Timing chain & tensioner '92 525i

[whiskychaser]

This is a follow up to a thread I started some time ago under 'blind panic'. Bascially, the main timing chain was loose and took out the bolt that holds the timing chain guide in place. You dont want that rattling around! A couple of points I thought may be useful to anyone else thinking of doing the same:

1. You can do this without dropping the sump or taking off the head
2. The main chain may not come off without removing the tensioner arm
3. The arm pokes up through the head so you need to remove the pivot at the bottom to get it clear. The diagrams you will find at real.oem etc are wrong-it isnt a bolt but a dowel.
4. There are dirty great timing marks on the flats of the camshafts so dont panic if you are not sure where the lobes are supposed to be
5. If you get hold of the special tool to lock the crank and cam read the manufacturers notes. They may say the crank lock wont fit because of rust in the hole and to get the cam lock to fit you need to snuggly you need to put some feeler guages between the tool and the cams :-)

I replaced both chains, both guides and the tensioner arm and spring. They were all shot. Total costs incl gaskets was about £140 inc VAT.

[632 Regal]

the thought of messing with timing chains on these things scares the crap outta me. Congrats on a great job!

[yaofeng]

I'd be interested to see a picture of the timing marks on the cam shafts. I din't find any. There is a timing mark on the exhaust cam sprocket, however. But none on the intake cam sprocket for the VANOS engine.

I did not use a special tool either for the crank lock or the cam lock at No. 1 piston TDC. A 1/4" diameter drift works very well locking the flywheel to the engine block. The hole is under the starter capped by a piece of rubber. As for the camshaft the end of which is square. They should be in the horizontal position in line with the very vague Bentley description that the first cam lobes face each other ar 10 o'clock and 2 o'clock.

[whiskychaser]

I'd be interested to see a picture of the timing marks on the cam shafts. I din't find any. There is a timing mark on the exhaust cam sprocket, however. But none on the intake cam sprocket for the VANOS engine.

I did not use a special tool either for the crank lock or the cam lock at No. 1 piston TDC. A 1/4" diameter drift works very well locking the flywheel to the engine block. The hole is under the starter capped by a piece of rubber. As for the camshaft the end of which is square. They should be in the horizontal position in line with the very vague Bentley description that the first cam lobes face each other ar 10 o'clock and 2 o'clock.

Located the hole to lock the flywheel but the tool wouldnt fit. I actually used an allen key - as its bent you can wiggle it around easily. It occurs to me that Bentleys make a big deal of the 'arrow' on the sprockets pointing up. There are 2 arrows at 12 and 6 o'clock. Which one do you pick? :-) The only reason I can think they are there at all is to help you line the bolt holes up. Have got pics but the link to my pc has 'gone technical'. Will post them soonest. And thanks Regal for the congrats - it took me half a day to drill out the stud without wrecking the threads! :-)

[yaofeng]

There are 2 arrows at 12 and 6 o'clock. Which one do you pick?

I only saw one. And none on the intake sprocket.

[yaofeng]

Actually you're right. Looking at the picture again, there are two arrows on the exhaust cam sprocket. I wasn't paying attention. Again the arrow and Bentley's vague description "first cam lobes pointing at 2 o'clock and 10 o'clock" blah, blah, blah...come into play.

[whiskychaser]

Actually you're right. Looking at the picture again, there are two arrows on the exhaust cam sprocket. I wasn't paying attention. Again the arrow and Bentley's vague description "first cam lobes pointing at 2 o'clock and 10 o'clock" blah, blah, blah...come into play.

Yes there are two arrows on all 3 sprockets . If you look closely there are two arrows in the Bentley's pics too:-) They have also tilted their engine so the arrows are vertical when we all know the engine is cranked to the left:-) Anyway, the camshaft timing marks I meant are on the flats at the other end of the camshaft - two large dots plus two letters which I take it mean inlet and exhaust. Pretty simple stuff. Will sort out my link and post some proper pics!

PS Just noticed from your pic that slots in the sprockets are not alligned to the left :-)

[yaofeng]

Not on the VANOS engine intake sprocket because the timing is variable. Do you mean the mark on the end like this?

[whiskychaser]

Oops. Mine is not vanos. But yes the two dots are the marks I meant. Provided you have the two flats in a straight line then you should be fine. In the pic yours seem a bit out but I'm sure you didnt leave them like that :-)

[yaofeng]

Well the pictures were taken more than a year ago and the car is running. The one that was a bit out is the intake cam where variable timing is hydraulically actuated.