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M3 Engine bay wiring restoration.

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  • M3 Engine bay wiring restoration.

    Hi,
    The following repairs were carried out prior to Christmas last year, due the site being under repair I have delayed posting
    up what I did hope it will be informative and interesting. All done toiling away in the garage with no hi-teck tooling etc.

    Late 2013 I replaced the heater core, water valve and alloy pipes they were not leaking but I would rather do preventive maintenance rather than waiting for it to leak.







    At Christmas I completed the restoration of the engine bay wiring harness; I did from the fuse box to the terminating end at the RF headlamp I did it in two stages due running out of tape half way across the grill.
    All the wiring was done in accordance to the BMW M3 wiring diagram and I maintained correct colour wires especially with regards to the a/c wiring to the new style plugs for the compressor and single receiver dryer pressure switch.

    No time for a picnic.


    First stage strip back the insulation clean and inspect wires and plugs, I used wax lacing cord to re lace the used loom and then clipped it in to position this allowed me to see the lay out/lengths prior to cutting out the old wires.
    I laced the new wires to the harness along side the old wires prior to cutting out the old wires, this ensured the new plug arrived at the correct spot post splicing.
    Then removed the harness for wire splicing.



    Spliced in replacement ABS wiring, one of the bigger jobs was to correctly wire the A/C system it originally had two pressure switches and was converted to one switch in the past and who ever did it somehow bypassed the switch in the thermostat and wired the compressor to the pressure switch not using the compressor wire in the loom also managed to cut the plug of the new single switch. The A/c is correctly wired now with correct wire colours, terminals and plugs.





    Now spliced in.
    New pressure switch wires spliced in removing duel switch plugs.



    ABS spliced in, nb-large heat shrink removed just used the smaller size.



    Used new wiring ends and terminal plugs where required and the odd used ones which were in good condition.

    Managed along the way to order more new items, which don’t fit my car in the form of different terminal plug housings.
    The splices I have used are Raychem D-463-36,37&38 series and the outer casings are clear heat shrink plastic, just have to be careful not to melt the insulation on the wire they are intended for use on hi temp aircraft wire. The way I did it was to use the exhaust heat on my butane soldering iron.






    I did find one very thin black wire which is not used on my M3 at the R/h front end of the harness for this I cut it of and in stalled terminating blank which can
    be seen sticking out from the harness incase it may be required.



    The wires, terminals and plugs for the washer bottle proved a challenge to replace the wires while having good fitting new pvc wire casing and no visible joint.








    Also removed the heated washer jet loom from part way up the bonnet replaced wires, plugs and pvc casing all with new then spliced it back in, along with new washer hose. In the photo you can see the sleeve which I slid up and then glued it all up with plumbers pvc glue to make it weather tight.





    For those who have not re-taped a harness the method I use is to start taping 2 inches out from the terminal plug then tape towards the plug then tape back over towards the loom and continue 3-4 inches in to the loom past the point which the wires are going to exit the harness.
    When all of the wire/terminal branches have been taped up then use lacing cord to tie up the harness up, put it in place check branch exit points adjust then remove and tape the main harness up from either end I taped from the fuse box to the center of the grill and ran out tape, 12 months later finished of by taping from the RH end to the center of the grill.




    With the terminal branches pre taped into the loom taping over them and the lacing cord is very easy and looks good imho, and no tape ends to unravel at a later date.





    Next challenge made a new harness for a/c temp and thermostat fan switch to front chassi harness for this I had to do some research to find hi temp black casing (500 oC should cope with the odd spirited drive) which I would be happy with to have a factory new condition look about it and blend in with the rest of the harness.




    Rated at 500 deg c with heat proof silicone coating also used it on the A/C pump wire, I brought 4,6& 8mm.








    Sealed up all the joints with Toyota FIPG then heat shrink over top.
















    That just leaves installation of the main harness.










    That just left replacing some relays.



    This was one job I really like doing and had a good result all round car back 100% reliable with no defects and looks good finish, I had to visit the wrecker yards a few times with my side cutters to collect the correct colour wires for splicing in.









    Charged up the battery night before and all was going well testing the systems which had been repaired until started to have a/c clutch intermittent not working and screen washer not squirting out water very well, after a bit of head scratching figured the battery had gone flat.
    At that stage did not know the requirements of the new calcium calcium batteries would not charge properly on the old style battery charger, more on that at a later date.
    That’s all for now folks,
    Dave.










    Attached Files
    Last edited by Dave @nz; 05-20-2014, 10:33 PM.

    E30 M3 1987
    Mini Clubman GT
    BMW E36 323 Msport
    Toyota Corona
    KTM 200EXC
    Honda CB50 (1979)

  • #2
    Wow i am SO jealous of your engine bay. I hope mine looks like that when I'm done. Is that the stock s14 power steering pump? Looks different from the one i have on my car.

    Comment


    • #3
      HI,
      Thanks for the complement, I spent a lot of time to get where it is now I try to do something each winter when it is of the road, I think you may be commenting on my A/C compressor it looks different than most and was fitted prior to my ownership.
      It is a BMW mod to convert to r134A which includes new compressor, compressor bracket receiver dryer and tx valve.
      Good to see the work you are doing on your M3 also.
      Dave.

      E30 M3 1987
      Mini Clubman GT
      BMW E36 323 Msport
      Toyota Corona
      KTM 200EXC
      Honda CB50 (1979)

      Comment


      • #4
        Yeh thats what I meant. Realized this morning when I woke up that I had the two confused. My AC compressor is in pretty rough shape. Not sure if the black goo on it is from oil leaks from above because of worn out gaskets or if its leaking grease out of the compressor mechanism itself. My guess is the former.

        My AC blows fine, but only on high and not cold. I was going to do a full R134 conversion but my indy said just to recharge it with R134 and an adaptor kit and it should work - figured that might get me through the summer until the winter when i plan to pull the engine for a build. I also found a DIY about cleaning off a circuit board in front of the fire wall that should help with the only blowing on high.

        Can't wait to pull the engine and start really cleaning up the engine bay. Did you have your valve cover and intake re-powder coated or painted? Who did you use? Looks great

        Comment


        • #5
          Simply outstanding!! I wish I had your patience to do this with my wiring.
          88' E30 M3 | Zinnoberrot & Tan | Various Goodies = OEM+

          Register your E30 M3!
          http://www.bmwmregistry.com

          Comment


          • #6
            Hi Holt and Currus Dei
            The valve cover and air plenum were imersed in a degrease bath at a local engine conditioners this removed the grime and most of the paint, then I glass bead blasted remaining paint and corrosion from them and crinkle painted them with rattle can black crinkle paint. Leave for a week in the sun to harden up then take to a good machine shop.

            Be sure to remove the air baffle from under the valve cover if you are going to bead blast otherwise glass bead could enter that area.

            A milling machine was used to highlight the BMW etc on these items and had a factory type finish when completed.

            ​Yes plenty of patience and planning involved lucky I had some spare time on my hands and it was warm in the garage.
            Some of it was not straight forward and quit complex to avoid visual joins & make it look factory new and also fit well
            that is why I have posted this up hopefully helps someone else who might be tempted to give it a go.
            Last edited by Dave @nz; 05-22-2014, 09:26 PM.

            E30 M3 1987
            Mini Clubman GT
            BMW E36 323 Msport
            Toyota Corona
            KTM 200EXC
            Honda CB50 (1979)

            Comment


            • #7
              that is a gorgeous bit of work

              Comment


              • #8
                Love it. Makes me want to redo mine.

                Comment


                • #9
                  Very nice work! I Just did some wiring work myself but don't think I would have the patience to do what you have done here! keep up the good work and the car looks very nice.

                  Hugo
                  Photobucket

                  Comment


                  • #10
                    Cheers guys,
                    If you are looking for a really good mod installing a 14.6V regulator in the alternator is what I would recommend especially if you have a calcium battery it is dead easy to do and relatively in expensive.

                    14.5 v regulator
                    http://www.ebay.com/itm/190566507640...84.m1439.l2649

                    First one sent was 14v so check with the seller first to get 14.6 as shown in the photo.
                    For me the best part was the light surge/ hesitation when cold (which I have been slowly chasing for the last 2 years) has now gone and it drives and pulls dead smooth just like a modern car.

                    E30 M3 1987
                    Mini Clubman GT
                    BMW E36 323 Msport
                    Toyota Corona
                    KTM 200EXC
                    Honda CB50 (1979)

                    Comment

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