stupid question

[RAINMAKER]

CCT again, why does the engine position matter? my supposition is that if the tensioner is automatic why does it matter what position the engine is in, surely if its automatic when the engine is running could you not remove tensioner and just pop in new one and turn engine over by hand...........until it finds its tension?

What would happen if you did this and why?

Told you it was a stupid question but Its been bothering me and up till now did not want to look a twit...

[benny hedges]

it's probably been said before - there are no stupid question, just stupid answers!
(watch someone come up with a genuinely stupid question now!!!)

the reason is so you can tell if the chain jumps a tooth during installation, or is already out before you start.
you line up the markings and keep it there so you know the cam timing is spot on before you box it all up again.

haven't done mine yet like, but having done a few before, and cam belts on cars.... dreading doing the vvt belts on my mg bubble!
on the mg i have bought some cam locking tools that lock the cams (surprise!) so it can't move when doing the job..

if the engine is in any other position than top dead, it will have a tendency to find it'self there especially when the tensioner is removed...
the markings are to show top dead centre on the relevant piston, and also the cam gear position.

does that make sense???

[sirch345]

Blimey Paul you've been taxing your brain

Just to add to what has already been said. When removing a cam chain tensioner, if the piston is not at TDC on the compression stroke, depending on which part of the cycle the engine was stopped at, there's a very good chance the inlet or exhaust valves or even both are either partially or fully open. That will mean there is tension on the cam chain. So once you remove the cam chain tensioner (this will allow the cam chain to become slack) the cam chain will then jump the teeth on the cam wheel sprocket(s) as the tension from the valve springs of the open valves force the valves shut. Hence you will then need to reset the valve timing as well as the CCT's.

Follow my link "How to remove and refit CCT's on the firestorm" in the Workshop Knowledgebase and that will save you a lot of extra work.

Chris.

[RAINMAKER]

so, the cam chain is itself under a lot of tension, and will shoot off the sprocket? doh!! the light begins to dawn.

[benny hedges]

doh!!

no problem bud, better to ask than find out the hard way!

(sideshow bob standing on rakes moment.......)

[slabm7]

so, the cam chain is itself under a lot of tension, and will shoot off the sprocket? doh!! the light begins to dawn.

I just changed mine last week and was scared shitless to pull them.

2 Things cause pressure on the chain, the tensioner and the pressure of the valves wanting to close, so if you are going to take out the tensioner you have to make sure the pressure from the valves is gone so nothing can cause those sprockets to jump the loose chain.

If you are not TDC on the compression stroke one of the cam lobes will be touching a valve, that valve will want to close if you let it. So if you take the tension off the chain when a lobe is touching a valve the chain could go loose enough that the pressure from that valve could turn the camshaft and cause the chain to jump the sprocket.

So if you are TDC of the compression stroke all the valves are already closed and neither of the lobes will be touching a valve so there will be no outside tension on the chain when you pull the tensioner.

This is the way I understand it.

[Fireman on a Storm]

stupid question
Stupid answer= 37!

[RAINMAKER]

stupid question[/b]
Stupid answer= 37!

Oh you cruel beast