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We are rebuilding a 2013 non turbo Mini with a cylinder head from a 2010 Countryman and a new to us long block from a N16. Everything is supposed to match. New gasket, bolts, temperature gauge, o rings, water pipe,plugs. Head is ok. Hooked up and it is dumping coolant into the oil pan like crazy. We are at a loss on how to proceed. Original head is twisted due to overheating. We tried to fit originally with a thicker gasket and no luck same thing, dumping into oil pan. Any ideas?
Key word here is "supposed" to fit; according to realoem.com, the part numbers for the cylinder head and cylinder head gasket on the N12 and N16 engines are identical. That means all the oil and cooling passages are going to line up. Did you have a valve job performed on the N12 cylinder head before you installed it? Did machine shop plane the head? If not, a thicker gasket is going to lower your engine compression, and that will hurt performance. The cylinder head contact surface needs to be perfectly flat or it will not seal.
Have you measured the engine block and cylinder head contact surfaces for flatness? The spec for the head is .004" (max) of deviation on the longitudinal axis and .001" (max) on the lateral axis. You must also have a precision straight edge to perform this check. If you don't have the tools, a good machine shop can help you.
There's no external oil cooler on the N12 and N16, so replace this gasket (4) anytime you've got the cylinder head removed; it's known for leaking, especially on engines with over 100K miles. This is a point where the coolant can mix with the oil if the gasket has failed.
Be sure to pressure check the cooling system before you add water. This is a good kit (link below): You also need this kit to evacuate all the air out of the MINI's cooling system before you fill it (vac-u-fill). This kit makes it easy and will prevent overheating (damaging that new cylinder head) due to air pockets in the system.
A word of warning about R56 N12, N14, N16, and N18 cylinder heads; they are notorious for dropping valve seats, especially after a valve job; Make sure you get all the valve seats replaced; also, the valves are so thin that there isn't enough margin left when the valves are ground; a good machine shop will tell you that. That means the valves have to be replaced if you don't have good sealing. And don't forget to check the height of all the lifters; the spec is listed on the Rock Auto "info" page for the lifter. The last head I installed had three dropped valve seats, and it got all new valves and lifters, but that engine had over 150K miles on it. I also recommend the ARP head stud kit; it a little bit of a PITA to install the number 1 cylinder head stud nut because you have to remove the #1 cylinder vanos spring (special tool required) to get a socket on the nut, but if the head ever has to come back off, you don't have to change the hardware again.
I know on the turbo models there is a freeze plug in the valve land that can sometimes fall out, which would allow all the coolant to dump out. Not sure if the same plug exists on the non turbo models…
That is exactly what was wrong. I had mentioned to hubby to check for the infamous freeze plugs and he never thought there would be one hidden so well. Plugged it and viola. Started up no leak and the engine sounds fine. Thanks for all your help!
