No compression - wtf?

[whiskychaser]

I just changed both timing chains, guides and tensioner on my '92 525i non vanos engine. Due to my work I have a limited amount of time to spend so this has taken a while. While I appreciate you need to have a warm engine to get an accurate reading I am getting zero on all 6 cylinders. I dont even the 'chuff chuff' sound. Not surprisingly, the engine wont fire. Timing was set up as follows:

Timing mark on crankshaft pulley dead in line with pointer on chain housing
( I have the flywheel locking tool but couldnt get it in)
No 1 cylinder cam lobes up and leaning in towards each other
Two dots on flats at rear of camshaft facing upwards and flats level
Arrows on camshaft sprockets point up

I am curious that this set up makes the 'pointer' behind the inlet sprocket face down but this appears to be correct per photos in Bentleys. Strange as the sensor for it is 90 degrees before that?

I can get a 25 thou feeler gauge between the bottom of the inlet cams and the followers but not on the exhaust. Is this normal? I'm thinking bent valves - but on all 6??

Advice appreciated. Especially the kind that says 'just turn this screw and all will be well'

[yaofeng]

Bent valves on all six cylinders is my guess. Don't know what to tell you. You need to retrace all the steps you took to come to this point to see where you did wrong.

If you turn the engine by hand, you should hear each cylinder compresses and make a sound similar to passing gas if the engine is healthy.

[whiskychaser]

Bent valves on all six cylinders is my guess. Don't know what to tell you. You need to retrace all the steps you took to come to this point to see where you did wrong.

If you turn the engine by hand, you should hear each cylinder compresses and make a sound similar to passing gas if the engine is healthy.

I changed the chains as the engine had 'died' on me. They were stretched badly and the two guides were wrecked. I had hoped that was the cause of the problem.

I know I can drop some oil down the plug hole and see if this brings the compression up. But what I really need to know is should there be a gap between the follower and the bottom of the cam? If not, then it looks like all the inlet valves are bent. But its a bit strange the gap is consistent

[yaofeng]

If you see a gap between the cam follower and the cam lobe, either the cam follower is bad or you have a bent valve.

I suspect when the engine died on you the valves were already bent. What were the symptoms?

[whiskychaser]

If you see a gap between the cam follower and the cam lobe, either the cam follower is bad or you have a bent valve.

I suspect when the engine died on you the valves were already bent. What were the symptoms?

Engine started ok. Drove about 25 yards and heard noise like somebody using a chain saw under the bonnet. (Hence my conclusion chains were shot. Bolt from the chain guide also sheared -fished it out of the sump.) Engine lost all power and sounded like a steam train. Stopped immediately and had the car towed. Not that clear about hydraulic tappets - if the valve springs push the follower against the cam lobe, where does the hydraulic bit come it?

[Ross]

Sounds like you stuffed the valves at the time of the original failure. If zero compression the vale timing is way off or valves aren't closing(as in bent).
A used head is probably the cheapest solution.

[whiskychaser]

Sounds like you stuffed the valves at the time of the original failure. If zero compression the vale timing is way off or valves aren't closing(as in bent).
A used head is probably the cheapest solution.

It was always in the back of my mind that the valves/pistons may have collided at that time. Thats why I did the comp test before trying to fire it up. There is no gap between the the exhaust lobes and followers so it looks like it 'just' took out the inlets.

[yaofeng]

Engine started ok. Drove about 25 yards and heard noise like somebody using a chain saw under the bonnet. (Hence my conclusion chains were shot. Bolt from the chain guide also sheared -fished it out of the sump.) Engine lost all power and sounded like a steam train. Stopped immediately and had the car towed. Not that clear about hydraulic tappets - if the valve springs push the follower against the cam lobe, where does the hydraulic bit come it?

The valves were bent when the timing chain went. Did you install the new plastic guide? The old chain guide is aluminum. I had to saw it in two to remove it. Of course the new plastic guide just snapped into place.

http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_525i/DSC_1705.jpg

This new guide pin is supposed to be used with the new plastic guide. I didn't use it because I didn't know how to remove the old one.

http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_525i/DSC_2706.jpg

I shortened a piece of the original timing chain guide base pivot ring to work with the new plastic guide. The aluminum ring is behind the new guide.

http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_525i/DSC_1710.jpg

[Tiger]

I am confused... even if you did compression test before changing chain and tensioner. It wouldn't read anything if you are lucky.

The fact you got zero compression on all 6 means timing is all wrong. With first cylinder all the way up as in compression with both valves closed... the timing mark should be zero at the harmonic balancer.

[whiskychaser]

The valves were bent when the timing chain went. Did you install the new plastic guide? The old chain guide is aluminum. I had to saw it in two to remove it. Of course the new plastic guide just snapped into place.

This new guide pin is supposed to be used with the new plastic guide. I didn't use it because I didn't know how to remove the old one.

I shortened a piece of the original timing chain guide base pivot ring to work with the new plastic guide. The aluminum ring is behind the new guide.



Your first pic is the chain tensioner. Like you, I cut mine in half to save removing the head. On my car this pivots on a dowel. I removed the dowel, poked the end of the new tensioner up through the head and tapped in a new dowel and fitted a new circlip at the end.

Your second pic looks like the pin that you push the chain guide on to. It was one of these pins that sheared and I found it in the sump. On my car these pins have threads. I fitted two new pins and a new guide. (I also fitted the other guide that bolts on top of the head and two new chains)

I'm not sure what your third pic is I can only guess this is what the chain tensioner pivots on in your car?

[whiskychaser]

I am confused... even if you did compression test before changing chain and tensioner. It wouldn't read anything if you are lucky.

The fact you got zero compression on all 6 means timing is all wrong. With first cylinder all the way up as in compression with both valves closed... the timing mark should be zero at the harmonic balancer.

The lobes on no 1 cylinder were pointing up and towards each other. The two dots on the flats at the back end of the cams were facing up and flats were in a horizontal line. Valves on no.1 cylinder were def. closed. I made a physical and visual check that no.1 piston was at TDC. I lined up the timing mark on the timing chain housing with the mark between the O and T marks on the crankshaft pulley. (As the pulley is in two parts, I made sure the lug from the back section was in the hole of the front before bolting it together)

I dont know what the harmonic balancer or how you mean the mark is zero but I'm very keen to learn!!

[yaofeng]

Your first pic is the chain tensioner. Like you, I cut mine in half to save removing the head. On my car this pivots on a dowel. I removed the dowel, poked the end of the new tensioner up through the head and tapped in a new dowel and fitted a new circlip at the end.

Your second pic looks like the pin that you push the chain guide on to. It was one of these pins that sheared and I found it in the sump. On my car these pins have threads. I fitted two new pins and a new guide. (I also fitted the other guide that bolts on top of the head and two new chains)

I'm not sure what your third pic is I can only guess this is what the chain tensioner pivots on in your car?

After 9/94 BMW replaced the aluminum chain guide (BMW call this chain tensioner, I am used to the SAAB convention calling it the chain guide. But tensioner it is.) with one plastic. My 525i was a 5/94 production. It came with an aluminum tensioner. I cut it in half to remove it like you did so I did not have to remove the head. The only way I can fit the chain tensioner back was to use the plastic one because I can snap it in place. It is not possible to reinstall the aluminum tensioner back with the head in place. Since I didn't know how to remove the old tensioner pivot pin to install the new one which works with the plastic tensioner, I had to make use of the old pin. The plastic tensioner has a shorter width then the aluminum tensioner at the pivot. (Fortunately the pin diameter is the same.) To make it work I need to make up the difference in width. So I cut a piece from the discarded aluminum tensioner pivot to slip onto the old tensioner pin and reused the snap ring. The new plastic tensioner doesn't require a snap ring if fitted with the new guide. It just snaps in. I had to reuse the metal snap ring with the new tensioner, old tensioner pin combination.

[yaofeng]

The lobes on no 1 cylinder were pointing up and towards each other. The two dots on the flats at the back end of the cams were facing up and flats were in a horizontal line. Valves on no.1 cylinder were def. closed. I made a physical and visual check that no.1 piston was at TDC. I lined up the timing mark on the timing chain housing with the mark between the O and T marks on the crankshaft pulley. (As the pulley is in two parts, I made sure the lug from the back section was in the hole of the front before bolting it together)

I dont know what the harmonic balancer or how you mean the mark is zero but I'm very keen to learn!!

The picture below is what he meant. But I think your timing set at No. 1 piston TDC was dead on except it was set on one with bent valves.

http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_525i/DSC_1733a-1.jpg

[whiskychaser]

[QUOTE=yaofeng]The picture below is what he meant. But I think your timing set at No. 1 piston TDC was dead on except it was set on one with bent valves.

I have to agree :-( The only thing I WAS slightly unhappy about was that I coudnt get the left side of the slots in the main chain sprocket to line up with the bolt holes in the end of the exhaust cam. They are to the left, but not as far over as I wanted. But if the crank and cams are fixed, that position is dictated by the length of the chain which of course I pulled tight. Either way, the marks tally in practise.

I dont know exactly how hydraulic cam followers work, but even with a cold engine I dont expect to find 25 thou between the follower and the cam.

Will have to either take the head off or pop down the local hospital and see if I can borrow an endoscope :-)

[grave77]

when u heard that sound, you have bent some valves, broke some maybe, a dead chain with an engine running = dead engine. I have seen an engine trashed cuz of that while driving at 50m/h M20 engine lost the timing belt and grind all the valves into the pistons.

better now you remove the head, and see what the damage you have, also check the oil pan for any metal fragments this would tell you if you smashed any of the pistons with a broken valve fragments.

[632 Regal]

I dont know exactly how hydraulic cam followers work, but even with a cold engine I dont expect to find 25 thou between the follower and the cam.


there is only a certain amout of interferance between the valves and pistons which would explain the .025 clearance on all the intake valves. There should be NO clearance weather the engine is cold or warm or running with hydraulics.

new head time :(

[whiskychaser]

when u heard that sound, you have bent some valves, broke some maybe, a dead chain with an engine running = dead engine. I have seen an engine trashed cuz of that while driving at 50m/h M20 engine lost the timing belt and grind all the valves into the pistons.

better now you remove the head, and see what the damage you have, also check the oil pan for any metal fragments this would tell you if you smashed any of the pistons with a broken valve fragments.

Some years ago I had a timing belt go on a Honda 16 valve doing 85mph in the fast last of the motorway. Did no damage to pistons/valves. Two miracles is too much to expect. I better read up on how to take the cams off without snapping them

[whiskychaser]

there is only a certain amout of interferance between the valves and pistons which would explain the .025 clearance on all the intake valves. There should be NO clearance weather the engine is cold or warm or running with hydraulics.

new head time :(

Thanks for clearing that up. My guess is the inlet valve heads are larger and they took a hit whereas the exhausts may have escaped.

[632 Regal]

correct, pull the head and make sure before you buy a new one.
Thanks for clearing that up. My guess is the inlet valve heads are larger and they took a hit whereas the exhausts may have escaped.

[Paul in NZ]

my old toyota broke the belt and did no damage...a non intereference engine i think,tow to shop,new belt,drive home

[whiskychaser]

correct, pull the head and make sure before you buy a new one.

Yep. First job has got to be see what damage has been done.

Will post the outcome. Meanwhile thanks to everyone for support

[whiskychaser]

Just read this article about removing cams. This guy reckons you should be able to spin the cam followers if the valves are closed as there is a small gap between the follower and the cam. I thought there shouldnt be a ANY gap. I dont call 25 thou a small gap. 9 or 10 on an old style head maybe. Either way the head is coming off.

http://www.pelicanparts.com/BMW/techarticles/E36-Camshaft-Removal/E36-camshaft-removal.htm

[Ross]

The hydraulic adjusters take up the "lash", without oil pressure they ought to spin. 25 thou is a lot, chances are a bent valve is dangling open a bit.

[632 Regal]

IDEA!!!

hook up the compression tester to compressed air to see if the valves are actually open when the lobes are not holding the valves open.

Dont know why I didnt think of this sooner.

[whiskychaser]

IDEA!!!

hook up the compression tester to compressed air to see if the valves are actually open when the lobes are not holding the valves open.

Dont know why I didnt think of this sooner.

To be honest I had thought of that but I dont have access to comp air where the car is. I believe it works in principle as I heard Ford in UK used to use comp air to hold the valves up (closed) while they changed valve stem oil seals. Saved them taking the head off. My only concerns are locating the block drain and if my torx sockets are thin enough to get at the head bolts. Oh, and the price of the parts:£80 just for a head gasket?!!!

[Ross]

Fire up a big ole cigar and blow the smoke in the cylinders through the plug hole and see if it comes out the intake. Okay maybe that's a bit primative. It might work.

[632 Regal]

smoke bombs?

Fire up a big ole cigar and blow the smoke in the cylinders through the plug hole and see if it comes out the intake. Okay maybe that's a bit primative. It might work.

[grave77]

but he has to remove the intake manifold to see it right away. I guess since he fixed the timing before it's better he removes the head and work with eyes open, we are all assuming things and it can all be seen when the head is removed.

[whiskychaser]

I'm going to try the 'cigar test' but as I dont smoke cigars it will have to be cigarette smoke :-) I will just get someone to press the throttle to make sure the butterfly is open. I realised my lady bought one of those jump start kits that incorporate a compressor for pumping up tyres. Its useless for starting a car but I'm going to try check for compression with it as suggested.
Then I'm going to take the head off

[yaofeng]

A borescope into the spark plug hole should work better.

[whiskychaser]

The 'cigar smoke' test works very well with the inlet manifold off. No damage to the pistons or valve seats. But the pic shows why I didnt have any compression:

[Jon K]

WOW... you couldn't tell you had bent valves!? Damn!

[Ferret]

The 'cigar smoke' test works very well with the inlet manifold off. No damage to the pistons or valve seats. But the pic shows why I didnt have any compression:

Holy cr*p, your valve guides are still intact with them like that?

[Tiger]

Mmm... and you didn't believe you set the timing wrong? Let me ask you... prior to you working on your timing chain... was the engine running? Boy, do you need a complete head job...

[whiskychaser]

Mmm... and you didn't believe you set the timing wrong? Let me ask you... prior to you working on your timing chain... was the engine running? Boy, do you need a complete head job...

The engine wasnt running prior to my changing the timing chains:-) I always knew there was a good chance pistons/valves had collided. I just hoped they hadnt :-) No, I didnt set the timing wrong.

The cams, valve guides and lifters are all in good shape. There isnt a mark on the head. The head gasket I took off measured 1.9mm so I'm going for the thicker 2.05mm gasket when I come to refit the head

[Tiger]

Ahh... yes, then you didn't do it... okay... whew!

[DaveVoorhis]

The head gasket I took off measured 1.9mm so I'm going for the thicker 2.05mm gasket when I come to refit the head
Why? Are you having the head skimmed?

[whiskychaser]

Why? Are you having the head skimmed?

I dont plan to but I suspect it may already have been skimmed. The standard gasket is 1.75mm but the one I took off was still 1.9mm thick after being compressed. I dont want to risk valves hitting pistons again by fitting a gasket thats too thin.

[grave77]

congratulations ... all bent ... but also you are lucky that you have ur pistons intact

[grave77]

better you get a rebuilt head, anyway when a head is skimmed it gets more fragile to heat than before. the engine will not be as durable as it was before.

[whiskychaser]

congratulations ... all bent ... but also you are lucky that you have ur pistons intact

Yep I will count myself very lucky if I get away with 12 inlet valves. Had I changed the chains sooner I wouldnt even be doing this. I had compressions around 220 psi before :-(

[grave77]

still you have to count your self very lucky, the last engine I've seen was an M20 with failed timing belt ... it was an engine out of the world war I guess ... valves chopped broken into the pistons and engine block was totally damaged with valve fragments ... you wont like to see how bad it was ... sure it was all useless and that guy had to buy a full engine head+block.

[whiskychaser]

Put in 12 new valves, torqued the head down with my new certified wrench and she runs beautifully. But I now have a coolant leak. Cant see where. So my brother takes apart his web cam, puts it on the end of a stick with a tiny torch and we go boldly where no man has been before:-) The leak is running back from the join between head and the timing chain cover. Next job is loosen the timing chain cover and sump bolts and see if I take take up the slack and stop the leak. Will post pics if I can get a frame out of the video :-)

[632 Regal]

lol, I hope you find it!
if I can get a frame out of the video :-)

[whiskychaser]

May seem like a daft question, but how many bolts are there between the head and the bottom timing chain cover? Bentleys states 3 but in the diagram there are only two arrowed:-) Following link seems to confirm there should be 3:
http://www.realoem.com/bmw/showparts.do?model=HD68&mospid=47405&btnr=11_0157&hg=11&fg=10

I have replaced the upper chain guide rail. Originally there were 3 bolts but the new rail has one blanked off by an 'X'. Its part no. 5 at:

http://www.realoem.com/bmw/showparts.do?model=HD68&mospid=47405&btnr=11_1286&hg=11&fg=25

I'm trying to find the cause of a coolant leak. Its from the area close to where the hose connects to the rear of the timing chain cover

[yaofeng]

There are 14. 12 on the cover and 2 inside the valve train hidden by the upper chain guide support.

[whiskychaser]

There are 14. 12 on the cover and 2 inside the valve train hidden by the upper chain guide support.

Hi, I can locate all the bolts that come up from the oil pan and those that secure the timing chain cover to the block from the front.

Two that go down thorough the head are very clearly marked in Bentleys-they correspond with the outer bolt holes in the link of the timing chain cover in my last post. It is what goes down the middle hole I'm concerned about (right below the no.1 in the diagram). I'm pretty sure its the long bolt that holds the upper chain rail down but was just looking for confirmation. As I said the previous rail had 3 bolts, this one has 2. Sure you posted a pic of the 'new' rail but search button isnt working again :-(
I'm going to take the timing chain cover off to get to the bottom of the coolant leak but wanted to make sure I hadnt 'missed' a bolt last time round

Coudnt copy pic but link with blanked off rail here:http://www.bimmer.info/forum/showthread.php?t=33101&highlight=blind+panic ( i hope :-) )

[yaofeng]

I am confused by your question. Are you talking about the number of bolts on the guide rail? I think there are three. But I don't have a good picture to show you. The closest ones are below.

http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_525i/DSC_4827.jpg

http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_525i/DSC_4826.jpg

http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_525i/DSC_4824.jpg

[whiskychaser]

I am confused by your question. Are you talking about the number of bolts on the guide rail? I think there are three. But I don't have a good picture to show you.

I just mean the total number of bolts that go down through the head into the top of the timing chain cover. The one at each side of the head is easy to see but I think the one in the middle doubles as a guide rail bolt.

Actually, I think I answered my own question- the link to the other thread shows a very clear picture of the guide rail on your head, complete with mystery 'x' blanking out the hole where a bolt used to go :) Must be the bolt on the right (which you can just see) that goes straight through?

[yaofeng]

I just mean the total number of bolts that go down through the head into the top of the timing chain cover. The one at each side of the head is easy to see but I think the one in the middle doubles as a guide rail bolt.

Actually, I think I answered my own question- the link to the other thread shows a very clear picture of the guide rail on your head, complete with mystery 'x' blanking out the hole where a bolt used to go :) Must be the bolt on the right (which you can just see) that goes straight through?

If you mean the timing cover, I am very sure there are only two bolts inside the valve train. Two years ago I relied on Bentley's picture to remove the timing cover by removing only the ones on the side and in the bottom, not realizing there are two inside the valve train. I started prying with two bolts still lodged and cracked the timing cover (naturally). That's why the timing cover in the picture is so new.

http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_525i/DSC_1733a-1.jpg

[whiskychaser]

[QUOTE=yaofeng]If you mean the timing cover, I am very sure there are only two bolts inside the valve train. Two years ago I relied on Bentley's picture to remove the timing cover by removing only the ones on the side and in the bottom, not realizing there are two inside the valve train. I started prying with two bolts still lodged and cracked the timing cover (naturally). That's why the timing cover in the picture is so new.

I have had the cover off before but couldnt remember if I had the guide rail off at that time. Didnt want to damage the cover as unfortunately happened to you. But I also want to make sure I get a proper seal between the head and the timing chain cover. Not looking forward to trying to drive those locating pins out again. Got new gaskets on the head and timing chain cover but something is clearly not right

[Ross]

I'm a bit confused by this exchange. My advice is to look at the new gasket to understand where all the bolts are.

[yaofeng]

I'm a bit confused by this exchange. My advice is to look at the new gasket to understand where all the bolts are.

That won't help you. The two bolts inside the valve train have no gasket.

[yaofeng]

[QUOTE=yaofeng]If you mean the timing cover, I am very sure there are only two bolts inside the valve train. Two years ago I relied on Bentley's picture to remove the timing cover by removing only the ones on the side and in the bottom, not realizing there are two inside the valve train. I started prying with two bolts still lodged and cracked the timing cover (naturally). That's why the timing cover in the picture is so new.

I have had the cover off before but couldnt remember if I had the guide rail off at that time. Didnt want to damage the cover as unfortunately happened to you. But I also want to make sure I get a proper seal between the head and the timing chain cover. Not looking forward to trying to drive those locating pins out again. Got new gaskets on the head and timing chain cover but something is clearly not right

Look at the timing cover. There are two built-up portion with fattened metal are where the vertical bolts are located.
http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_525i/DSC_4812-1.jpg

[whiskychaser]

I'm a bit confused by this exchange. My advice is to look at the new gasket to understand where all the bolts are.

Good call Ross. Laid the old head gasket on top. Hole in middle of the gasket lines up with the back bolt on the chain rail. So there are def 3 bolts from the above if you just want to take the timing cover off. I'm not missing a bolt but still have to take it off to find the cause of the leak :(

[whiskychaser]

Leak coming from the timing chain to block gasket just above the water pump. Swift kick up the arse to yours truly who fitted it. :(