Engine Replacement - Advice or experience?

[ahager]

I have a 1990 535i with a manual transmission that needs a new engine; the current one runs, but is nearing a time when it is going to need some significant attention including a head gasket replacement, and whatever else makes sense to do at the same time. I am thinking about purchasing a new rebuilt engine and am looking for feedback and experience from anyone else who has don this from where you bought the rebuilt engine to putting it in the car.

I am an "experienced" shade-tree mechanic and feel confident about "replacing" the engine but I would NOT consider myself qualified to rebuild one. THANKS IN ADVANCE!!

Andy
Boston Area

PS - I have a VERY SIMILAR condition with a 1984 e23 and will be posting a similar message there. Both are high mileage and I want to keep both.

[Kalevera]

I'm not normally one to question abilities, but if you're an experienced shade tree mechanic, then you'd know that a failing M30 head gasket is hardly a reason to replace the engine. In fact, it can be done in a few hours without much work at all (even without removing the head or intake from the car). M30s die from abuse, not wear. A little top end work is expected around 200k.

If you buy an engine, get it from the dealer. I can't think of an operation out there that knows how to build them correctly, en masse, that will ship to your door. You'll also have a 2 year, unlimited mileage warranty.

best, whit

[ahager]

Dude ... if you know of a ways to repalce a head gasket without removing the head, I would sure be interested in the procedure. Thanks in advance!

[Kalevera]

I committed a bit of an amphiboly there. The head still needs to be removed from the engine, but it can stay in the car, and the intake can remain bolted to the head. One can get enough clearance to replace the gasket with a little work. Obviously, if the head or block are warped/cracked/otherwise compromised, the head or block have to come out of the car:

- Disconnect battery, pull intake plumbing to throttle body.
- Disconnect exhaust at manifold outlets, drain coolant.
- Disconnect coolant hoses from thermostat housing, pull two hoses from hangers under intake.
- Remove M8 bolt securing intake to block, disconnect throttle and cruise cables and bracket, disconnect vacuum take-off for brake booster, disconnect fuel send and return lines at the intake where they meet the metal fuel rail lines.
- Set engine to TDC/pull cap/rotor/wires, disconnect CPS harness connector, remove upper timing cover, and pull chain cog after detensioning the piston.
- Disconnect engine wiring harness at the starter, 02 and charge harness connectors, and charcoal canister purge valve. Remove the lead from the starter terminal running to the positive charge post. It may be necessary to pull the harness completely from the fuel rail, depending on how brittle and stiff it has become over the years.
- Pull valve cover, remove head bolts.

Now, the head can be lifted enough to adequately clean both surfaces, clean the heck out of the bolt holes, check for any damage, and seat a new gasket. You can probably get away with disconnecting fewer things on the intake side, but we're after maximum clearance here. Buy new head bolts. And don't forget to clean the heck out of the two surfaces and bolt holes. The thing needs to be clean and dry. The only thing more important is torquing the head bolts correctly and setting the timing when putting it back together.


best, whit

[genphreak]

Dude ... if you know of a ways to repalce a head gasket without removing the head, I would sure be interested in the procedure. Thanks in advance!Nope, but look on the bright side, a gasket kit is only $100.

Tools, procedure, liquids, time and effort are the only trouble. The learning comes free and info from board members is free if you ask nicely. There are plenty of write-ups around if you do searches on this board and its archives. :) Nick

First thing to do is plan, get everything together and remove the valve cover- see if anything else needs to eb changed at the same time- ie worn cam lobe or rockers, etc. Just post good pics of them all and we'll tell ya if they look alright or not, that way you can avoid changing a gasket on a motor that has unforseen wear or other troubles...