valve clearances - 1.7td Cavalier

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Sat 11 Feb 2006 10:53
valve clearances - 1.7td Cavalier - cavi
hello all, i posted a question about the valve clearances on my L reg cavalier (isuzu 1.7 td) some time ago and was advised to re-shim as as the clearances close up. now i haven't actually got round to it yet as some unforseen events had taken place. my question now is how can these clearances decrease over time? is it because the valves are wearing further into their seats, or is it something else? i would have thought that the clearances increased . can anybody clear this up please, thanks in advance.........
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Sat 11 Feb 2006 13:08
valve clearances - 1.7td Cavalier - Screwloose
cavi

Yes; that's it in a nutshell. The valves steadily regress into the head - probably due to the abysmal low-sulphur diesel; they always used to increase the gaps - and with the very small amount of clearance that exists to start with, it doesn't take that long before there is no cold clearance at all.

With an alloy head, once started, the metals' differential expansion rate quickly restores a tiny clearance and the problem - low compression - then disappears... Until it cools down again.
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Sat 11 Feb 2006 18:41
valve clearances - 1.7td Cavalier - cavi
hi screwloose thankyou for clearing that one up,its been driving me potty!
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