S52 Rebuild Progress

[MyE30]

I have a S52 that has nearly 178k miles on it. Although the motor runs great, it leaks significant oil. So I am rebuilding it and putting the motor into my E30. Through some research, it seems that it's not really common practice to rebuild these motors. Just not documented, cost or the fact that these motors are over engineered and last forever perhaps? Either way, I plan on putting at least 150k+ miles on this motor so I am attempting to reset the clock. Here is my progress so far. Hope everyone enjoys the pics.

miles when motor was pulled


in its home


pulling the S52 out



valve cover off. not bad for nearly 178k miles


head off


pan off


main bearings look brand new. the rod bearings are shot though and definitely need to be replaced (sorry no pic). going to replace all main and rod bearings.


going to have the head cleaned and valve job gone and the block will be cleaned and honed.



I will update with the more pictures soon.

[berlow94]

Looks great! I have a fully blueprinted S52 in my track car. IMO S52 rebuilding isn't too mainstream because all of the guys looking for huge power just go the S54 or V8 route. With that being said, the power my motor makes, and more importantly the throttle response, is amazing!
What cam's are you going with? what valve grind? Pistons?
Here's the build thread for my car: http://www.r3vlimited.com/board/showthread.php?t=283622

[MyE30]

Looks great! I have a fully blueprinted S52 in my track car. IMO S52 rebuilding isn't too mainstream because all of the guys looking for huge power just go the S54 or V8 route. With that being said, the power my motor makes, and more importantly the throttle response, is amazing!
What cam's are you going with? what valve grind? Pistons?
Here's the build thread for my car: http://www.r3vlimited.com/board/showthread.php?t=283622

Thanks! I never though of it that way about the S54 and V8 options. I guess it's because I always felt the S52 was such a direct fit.

The head just received the factory spec refresh 3 angle valve job. I am retaining the stock cams and pistons. The pistons all measured in at 0.040 clearance which I have had the skirts coated with PC9 and replaced the rings. In short, I am basically rebuilding the motor to factory specs because this car will be my daily and HPDE.

Your build is amazing!

[MyE30]

All the parts that will be going into the motor

[AwakenNoMore]

All those parts look like Christmas to me! How much is this rebuild costing you? If you don't mind me asking.

[AndrewBird]

Looking at the bearings won't tell you if they are worn. You need to plastigauge them to see how much clearance there is.

Honestly though, they are only $100. Just replace them since you are in there anyway.

[berlow94]

Good stuff! Can't wait to see the outcome!

[MyE30]

All those parts look like Christmas to me! How much is this rebuild costing you? If you don't mind me asking.

I'm a little embarrassed to say...I'm into the rebuild a little over 2Gs right now, only because 90+% of the parts are genuine BMW parts.

Looking at the bearings won't tell you if they are worn. You need to plastigauge them to see how much clearance there is.

Honestly though, they are only $100. Just replace them since you are in there anyway.

I agree with you 100%. I was simply stating the visual condition of the bearings (for 178k miles they look great). I also stated I would be changing all main and rod bearings in the same caption. The new main and rod bearings are picture in post #4; see the white boxes in the lower left corner of the pic?

[Dphraner]

Hey, looks good. Are factory s52 pistons dished? they look like they are dished in the pics. Im doing a rebuild on a m52 and it has flattop pistons. im just wondering maybe its the angle of the photo.

[MyE30]

Yes, you are correct the S52 pistons you see in the picture are dished.

[MyE30]

Had the block cleaned, magnafluxed, and honed. The deck was verified flat so no need for a resurface.



Had the pistons skirts coated with PC9 and the rod bearings coated with PPM dry lubricant.


The whole rotating assembly received a nice balancing. Surprisingly, all the pistons/pins weighed the same and the dampener was good.
Crank balanced and journals micro polished as well.


Rods balanced; two big ends and three little ends need some material removed.


Flywheel and pressure plate balanced together; painted for reassembly reference.

[kendogg]

Looks like a great build. It's nice to see somebody take this approach. No surprise the pistons were perfect, BMW puts a LOT of care into these engines. I am surprised the rods needed a little work though. Who balanced the crank? As far as I'm aware, not many places in the US can balance a BMW crank, since they're so long and needing to be treated as a flexible rotor and whatnot. Regardless, unless they're scored, they never have issues either.


FWIW, dampers are pretty cheap. I'd consider replacement anyways. With 175k miles, they go thru heat cycles. It's not like an 8500 RPM S54, but.... Also, are you planning to replace all of the timing chains and gears?? I'd highly recommend it.

[MyE30]

Thanks. BMW really does put a lot of care into their motors. As per the TIS, BMW has an allowable +or- 4 gram weight deviation for the connecting rods. Maybe that's the reason why my rods needed some small adjustments. I don't believe I saw any weight deviation limits for the pistons though. Being they are manufactured by Mahle, they are probably balanced from the factory.

From my understanding, inline 6 cranks were balanced in the same manner. Could you point me to some sources for my own education? Hopefully, SDEB took care of me and my rotating assembly.

I did price the vibration damper initially when I was ordering all the parts for the S52 and the best I could find was over $600 for the genuine part. Yes, I have all new replacement chains and a new crank dual sprocket.

[kendogg]

Thanks. BMW really does put a lot of care into their motors. As per the TIS, BMW has an allowable +or- 4 gram weight deviation for the connecting rods. Maybe that's the reason why my rods needed some small adjustments. I don't believe I saw any weight deviation limits for the pistons though. Being they are manufactured by Mahle, they are probably balanced from the factory.

From my understanding, inline 6 cranks were balanced in the same manner. Could you point me to some sources for my own education? Hopefully, SDEB took care of me and my rotating assembly.

I did price the vibration damper initially when I was ordering all the parts for the S52 and the best I could find was over $600 for the genuine part. Yes, I have all new replacement chains and a new crank dual sprocket.

Here's a couple I found with a quick Google:

http://forums.bimmerforums.com/forum/showthread.php?888173-HELP-TDC-mark-is-off-WTF-Any-ideas/page5

http://en.wikipedia.org/wiki/Straight-six_engine

And DAMN, I didn't think the TV dampers were that much money. I hope you've got a hookup for parts and aren't paying full retail for all this stuff.

[MyE30]

Thanks for the links. The machinist did mention dynamic balancing and resonance in a discussion we had about the crank. Hopefully, BMW inline 6 crankshafts don't require some magical BMW specific balancing machine. I believe I'm good but we'll have to wait and see.