGE
CYLINDER NO. 3 - 90% LEAKAGE
CYLINDER NO. 4 - 64% LEAKAGE
LEAKAGE IS PRESENT IN EXHAUST SYSTEM WHEN VALVES ARE CLOSED AND PISTON AT TOP DEAD

 

Sounds like you have the dreaded leaking cylinder seals (the head exhaust/intake valves). The oil is burned inside the combustion and builds up garbage on the valves which causes them not to seal off, hence lose power.
4 grand to look inside engine, is high. You could pull the head and install a rebuilt one yourself. The top of the pistons will need carbon removed no biggie. MEK and 3M scruffie pad will clean off carbon. Once you pull head you can see if the piston wall look OK, too. Mine were fine, the head sucked.

 

I would re-do the test. Can't see how it was driving one day and then produced these compression results the next day.

 

I signed up here in order to ask the EXACT same question. We have a 2010 S, about 135,000 KM's on it, had been running just fine, no codes, until one day it didn't start. Tried a couple things but figured I'd have a friend tow it to the local Mini for some diagnostics. Exactly the same result as yours, very low compression on all cylinders and leakdown test showed similar #'s to yours.

They said the next step would be to send it out for machining, would cost at least $3500 for that, and they were guessing that this would only be the start. Mentioned an oil leak that would have to be looked into, but just the labor cost of taking apart, sending it out, and putting it back together was going to be closer to $5000, and no guarantees that it would fix it.

They weren't pushing me to get anything done, quite the opposite actually. Feels like they just didn't want to bother with it.

I have the time and space to try to make some fixes myself, so that's my plan. I'd be very interested in your progress!

 

I just completed rebuilding a base mini. Very impressive info discovered here that help me accomplish job. I bought a remanufactured head from a city a few hours from home, which saved me $400, plus shipping core return. Once I got inside under cylinder head I discovered cylinders were in great shape. In way better than ahape cheesey scope camera made it appear. You can check your cylinder bore with a new ring. You don't need special tools. Stick the ring in cylinder and measure gap. If it's = to or less than .005" roll. All mine were right at 5 thousandth after honing. Popped in new pistons and boom, fired right up. You have to pay attention to all the the shims on crank shaft (the name eludes me), which direction they face. Go off the timing end as reference to which way things face. Car smoked for about five minutes aft start up. Also, put a good Wix filter in it for the break in period (500 miles). Don't use synthetic on that initial oil either. I added an oil plug that has the magnet on it. After first drive, I pulled plug and put my finger over oil pan hole. My wife cleaned off the magnet which had some real fine metal, about the size of those toys that use a magnet to create a beard on a man's face. I have another couple hundred miles to go before oil change.
You can do it if you have the time and patience. Mark everything, tag hoses and bag all parts with their bolts amd nuts. Take a ton of pics. Somebody on this site detailed pulling an engine and he had great information.

 

I checked compression after rebuild and all cylinders were around 200 to 210# compression. I tested them dry, did not add any oil in cylinder before cranking engine. You may be surprised by the shape of you small block cylinders. Trying to find anyone to do the small block work is very, very difficult. No body works on Minis.

 

Well done on the rebuild!

I rebuilt my entire long block with Sneed4 short block in 2019 (see signature) with all new peripheral component (such as thermostat, oil pump, water pump, oil filter housing, etc.). My take on Sneed was his communication was decent. The shipping was spot on with tracking -- only challenge was that I needed to travel 30 min (one-way) to the freight company -- none of which could have happened without solid communication. However, "post"-pandemic coupled with shipping and production delays, and personnel turnover and shortages, who knows what challenges are present these days.

I am patiently awaiting overseas items to arrive, and the delivery date continues to get colloquially "kicked down the road." This all likely stems from a multitude of unforeseeable export challenges between Japan (custom production warehouse) and my door. On the bright side, all of the parts are paid off after 5 months of waiting and will arrive when the weather is warmer in the Midwest.

 

Can't wait until you get it tuned but if you're getting tuned...how about a JCW 41mm or JTMC Super 42 while you're at it??? One of my cams was 180 out and wouldn't crank so we had to tear it back down and correct it so it is very possible to do!!