Looking for another project car and found one. Scooped up a black on black '12 S hatch with a manual trans to play with. I do have an issue with coolant in the oil and trying to pinpoint if its a head gasket vs. an oil cooler issue. It looks like oil cooler failures are common on these cars, but Id love to know if its possible to diagnose if its an oil cooler or headgasket BEFORE I start the tear down. Any tips?

Pulled all 4 plugs - black with soot from running rich, all virtually the same appearance with none specifically looking washed out with coolant that you would normally see with a blown head gasket in the cylinder, but of course it could be a blown head gasket outside the cylinder in an oil/coolant passage. I thought about pressure testing the cooling system, but that wouldnt definitively tell me which one is bad. No significant smoking from the exhaust or coolant smell, but there is definitely coolant in the oil.

It also seems that the speed of which the coolant goes into the oil is extremely fast, thats why I suspect its an oil cooler. Only codes are for a vanos actuation and boost being turned off, which I assume is related to contaminated oil causing the vanos fault and the vanos fault causing the boost being turned off. Also, any tips for cleaning out the coolant if it is just the oil cooler (I assume just multiple engine oil changes)? I appreciate all of the knowledge and advice.

 

Instant project car!

Have you done a compression check or leak down check yet?

Getting the coolant out of the oil is as simple as drain and fill. Might be worth it to change the filer housing gaskets just because at this point, whether they are the root cause or not.

Another spot to check is the cam area. Apparently there is a freeze plug in the head below the cams that lets go on some cars, and drains all the coolant into the crankcase.

 

COol! thank you for the advice. Havent done anything with the car yet as far as compression and leakdown. didnt want to do anything until I at least drain the engine oil. Can you give me a little more detail as to where the freeze plug is located? Thank you!

 

You can see the freeze plugs in this picture, in between the camshafts -
https://cdn.shopify.com/s/files/1/06...g?v=1628608719

 

are we talking about the two between cyl 1/2 and 3/4? Looks like I might be able to inspect those without even having to take the valve cover off. That would be sweet. Thank you! Hard to believe this is a common (or not unheard of) failure...wow.

 

I would think you'd need a scope to see down in there without taking the cam cover off.

I don't think it is a common failure point, considering how many of these engines have been produced...

 

Yeah the N18 has the freeze plug in between cyl. 2 and 3. That is the one that generally fails. I have seen one oil cooler on the side of the filter housing fail but most of the time its the freeze plug in the head. If you pull the fill cap and power water in the expansion tank and look for it to come out in between those cylinder. more than likely the head is warped, now i did see someone thread it and insert a plug. I probably would deck it just replace the gasket and tighten it back down.

 

took valve cover off. Found the freeze plug popped off. went on real oem to find p/n for freeze plug and it looks like its not available separately. Any tips on how to repair this? Im thinking that re-installing this original freeze plug is probably not going to work although it looks to be in prefect shape. Maybe source another one from another application that is the same size? or tap and thread on a new plug?

 

https://www.vibra-tite.com/retaining...ning-compound/

https://www.permatex.com/products/th.../?locale=en_us

 

how does that work with a press-in plug?

 

It's designed for use with a press-in plug.

There's also Loctite 540.

 

thank you very much! never used a sealant when doing freeze plugs. Learn something new every day! Thanks for the info.

 

I think it's less of a sealant, and more doing a job of retention. However, I'd still take care to spread an even layer all around both surfaces.

 

well, The good news is that the replacement plug i used holds pressure... Bad news is that I think head gasket has gone bye bye. I flushed the cooling system and the oiling system and while Im not getting any oil/coolant mixing, it does seem that the cooling system is getting pressurized. Strange that the car runs ok, all 4 plugs are evenly carboned (as are the piston tops), but I do get bubbles in the cooling system when running requiring constant bleeding. Looks like I may have to do a head gasket now. Any special timing tools required for this job?

I see that a slightly thicker 1.20mm head (+0.3mm) headgasket is offered (I assume for people that needed to machine the head). Is this what is recommended for a blown headgasket on the N14? Also, Im assuming I will need replacement head bolts. Any concerns with the block being warped, or the threads pulling out of the block like the BMW blocks when they get overheated? Thanks for the continued help!

 

anyone done a head gasket on a n18? or is the entire engine usually shot when overheated?

 

bump