opinion on chain/sprocket, please

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Bhart
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opinion on chain/sprocket, please

Post by Bhart »

I have dug down and am having a look at the timing chains on my 148,000 mile S38. As you can see on the pictures, there is some scuffing on the upper chain guide and some polishing on the bottoms of the sprocket notches (dark areas are reflection). Cold starts, after sitting for a week, have no chain rattle. Opinions please.

Prior to all this work, the car ran fine. I'm just being cautious about what items are potentially dangerous and what can be done later. I have no real history on the work done to this car. While I've been working on it, most parts coming off seem to be original. One fuel line had a date stamp of 10/85 so a full 13 months older than the car's build date of 01/87. Main issue right now is valve clearance - they pretty much all measure out at less clearance than required. Shim kit is on order. I am still planning to change over to the M50 tensioner, since it has better preload and less overall tension at high revs.

A timing chain job is not something I'm prepared to do myself. Finding a suitable shop will take time and I'm hoping to be able to drive this for a while before that job gets done.
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chains.jpg
chains.jpg (261.56 KiB) Viewed 2861 times
chain.jpg
chain.jpg (169.23 KiB) Viewed 2861 times
guide cu.jpg
guide cu.jpg (250.3 KiB) Viewed 2861 times
guide.jpg
guide.jpg (281.09 KiB) Viewed 2861 times
01/1987 M6

past Bimmers;
1970 2800CS
1988 325is
1985 325E
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hornhospital Online
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Re: opinion on chain/sprocket, please

Post by hornhospital »

The guides don't appear to to be worn alarmingly, but the sprockets definitely are, at least to my eye.
Ken Kanne
'84 633CSi "Sylvia"; '85 635CSi "Katja";'85 325e "Hazel Ann"; '95 M3 "Ashlyn"
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Brucey
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Re: opinion on chain/sprocket, please

Post by Brucey »

the parts you can see don't look too bad. Unfortunately they are not the bits that wear fastest. Thus if you want to be sure of the condition of the parts then you need to look at the ones that wear fastest. This would be the tensioning slipper face (the upper part of the longer (lower) section) and the crank sprocket.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Bhart
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Re: opinion on chain/sprocket, please

Post by Bhart »

That's going a bit deeper than I'm currently wanting to do. But it is on my plan and it was going to happen after I resolved the intake issues that I'm currently finishing up. The chain may be the one job I'm giving to a specialist.
01/1987 M6

past Bimmers;
1970 2800CS
1988 325is
1985 325E
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