Halfway through my first timing belt/water pump/cam & crankshaft seal project and all is well - except for the fact that it's not really very rewarding replacing parts that appear almost new. Thanks to Mitsu reliability, my timing belt, water pump and all other parts look like they could go for another few years - even though it's been more than 110K miles since the last replacement.

So now I'm confused about the belt tensioner. As you can see in the photo, the new dealer part is quite a bit different from the OE part. The new part's bore is bigger and there is no extension on the top for the air vent/diaphram. I called the dealer and they confirmed that the new part is correct for my VIN but I wondered if anyone knows why they changed the design.

Since my car was running perfectly before, I'm reluctant to make any unnecessary changes so I'd welcome any advice.

One more thing - why are they called hydraulic tensioners? I expected there to be an oil inlet like hydraulic valve lifters - but there's no such thing. Are they really just pressure filled units like hood struts?

I plan on finishing the job tomorrow so any feedback would be appreciated.

Thanks,

Ron

 

If that's what the dealer gave you that would be the correct part.

They usually check your VIN# for ordering parts. Dealer Do Not Go By the year of the car. they check accuracy by using your VIN# whatever matches your VIN# on the parts department they will give you that part. new or redesign parts.

It should fit.

By the way if it is not broken DO NOT FIX IT. if it is running well without any problem. do not replace it
it will run the same but newer parts.

 

yes, replace it. Mitsu redesigned them due to reliability. Although not a common failure, there have been enough that mitsu redesigned the part. Thats NOT a part you want to fail.

they're called hydraulic tensioners because theyre filled with oil. They act like a valve lash adjuster in that they're spring loaded, but the hydraulic fluid doesnt allow rapid movements inward. Only outward. So, if its collapsed it will instantly extend if the force applied to it is removed... But if you apply force to it, it only SLOWLY collapses.
Theyre used by many, many automakers nowadays.

 

Thanks Manybrews - that makes sense.

I just got everything back together (with the new tensioner) and the engine runs better than ever. According to the workshop manual the plunger is supposed to have 1mm end play. The new version had just that but my old original part had no play whatsoever. I can't explain it but the engine has never idled so smoothly.

It took me three days but I now have a new belt, water pump, tensioner, cam seals and crank seal. And about 10 scrapes and cuts plus lots of aches and pains. But hopefully it's good for another 100k miles. (the engine, not me)

Thanks to all for the input.

Ron