m52 main/rod bearing diy

[polkadot_boxerman]

I just finished putting a headgasket kit on my m52b28 because I was getting coolant in my oil. I filled the oil up, cranked the car and heard some hissing. Looked under my car and oil was spewing out the back of the engine. I stupidly did not replace the rear main before I put the engine in

My question is. I had a buddy over when we cranked it and he said that it sounded like I had a bad main or rod bearing so he recommended replacing both whenever I'm doing the rear main job.

What's the best way to tackle the bearings. I don't want to pull the engine to do it. anyone have any links? I couldn't really find anything.

I'll be buying:
main bearing
rod bearing
rear main seal (with easy sleeve)
rod bolts

I believe I read somewhere that only the rod bolts need replacing as they are one time use, but I can reuse the main bolts. Can anyone confirm this?I replaced the oil pan gasket when I did the swap 2 months ago, will I need a new one of those also?

thanks in advance guys

[samiam3356]

The main bolts are TTY as well. I would pull the motor if it were me and check everything out good. But I guess m52's are a dime a dozen in Atlanta so if you want to cheap out on it you can always replace it cheap.

torque on the main screws = 20nm with a 50 degree turn after that

Here are the rest of the torque values for the motor. Ctrl F FTW!

http://www.e38.org/bmw_torq.pdf

[polkadot_boxerman]

Well I've already spent enough money between the headgasket kit, chain guides, rear main and everything else. If they are TTY then I'll be replacing those as well because I want to make sure everything is good.

As far as pulling the motor, that isn't a possibility. So I'll be making a makeshift hoist to hold the engine that I saw on an m3 forum.

thanks for the tq spec also

[samiam3356]

Those hoist are cool as fuck. Be careful though man. Thats a lot of weight be held up there.

[polkadot_boxerman]

The main bolts are TTY as well. I would pull the motor if it were me and check everything out good. But I guess m52's are a dime a dozen in Atlanta so if you want to cheap out on it you can always replace it cheap.

torque on the main screws = 20nm with a 50 degree turn after that

Here are the rest of the torque values for the motor. Ctrl F FTW!

http://www.e38.org/bmw_torq.pdf

sweet! I love printing 122 pages worth of torque values at work :D

[samiam3356]

No need. Cntrl f, put in m52 and print the pages that show up. Btw I have a folder with every page as well. :)

[mentaleeill]

are you gonna check the tolerances with plastigauge or mic torqued bearing size and journal size, or do you just plan on winging it? there's no guarantee that an off the shelf bearing is just gonna work, they offer standard, or oversized incase the crank needs to be cut. if the tolerances are too loose/ or tight, you'll have wasted your time, and be doing it again shortly.

i highly recommend doing this on a stand, much easier.

[polkadot_boxerman]

Judging by the condition that the engine was in when I got it. I doubt that the previos owner ever did any engine work whatsoever. If the crank was never taken out and re-ground wouldn't that mean that I don't need the oversized bearings?

[The Humjet]

It means you will need oversized bearings meaning they're thicker than stock. If you really want to do it in the car suit yourself I'd much rather prefer doing it all on and engine stand. So you car really see what's inside your motor. If your bearings a fucked how will you know the rest of the motor is in ace condition.
Either way, the way I'd go about it is pull out the crank, rods and pistons. Inspect them all, if all is good then I would replace the bearings with the same size it came with. The size should be stamped on the outside of the bearing shells. The bearings I work with will say std meaning standard. 010 meaning .010" oversize etc. I'm not sure what bmw bearings say since I've yet to open one up. But I'm pretty sure they have to have some sort of indication or else that is plain stupidity on BMW's end.

Also forgot to mention. Don't mix anything. Main caps should have the numbers and arrows marked into the castings if not label them along with arrows pointing in the direction they were faceing. Same thing applys for big end caps. DON'T MIX THEM UP. I'm sure you know at least the basics of engine reconditioning if you have the courage to reco the bottom end yourself. I'm just telling you just in case. My first day as an apprentice I mixed the wrist pins and pistons up right after they were balanced. I can never forgive myself for that.

[polkadot_boxerman]

It means you will need oversized bearings meaning they're thicker than stock. If you really want to do it in the car suit yourself I'd much rather prefer doing it all on and engine stand. So you car really see what's inside your motor. If your bearings a fucked how will you know the rest of the motor is in ace condition.
Either way, the way I'd go about it is pull out the crank, rods and pistons. Inspect them all, if all is good then I would replace the bearings with the same size it came with. The size should be stamped on the outside of the bearing shells. The bearings I work with will say std meaning standard. 010 meaning .010" oversize etc. I'm not sure what bmw bearings say since I've yet to open one up. But I'm pretty sure they have to have some sort of indication or else that is plain stupidity on BMW's end.

Also forgot to mention. Don't mix anything. Main caps should have the numbers and arrows marked into the castings if not label them along with arrows pointing in the direction they were faceing. Same thing applys for big end caps. DON'T MIX THEM UP. I'm sure you know at least the basics of engine reconditioning if you have the courage to reco the bottom end yourself. I'm just telling you just in case. My first day as an apprentice I mixed the wrist pins and pistons up right after they were balanced. I can never forgive myself for that.

thanks for the advice. The friend helping me actually graduated recently from a local auto school so I should be fine with his help. I'm just trying to do some research before I tackle the job and make sure that there isn't anything bmw specific that I need to know.

As far as knowing if the rest of the motor is in nice condition. The car drove great before I replaced the headgasket. the problem is, the rear main seal.

When I drove to my buddy's house to to the HG job, when I pulled into the driveway I looked under the car and my car looked like it emptied every bit of oil out.

The problem is I don't know how bad it was leaking on the drive to his house. So if it drove with low oil/oil pressure that could cause the bearings to go bad.

So that, with the noise heard once the car was cranked lead us to believe that the bearings need replacing.

hope this makes sense

[The Humjet]

Was the rear main seal badly worn or wansnt it installed correctly? I guess its just bad luck. Let's all hope you'll only need to replace the bearings. If dropped oil pressure then the low oil pressure light should've come on? That would've caused a whole lot of problems.

[dirty30]

Just buy a known good block, OEM dealer main bearings will run you about $450ish plus a line bore, crank runout check etc... not worth it.

[328ijunkie]

Pull engine. Youre gonna have a lot of fun trying to do bearings upside down. You need to accurately measure tolerances and stuff which you cant do when the engine is in the car.

[polkadot_boxerman]

Just buy a known good block, OEM dealer main bearings will run you about $450ish plus a line bore, crank runout check etc... not worth it.

$95 for main, $45 for rod from pelicanparts.com

[polkadot_boxerman]

Was the rear main seal badly worn or wansnt it installed correctly? I guess its just bad luck. Let's all hope you'll only need to replace the bearings. If dropped oil pressure then the low oil pressure light should've come on? That would've caused a whole lot of problems.

well maybe I'll just replace the rear main. crank it up and see if I actually hear anything and go from there.