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Upper timing chain tensioner info?


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Hi all

My 1997 model has had a bit of a rattly upper chain issue since I bought it, although every one I test drove I could hear the chains on. Having listened to a few recently, I've realised it's not normal after all.

I recently took the top covers off and it the tensioner really didn't seem to be doing it's job causing the slack side of the chain to flap against the upper guide rail a little. There's no visible wear on the chains, pulley's, guide rail or tensioner surface.

After speading to dlea while at tatton I swapped out the upper tensioner bolt this week and it cured the problem completely, no rattle at all to be heard.

However, after a few days driving it's come back - not as bad as before but still there.

I took out the new bolt tonight to inspect and it had no oil left in it - I could press it in all the way and all that came out past the seal was air. Loading it with oil again and re-fitting cures the problem.

I need a little info on the bolt as I don't know if..

a. It's supposed to retain the oil as it seems to do when refilled (you can't push the oil out then, it's solid)

b. It's not getting a proper supply of oil to keep it pumped up and the bolt is normal

c. I've just managed to have 2 faulty ones with poor seals in

When filling, it seems to have a non-return valve in it so I can't imagine it's supposed to drain down completely during normal use - possibly some seepage back but pumped full when the pressure gets up?

Any ideas?

PS I think it's possibly just the newer spring in the new bolt keeping it quieter at the moment once the oil has drained out through a bit of running/driving.

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Wow, tumbleweed. ;)

It's definately much quieter than it used to be but I'm thinking along the lines of some sort of oil blockage for it's feed. Drained the oil and filled with a synthetic tonight which should flush it a bit due to the higher detergent levels.

Not sure I'm ready to run an engine flush through it yet as they're a bit harsh.

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Yes it's the later one as it's a 1997 model.

Vast improvement today though after the oil change. Sounded about the same this morning when I started it to drive to work.

When I started the engine at work to come home it was much quieter and by the time I'd driven home it's now quieter than it's been since I bought it.

If I listen hard when the car is parked, I can just about hear the chains still while in the car but that might improve further yet. Strangely though the whole engine is quieter - it's weird, I never thought there was any noise from the tappets but the virtual silence now had me checking the rev couter at the lights to make sure it was running! I'm not joking either. :^)

I've also now noticed I think I have a small exhaust leak. Never heard it before though. :-*

This is a car that's had Quantam Synta Silver from myself and mangold the previous owner at least. I've only changed the oil a couple of times so that's between 4-6,000 miles tops and doesn't get driven that hard. Maybe this suspected restriction goes back further though.

I'm pleased at this point it has to be said. Hopefully it will stay like this and not drop back again like it did after fitting the new bolt, I can't see how it would as I didn't refill the bolt last night, I just left it as it was.

There must be a bit of crud floating around so it's probably best to swap the filter this weekend if I get chance then change oil and filter again in maybe 1000 miles.

Liquid engineering anyone? ;)

Got to say a big thanks to dlea who pointed me in this direction.

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  • 1 month later...

OK, the chain noise is back. I'm pretty sure it's an oil feed to the tensioner bolt issue.

I've a feeling running the synthetic has loosened some varnish/crud and the bolt is struggling to get enough pressure to pump it up at low revs. Those feed holes are pretty tiny.

I have the old bolt, which I'm fairly sure is actually fine. I might try increasing the oil feed holes on it and also getting some wire in the feed to the bolt area to poke through any potential blockages.

Maybe it's just time to stick a flush through the engine and try that too.

If a prefilled bolt quietens it down, I can't see that replacing the chain is going to cure it but that might just be a last resort.

Any ideas?

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  • 5 weeks later...

Once the chains start to rattle there is only one way I am afraid. Have the same problem with mine also a 1997 model. Has only 55k on the clock. The problem is a bad oil-pump that is giving too much pressure as I have read in several other forums on the Internet. The too high pressure on the tensioners has streched the chains so I don´t think you can do much to change that. New chains, tensioners and what else comes with the chains - and a new oilpump. that should do it. The oilpressure must not increase 7 bar on a cold engine - but the faulty oilpumps has been seen to give anything from 10-18 bar pressure. There is a return valve in the oil-pump that mailfunctions when pressure is getting too high.

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Thanks for the response but I don't think that's the issue I have.

It really does seem like it's the oil feed to the bolt that's causing the problem. I've previously checked the chain and is doesn't seem stretched at all and the tensioners are pretty much unmarked. I suspect they'd be fairly heavily grooved if the tension was enough to stretch the chain and I'm not so sure the tensioner itself could take the 2-300+ lbs/in it would require.

However, it could be a perfectly valid point - do you have any links to the forums you mentioned so I can also read up? It would be the pressure relief valve not opening if this was the fault and this is part of the oil pump as you've said - it's part of the lower casing.

In the mean time, it does look more like an oil feed problem. Each time I short change the oil it's improving and prefilling the bolt cures the problem until the bolt drains down.

dlea had a similar problem and it took about 5 short changes until his was flushed out enough and the problem went away. For now I'll keep changing the oil regularly with some added detergent prior to each drain which seems to keep showing improvements.

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