Technical question about cambelt tensioners

[hogfisch]

Hi all,

Not the most inspiring topic but I have a question about cambelt tensioners on a Mk2 MR2 3S/GE engine. The tensioner is a spring type, not a hydraulic one.

Basically, I am having problems with my recent new cambelt install. The belt seems very slack between the two cam pullies and also between the right hand pulley (exhaust cam) and the pulley immediately below (the oil pump pulley I think). The car fires up and runs but if the throttle is blipped and the engine allowed to return to idle, the No.1 idler pulley (the one tensioned by the tensioner) seems to 'chatter' and vibrate quite badly. This suggests a problem with the tensioner, i.e. it is not providing enough sprung tension to the no.1 idler pulley. The no.1 idler pulley pivots freely when bolted to the engine so think this is OK. There is no discernable freeplay in the no.1 idler pulley either.

My questions are:

Is the tensioner pin when extended out meant to 'lock' in place as I can retract mine simply by squeezing in a vice?

If it is knackered, is it a Toyota main dealer part only?

I hate doing MR2 cambelts!

Cheers

Hogfisch

[stevel]

Is the tensioner pin when extended out meant to 'lock' in place as I can retract mine simply by squeezing in a vice?

You should be able to squeeze it using a vice but there should be a some effort to do it

If it is knackered, is it a Toyota main dealer part only?

Believe so about £45

I hate doing MR2 cambelts!

Nobody does

[hogfisch]

Cheers Steve. I have just read the Toyota Manual CD and I think my tensioner is duff. The pin retracts if I push it against a wall and according to the manual, it should take more effort than that.

Looks like my wallet is going to be loosened by £45 then!

[stevel]

That’s defiantly duff. Shouldn’t be able to push it in like that.
After you fit the new one turn crankshaft pulley around clockwise & check that all your markings still match up. You may find the force of the new tensioner may knock it all out a couple of teeth’s.