John Speake

Since I changed the WP (Laso from Roger), belt (Gates), tensioner arm bushes and tensioner arm pivot bolt the cambelt on my 86 S2 has run near the front of the RH cam gear. Like 2mm from the edge.

This is much nearer than previously, as I can see from the slight wear marks on the cam wheels.

I've just checked over the system again, even replaced the tensioner arm bushes and tensioner arm pivot bolt again. Just started it up and its still at the 2mm point. Opinions ?

GregBBRD

Pretty normal, as far as I'm concerned. Belt position, when the bushings and bearings are good/new is determined by the location of the pulley on the water pump. Slight variation in that position will result in a slight variation of the running position on the cam gear.

the flyin' scotsman

to be clear John are we talking Porsche convention for RH or when in front of the car?

John Speake

Thanks Greg, that's reasuring :-) I was narrowing the difference down to the WP...

Malcolm, RHS Porsche convention. Pass side in N.America...

newworld

87s4 aut. i cjust removed my cam belt the other day and i also noticed that it was tracking closer to edge i,e, front of engine towards radiator. there was not equivalent distance to both edges, definitely geared toward front on both cams.

as a side question for the experts, when i aligned TDC, both cam marks were dead on, and then i rotated the crank to get to 45 deg, then marked both cams, when i took belt off, the right cam stayed the same i,e, on the mark, the left o drivers cam kicked loose as if under some pressure and moved off the 45 mark, i would actually say several tooths.....

James Bailey

Crank gear has guide washers as well sometimes the slightly curved washers one or both is flipped 180 degrees which wears the edge of a new belt might push it over a bit too. Like most anything if it can be put on backwards, sometimes it will be....
Water pump pulley alignment makes the most sense especially if it had a rebuilt pump before since they all grind the face of the castings in the "rebuilding" moves the pulley in toward the engine. Plus when they press on the pulley it is less than precise how far on it goes.

James Bailey

Yes it will move as there were valve springs compressed. You will need to fight that tension as you put on the new belt while holding it at the 45 marks you made. And odds are you will be a tooth off the first time

John Speake

The pump was a new Laso..... the pulley looks the same distance down the spindle as the old one...

James Bailey

Yes but if the old pump had been resurfaced....

John Speake

I see your point.....the old pump was old in years but young in miles....fitted by the local PC, it looks like my new Laso, and has a plastic impeller. Cambelt ran smack in the middle of the gear. Maybe that was less typical than I assumed.