Rebuilding M52

[Rdannyr]

I went to the junk yard and came back with an m52b28. It was an impulse buy seeing as they were having a %50 off sale.
I've never pulled an engine or done a swap before but I'd been doing a lot of research.

But since its a junk yard motor I want to refresh it or at least the head. Doesn't anybody have idea how much work I should put into it. Is just head work enough.

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[jph]

Start with a compression test if you can to see if everything is working properly and the cylinders are holding pressure. If they are and you want to pull the head then go for it. Pulling the head will give you the chance to check out the cylinder walls as well to see if something is coming due. I would, at a minimum, check/replace the connecting rod bearings. Remember all the bolts in the bottom end that house bearings are one-time use due to their torque-to-yield design!

BTW, how many miles did your engine have when you pulled it?

[Rdannyr]

Unfortunately i was not able to check. but i figured for $200 It was worth it.
im not looking to add power just make sure its reliable. so if i was to take it apart what should i ask to be done? thank a lot and sorry for the late reply i didn't seem to get a notification.

[jph]

Unfortunately i was not able to check. but i figured for $200 It was worth it.
im not looking to add power just make sure its reliable. so if i was to take it apart what should i ask to be done? thank a lot and sorry for the late reply i didn't seem to get a notification.

Really depends on how far you take it down. If you're set on pulling the head I would bring it in for a decking and pressure test and have them pull all the valves and mic them out for trueness and make sure they're all in spec. The should also replace the valve stem seals ($100 for OEM parts here) and do a three-angle grind to factory specs when reinstalling them.

You can take a look at the cylinder walls once the head is off and see if there are any unusual wear patterns. If the factory crosshatch is still intact then chances are the bores are in decent shape. Any areas where crosshatch is worn smooth are suspect and should be checked for spec by a machine shop. I would pull the rod bearing caps and check for bearing condition. Buy a full set of 12 OEM rod bolts to replace them with as they are one-time use. If you decide to pull the crank and replace main bearings and/or piston rings you best be ready to spend some $$$ on getting it built back up correctly or you may find yourself pulling it all back apart again in short order. My advice is not to pull the bottom end apart for anything more than a visual inspection of the rod bearings if the cylinder walls look good. If the rod bearings check out ok then chances are the crank bearings are in similar condition. Have the head serviced and checked out and replace the head gasket and drop the motor in.

I myself bit the bullet and tore down a perfectly good motor to the bare block because I'm OCD. My engine rebuild is going to cost me north of $4k because damn near everything is getting replaced and the machine work alone for the block and head is going to run me about $1k. All new bearings, pistons rings, timing chains and tensioners, etc add up VERY quickly to staggering figures. Be more reasonable than I was. "If it ain't broke, don't fix it" fully applies in the case of freshening up these BMW engines. Some things just make sense to replace while you're in there like the valve stem seals, etc. Bearings and rings are another story! The bottom ends on the M50/52 & S50/52 are rock solid in most cases unless the engine saw oil starvation or overheating.

[Rdannyr]

Thank you very much that's all I wanted to know you we're very helpful :)

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[jph]

No problem. Others may be able to offer more guidance as well. Best of luck to you and you can always PM me if you want to talk more.

[4DR_Lou]

When I used to live in central valley California, there were countless M50, M52, M54, and M60/62 laying around at the pick and pull near where I lived. I would have pulled one myself, but it was 100F and above outside and only a few cranes available. I'll give it to you for pulling that thing out! good luck with your find! For me, I decided to go the easy way via donor car :]

[NotJesus]

What tends to happen when bottom end bolts are re used? For example I've heard of people removing a big end bearing cap to remove the oil pickup bracket for an e30 swap, and re using those bolts. Is torque stretch so much that it would cause issues?
Not that I'm promoting this at all, just out of curiosity.

[Northern]

Some people will just bend that bracket back and forth until it work hardens and snaps, then you don't need to remove the bolts or deal with swarf from cutting it off.