Tell tale signs of a warped head.

[Dogbox]

I bought an M20B25 from A local BMW parts dismantler to swap into my e21 323i, and it leaks oil+coolant from the very front and very rear of where the head sits on das block. It leaks PROFUSELY from these points. It also burns oil and coolant. Without having the head actually off the block, what are some other tell tale signs of the head having warpage. I will be pulling the head off over the weekend and will post results from that+pics after I inspect it.

[smooth]

I guess you could check compression and/or leakdown. But it doesn't seem like there's much of a question in your case :O

[FrantiC]

Hope you got that for damn cheap, Sounds like it's F'd.

blown headgasket?

[Dogbox]

I am hoping it is just the head gasket and not a warped head, but if it is, so be it. The place I got it from gave the engine a 90 day warranty which is still valid and they said they would cover anything that is wrong. Believe it or not, compression is great, a solid 220 across the board, so I don't know what the deal is with that. I am hoping to maybe score an 885 head out of this ordeal and get it worked for higher compression . The engine starts eagerly, it just smokes and runs a little rough.

[smooth]

the head on there should already be an 885 and you've already got 220 psi across the board...what are you trying to accomplish?

the oil seepage doesn't alarm me because I have 180ish across the board and mine seeps oil from the HG. I think I read it's a common issue on the 325. The coolant is concerning, however. I don't know, dude, the answer to your question is that the only sure way to test a warped head is to pull it off and test it.

None of this is going to net you a new head, though. You just shave the head for flatness. If you want to work your head, just pull it and do the one you have. But I don't think you're going to get any performance gains.

[FrantiC]

They don't shave a warped head. They head it and use clamps to flatten it at each end and keep going until the straight edge shows it's more flat. Then they mill it.

[smooth]

oh my bad, my point was that warped heads aren't always unfixable.
it's not an automatic head freebie.

and I thought he said he wanted to change his compression, so I thought that you do that with shaving the head. do you have to do all of what you said until it's true and then shave it?

[FrantiC]

Yeah I would think so. I used to work in a engine specialist shop doing working in the head department disassembling heads for repair.

Ones that had overheated and warped where checked with a straight edge, Then they have determined points of where heat must be applied with a gas torch. They heat the points, clamp the head flat at each end and continuously check it until it is flat again. Then they mill it.

If its warped and they just mill it, Then the head is still warped and bent somewhere, So the camshaft might not sit properly, some combustion chambers might have lower compression than others due to the head being shaped like a banana then shaved flat, So like the outside ones don't get milled so much yet the middle ones do or whatever.

TBH I don't know why, but it makes sense. Straighten it then mill it..

[Shadow86325e]

I'd take it back and save yourself some trouble, tell them that it leaks coolant and oil and get it swapped out with an engine that doesn't.

[Dogbox]

The thing does not seep oil and coolant, it spills it like a cut vein and burns both eagerly. I am going to begin pulling the head today and I need some tips on what to look for. I would take the whole engine out and trade it in if the bottom end wasnt so solid and I had a shop to do it in instead of my driveway. The place I got the engine from said they would give me another head if the one on this engine is warped.

Stupid question; can you use head bolts twice or can you not?

[FrantiC]

No, You cannot. They are torx headed "torque to yield" meaning once you have torqued them once, They cannot be used again.

[Dogbox]

Yea makes sense, thanx. Anything else that I should look out for? Oh and what are the Torque specs on the head bolts, exhaust mani. studs nuts and intake mani. stud nutz? What size Torx socket do I need?

[Dogbox]

Bump. Still need the Q's in the last post answered thanx.

[FrantiC]

You will have to search the exact numbers. I think its 30ft/lbs then 2 90 degree turns.

[1988 325ix]

Most of the time heads on M20's don't warp they crack in the valve train.

Do a comp test, leakdown is only good for valve seating/sealing.