help with possible timing issue (no-start)

[ovedd]

Hey guys I'm wondering if anyone can help me with my most recent no-start issue. I recently replaced the cylinder head on my m42 because it was badly cracked on both the exhaust and intake sides. I didn't use the special cam removal tool do move the cams over to the new head, but I arranged them in the same direction as they were in the old head at TDC. The problem is, I removed the timing chain from the gears so when I put the chain back on its possible that the links aren't on the exact gear they were on before I removed them. Also, I may have broken the timing chain tensioner (its the original m42 one) by trying to compress it in a vise. when I put it back together after disassembly, I put oil in it (which I now know I shouldn't have done) and when compressing it I heard a large BANG like a gunshot. After I put everything back in my car, including the tensioner, I started it up and heard a loud rattling sound. I assumed it was the broken tensioner and got a replacement m44 tensioner, but after I put it in uncompressed (the easy way, apparently), the rattling persisted and the car would barely idle without stalling. I then revved the engine to 3000 rpm and the rattling went away, but the engine stalled immediately afterwards. Now when I try to start the engine it will not go above 500rpm at full throttle and it dies as soon as I let go of the gas. I removed the new m44 tensioner and noticed that it was still uncompressed. That's the full story as far as I can recall, and I'm not sure where to go from here so I hope one of you can give me some input. Any help is appreciated. I'll post a video of what the car sounds and looks like soon. Thanks guys!

[bmwman91]

First, you need to pop the tensioner loose. The easy way is rarely the right way with anything in life. I cannot imagine why the service manual says to do it that way.

Second, you need to get the cam and crank aligned properly, or make sure that they are aligned. It is easy to get the crank to TDC. Just use an 8mm bolt in the hole in the bell housing that will lock the flywheel. You need to pull the plugs for cylinders 1 and 2 to make sure that cylinder 1 is at the top and 2 is at the bottom. I believe that the flywheel has two 8mm holes, so sometimes people get it backwards (granted, the engine would not run at all if you did that). You can also stick a rod down the plug holes and make marks, and you should have 81mm between them if the pistons are at TDC. The cams are easy to get aligned. The lobes for cylinder 1 (frontmost) should point up and in and the square ends by cylinder 4 should be flat and parallel to one another. You can use a ruler to check that. I use a crescent wrench to hold those while I tighten the cam sprocket bolts. Once you think you have it all aligned, turn the engine a couple of times by hand and verify that it all lines up still. You really need that tensioner piston to be released as it will put some tension on the chain when doing the alignment. I usually gave a large screwdriver pushing on the tensioner rail to put extra tension in there when making the alignment.

Third, you need to do a compression test. Pull the 4 plugs and get a compression gauge.

[ovedd]

Great! Thank you for the help. When I put everything together I did exactly as you said to align the cams and pistons, but I did not turn the engine manually. Could that be part of the problem?

Also, could you explain again what you mean by releasing the tensioner? It is fully extended at the moment, is that how it should be?

I plan to test the compression tonight, but seeing as I am now confident that the cams are aligned properly, is it possible that it is just the chain that isn't aligned? If so, how do I go about fixing just the chain? Thanks again for the help, bmwman91.

[ovedd]

Here is a link to a video of what the car currently sounds like posted by my friend:

https://picasaweb.google.com/118320209921375590216/CameraUploads02?authkey=Gv1sRgCOPaz7D6rcO3tQE#5899060701290728418

[bmwman91]

By "releasing the tensioner" I mean it should be a pain in the ass to install. It comes compressed, and you should pop it so that the piston is extended, and you have to compress the internal spring when you go to install it. That ensures that there is some tension on the chain.

The position of the chain itself does not matter at all. The only important thing is the position of the cams relative to the crank. Also, when you installed the cam sprockets with things at TDC, were the little arrows on them pointing up? Those sprockets do need to be in some general alignment so that the cam position sensor can read things properly.

If opening the throttle all the way only got it to 500RPM, then something was really off. Honestly, I can't offer any more advice until you get those compression numbers. I am crossing my fingers for you, but it sounds like your valves may be bent.

[ovedd]

Ok, so I did a dry compression test and got zero compression for the first two cylinders, 135 psi on the third and 190 psi on the fourth. Unsure of the results, I tested it again (dry) and got the same results for all cylinders except for the third cylinder, which was 90 psi the second time around...

[bmwman91]

Did you have all 4 spark plugs removed for the test?

[ovedd]

Yes all of the spark plugs were out

[bmwman91]

Well, with zero compression on two cylinders it sounds very likely that the valves are bent. If you damaged and re-used the tensioner piston, then it is likely that the chain was super loose and jumped some teeth on the sprockets.

Sorry, I wish I could give a more positive prognosis.

[ovedd]

Ok I've been out of the country for a while so I haven't been able to give the car any attention until now. So if it is the valves that are bent, can I use the valves from my old head? What else should I look for that might have been damaged? Also, what needs replacing when doing the valves?

[DesktopDave]

I've never rebuilt one of these motors, so take my advice with a grain of salt.

You should be able to re-use the old valves.  IIRC the M44 has thinner valve stems but the M42s are all the same part.

BMW has a spec for valve stem wear and valve spring length in their workshop manuals, IIRC the E36 Bentley does too.  The timing chain can be checked in terms of length, and the cam gears should not have pointy teeth.

At a minimum, you'll need a new head gasket.  I'd be strongly tempted to buy a top-end kit and replace all the gaskets & seals while I was in there - valve stem, cover gaskets, profile gasket, thermostat cover gasket, oil filter housing seals, etc.

[ovedd]

Okay, so I got the head out but I'm not sure if the block is expected to look like this just from bent valves. I'm not sure if you can tell from the picture, but a green film (coolant?) is present on top of what looks like pools of oil. Is that expected, or do you think there is another issue on top of the bent valves?

[ovedd]

On the plus side, my cam gears look good and I bought a new gasket set. Do you think I need new valve guides as well or are those reusable?

[blackslicktop91]

HELLO Iam NEW ON THIS WEB SITE TO START OFF I HAVE A 91 318IS SLICKTOP MY BABY I SAVED HER FROM BEING TRANSFORMED IN TO A BAJA CAR THAT SOME RED NECKS WE'RE GONNA DO LUCKY ME
.
SEC I REBUILT THE WHOLE MOTOR NEW CHAIN NEW HEAD PISTON RINGS EXT... I CANt SEEM TO TURN IT ON AT ALL AT FIRST I HAD NO FUEL AND NO SPARK I FOUND THE PROBLEM THE SMALL FUSE IN THE TRUNK BLEW REPLACE iT AND  NOW I have fuel and spark but not turning on. DONT KNOW WHAT TO DO?? I NEED HELP ON THE TIMING I DIDN'T USE A SPECIAL TOOL FOR THE CAMS JUST A RULER.I NEED TO KNOW
-WHERE ARE THE TIMING MARKS?
-HOW DO THEY GO?
-AND WHERE IS THE HOLE FOR THE TRANNY TO LINE UP THE CRANK AND CAMS? HOW
COMPRESSION IS AT 190 ALL 4
FUEL PRESSURE 36 PSI
SPARK STRONG
NEED HELP

[mabeer]

Hey Blackslicktop welcome to the club.  I'll answer here but you may want to start your own thread so it doesn't get burried.  Timing is pretty simple. if you follow a couple of rules: 1) front cam lobes pointing up and slightly towards each other and flats at rear lined up so a ruler can be placed flat across them kind of like this

2) There is an arrow on the oil filter housing


That needs to point to the tooth with this mark on the harmonic balancer

If you do that you should be good to go.

The hole in the block that allows you to lock the flywheel is underneath the starter between a web-like casting.  There should be a plastic plug in it.  If you follow the rules above you should be able to slide a drift, punch or socket extension into the hole to lock the flywheel/crank but I wouldn't rely on it to set timing.

Edited to add:  Oops forgot to mention 15 timing chain pins between timing gear marks.