Announcement

Collapse
No announcement yet.

Need advice from experience for an M42 rebuild

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • JonsE30
    replied
    thanks guys for the advice, placed the order while the site was down. parts are shipped and in transit! i will try to vlog and snap pics of the reassembly so i can document as much as possible.

    Leave a comment:


  • roguetoaster
    replied
    ^
    This is correct, but considering the high cost of hardware failure and PITA factor they should be replaced whenever you remove the FW. Also, some M42s came with 8.8 bolts, and those should get 10.9 bolts according to some obscure TSB.

    Further info for that same area, it should be remembered that there are 2x pilot bearing sizes amd what you'll need will be predicated by your input shaft.

    Leave a comment:


  • varg
    replied
    They aren't TTY, you can reuse them as long as they aren't stretched or damaged, they just need thread sealant.

    Leave a comment:


  • roguetoaster
    replied
    They can be reused if you don't have an alternative, but it's not suggested at all. For $20 I'd replace them.

    Leave a comment:


  • JonsE30
    replied
    clutch was replaced less than 30k ago, can the flywheel bolts be reused?

    Leave a comment:


  • roguetoaster
    replied
    No, yes if not delaminating, not really, and yes, but I skipped the loctite. YMMV.

    Leave a comment:


  • JonsE30
    replied
    ok i'll do the entire reassembly.

    can the exhaust manifold, upper&lower intake manifold and throttle body gaskets be reused?

    how about the crank bolt being reused with loctite?

    Leave a comment:


  • Gloff
    replied
    Originally posted by roguetoaster View Post
    Again, install the engine and transmission together. You can only really leave the alt/PS pump/AC comp/fan off during the first startup.

    I suggest adding a coolant pipe (the plastic one), manifold gaskets (intake, exhaust and downpipe too). If I were you I'd put the engine together on a stand, leaving off the intake manifold/accessories.That way you only need to lay the under intake wiring in place, add accessories, coolant lines, intake, and go.

    2nded, that's the way I did it. Eng/Trans together, exhaust manifold on, bolt up everything except the intakes and coolant hoses, drop in car, then put the intake and cooling hoses in. I deleted the A/C compressor, you'll need two shorter bolts for the front cover if you do that.

    For first startup, I only left the hood off, everything else was bolted up. Do the reassembly slowly and methodically, and have faith in your reassembly skills.

    Leave a comment:


  • roguetoaster
    replied
    Again, install the engine and transmission together. You can only really leave the alt/PS pump/AC comp/fan off during the first startup.

    I suggest adding a coolant pipe (the plastic one), manifold gaskets (intake, exhaust and downpipe too). If I were you I'd put the engine together on a stand, leaving off the intake manifold/accessories.That way you only need to lay the under intake wiring in place, add accessories, coolant lines, intake, and go.

    Leave a comment:


  • JonsE30
    replied
    thank you all for the tips, all really good info!

    so once it comes back (2-3 weeks) i will reassemble the head, mate it to block then drop it in the engine bay. what are the must have to do a test fire before buttoning everything up? i don't wanna do a parts order haul then get stuck on the engine trying to start.

    i am guessing, main wiring harness, computer, crank and cam position sensors, fuel system?

    i am also guessing the starter is needed but that mounts to the transmission so i would have to marry to the transmission too?

    do the intake and exhaust manifolds need to be reinstalled? throttle body? thermostat?

    i am going to be placing an order the must haves for right now to get the engine assembled:

    head gasket
    valve cover gasket
    spark plug seals
    timing gaskets and seals

    is there other must have for 1st test startup" part i am missing?

    i am getting excited, everyone else is so helpful, always looking forward to your advice, thanks in advance!

    Leave a comment:


  • Gloff
    replied
    Originally posted by roguetoaster View Post
    Gotze for the HG is best, or so folks say, mine has lasted for 9 years after the VR one failed right out of the box, of course it's possible that I installed it incorrectly but I don't think so. Elring is the same as VR IIRC.

    If the lifters are new which I would highly recommend then they should be, but don't need to be bled. Old lifters should still be fine, but I would soak them in some ATF or something similar and then drop them in a container of oil overnight before installing. Clearly a vacuum setup is best for the lifters in terms of removing all of the air, but I have not had issues without it.

    Any rotating assembly should get some kind of lube, and as you correctly identified the lifters may rotate, but I think dumping oil on top of them prior to startup will be fine.

    In my case I put assembly Lube on the cams and then dumped all of my oil directly on the valve train prior to installing the valve cover and starting it. I did initially get clatter but it went away after about 15 to 20 seconds and I have found that if you have clatter you can often run the engine for a few 5 second intervals to make it go away.

    I reused the original lifters both times I did the HG and once was after they sat for a month and got clatter both times as well. Ran it for about 3-4 min, shut down and restarted the next day and the clatter went away.

    I'd recommend putting the valvetrain in after mounting and torquing the head, makes it easier to torque the headbolts and you don't have to worry about oil running down while you're trying to plop the head on. On that note, you have to rotate the crank approx 45 reverse when you mount the cams, mount the cams locked at TDC, once torqued, you have to let it sit for 15-40 min (depending on ambient temperature) to let the valves move back up before setting TDC on the crank.

    Leave a comment:


  • roguetoaster
    replied
    Gotze for the HG is best, or so folks say, mine has lasted for 9 years after the VR one failed right out of the box, of course it's possible that I installed it incorrectly but I don't think so. Elring is the same as VR IIRC.

    If the lifters are new which I would highly recommend then they should be, but don't need to be bled. Old lifters should still be fine, but I would soak them in some ATF or something similar and then drop them in a container of oil overnight before installing. Clearly a vacuum setup is best for the lifters in terms of removing all of the air, but I have not had issues without it.

    Any rotating assembly should get some kind of lube, and as you correctly identified the lifters may rotate, but I think dumping oil on top of them prior to startup will be fine.

    In my case I put assembly Lube on the cams and then dumped all of my oil directly on the valve train prior to installing the valve cover and starting it. I did initially get clatter but it went away after about 15 to 20 seconds and I have found that if you have clatter you can often run the engine for a few 5 second intervals to make it go away.

    Leave a comment:


  • JonsE30
    replied
    so i got a call back from the shop after the tear down and the quote i was given was pretty much what to i expect for a rebuild, i just of course wish it was lower.

    once it comes back i will finish re-assembling the head, and i'd like to prepare for it to mate to the block.

    i removed the camshafts, trays and lifters from the old head to transfer to the re-valved head.

    do i need to prime the lifters with oil and bleed it with vacuum pump?
    do i need to use assembly lube on the walls of the cam tray where the lifters slide in?

    i was looking for a head gasket and found a "cylinder head gasket set" from elring on ecstuning that looks like it has all the seals and gaskets from the block surface deck up. except the 10 head bolts and 10 head bolt washers. is this good for just a basic street car?

    i mainly here to stay away from victor reinz but hear elring is a good alternative.

    Leave a comment:


  • digger
    replied
    Originally posted by JonsE30 View Post
    Got a status update on the block from the shop. The block got torn down and inspected crank is good, rods can be recondition but cylinder walls need to bored and I will need new oversized pistons. He is still preparing a quote/estimate but now I have an idea what I’m in for but hopefully all you m42 gurus can help guide me to the next step.

    As I was trying to keep costs low, would it be possible to reuse the stock piston and just have a slightly larger ring gap? Or does it HAVE to be a new piston/ring set?

    I see a bunch of forged piston options which are a bit pricey. Are they are non forged alternatives like the oem one but for the larger bore size? Is there another bmw engine’s piston I can use with the recondition connection rods?

    I don’t plan on racing, tracking etc. I just want a dependable reliable rebuild that I can drive on 2-3 times a week so I don’t need all the high performance spec but if prices are all on level playing field I’ll opt for whatever is better reliability in the long run.

    Main bearing cap bolts can be reused?
    Buy new connecting rod bolts?
    Have the shop install the new crank bearings (upgrade to that 360 full thrust bearing I keep reading about from the m50)?

    Thanks in advance.
    you'll almost certainly need replacement pistons to keep the piston to wall in spec by the time the bores are trued up properly, sounds like the machinist advised this? BMW sell oversized pistons which might be cheaper than aftermarket forged but not by a large amount if at all.

    you cant beat an OE piston for reliability they are actually engineered for the engine by the piston manufacturers and BMW and tested. a lot of aftermarket forged stuff is not done properly.

    forged aftermarket pistons are really what you want only if you're building a high performance engine, changing stroke, CR or running more aggressive cams where you need a piston that's physically different to whats available from the OE...

    new rod bolts are recommended, main bolts bmw seem to say to replace them for the M42.

    https://workshop-manuals.com/bmw/3_s...lls_(m40_m42)/
    Last edited by digger; 07-16-2019, 05:14 PM.

    Leave a comment:


  • roguetoaster
    replied
    Consider displacement increases now. Look at what folks have done to get a sub 2.0L M42, and many have used other than M42 fitment BMW pistons, but YMMV.

    Anything that's TTY should be replaced, and I'd get new rod bolts for peace of mind. Might as well spend $40 now than 2k later.

    The bearing surface is about the oiling groove, not additional thrust bearings.

    Basically, let your machinist tell you what size items you can/should use and then you can explore getting parts.

    Leave a comment:

Working...
X