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Thread: Swapping an E36 M42 in to my 78 E21

  1. #1
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    Swapping an E36 M42 in to my 78 E21

    Late M42 in to E21 Swap Thread
    This summer, I decided it would be an excellent and cost-advantageous decision to take a perfectly-good and working M10 engine and throw in an M42. (a hint of sarcasm)

    This will be a pseudo build thread for another E21 swap project. What's different is two-fold. First, Im in the bottom quartile of capable mechanics in this forum, so that will be an interesting perspective. Second, as far as I know, this is one of the few late M42 swaps. Tom's son, i pet a kitty, put together a nice example of a late M42 swap, however it used the E30 intake manifold. Sellick started a late M42 swap but unfortunately the project is at a pause. I hope he gets it started back up to completion, however. If youre looking to do this swap, visit his thread. He compiled pretty much every resource needed.

    Project Goals/Requirements:
    • Primarily, learn more about the internals of an engine.
    • Scope out potential of a DISA intake in the E21
    • Refresh the M42 (details below)
    • Figure out the speedometer. Either my e21 mechanical speedo, or fit in the E36 electronic speedo
    • Acquire necessary E30 parts
    • Relocate battery
    • Potentially relocate brake booster
    • budget permitting, refresh of front-end suspension, etc.


    M42's in e21's are common, but my goal is to get the late M42 intake in my E21. I have found ONE image of an M44 in an E21, and it included a relocated brake booster, so likely that is a must to make this work.
    m44 in e21 relocated brake booster.jpg
    I will have to determine if this makes sense just to keep with the original envision of my swap. It may be a fruitless endeavor, and really, would the work be worth a few extra HP and torque gains? To be determined...




    "If anyone tells you the stock M42 is a great engine, they are pulling your leg or don't know the M42 very well. The stock M42 is very self destructive."
    -peerless



    I didnt start off looking for an E36 M42. Ideally, everything would be sourced from an E30. And if I knew then what I know now, I'd keep it to an E30 M42. My original thought/fallacy, however, was that I wanted to avoid a total rebuild and every e30 M42 example was extra high miles or would require some sourced parts from another E30. However, I stumbled on some pretty critical M42 refresh necessities AFTER acquiring my late M42, so lesson learned. Just about any M42 will need at least a minor refresh. If not done by the PO, it should be done before the swap. While not performing all of these items, I will be undertaking most.

    Details of the refresh:
    • Update the thrust bearings, from the factory 180 bearings to updated 360 bearings.
    • Update the timing case, replacing critical components. One perk of the late M42 is some of this was done at the factory.
    • Update the oil pressure release valve and surrounding components.
    • Update the oil pump to M44's offering
    • Replace just about every gasket
    • Replace rubber hoses
    • New thermostat and water pump
    • A few other refreshed items here and there that I am forgetting about here.



    I hope this will be a resource for anyone that acquires a late M42, otherwise this will drive me to make sure I keep up on this project. I've hit a few fallacies already. Noted above, this project will necessitate at least a partial rebuild. This project will not be as cost-effective as I thought.
    Already I am down $400 in refresh parts, and I still have to get to hoses and other odds and ends items. I still need to acquire the transmission and driveshaft. I will also need a good working radiator. Plus I may find that I want to go to the M20 flywheel set-up over stock M42 offerings, right now thats a good $300-400 I dont want to spend.

    If people are interested in an M42 rebuild, first look here, then maybe here. But thats for later. For today... I'm looking at a stripped down M42, waiting for parts from Pelican Parts to begin the rebuild. Also, many late M10 parts I had extra will enter the market, I'll list those soon.

    More to come...
    Last edited by jaredmac11; 01-07-2017 at 04:37 PM.

  2. #2
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    two things....
    1) i dont believe the brake booster in the photo below has be relocated, thats a right hand drive setup.
    2) whoever you quoted below is full of shit!

    Quote Originally Posted by jaredmac11 View Post
    m44 in e21 relocated brake booster.jpg

    If anyone tells you the stock M42 is a great engine, they are pulling your leg or don't know the M42 very well. The stock M42 is very self destructive."
    Tom D

    77 e21 - m42
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  3. #3
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    Quote Originally Posted by Tom D View Post
    2) whoever you quoted below is full of shit!
    If you consider the average 318ti driver, some part of the car/human relationship is definitely destructive to the engine. It's easy to see how the blame might get misplaced.

  4. #4
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    Quote Originally Posted by Tom D View Post
    two things....
    1) i dont believe the brake booster in the photo below has be relocated, thats a right hand drive setup.
    2) whoever you quoted below is full of shit!
    You're correct!! I just looked again, and these guys are in europe. I thought I had an answer.

    And I dont think that guy is completely wrong, the early m42 is a bit of a time bomb, but it went through some substantial updates for the better with the late M42 and then again with the M44. I have some pretty good photos from a buddy of mine also refreshing his early m42 and his timing chain sprockets look like vampire teeth rather than what youd expect gears to look like. Also I think that user, peerless got banned from this forum for some %!&^ talking AND he was a mechanic so he only saw the worst of them all. I only saw the cam sprockets and mine looked good. Im not doing a $2500 rebuild for a $500 engine, no thanks.

    But what do I know? The only M42 timing case I've seen with my own eyes is the one in front of me.
    Last edited by jaredmac11; 09-12-2016 at 04:05 PM.

  5. #5
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    My 'build thread' has minimal pictures and is not complete, but it has some info you might find helpful. One thing you will definitely need from the early M42 is the oil pan, there's no way around that.

    http://www.bimmerforums.com/forum/sh...p%26%239658%3B

  6. #6
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    E30 oil pan, flywheel, starter, clutch, mounting arms, and intake manifold are all in my garage. Got a good deal on those. I am missing a few things on the drivetrain. Otherwise I should be good based on what I read here.

  7. #7
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    OK so, a lot has happened in a month. Had a bit of a distraction with our second son being born, dude is needing things like diapers and feeding over me working in the garage. Go figure..

    I've slowly been acquiring parts from online vendors and from a buddy of mine who has about two M42's worth of parts so he has been a resource. Most of this has been getting the engine down to the block, snapping tons of pics, and using Google Photos to document it all (it's been super helpful).


    Fun stuff...

    Questionable main bearing cap.
    http://imgur.com/a/jBSpY
    To be honest, Im not even wholly sure if this bearing spun and wore out the cap and crank wall or if the factory decided 1/5 caps needed to be unique (thinking the former). It seemed to be in spec, but I feel like I measured wrong. This doesnt look right at all. I'll have to be more careful on future measures.

    The water pump was a complete pain in the ass to remove. Took at least a week going to the garage for 30 minutes til Id get frustrated and stop. Finally picked up a 3' pry bar that did the trick. It wouldnt have been as big an issue if I wasnt on a stand. I just couldnt get good leverage and keep the stand from rolling/moving
    IMG_20161006_193220.jpg

    The engine isnt the cleanest I've seen but its not awful. There is some sludge around the valve springs. The entire engine has a nice maroon/brown color. I havent seen many M42 but I know a few build threads had much cleaner heads..
    IMG_20161009_160815.jpgIMG_20161009_160806.jpg

    Finally, my timing case components are in *mostly* good shape. Sprocket teeth look good. Most of the rails look good, but I think I will get a new tension rail and I know I need a new guide rail. Unfortunately ALL of these are BMW parts exclusively. There are no aftermarket costs so this will cost the price of the engine pretty much.
    In the pic you can see the microfractures all over the guide rail.
    IMG_20161007_143758.jpg


    I am starting to see what people mean by saying the M42 rebuild is 'S52 territory'. The engine is cheap, but some of these parts are excruciatingly expensive (looking at you, timing case). Plus I will likely need to source a new crank.



    I havent lost faith yet. Once I acquire the crank, its all going to start going together. Then all I need is the transmission and a few hoses and I'm gold. The M10 will come out when the M42 is mostly together and passes compression tests and spec measuring following my build. My hope is by Feb 2017 I'll have a running car. Slowest swap ever.

  8. #8
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    Quote Originally Posted by jaredmac11 View Post
    I am starting to see what people mean by saying the M42 rebuild is 'S52 territory'. The engine is cheap, but some of these parts are excruciatingly expensive (looking at you, timing case). Plus I will likely need to source a new crank.
    S52's also aren't expensive at all right now.


  9. #9
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    congrats on your new baby!

  10. #10
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    If you go with the S52, I can save you a lot of time and hassle by supplying a set of custom made motor mounts based off my S50 euro swap and for use with a 323 subframe. TreeHouse Racing made a crossover wiring harnes (plug & play) for me. This company appears to be capable of creating a crossover wiring harnes as well. http://www.ebay.com/itm/Bmw-E30-Engi...-/252024062641

    Have fun!

  11. #11
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    Not to highjack your thread, but why doesn't the M-44 get any love as an e-21 swap candidate? I would imagine there are more of them out there than M-42's.

  12. #12
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    Tom D

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  13. #13
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    Slooooow to update. I was way over budget from various components, having to acquire a transmission, etc. so I've been spacing out my rebuild accordingly. My buddy abandoned his M42 swap in to his e30 318i about two months after I embarked on my project. Wish he did that earlier!

    But I was able to get a complete M42, and additionally.. 2 good heads, 2 harnesses, 2 sets of accessories for cheap, a few extra oil pans... basically enough parts to do another M42 swap in the future with spare parts. I'm saving this for either a future 2002 project or a future turbo project.. or a get out of jail free card in case I botch this.

    It was a good thing I had an extra head because it turns out there was a crack in my head. Worked a deal with the machine shop and swapped out an E30 head I had extra for an E36 head they had + core. I'm now confident a GOOD head is going on the block, I opted for a valve job as well. The head looks brand spanking new.
    IMG_20170106_155307.jpgIMG_20170106_155534.jpgIMG_20170106_155627.jpg

    Updated the bearings a month back as well..
    IMG_20161118_135839.jpg

    Got the new headgasket on today, really hope I didnt botch that up. I spent a LOT of time cleaning the block surface, scraping clean, wiping down again, etc etc.
    IMG_20170107_141630.jpg

    Gotta get the timing case back together next. I need 2 more timing guide rails, that should be another $300 then I THINK I've got all the parts I need going forward. Unless I convince myself to get a lightened fly wheel.


    I cant believe how expensive this all is. Timing components especially... But at least I havent given up yet and it's going together.
    Last edited by jaredmac11; 01-08-2017 at 11:17 AM.

  14. #14
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    Pics aren't showing up in last post?
    91 318is
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  15. #15
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    Quote Originally Posted by captain awesome View Post
    Pics aren't showing up in last post?
    Seemed to have some issues yesterday. I just deleted them and re-uploaded them.

  16. #16
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    Nice work so far! I always dread cleaning up the block surface for a head gasket, it just never looks good enough...especially when you are looking at the beautiful milled surface on the rebuilt head.

    I could be wrong but I thought an M20 flywheel could be used as a "lightweight" single-mass alternative on the M42. If so that should not be too much $$$.

  17. #17
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    It adds up fast though even for an m20. Add in clutch, tob, and bolts it gets up there.
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  18. #18
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    I'm late to see this thread, but want to add the M42 that came in the e30 318 is a great motor. The only complaints some have are the main timing case having a idle bearing gear instead of a third rail like the later M44. It's possible and common to find guys swapping the m44 stuff over "updating" the M42. I've knock on wood never had the idle gear setup fail myself and two cars have seen over 1/2 million miles combined. One is on it's second engine after 380k miles. The other daily driver I use has over 250k. Still using the original system but new parts.

    The crappy part of the later model M42/M44's is the topend has rockers and the disa intake. Both favorable for low end power but can lack up top if a track weapon will make you wish for a swap.

    Going gasketless with loctite/permatex 518, updating the exhaust nuts to top lock metal ones, use e36 nissen radiator, all make it a bullet proof performer in my book. Another neat additive is using the VW hydraulic tappets. They are about 1/3 the weight of stock which helps valvetrain mass a good amount. Common M50 upgrade also since they share the same buckets.

    Great fun motor in a light car. I'll add the last one we rebuilt was about $1600 after machine work and self assembly. Timing components weren't as bad except if need that idle bearing gear it was like $140 itself. Everything else is cheap at places like rockauto or partsgeek.
    Last edited by autox320; 01-10-2017 at 07:29 AM.
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  19. #19
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    Quote Originally Posted by mjweimer View Post
    Nice work so far! I always dread cleaning up the block surface for a head gasket, it just never looks good enough...especially when you are looking at the beautiful milled surface on the rebuilt head.


    I could be wrong but I thought an M20 flywheel could be used as a "lightweight" single-mass alternative on the M42. If so that should not be too much $$$.
    I think in spring, stretching for the single mass flywheel shouldnt be too bad. Prices were $200 when I last looked.


    Quote Originally Posted by autox320 View Post
    I'm late to see this thread, but want to add the M42 that came in the e30 318 is a great motor. The only complaints some have are the main timing case having a idle bearing gear instead of a third rail like the later M44. It's possible and common to find guys swapping the m44 stuff over "updating" the M42. I've knock on wood never had the idle gear setup fail myself and two cars have seen over 1/2 million miles combined. One is on it's second engine after 380k miles. The other daily driver I use has over 250k. Still using the original system but new parts.

    The crappy part of the later model M42/M44's is the topend has rockers and the disa intake. Both favorable for low end power but can lack up top if a track weapon will make you wish for a swap.

    Going gasketless with loctite/permatex 518, updating the exhaust nuts to top lock metal ones, use e36 nissen radiator, all make it a bullet proof performer in my book. Another neat additive is using the VW hydraulic tappets. They are about 1/3 the weight of stock which helps valvetrain mass a good amount. Common M50 upgrade also since they share the same buckets.

    Great fun motor in a light car. I'll add the last one we rebuilt was about $1600 after machine work and self assembly. Timing components weren't as bad except if need that idle bearing gear it was like $140 itself. Everything else is cheap at places like rockauto or partsgeek.
    That's impressive that your cars have lasted that long and are still going. I have 3 M42 in my garage now (1 is completely bad, minus some parts) and all 3 have cracking guide rails. One guide rail completely fell apart and I believe that's what caused it to throw a rod. No idea on miles. My e36 M42 had 155k miles and I thought it was a good buy, but I clearly had no idea. Probably one of the worst buys I made. Hindsight is 20/20 and it was a learning experience.

    I'll look in to the VW hydraulic lifters. A few people have used those before. I'm not sure which would, if any, would work for the E36.

    Interesting info on the DISA. I think low-end torque would be best for my use, I dont plan on tracking my car at all. It's just a weekend toy that I want to hold on to as long as I can. As for rockers, that mustve been introduced at the M44, they arent on the late M42. The late M42 has just a single spring and lighter valves, however. The early M42 can pull higher compression with the dual springs, but it's contending with heavier valves. It's all interesting gives and takes and I'm interested to see what the e36 M42 can do. Never driven one. I also have an E30 M42 partially built so maybe some day I'll be able to try both.

    I'll share my build price after a bit. Right now its close to $2000... I feel sick.... (dont tell my wife)

  20. #20
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    The lifters I use are part number 050109309H
    Bought my sets from http://www.autohausaz.com
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  21. #21
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    Quote Originally Posted by autox320 View Post
    The lifters I use are part number 050109309H
    Bought my sets from http://www.autohausaz.com
    Thank you! Do lighter lifters provide any noticeable gains?

  22. #22
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    Honestly it's more for if always in top revs. It's noticeable to me. If need lifters great, if not then wouldn't worry about it for a street car. If zing it to the higher chipped redline a lot then worth it to me. Best chip IMO is the one from MarkD http://www3.sympatico.ca/mdsylva/

    General numbers of weight savings are 48 grams vs 60. It adds up especially in a 24v. So in a 16v your talking 0.423 lbs weight savings off the valve train. Only thing better than that for a race M42 is solid lifters.
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  23. #23
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    I have three chips, mark d, diana, and stock, they all preform differently and I prefer the mark d for road work. someday I'd like to see how they differ on a dyno.
    Tom D

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  24. #24
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    Quote Originally Posted by Tom D View Post
    I have three chips, mark d, diana, and stock, they all preform differently and I prefer the mark d for road work. someday I'd like to see how they differ on a dyno.
    I assume the chip is worth the cash then?
    91 318is
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  25. #25
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    Did Mark D put out a chip for the e36? back when i googled this last year, there were plenty of results for the Turner/Conforti chip, which I'd consider.
    Last edited by jaredmac11; 01-10-2017 at 04:38 PM.

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