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    M20 Refresh - Suggestions

    Working on the field rescue 1989 325i. It was parked in 2010 after the engine started to make "a bad noise".


    I bought it home and found a broken rocker arm.
    Decided the car is nice enough to refresh. Pulled the engine/trans to fix the head, clean up the block and bay, then swap in a 5 speed.


    Engine is out an head is off. It's going to the machine shop this week.


    This is my first M20. I'm looking for advice on the refresh. Trouble spots to address while I have the engine out. Parts suggestions, etc.


    I'm going to pull the oil pan in the next day or two. Assuming things look OK I'm not going to pull the rotating assembly.


    Here is my initial plan.


    Pull and clean/check oil pump and pickup.
    Replace front/rear main seals.
    Clean/check/replace sensors.
    Clean/check throttle body
    Clean/check ISV
    Clean/check alternator
    Clean/check starter
    Replace AC compressor
    Clean/paint intake manifold
    Clean/paint valve cover
    Clean/paint block
    Replace engine mounts
    Replace coolant hoses
    Replace fuel lines
    Replace vacuum hoses
    Send out injectors for rebuild/balance
    Check wiring harness and connectors


    Clean engine bay, touch up paint as needed.














    1991 318iC
    1989 325i Field Rescue

    #2
    and you'll replace the timing belt as well.
    ~~~~~~~~~~~~~~~~~
    '90 325i sedan daily driven
    '85 325e coupe also a daily

    Comment


      #3
      Originally posted by cheffy30 View Post
      and you'll replace the timing belt as well.

      Replace all belts.
      Replace water pump.
      1991 318iC
      1989 325i Field Rescue

      Comment


        #4
        engine out head off may as well check the rotating assembly, piston, bores etc...IMO
        89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

        new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

        Comment


          #5
          Originally posted by digger View Post
          engine out head off may as well check the rotating assembly, piston, bores etc...IMO



          Any pointers with this?


          I'm ok taking things off and putting them back on. Engine internals are out of my element.
          1991 318iC
          1989 325i Field Rescue

          Comment


            #6
            In my point of view it's almost criminal to not stroke it with 2.8 crankshaft when it's opened :). But if internals are not familiar to you, I understand.

            Comment


              #7
              Originally posted by Poorhouse View Post
              Any pointers with this?


              I'm ok taking things off and putting them back on. Engine internals are out of my element.
              Depends on budget I guess and long term plans, should check pistons and bores just get machine shop to do it based on that there may be decisions. Also cleaned, new bearings and that kind of thing.

              It's about 2k extra to get a 2.8l as you need
              - Crank
              - Pistons
              - Sleeve
              - Additional machine work

              Which makes probably only makes sense if the piston are not salvagable

              If you have no long term plans for the engine and you know it runs well then you can let sleeping dogs lie sometimes
              89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

              new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

              Comment


                #8
                Did you compression test it before you removed it? Have you got any idea on the condition of the rings? If you have no idea it would be annoying to do the top end and put it all together then realise the rings aren't great.

                Comment


                  #9
                  Originally posted by hasa View Post
                  In my point of view it's almost criminal to not stroke it with 2.8 crankshaft when it's opened :). But if internals are not familiar to you, I understand.
                  Originally posted by digger View Post
                  Depends on budget I guess and long term plans, should check pistons and bores just get machine shop to do it based on that there may be decisions. Also cleaned, new bearings and that kind of thing.

                  It's about 2k extra to get a 2.8l as you need
                  - Crank
                  - Pistons
                  - Sleeve
                  - Additional machine work

                  Which makes probably only makes sense if the piston are not salvagable

                  If you have no long term plans for the engine and you know it runs well then you can let sleeping dogs lie sometimes



                  I would love a 2.8, maybe in phase 2.


                  This car sat for 9 years. I don't have the confidence in it to spend any real money yet.


                  Phase 1 is getting it running with the 5speed swap and back on the road. Then I can get it fully sorted and decide where to take it from there.

                  Originally posted by e30davie View Post
                  Did you compression test it before you removed it? Have you got any idea on the condition of the rings? If you have no idea it would be annoying to do the top end and put it all together then realise the rings aren't great.

                  I did do a compression test.


                  Results were 130-150 cold.


                  I thought that was pretty good considering how long it sat and a cold engine.


                  Looking at the cylinder walls I'm not seeing anything scary.
                  1991 318iC
                  1989 325i Field Rescue

                  Comment


                    #10
                    Pulled the oil pan last night.





                    1991 318iC
                    1989 325i Field Rescue

                    Comment


                      #11
                      I understand the hesitation to really go through it, but nothing will kill your confidence faster than putting a worn motor back together and finding the next weak link in the chain the hardware. You've got this, a rough bore check isn't too difficult, just a little time and patience. Same goes for a hone and fresh rings.

                      Based off of the coloration visible on that bottom end, you are probably going to find worn main and rod bearings. The pan has also been broke before, based off of the oil pump dings. The machinist can do an inspection and micro polish on the crank for not too much money. You'd be out bearings, rod bolts, rod bearings, and polish costs for a LOT more peace of mind.

                      Just food for thought. Best of luck, you are only a few small steps away from a lot more peace of mind. This is NOT outside your wheel house if you've already come this far.

                      Also, you are lucky to be up in Whitefish! I was raised up there and want to return. Can't wait to get my family out of California.
                      ADAMS Autosport

                      Comment


                        #12
                        All good points. This is how quick projects snowball.. going to discuss with mechanic friend and machine shop that has head.

                        A local?! Nice! I've been here about 20 years, grew up by Red Lodge.

                        It's a Powder Friday here. I have the day off and was going to work on the car...

                        Deep thoughts by Rhyan*:
                        6:00 a.m. Report: Powder Alert! The village has received 9 inches in the last 24 hours! The summit stake received only 4 inches, likely due to wind transport. Protected and lower areas will be harboring more snow. The temperature in the village 16 degrees, higher than the forecasted high temp, which could explain the sudden bump in snowfall totals. The snow is super light and dry. It remains cold on the summit, and we're expecting another 4-8 inches of snow during the day. It's going to be a good one!
                        1991 318iC
                        1989 325i Field Rescue

                        Comment


                          #13
                          Heard back from the machine shop.
                          Cam is damaged at the broken rocker lobe.
                          They recommend replace cam and all rockers.
                          They are working up pricing for stock parts.

                          If I wanted to upgrade what would be the recommendation?
                          1991 318iC
                          1989 325i Field Rescue

                          Comment


                            #14
                            Originally posted by Poorhouse View Post
                            Heard back from the machine shop.
                            Cam is damaged at the broken rocker lobe.
                            They recommend replace cam and all rockers.
                            They are working up pricing for stock parts.

                            If I wanted to upgrade what would be the recommendation?
                            All depends how far you want to take it and your budget. Strocker motor? Just a little wilder cam?

                            IMO, I would not let the shop do the assembly or purchase parts. Based on your previous posts above, you should be able to do the assembly yourself with a little research. Money saved could buy you some upgrades and quality OEM parts.

                            Have them cut valve seats, check/replace valve guides, surface the head, hone bores and surface the block. Bring it home, clean very well and do your thing.
                            You can buy all parts yourself and put it back together.

                            Comment


                              #15
                              I would like to do that some day. I just don't have the confidence I wouldn't fuck it up.
                              I don't know how to check bearing clearances or crank shaft end play. Plus all the other things I don't even know I don't know. If you know what I mean...

                              Another question, how are DIYers replacing the front crank seal?
                              Bently lists states a special tool to hold the crank is needed and the bolt is torqued to 400 ftlb!!
                              1991 318iC
                              1989 325i Field Rescue

                              Comment

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