3.8 motorblock wanted!! - The Unofficial BMW M5 Messageboard (m5board.com)

hessel01 · 8th February 2009, 11:14

Hi, I'm new here at the board since I bought a M5 Touring that ran on 5 cylinders. We got the head off but it turned out to be a whole in the 6th piston

and a tiny dent in the cylinder

. I probably can't fix it with boring up so I think I need a new block, and if possible, just the cylinderblock.

Can anybody help me out because in Holland the 3.8 blocks are extinct!

GoneAgain · 8th February 2009, 12:32

I'm sure I read (translated version) of someone on e34m5.de who put in a new cylinder liner. Don't have anymore details though.

Could a 3.6 block be bored?

farrell · 8th February 2009, 12:58

It's possible to repair one cylinder by line boring the block & inserting an interference
fit repair sleeve with i/d matching o/e original piston size.

This maintains a sensible cylinder wall thickness on the B38 which is getting
pretty thin @ 6mm.
repair pistons size is not recommended to go more than 0.5mm diameter over
stk.

B36 & B38 blocks are not the same due to crank & cylinder head irrc.
That may be supported by different front timing covers externally etc.

Cyrus · 8th February 2009, 19:03

I have a customers Touring at work with 0.4mm over bore. It's noticeably more powerful through the rpm range with it's 3827cc. He has a spare set of brand new pistons if your interested.

hessel01 · 9th February 2009, 17:14

what size are the pistons? Original or also overbore?

Stevie · 9th February 2009, 17:22

Send a PM to member "midnightsun" or his mate "crash&burn". Midnightsun scattered his M5T's engine over about 2km's of autobahn a few months ago, and has since found a few good parts & engine suppliers in germany. His touring now runs a 144k km engine, gearbox and diff.

JED · 10th February 2009, 09:07

Hi Hassel

I currently have a piston and rod set for sale with the above mentioned 0.4 mm overbore. PM if interested.

John

hessel01 · 13th February 2009, 00:37

we've just bored the cylinder today and it's now 0,6 over stk, so the bole is gone now but the diameter is too big!. Now we're going to bore it to 0,95 and put a repair sleeve in so we can install a set of new stk pistons. So the 0,4 overbore pistons are of no use JED, thanks anyway. Does anyone have some stk pistons left over (new offcourse)?

GoneAgain · 13th February 2009, 13:25

Where are you getting the liner from? Who is doing it for you?

I will have a 3.6 block with a damaged bore after my rebuild.

Might think about repairing it for future use.

hessel01 · 24th February 2009, 19:12

The liner is in now and it looks very good! So if anybody know's a pair of stock Pistons for sale let me know! Than i can drive it again in 2 weeks!