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    Changing Cam Sprockets

    So as some of you may know from a recent thread, my old cam sprockets are worn. I managed to source a set of nice ones from a member on here, as well as a new chain tensioner.

    While I'm waiting for that stuff to arrive, I'd really like to figure out how to do this. I've looked at various tutorials and DIYs on this, but I haven't seen anything that specifically tackles how not to screw up your cam timing. I'm not really concerned with how to remove the cam sprockets and install new ones, but rather how to ensure that I don't end up moving a cam and bending a valve as soon as I run the motor again. I've looked at cam lock tools, but a lot of them use the cam sprockets themselves to hold the cams in place, which is useless for obvious reasons. The other thing I thought of was maybe marking the cam position somehow so that I can set them the exact same way again if they move.

    I'm really just looking for tips from people that have done this before, how they solved their cam dilemma. I've never assembled a motor before, so I don't know how to set timing.

    #2
    You can remove them without having to take off the upper timing cover. Remove the valve cover and remove the bolts with an offset wrench. Just lock the cams in place. You also have to slide both sprockets off at the same time to remove them this way because chains don't like to move sideways. Put the new ones in and make sure you don't skip any teeth.

    That's the super lazy don't wanna take out the thermostat housing and run the risk of having to bleed the system again.

    Otherwise just remove the valve cover, top timing cover, and the tensioner and do it that way. Still need to lock cams in place and keep tension on the chain if you don't wanna have to redo your timing.

    (Timing is easy, for the most part. Maybe just a bit tedious. There are plenty of threads on the topic and pics to show)
    DENY IGNORANCE!
    Schwarz 325-totaled
    brilliantrot 318i-daily

    Originally posted by mkcman17
    don't think your hamster wheels are fast now. you will still have to give up when trying to pass that V6 odyssey to make your offramp.

    Comment


      #3
      You have my sympathies. You’re at the top a slippery slope right now.

      Get your hands on an e36 Bentley manual (available online with some searching). This will provide you with detailed instructions, torque specs, etc.

      Use loctite on everything you put back together.

      “While you’re in there”:
      updated oil valve
      updated chain guides
      updated water pump w/ metal impeller
      Intake gaskets?
      valve cover gasket set
      Oil canister to block gasket + O-ring and fresh mounting bolts (those canister-to-block gaskets are always leaking)
      Drive belts
      Fresh coolant
      Fan clutch
      Front crank seal
      O2 sensor
      upper and lower oil pan gaskets
      New 10grade oil pan bolts
      New crank bolt

      OK – then here’s the real fucker..
      At one point, things will get stripped down to this:



      God dammit !!
      After doing so much to get to this point, taking the main timing case off is a good idea. Why? Because likely as not, the profile gasket is in need of attention. Electrolysis can deteriorate mating surfaces. The timing case gasket might as well get replaced. So then the head needs to come off..

      Head gasket
      Head bolts
      Timing case gaskets
      Exhaust manifold gaskets and manifold mounting hardware

      Then you might as well pull the exhaust and drive shaft, then drop the transmission for new clutch, replace

      rear main seal
      Rear crank housing gasket
      Flex disk
      Central support bearing
      shift linkage bits
      Spark plugs
      Spark plug wires or COP conversion?
      Throttle cable
      engine mounts
      transmission mounts


      Originally posted by Solarian View Post
      I'd really like to figure out how to do this. I've looked at various tutorials and DIYs on this, but I haven't seen anything that specifically tackles how not to screw up your cam timing.
      Five rules of m42 timing:
      1. Rear “cam squares” held parallel
      2. Cam sprocket arrows parallel and straight "up"
      3. Cam sprocket slots set at middle
      4. 7 chain links between cam sprocket arrows
      5. Front fan pulley mark pointing at arrow on oil canister (TDC)

      Two crescent wrenches can/do work for holding/adjusting camshaft position.

      This is a link to many photos of the process
      Last edited by Simon S; 01-12-2013, 01:50 PM. Reason: updated for thoroughness
      -----Zen and the Art of e30 Maintenance - / - Zen TOC - / - Zen Summary

      Comment


        #4
        I remember when my engine looked similar to that. Lol good times. Doing the timing bits are easy. If you have all your tools available.

        There's a thread somewhere about taking the timing case out without removing the head. I think on M42 club

        From reading your post it doesn't seem like you have much experience with engine work. It's not hard, just do your research and make sure you understand how everything works and it'll all make sense. Especially while you're doing it.

        And ALWAYS remember, when tightening the bolts on the timing covers, they will still feel like they can be tightened more after they're to spec.... Do yourself a favor and don't keep going. It'll only lead to trouble, snapped bolts, stripped threads and more headache down the line.
        DENY IGNORANCE!
        Schwarz 325-totaled
        brilliantrot 318i-daily

        Originally posted by mkcman17
        don't think your hamster wheels are fast now. you will still have to give up when trying to pass that V6 odyssey to make your offramp.

        Comment


          #5
          the only way to have a problem free m42 is to pull the engine and do a complete refresh.

          sucks to suck buts its the truth. especially on engines that have been neglected for 150k miles...

          Turbo M42 Build Thread :Here
          Ig:ryno_pzk
          I like the tuna here.
          Originally posted by lambo
          Buttchug. The official poster child of r3v.

          Comment


            #6
            I finally got around to doing this today as I had some free time between school, and I managed to finish the subframe/suspension/e36 steering rack swap.

            I'm going to outline what I did and what I had some problems with figuring out so that it's easy for whoever tries it next.

            First, the stupid clutch fan. I tried what other people suggested about giving it a quick whack, but it wasn't doing shit, it would just slip. What I ended up doing is easy, foolproof and works every time, but requires two people.
            Get a flathead screwdriver, and wedge it on the water pump pulley so that you can keep it from rotating. Do like an over/under, it'll make sense when you look at it. Now second person grabs the enormous wrench and turns (this is a reverse thread!). Nothing is slipping because you're holding the water pump pulley and eventually the fan comes off. Life is good.

            Second, maybe most of you aren't dumbasses and already knew this, but the direction of rotation of this motor is clockwise. I had to search this a lot because I didn't know, and I didn't want to risk turning it the wrong way, I heard the chain can catch on something and get messed up.

            Picture time:
            This is how you find TDC (take out your spark plugs and make sure your car is in neutral before you try turning the motor. It should turn pretty easily, I didn't even need the breaker bar, just got my half inch ratchet.

            It's hard to see in this stupid thing, but there's a little notch in one of the teeth on the crank pulley, and that lines up with the arrow on the block. You can actually confirm TDC in three different ways, so it's kinda impossible to screw up. Once you line this bad boy up, grab the flywheel locking tool from your trunk tool kit. If you don't have it, any long, 8mm thing will do. This is a picture of where you stuff it. My car had a little plug blocking that hole so that crap doesn't get in, so take that out first.


            These pictures look absolutely atrocious due to flash, but I think they get the point across. Anyway, that thing won't go in all the way unless you're at TDC. I tested this by slowly turning the motor as it approached TDC, while pushing on that pin. It only popped in when they lined up. Then I tried turning the motor and it wouldn't move, so yea, it locked it up real nice.

            (some steps missing here, but basically they're just undo bolts and take things off. Plus I had already done this before I started this process)

            Now you look at your cams. The first two should be kinda pointing at each other, and the squares at the back should be level with each other. Mine were not.

            Considering everything that I've found wrong with this car so far, I'm truly amazed it ran as well as it did when I test drove it. I can only imagine how great it'll be when it's in actual proper running condition.

            So, the next step I forgot to take a picture of. But I went and grabbed a permanent marker, and I made a mark on the timing chain where the arrow on the sprocket is. That way I'd know exactly where to stick the arrow on the new sprocket.

            Oh, one more thing, if your cam timing was set properly, you might want to go ahead and lock it in place using the proper tool, or just really any home made thing you have. You can build this from a piece of wood pretty easily. I didn't do this, because my timing was off, so there was no point in preserving wrong timing.

            Now you want to pop off your chain tensioner. I was also swapping in the new M44 chain tensioner along with the sprockets. I had to use a breaker bar to take it out, as it was torqued in by the hand of god. Not only is this his chariot, but it appears that he wrenches on it too.

            After the tensioner is out, you have slack in your chain, and you can finally take off the sprockets. Yank em out, line up the arrows on the new ones with the marks you drew on the chain and pop em back in.

            At this point, you want to put in either your old tensioner, or a new one like me. I couldn't use the r3v to 3500rpm method because my motor is mostly apart, so I did it the other way. It seems much easier and safer. Basically, expand the new tensioner and push it in by hand. It's not that stiff, you can do it. That way I got full tension back on the chain so that my cam gears weren't wiggling about and I could set the timing.

            This next part you might not need to do, but my timing was wrong, so I did. I popped in the bolts for the cam gears, but only tightened them slightly, by hand so that they can move in reference to the cams. I then grabbed a big ass adjustable wrench and put it on the cam square and turned until I got it where it needed to be. I did this one by one on the cams. When I would get a cam right, I would tighten the bolts. Then I did the other one. I had to actually repeat this a couple of times to get it perfect, but at the end they lined up nicely with the ruler. Kinda hard to see because my hairy arm is in the way, but they are perfectly in line.


            I then made an executive decision to use loctite blue on the bolts so that they don't loosen up in the future and mess up my cam timing. I'm not sure if you really should, but the blue kind can still be undone by hand tools, so I felt comfortable with it. I did this one by one bolt so that the cams don't move on me. I kept checking, double checking and triple checking the squares in the back.

            When all was said and done, I had this


            Lots of meat on these bad boys, they should last for quite some time. The intake cam sprocket looks like the cams aren't centered on the sprocket, but the timing looks right physically, so I don't know what's up with that. It's possible that the old cam was off by a tooth, so I matched it to the wrong one when I put the new one in, but I can't see it giving me problems. The cam angle sensor reads from the exhaust, not the intake so it shouldn't make a difference.

            This is what my old ones looked like:


            Pretty crappy. Glad they're gone.

            Motor isn't back together yet because I forgot to buy gaskets early out of stupidity, so I have to wait for them to come in. I cleaned the surfaces to get rid of the old gaskets though, and I'll be re-assembling it when the new ones come in.

            So there goes, second major part done, a million more things to go before this car is up and running. I'll put up a build thread at some point when I start working on it more regularly.
            Last edited by Solarian; 06-21-2013, 03:22 PM.

            Comment


              #7
              Thanks for the post, my gears look similar to yours above, am planning to swap and this write up helps



              318iS Track Rat :nice: www.drive4corners.com
              '86 325iX 3.1 Stroker Turbo '86 S38B36 325

              No one makes this car anymore. The government won't allow them, normal people won't buy them. So it's up to us: the freaks, the weirdos, the informed. To buy them, to appreciate them, and most importantly, to drive them.

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