Swapping m42 engines, need advice

[Victell]

My 318is has a blown head gasket or worse. I will be swapping a known-good m42 from a donor car in order to get back on the road as soon as possible. My buddy is letting me borrow his 2-car garage for the swap so thats another reason to finish quickly. In the interest of minimizing potential issues and time working I need advice.

Which is easier, pulling the engine out by itself or pulling the engine and trans assembled as one unit? The pros and cons as I see it:

Pull engine alone
+ pro: only have to remove downpipe portion of exhaust
+ pro: easier to maneuver than engine+trans together
- con: may have difficulty mating engine and trans back together in the car

or

Pull engine and trans as one unit:
+ pro: don’t have to worry about getting engine and trans mated back together
- con: have to R+I exhaust, heat shields, driveshaft, shifter, clutch slave
- con: more difficult to maneuver

Ive never pulled an engine or trans on e30s. But on other cars I've been stuck and had hours of frustration trying to get an engine and trans to mate back up in the car. Sliding the trans input shaft through clutch disc and into the pilot bearing can be a bitch sometimes. Ive never done it on an m42/g240 but am worried it could be the same or worse. What should I do?

[bmwman91]

Engine + transmission together. Get a load leveler for the engine hoist. I got this one and it made the whole deal a lot easier (also, you can't do it without one).

https://www.harborfreight.com/3-4-quarter-ton-capacity-heavy-duty-load-leveler-67441.html

I have also done clutch jobs a few times, and getting the G240 on/off is not too bad if you are in decent physical shape. As long as you get the clutch disc aligned with the pilot bearing, it is simple.

Either way, as I assume you know, do not let the input shaft bear the whole weight of the transmission. Support it with a jack or a friend while undoing the last couple of bolts.

[Victell]

Engine + transmission together.

Is it that hard to put the engine and trans back together that its worth the extra time to take off the exhaust, driveshaft and shifter?

getting the G240 on/off is not too bad if you are in decent physical shape. As long as you get the clutch disc aligned with the pilot bearing, it is simple.

I've done clutch jobs also, mostly T5 transmissions in mustang and camaros. Everything you say is true. But this time I'd be putting the engine in, not the transmission. I have only done that with automatic transmissions.

If I pull the engine but leave the clutch bolted up, should the clutch disc stay clamped and aligned correctly so it should slide back in? Or will all the jostling likely move the disk out of place?

[jrobie79]

Is it that hard to put the engine and trans back together that its worth the extra time to take off the exhaust, driveshaft and shifter?

I changed mine without a load leveler, and I left the exhaust manifold connected. Granted I used a 2 post lift to lift it up and basically rolled my car slowly towards it while also having my father lower the lift until it was in position.

[bmwman91]

Is it that hard to put the engine and trans back together that its worth the extra time to take off the exhaust, driveshaft and shifter?

If I pull the engine but leave the clutch bolted up, should the clutch disc stay clamped and aligned correctly so it should slide back in? Or will all the jostling likely move the disk out of place?

I have never tried to pull the engine without the transmission, so really can't say if it would be more or less work to do them together. My gut feeling is that it would be a huge pain in the ass to try to disconnect the transmission and then move the engine off of the input shaft. Also, I left the header on and just disconnected the cat section from it. The driveshaft is pretty easy, too, since you just need to do the 6 bolts at the output shaft, 2 on the CSB and then loosen the collar nut to let the front section scoot back all the way into the rear.

I would not expect the clutch disc to move if you keep the pressure plate in place. Additionally, if you pull the engine and transmission as a unit and do not remove the transmission, then it is a non-issue.

[Victell]

I ended up pulling just the engines and leaving the transmissions in vehicle. I wanted to keep my trans, so would have had to pull them apart anyways. Also I was concerned if I could maneuver the engine+trans over the radiator core support and still clear the garage door above.

I used a load leveler as recommended by bmwman91 and got three m12-1.75 100mm threaded rods to use as extended guide pins. These two things helped and we got them mated back up about 90 minutes first engine, 45 minutes 2nd engine.

[roguetoaster]

Good to hear! Happy reassembly.