Cam belt change question
Discussion
if during a cambelt change, you accidentally mis-align the cam or crank by ~30 degrees clockwise, do you just bring it back to the timing mark by rotating anti clockwise?
Do timing marks always suggest TDC? Is there a sure way to check for TDC? I have only ever found piston numbers by checking online forums for certain cars, is there a way to find piston #1 by other means?
If the engine is a V6/V8/V10/V12 layout, do you still align everything so that piston #1 is at TDC?
In general do you just need to rotate the engine with the old belt on to match the timing marks and then put a new belt on?
Do timing marks always suggest TDC? Is there a sure way to check for TDC? I have only ever found piston numbers by checking online forums for certain cars, is there a way to find piston #1 by other means?
If the engine is a V6/V8/V10/V12 layout, do you still align everything so that piston #1 is at TDC?
In general do you just need to rotate the engine with the old belt on to match the timing marks and then put a new belt on?
Edited by 321boost on Tuesday 17th December 16:38
There are normally match marks for cams and crank, what car is it?
If you've moved things and are unsure then 100% whatever you do I would fully rotate the engine by the crank pulley by hand/ratchet a couple of times to check nothing interferes/ie goes solid, last thing you want is it to bent valves etc.
If you've moved things and are unsure then 100% whatever you do I would fully rotate the engine by the crank pulley by hand/ratchet a couple of times to check nothing interferes/ie goes solid, last thing you want is it to bent valves etc.
If there's a mark and you were keen you could remove the no.1 spark plug and pop a drinking straw down and then rotate the cam and watch the rise and fall of the straw.
That said I have seen it said it's not advisable to rotate the engine backwards? but you can go forwards a few times to note TDC, especially if there is a mark.
That said I have seen it said it's not advisable to rotate the engine backwards? but you can go forwards a few times to note TDC, especially if there is a mark.
There are two cars, one of them is a mk1 mx5 with a non-interference engine and the second one is a clio destined for scrap which I’m not sure has a belt or a chain. This is just to learn so I’m not worried about messing up. Sorry for the newbie questions.
One advice I have read is to rotate the engine with hand before replacing the belt to get a feel and then rotate it after replacement to check for tight spots.
If using the straw method then will the piston reach TDC when the timing marks are reached on the cam gears and the crank gears?
If you were to remove the cam gear to replace a seal, is there always a key on the cam to put the gear back on correctly? For example to prevent putting the gear 180 degrees incorrectly and then timing it to the wrong mark which is mis-aligned by 180 degrees?
One advice I have read is to rotate the engine with hand before replacing the belt to get a feel and then rotate it after replacement to check for tight spots.
If using the straw method then will the piston reach TDC when the timing marks are reached on the cam gears and the crank gears?
If you were to remove the cam gear to replace a seal, is there always a key on the cam to put the gear back on correctly? For example to prevent putting the gear 180 degrees incorrectly and then timing it to the wrong mark which is mis-aligned by 180 degrees?
The MK1 MX5 timing belt, although a relatively simple job as far as timing belts go can be a little annoying because if I remember rightly one of the cams (I think exhaust) is always fighting a valve spring in the timing position and has a tendency to go out by one tooth if you're not careful. Also it's annoying that to remove the water pump the cam sprockets themselves have to be removed, but at least they're keyed onto cam.
As for your question regarding other engine configurations...the timing position is often dictated by ease of build. Quite a few Vee engines have their timing position such that the crankpin itself is 'vertical', meaning piston #1 will be at 45deg in a 90deg Vee or 30deg in a 60deg Vee and so on.
As for your question regarding other engine configurations...the timing position is often dictated by ease of build. Quite a few Vee engines have their timing position such that the crankpin itself is 'vertical', meaning piston #1 will be at 45deg in a 90deg Vee or 30deg in a 60deg Vee and so on.
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