help the new guy..

[suprafabs]

whats up guys, just picked up 89 325is 5spd., guy who i picked up the car from forgot to tell me that the car has a 325e (2.7l) bottom end, and the stock 325is head on the motor, also just found out the cylinder 2 has low compression, so my question s kinda like where do i go from here? i dont even know why he would do such combination with that block and head?

thanks

[bimmerjon]

I'm not that skilled when it comes to the M20, either the m20b27 or the m20b25 I'm strictly a maintenance tech but I personally have an 89 325is with original m20b25. Sounds like you got a bit hosed on the deal that the seller left that fact out on the engine but he may not have even known or he was flipping the car, either way you own a great year (No airbag/ Plastic bumpers/ Big tail lights/ sports package/ etc) so its not all a waste.

This mismatch is fairly typical- Bigger bore lower end, more compression from the head? Not sure exactly but its for performance from what I've noticed.

As for the compression issue, it can be as simple as a head gasket. Check around that cylinder for leakage, if there is oil/sludge/dirt and a fairly clean area around it in a streak or line it could source the problem. Use a flash light and an inspection mirror to check. Another problem could be that the spark plug thread in the head is damaged and that can be re tapped and a helacoil can be installed to correct the problem.

I hope that helped. I've been an e30 owner since 2003 and wrenching on it for almost as long and became a certified mechanic last March as a General Automotive Technician.

Remember, when doing head work to replace head gasket, make sure the head is flush using a straightedge, remove the old gasket COMPLETELY and to replace head studs with NEW head studs. The old ones are stressed beyond their original tension and ARE NOT REUSABLE. ALWAYS USE A TORQUE WRENCH AND TORQUE TO FACTORY SPEC-- If unsure with torque specs, pm me or consult the e30 bentley manual

Best of luck! PM me with questions and I will do my best to help :D

[dashboardmonkey]

The motor combo you got is called the "budget stroker" the cylinder bore is the same. The 2.7 bottom simply has more stroke, if it is not the seta then the compression is lower than the M20B25. I have the same setup (eta bottom and "I" head) It's not bad, fun as hell with the 4.10 lsd.

[GT BMW E30]

It is done for little more power. I will be doing the same.