Author Topic: What year M42's drop into a '91 318i? (Read 4116 times)

dunny · « **on:** December 19, 2010, 07:35:37 PM »

I've been searching for a daily driver for a month and have found a 318i that I'm considering. Problem is that it needs the M42 replaced. The timing chain snapped (or slipped off) and from what I could tell the valves made some contact with the pistons. I won't be able to assess the damage until I pull the trigger on buying. It would probably be easiest to replace the engine with a good running example.

The guy who is selling said that he did some research and found that the only true plug and play engine would be an M42 from a '91. Is this true? If I could find a newer M42 (I think up to '95) what needs to be done (if anything) to make it work? I read something about the intake manifold not clearing the hood....but that is all I've found in the little time I've been able to search.

My other option would be a rebuild, which I'm not against as I do have experience building engines, but I fear this may run up the total cost and time of the project. Any idea of the total cost to rebuild? I assume new valves/springs will be required, as well as the standard stuff to replace the timing chain and headgasket.

Any input is appreciated. Thanks!

jakeb · « **Reply #1 on:** December 19, 2010, 08:41:47 PM »

The only......drop in is the 90-91 318i/is

But...the e36 m42 92-95 will work as well. You just need to swap the oil pan, intake, valve cover, wiring, sensors etc etc

VegasKyle · « **Reply #2 on:** December 19, 2010, 09:35:53 PM »

As far as I know in the US the only direct replacement is from another 1991 (318i, 318is, 318ic). The issue with the e36 M42 isn't the intake clearing the hood its the brake booster. Someone can correct me if I'm wrong.

As far as a rebuild I think it would be cheeper to find a used M42. However, If you go with a rebuild you get basically a new engine. You just have to decide what is more important to you; saving money or a better engine.

tom d · « **Reply #3 on:** December 20, 2010, 12:43:03 AM »

i will alway rebuild a engine rather than replace it with a used one. and even if i have to replace it with another, i will always rebuild that one before i install it.

dunny · « **Reply #4 on:** December 21, 2010, 06:56:40 AM »

Thanks for all the responses. Ideally I would rebuild but I can't justify spending a ton of money doing so. What is a rough estimate to rebuild the head? The bottom end may be OK but I may have to refresh that as well. After seeing valves cost $16 or so each I was a bit worried everything else would be expensive as well...

NisseJ�rnet · « **Reply #5 on:** December 22, 2010, 12:20:17 PM »

I dont know if there is a diffrence between the US E30 brake booster and EUR E30 brake booster but the intake clears both the hood and break booster with no problem.

I swaped my M40 for a -93 E36 M42 and i only used the oil pan and engine mounts/brackets from the M40 and the M42 bolted right in.
A little electrical work is needed at the round engine bay contact next to the fusebox and thats pretty much it.
Use the harness and ECU from the E36.

Ryann · « **Reply #6 on:** December 22, 2010, 10:15:51 PM »

Not sure that it's a factor, but another difference between the e30 and e36 m42 is that the e36 uses ribbed style belts/pulleys, and the e30 uses v-belts/pulleys. I know this is an issue when fitting the e36 DASC kit to the e30.

dunny · « **Reply #7 on:** December 25, 2010, 01:03:08 PM »

Thanks again for the replies! I ended up buying an M42 out of a '91 318i so I should be all set.

liquidfred · « **Reply #8 on:** December 27, 2010, 10:20:25 PM »

Where are you located? I might be interested in the popped m42 if you want to sell it. I'm in DE. LMK. Thanks!

sailer6460 · « **Reply #9 on:** January 01, 2011, 10:02:32 AM »

Recently picked up a really nice 318is here in Kansas, no rust, paint needed a good wheel job, and almost perfect interior. Car had sat for 3 yrs. Problem was with the engine (dropped compression on number 3 cylinder). Bought it for $300. The good news is that I had another good albeit but very tired chassis and engine as a donor car. Two weeks later (work got in the way a little), and I have a very nice example to drive. One thing to look out for with engine swaps on the 318 is the pilot bearing. BMW used a smaller diameter "nose" on the input shaft if the build date was before 9/1990. Other than that it was a drop in replacement form original car to new car.