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M20 Head: Used, rebuilt, or remanufactured?

7K views 5 replies 5 participants last post by  moapys 
#1 ·
First let me explain, I bought this 88 325is with 145k on it (6 cyl. 2.5L). I got a great deal the body and interior are immaculate and there is no rust. The engine had a tap (or steady rattle or something) and it was sitting for 3 years prior to my purchase. it smokes (white w/ anti-freeze smell) after it's warm. I was planning on replacing the head with a used one from my friend's wrecked 325ix until this afternoon, when I removed the valve cover and found this:

3 bearings inside the head that hold one of the guide rails for the rocker arms (on the driver's side) were broken off and sitting next to 3 of the valve springs. (maybe causing the irritable and hard-to-identify sound?)

I have not put it on the road yet, nor done any serious work besides replacing the timing belt.

I was already planning on eventually replacing the head with a remanufactured one, but money is tight right now and i don't want to spend without need. My friend will give me his for a very good price (about $100)

From what I've read you might as well pull off a junkyard (or a friend's wreck) rather than purchase a rebuilt head, but i'm open to suggestion.

Used, as opposed to a remanufactured head for around $1000, seems like a no-brainer... maybe...

I need a second opinion, hopefully a 3rd or 4th too.

(excuse my lousy computer skills i don't know how to get a photo on the post but it's attached)
 

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#2 ·
I would have to agree that for the money you should go with your friends cylinder head as apposed to a reworked one. Especially if later on you are going to do any rebuilding or aftermarket work (cam, valve springs, retainers, 3 angle job, etc.) any way. I say you lucked out with your buddy. Good luck.
 
#5 ·
Hi - I just suffered an "interference situation"; not a belt breakage - but the tensioner-idler shaft shearing...same effect of valve/piston collision.

My question: Beyond the usual bent valves (all intake <?>) and broken rockers (all six intakes <!>), I have one badly nicked piston top. I'd say that the depth is as much as a 1/16" in a few locations.

If I grind/polish out the high spots, is there much of a chance of "burning through" the injured piston? Thanks for your opinions.

Paul
 
#6 ·
Piston dings following valve-dance; how bad it too bad?

Here's a picture of the resulting damage. Opinions are split 50/50 on usable, versus needs a new piston (if not now; eventually)... I guess that I am seeking - beyond folks selling rockers and valves cheap <grin>, which I DO NEED - hearing about anyone else that is running a "concussion victim" piston successfully!

THX:crying:
 

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