Announcement

Collapse
No announcement yet.

DIY : Engine Rebuilds (Speciofically BMW S54)

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

    #16
    Yeap.

    So far I'm collecting bags and tubs with white/pink/yellow markers. Also collected a shit load of measuring devices.

    Setting up the shed and pulling the motor over the weekend.

    Idea is to measure it all up to max. tolerances - confirm it's usable. Have the crank micropolished, block and head skimmed and measure up bearings and head gaskets.

    On the head itself, what do I do ?
    *Send it stripped or with some hardware (valves/cams/springs)?
    *I assume skim is is just facing the head within tolerance, and service is skimming + checking all the springs, valve train and so forth.
    *I'm keen to use all the existing hardware, but refresh the seals and maybe springs (and the retainers).

    Hopefully I'll get to the stage of taking some photos of where the headgasket has failure over the weekend.

    Ps. Crash D, can't be 2 years! I've set a goal of having it back on the track, at the latest!, by Oct (this year).... but perfer to have it done by the start of August.
    Panzer Wagen

    M-Cars follow the idea that power should be felt & not seen

    Comment


      #17
      Machine shop or cylinder head shop will most likely suggest valve job and skim. They usually dip it and it comes back looking and being as good as new. Valve job involves cutting the seats and the edge of the valves for a perfect seal and they also cut the top of the valve again to make it perfectly square. (The bit the lifter sits on) When they dip it they will clear out any crap in any oil galleries and replace guides as well. This makes sure that the valve stays square when it's being slammed closed and opened.

      They do that because carbon build up and just general crap getting in there can pit the valve seat when the valve is smashing about. Sometimes the guide can be worn meaning the valve wont close square or seal properly. This will all become super obvious once you take it apart. Skimming it makes the head surface perfectly flat again. The finish becomes really important if you use metal layered head gaskets. It needs to be really flat.

      I dont know the specifics of your engine so I could be a little off but that should help you understand it. Things like guides, bearings, valve seals, replacement valves if required etc etc I find it best to get the machine shop to supply. There is no reason you cant know everything there is to know about what's inside your engine but these guys do this shit every day. Starting out it's not so bad to let them do a bit more.

      Comment


        #18
        The unfortunate thing about this exercise is, that after all the time, effort and money that goes into it. The improvement will be barely noticeable. Yes the hot oil pressure is a smidge better than it was and the compression pressure a little higher and maybe you can convince yourself it is a little crisper but you'd be barely able to measure it.

        I've seen engines go back together where you could see light through the gap between valve and seat, with 2nd hand used bearings, a selection of used rings from random engines and you couldn't say it made any more or less power than a good one.
        " Racing cars don't have doors. Toilets have doors" : Keke Rosberg

        Comment


          #19
          Fuck all this shit makes Rotaries sound easy. Time to go back to a FD Andy!

          Comment


            #20
            So...

            Re-did the compression test on a warmed engine, with two different compression gauges (both Repco branded, from Repco).

            Test 1 : 105 / 105 / 155 / 155 / 140 / 140
            Test 2 : 120 / 120 / 175 / 175 / 160 / 160

            It's still showing the leak, and a distinctively different sound during the comp test of Cyl1 & Cyl2, compared to doing the test on the other cylinders. Interestingly it shows a fairly noticeable difference between 3&4 and 5&6 now.

            Does anyone know if that sort of pattern is consistent with anything? ie. Warped head? Or does it even swing an analysis back the other way and just say head gasket 100%.

            Thanks.

            -Got some more tools today. W&B torque wrench, cam lock and tools.
            Panzer Wagen

            M-Cars follow the idea that power should be felt & not seen

            Comment


              #21
              anything more than 20% is cause for concern normally, but on a performance engine, closer to 10% really. So even a small change in calibration between those two gauges, the gaps are still basically the same with 1,2 as 40-45psi is a big jump. Difference between 3,4 and 5,6 could simply be chalked up to the battery turning over the engine slower or not holding the throttle open long enough. Especially if you did a wet test afterwards and readings changed again. It's really only the drastically low ones you need to be looking for, its only a tool to help decide if something is off and you need to pull the motor down. Its not really something 100% accurate to what the issue actually is.

              You can send the head with everything if you want, but you'll need to run it by the machine shop first as a lot of places have stopped fitting cams and/or cam gears unless they are doing the complete rebuild as stupid people have assumed that everything is timed properly, its lined up and ready to go, only to mess up the valve timing and blame the shop. So a lot of places just avoid it completely.

              If you dont want to be touching it again, you may need to budget for a new set of valves too to be honest. I havent seen many sets of bmw valves that werent trashed given high km or a hard life. Even if the stem is ok, the grooves for the keepers/collets wears out and they dont fit as tight in the grooves as they should. I was/am always paranoid about dropping a valve because of it. So id be having a good look at the grooves around the top of the valve stem, they should be even and nicely defined, but they shouldnt be sharp. When they wear they tend to leave sharp edges on the ridges of the groove. Normally you can confirm just how bad the wear is visually when you try and fit a new collet to one side of the stem and you can see the gaps between the groove and the collet. So id probably look at them closely. If you end up doing valves, 100% do a set of valve guides and see if the shop thinks the seats need replacing or if they will be ok to recut. If your valves are ok, check the guides for any wear. Very basically you can try rocking the valve when fitted and you'll get a feel for how tight they are, just remove the valve stem seal and grip the valve just above where the seal was, shouldnt really have any detected play, otherwise the shop should be able to check wear in the bore with a dial gauge.

              Supertech and ferrea do aftermarket replacement valves if you need them. BMW used to use osvat or queen for a lot of their factory valves, but aftermarket is fine.

              You will need a shim kit for doing the valve clearances, or the shop may need one if you have someone build it for you. Bank on replacing the cam followers, they are more or less a consumable at this point and you will normally find wear on the pads even if the cam lobes are ok. This really applies if you are fitting new cams or valves during the rebuild too as you can get some tapered wear on the follower.

              Id probably replace the vanos oil feed line from the accumulator too if you havent already. There are a bunch of companies selling flexible braided ones now instead of the brazed hard line of the factory one which can crack.
              Originally posted by Buford T. Justice
              This happens every time one of these floozies starts poontangin' around with those show folk fags.

              Comment


                #22
                Someone else has suggested that I've probably smashed the valves & fucked the seating.
                Panzer Wagen

                M-Cars follow the idea that power should be felt & not seen

                Comment


                  #23
                  Unlikely, there'd be more noise and carnage....
                  " Racing cars don't have doors. Toilets have doors" : Keke Rosberg

                  Comment


                    #24
                    DIY : Engine Rebuilds (Speciofically BMW S54)

                    I had a look at a 4AGE recently with similar compression readings.

                    Except it was 2 & 4 with the low figures, so cracked HG was a long shot. Squirting oil down the bores for a wet test didn’t raise the readings appreciably, either. When it was running there was massive blow by.

                    On stripdown it turned out that overheating damaged a couple of ring lands, hence the super low comp in a couple of the cylinders.
                    Japanese Nostalgic Car - Dedicated to classic japanese cars

                    Comment


                      #25
                      If you have a look at Bennys video, his cappuccino had low compression, was even lower when the plug next to it was removed, would at least remove a issue between cylinders
                      you cant spell advertisements without semen between the tits

                      Comment


                        #26
                        As there is no grinding noises or anything to suggest there's been a failure, remove the spark plugs and put a squirt of oil in each cylinder, then give it a "wet" comp test. If the results are the same as no oil, it would suggest there may be an issue with valves/guides. If it improves the results, it would indicate rings etc.

                        Comment


                          #27
                          Not sure where in NSW you are, but I have used a engine shop called Leons Engineering in Artarmon for a few head rebuilds/services.

                          Old school guy, that gets stuff done when he says he will, will be using him again for what I tackle an engine assembly as well!
                          Pain is temporary, quitting is forever - Lance Armstrong (drug cheat)

                          Comment


                            #28
                            Has anyone suggested a leakdown test and a stethoscope?

                            That might give you a better idea of where getting out

                            Oo___oO

                            Comment


                              #29
                              At this point I wouldnt worry. Its coming apart for a rebuild, so it's kind of a moot point when you'd be using these tests as a way to determine if you need to pull it down, not actually what the problem might be. A visual inspection will tell you all you need to know when you start measuring and checking things.
                              Originally posted by Buford T. Justice
                              This happens every time one of these floozies starts poontangin' around with those show folk fags.

                              Comment


                                #30
                                Originally posted by rolin7 View Post
                                Not sure where in NSW you are, but I have used a engine shop called Leons Engineering in Artarmon for a few head rebuilds/services.

                                Old school guy, that gets stuff done when he says he will, will be using him again for what I tackle an engine assembly as well!
                                Another vote for Leon. Shop looks filthy but he delivers. Often the way in my experience

                                Comment

                                Working...
                                X