Rather than looking for an opinion on what the root cause might be, I'm hoping someone has actual experience or knowledge of a similar failure.The

I'm getting exhaust gases into my coolant. New tank, new cap, newer water pump. Tank shows signs of escaping coolant at the cap. Also now leaking at the water pump. Coolant reeks of exhaust, and a chemical test shows exhaust in the coolant.

Oil is clean. Coolant is clean; it just smells like exhaust.

A very respected indy shop gave me an estimate of about 2700 before considering any required head work. They also said that head gasket failures of this generation of engine are rare, and it's possible there's a failure of either the head or block.

At least one Mini parts supplier has rebuilt engines, but at costs well above 3500.

I could have them tear into the engine and see what's up, but that probably means a $1k bet that there's no major issues.

Anyone gone through something similar? What did you do?

thanks.

 

With coolant smelling like exhaust, there should also be coolant losses thru the combustion process, is there? Maybe check the spark plugs for an exceptionally clean one? Might even find coolant in one of the chambers. Compression leaks into the coolant will also cause your pump and tank leaks. A compression test should also show at least one bad cylinder. None of these checks / tests require serious labor. If you don't have access to a compression tester, you can get one at any auto parts store, just take a spark plug with you to ensure you get a kit with the right sized adapter. Also note that the spark plug needs a "special" socket wrench. If you're not mechanically inclined, a real mechanic that works Mini's should have the stuff needed --- 1 hour maximum labor.

With luck, you only have a bad head gasket. Without luck, the block and / or head is shot. Either way, the fix will require the head to come off --- big labor bill! The $3500 quote is about right for parts cost --- no comment on labor costs. An '08 MCS is probably due for an engine replacement, depending on mileage, driving habits, etc.

My recommendation is for you to evaluate the cylinders as I suggested above. If you find signs of coolant, don't mess around with finding exact failure, unload it. The N14 engine isn't worth replacing, unless you want to start building a highly modified performance car.

Here's a link to my re-build thread --- https://www.northamericanmotoring.co...s-phoenix.html --- It has a pic of a blown engine with the head removed, and shows the coolant jacket around each cylinder. It's compared to a "strengthened" cylinder wall.

Disclaimer --- I'm a shade-tree mechanic, retired from the world of manufacturing, and hi-performance cars are my hobby, not a source of income. So, I'm not in disagreement with your sources, just suggesting you try a bit of fault isolation yourself. Best of luck ---

 

We see this all the time and it is kind of a gamble. If it is just the head or gasket it will be less than half the new engine. If it isn't then you end up needing an engine.
If it was in my shop I'd pull the head and go through it and check for cracks. Normally we don't see block failures so likely it is in the head. But no one can say till it's apart.

 

I recently had the same thing. My used, replacement engine came with a bad head gasket. Yipee. Same symptoms. Very slow coolant loss, pressurized overflow tank when fully cold, coolant smelled like exhaust and the chemical block test showed combustion gasses in the coolant.

Just got done replacing the head gasket and everything seems normal. I "machined" the head myself (big sheet of 3/4" thick glass and sandpaper), replaced the valve seals and installed a Elring Klinger headgasket.

 

Thanks! That was the kind of info I was looking for. I also talked to a BMW tech, and got similar feedback.

I'm going to try and talk my wife into keeping the car long enough to let me take the head off and get a good look. However, she's so hacked at BMW right now, it may be gone at any time.