tofufi
South West
Posts: 1,452
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Oct 11, 2018 17:22:15 GMT
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Hi folks, I've got a 1990 MX5 which is coming up to the cambelt change interval again. When I did it last time, I did a new waterpump and tensioners as the car was new to me at the time. 5-6 years on, it's due a replacement soon. It's only done 20,000kms since I did it last. Should I replace the idlers and water pump again, or leave them as they'll wear more due to mileage and use than age? Am I being stingy?  Cheers  |
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Last Edit: Oct 11, 2018 17:22:34 GMT by tofufi
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Oct 11, 2018 17:34:26 GMT
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Budget permitting, do all three.
The timing belt should come as a kit if it's a half decent one which will include the tensioner. They aren't very complex jobbies so don't cost much extra anyway, and far less than a rebuild if it fails 😁
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Too many projects, not enough time.
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Oct 11, 2018 17:48:51 GMT
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Hi folks, I've got a 1990 MX5 which is coming up to the cambelt change interval again. When I did it last time, I did a new waterpump and tensioners as the car was new to me at the time. 5-6 years on, it's due a replacement soon. It's only done 20,000kms since I did it last. Should I replace the idlers and water pump again, or leave them as they'll wear more due to mileage and use than age? Am I being stingy? Cheers As it's the idlers that tend to fail and take out the belt in the process, not replacing them is idiotic. The same applies to the waterpump if it's driven by the cam belt. This applies to any engine. |
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froggy
Posted a lot
Posts: 1,099
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Oct 11, 2018 19:16:34 GMT
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Non interference engine and I highly doubt you’ll find anything wrong with the parts fitted last time , I’d just fit a new belt
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stealthstylz
Club Retro Rides Member
Posts: 14,829
Club RR Member Number: 174
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Oct 11, 2018 23:44:33 GMT
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If you've already got breakdown cover just run the car till it snaps then put a new one on. I think the best I ever got was a Clio 1.2 which went 5 years and 50-odd thousand miles over the indicated mileage to change it.
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tofufi
South West
Posts: 1,452
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As it's the idlers that tend to fail and take out the belt in the process, not replacing them is idiotic. The same applies to the waterpump if it's driven by the cam belt. This applies to any engine. So you'd replace them after only about 12,000 miles use? Why would age be a factor in their longevity? I can see how the rubber belt would deteriorate with age, but struggling to see why a sealed bearing would |
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Last Edit: Oct 12, 2018 5:47:03 GMT by tofufi
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vanpeebles
Part of things
I am eastbound in pursuit of a white Lamborghini, this is not a recording.
Posts: 978
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Do it properly and replace the lot They will be tensioned to the old belt. |
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mk2cossie
Club Retro Rides Member
Posts: 2,946 
Club RR Member Number: 77
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Oct 12, 2018 11:38:43 GMT
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I'd be inclined to change the lot, and flush the cooling system as well. If I'm not mistaken, the radiator hose has to come off on the MX-5 to do the timing belt anyway  |
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Dez
Club Retro Rides Member
And I won't sit down. And I won't shut up. And most of all I will not grow up.
Posts: 11,712
Club RR Member Number: 34
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Oct 12, 2018 21:26:08 GMT
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I’ve they have a known pedigree as you describe, I wouldn’t bother. It the belt snaps it won’t break anything so there’s not much at stake, and as you say id expect a tensioner or pump to last a lot longer than a belt.
Personally on my own stuff I replace the tensioners every other belt, unless it’s a model that’s known for particular items failing prematurely. but that’s becuase I know their history and I know I’ve not cut corners on cheap parts.
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Last Edit: Oct 12, 2018 21:27:08 GMT by Dez
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Oct 13, 2018 21:07:05 GMT
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My wife's car (BG Laser/323 1.6) had the cam belt done at 242,000 km shortly before we got it (in 2012). We had it replaced again at 342,000 km as a precaution. Our mechanic had a look at the water pump and reckoned it was fine. Clicked over 426,000 km yesterday and still sweet. No idea about the tensioner. I'd replace it with the belt just to be safe. I have to question why you are replacing the belt after only 20,000 km though?
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Last Edit: Oct 13, 2018 21:08:59 GMT by igor
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tofufi
South West
Posts: 1,452
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Thanks for all the thoughts folks I have to question why you are replacing the belt after only 20,000 km though? Service interval for cambelt is 6 years or 100,000km |
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ChasR
RR Helper
motivation
Posts: 10,189
Club RR Member Number: 170
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Oct 14, 2018 12:28:55 GMT
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It depends. I'd personally leave the pump on an MX-5. Change the coolant with decent coolant when you should and it will be fine. If it were me I'd personally check the tensioner and go from there. If it spins too freely or is noisy I'd change it. BUT, if the car's a daily and you need it to get to work I'd change the tensioners. Yes, breakdown cover is cheap but no-one likes that bloke at work who was 'late again because of his car'... I know the engine is a safe engine but it's still time taken away waiting for the breakdown truck Basically, if you don't want the potential hassle, change the tensioners with the belt. As it's the idlers that tend to fail and take out the belt in the process, not replacing them is idiotic. The same applies to the waterpump if it's driven by the cam belt. This applies to any engine. So you'd replace them after only about 12,000 miles use? Why would age be a factor in their longevity? I can see how the rubber belt would deteriorate with age, but struggling to see why a sealed bearing would I've personally seen tensioners/pulley get rust on them after being stood a while which can have an impact on the life of the cambelt. Also, as things are stood, moisture etc. has a better chance of setting in than if it's always moving ; it doesn't get the chance after all. Once the moisture has set in, then of course your bearing is compromised. A good example is the IMS bearing in Porsches. It's a rare failure but a known garage I know has seen more issues with IMS on lower mileage engines than some well into 60 figures. He put it down to a similar theory. |
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gt
Part of things
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when i did mine on my mk1 just changed the belt idlers were fine and as the engine is a Non interference engine if it snaps you simply fit another and away you go, would recommend this in or complex engines that can do serious damage if the belt snaps.
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