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M42 from E36 into E30

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    M42 from E36 into E30

    My E30 318i is eating coolant, I replaced the head gasket, but it's still eating coolant even after machining the head, I've decided to swap the motor, but tracking down an M42 from an E30 is proving difficult. I've read a few threads that say you can drop an early OBD1 E36/ti M42 in by swapping the oil pan and intake over from my E30.

    Two questions:
    • Assuming an OBD1 motor, is this swap as easy as swapping the pan, intake, and leaving the knock sensors unplugged?
    • There are a few belt systems on the E36 version, the one I'm looking at is the serpentine style, can I leave that on or do all the accessories from my E30 need to be swapped?
    1991 BMW 318i Alpinweiß II Slicktop 231,000 Miles Build date: Wednesday, 1/30/1991
    2003 BMW Z4 2.5i Sterlinggrau Metallic 112,000 Miles Build Date: Monday 12/9/2002

    #2
    Technically, you can drop in any M42/44 as long as you have a workable bracket for the OBD1 crank sensor and swap accessories, including the intake, as required. That said, I can't immediately recall if the M44 cam sensor will work if plugged in to an E30 harness, but if it does that's a viable option.

    But certainly an OBD1 M42 from an E36 should be good to go.

    Apocryphal, but I remember reading somewhere that the E30 M42 management has a provision for knock detection, so if you wanted to explore that it would be awesome.

    Comment


      #3
      Thank you for the answer.

      E36 M42s have the same crank sensor as the E30 version though don't they? I guess that's neither here nor there, as my everything is currently on the old engine.

      What about the accessories systems, can I keep the serpentine style system?
      1991 BMW 318i Alpinweiß II Slicktop 231,000 Miles Build date: Wednesday, 1/30/1991
      2003 BMW Z4 2.5i Sterlinggrau Metallic 112,000 Miles Build Date: Monday 12/9/2002

      Comment


        #4
        I have an e36 m42 in my car. Earlier model, everything hooked right up except the e30 harness has no provisions for the knock sensors, so I just cut the wires short and capped em off. I put my e30 upper/lower oil pans and the intake manifold on.

        edit, the early e36 m42s have the v-belt system, so that wasn't an issue with mine
        1991 318is ---230K - DD
        1991 318i ---- 308K - retired

        Originally posted by RickSloan
        so if you didnt get it like that did you glue fuzzy oil to the entire thing?
        sigpic

        Comment


          #5
          So my 95 318ti has a serpentine setup and E30 style cam/crank sensors. With oil pans and intake swapped it would certainly work in an E30.

          I can check if the PS pump and AC compressor appear to be the same if interested.

          Comment


            #6
            Originally posted by roguetoaster View Post
            So my 95 318ti has a serpentine setup and E30 style cam/crank sensors. With oil pans and intake swapped it would certainly work in an E30.

            I can check if the PS pump and AC compressor appear to be the same if interested.
            That would be awesome, thanks. I was concerned with hookup for the alternator and clearance for the dipstick since it's front mount on the E30 and rear mount on E36. RealOEM has the alternator/ps pump/compressor as different part numbers, but I wonder if those will just hook up to the E30 connections. I have no issue running all the E36 accessories if the hookups are all straightforward.
            1991 BMW 318i Alpinweiß II Slicktop 231,000 Miles Build date: Wednesday, 1/30/1991
            2003 BMW Z4 2.5i Sterlinggrau Metallic 112,000 Miles Build Date: Monday 12/9/2002

            Comment


              #7
              Thanks for the help guys. I bought a used M42 from what I assume to be a 1995 318i/is/ti as it has the plastic oil filter cap. Sent an email to BMW Classic with the engine's serial number, so that I hopefully can get the VIN from the original car.

              The engine came from a local wholesaler called Engine World in Emeryville that only buys engines with less than 80k (supposedly). They charge a flat $650 for it. They had a couple, so if anyone else is in need of one, they have another 3 or 4 engines.They do a compression test right in front of you, even 200 PSI across the board, and it has a warranty so that's nice. The M42s were tucked in the far corner of the warehouse, he said they may have had them for years, as they don't get many requests for this engine. They recommend that you replace all the seals, so I'll be doing that out of the engine bay.

              The waterpump is frozen to the block, so that will be a challenge, reading the horror stories is fun, certainly BMW engineered it better in the future, because my E85 Z4's M54 WP came out super easy with similar miles to the claimed mileage on this M42.

              I plan to do a small write up on this swap to help others in the future. I'll be looking at the accessories, and may just keep the E30 original accessories, as I'm going to have to pull the crank pulley anyway.
              1991 BMW 318i Alpinweiß II Slicktop 231,000 Miles Build date: Wednesday, 1/30/1991
              2003 BMW Z4 2.5i Sterlinggrau Metallic 112,000 Miles Build Date: Monday 12/9/2002

              Comment


                #8
                Another side note, the later M42s use a 92° thermostat and the E30 uses an 88° one, but the housing and o ring are the same part number. Any reason not to run the E30 88° version?
                1991 BMW 318i Alpinweiß II Slicktop 231,000 Miles Build date: Wednesday, 1/30/1991
                2003 BMW Z4 2.5i Sterlinggrau Metallic 112,000 Miles Build Date: Monday 12/9/2002

                Comment


                  #9
                  Pretty sure the change in thermo temp was emissions related and had something to do with converting to an E fan.

                  Comment


                    #10
                    You did it right. The E36 has an updated timing cover and chain guide.

                    However, the E30 manifold flows significantly better, as do the equal length headers, so be sure to keep both of those for the new engine.
                    1986 325e Maaco Black M62 Project [SOLD]
                    2008 135i Alpinweiss III Cabriolet 6MT [SOLD]
                    2013 Subaru WRX [Daily]
                    1991 318is Slicktop Diamantschwarz Metallic [Thread]

                    Comment


                      #11
                      Originally posted by chriso View Post
                      You did it right. The E36 has an updated timing cover and chain guide.

                      However, the E30 manifold flows significantly better, as do the equal length headers, so be sure to keep both of those for the new engine.
                      In the plans. Right now this stupid water pump won't budge, wacked it with a ball peen hammer, tried prying it with a pickle fork, combination of the previous, nada, so I ordered a water pump puller that one of the members sells, hopefully that gets it, otherwise this motor goes back restocking fee be damned!
                      1991 BMW 318i Alpinweiß II Slicktop 231,000 Miles Build date: Wednesday, 1/30/1991
                      2003 BMW Z4 2.5i Sterlinggrau Metallic 112,000 Miles Build Date: Monday 12/9/2002

                      Comment


                        #12
                        Can you get a pipe wrench on the front of the casting to try to torque it free? Also, you might as well try the two threaded removal holes that accept M6 screws. Those allow you to put even axial force on it (alternately turning them like 1/8 turn at a time until it breaks free). If it is really badly seized, then the little wings will snap off, but then you will be looking at other means by then anyway.

                        Are there big signs of corrosion on other parts of the cooling system (tstat housing and stuff)?

                        Comment


                          #13
                          Originally posted by bmwman91 View Post
                          Can you get a pipe wrench on the front of the casting to try to torque it free? Also, you might as well try the two threaded removal holes that accept M6 screws. Those allow you to put even axial force on it (alternately turning them like 1/8 turn at a time until it breaks free). If it is really badly seized, then the little wings will snap off, but then you will be looking at other means by then anyway.

                          Are there big signs of corrosion on other parts of the cooling system (tstat housing and stuff)?
                          The ears already broke, that was what I tried first. The cooling system looks fine otherwise, this motor has been sitting a while though that much is obvious. There was some black looking stuff in the block behind the thermostat, but it looks like just old water/coolant. I'm probably going to hose it out before I go ordering all the seals/WP etc...

                          Once the WP comes out I should be able to get a better look at what's going on in the coolant passages.
                          1991 BMW 318i Alpinweiß II Slicktop 231,000 Miles Build date: Wednesday, 1/30/1991
                          2003 BMW Z4 2.5i Sterlinggrau Metallic 112,000 Miles Build Date: Monday 12/9/2002

                          Comment


                            #14
                            Thanks for the help guys. I bought a used M42 from what I assume to be a 1995 318i/is/ti as it has the plastic oil filter cap. Sent an email to BMW Classic with the engine's serial number, so that I hopefully can get the VIN from the original car.

                            The engine came from a local wholesaler called Engine World in Emeryville that only buys engines with less than 80k (supposedly). They charge a flat $650 for it. They had a couple, so if anyone else is in need of one, they have another 3 or 4 engines.They do a compression test right in front of you, even 200 PSI across the board, and it has a warranty so that's nice. The M42s were tucked in the far corner of the warehouse, he said they may have had them for years, as they don't get many requests for this engine. Now I am having the experience to write about this at https://edubirdie.com/scholarship-essay-writing-service, because students have problems with essay writing about engine specifics. They recommend that you replace all the seals, so I'll be doing that out of the engine bay.

                            The waterpump is frozen to the block, so that will be a challenge, reading the horror stories is fun, certainly BMW engineered it better in the future, because my E85 Z4's M54 WP came out super easy with similar miles to the claimed mileage on this M42.

                            I plan to do a small write up on this swap to help others in the future. I'll be looking at the accessories, and may just keep the E30 original accessories, as I'm going to have to pull the crank pulley anyway.
                            Thanks for this advice. Personally, I am going to change a new engine on my E30. I even think about non-BMW engines. Sorry for this :devil:

                            Comment


                              #15
                              Got the pump out, Super seized, almost broke the tool, needed a clamp to keep it from slipping off the flange!

                              Should I return this motor? It's pretty corroded in there, blackish liquid, doesn't look like oil, but who knows, this thing looks like that coolant has been in there a while. Got a couple days to return it.


                              1991 BMW 318i Alpinweiß II Slicktop 231,000 Miles Build date: Wednesday, 1/30/1991
                              2003 BMW Z4 2.5i Sterlinggrau Metallic 112,000 Miles Build Date: Monday 12/9/2002

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