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.



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.

[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?