Why would the following happen:

New cambelt fitted and all timed up, engine runs fine then slowly cuts out making the cambelt jump teeth round the crank.

Car is an WRX Turbo Estate 99.

Not my car, just trying to help someone out.

 

More likely it jumped the teeth and then cut out.


More info required.

How many teeth has it jumped and which way?

Which type of tensioner and is it new?

What does the belt tension look like now? Tight/saggy?

Who fitted the belt?

What was the car doing when it cut out? Idling/driving/having it's bollox thrashed off?

 

Hiya sorry for the lack of info.

It jumps 3-4 teeth, sorry don't know which way.
Tensioner is new
My mate fitted the belt and a mechanic checked it but he is baffled but as far as I know doesn't work on Subarus.

More info about the car. My mate bought it knowing the following:

Comperesion low on 1 cylinder, had 2 valves go so had engine out, heads sent away and lighly skimmed with new valves, new headgaskets etc. Engine has been put back together but now this problem occurs.

 

You start the car runs fine for a few minutes on idle then does it.

 

How many times has it done this then?

 

Sorry I don't know.

Thats as much info I have.

I just thought I'd ask the question in case anyone had come across it before.

 

Have you turned the engine over by hand ? Does it jump doing it by hand ?

 

I will ask the question.

 

Wether it's done it once or several times I would remove the covers and retime then turn over by hand with the covers off watching the tension of the belt and the tensioner.

If all looks ok then try restarting with the covers off and see what happens. (I don't have the centre cover fitted anyway to keep an eye on the tensioner which is a known weak point)

Should be ok if it is the crankshaft timing that has gone out a bit as long as the camshafts stay in time with each other or you run the risk of bending a valve.

This is assuming of course that it is being timed up correctly in the first place.



If it does it again without explanation then you need the experts to give it a good dose of looking.....

 

Belt timing as per pic below




or try JollyGreenMonster.co.uk for a decent set of photos, courtesy Jolly Green Monster

The photos show the more reliable tensioner, not the nodding thing that can give trouble.

 

Thanks all I will pass on the info.

 

Something is making the cam belt jump a few teeth - its possible one of the cams have siezed in the cylinder head.
Drop the timing belt off and check all the camshaft pulleys rotate freely.

Hope its something more simple than this though.

Mick

 

Got the cams in right possition? Belt on propa? you counted teeth between sections?

 

Thanks for the info will pass it on.


Guys how much should it cost to get heads skimmed?