timing sanity check

[m400kay]

I looking for help, i suspect , pretty certain flywheel /cams are now misaligned a bit due to a a small oversight on my part during cam belt change now need a simple sanity check to ensure it is all lined up, i have looked and some say as long as flywheel is top dead center then just need to align cams to exhaust/inlet but as i know a small error here can be terminal need some help, and not the why did u do it type, i now realise in hindsight with time spent so far and tools i would of been cheaper getting murrays to do it but i want to maintain car my self

[Mikie711]

Cam timing has nothing at all to do with the flywheel. Timing marks are on the front pulley and on the cam pulleys themselves. IIRC there are two marks on the front pulley, one at the front and one on the back. You need to check that the timing mark on the crankshaft pulley is aligned with the mark on the timing belt lower cover and that the timing marks on the camshaft pulleys are facing one another. It's all on page 11 of the engine overhaul manual for the S1.

[robin]

OK,

If you have not yet turned over the engine since getting this wrong it is important not to turn it!!

TDC is the wrong place to set cam timing as it is an interference engine (valve at full lift will hit piston at TDC).

90BTDC is the correct place to set cam timing (i.e. where all four pistons are at the same depth, 2 going up, 2 going down).

At this point the cams should read in->ex,in->ex (or ex<-in,ex<-in, doesn't matter which) and you be able to put a straight edge across the cam pulleys passing through the notches on both pulleys.

If you think you have the pistons and cam timing substantially wrong you are a bit fcuk as you now need to work out how to get the pistons back to 90BTDC without hitting any of the valves.

It sometimes helps to pop out all four spark plugs (as now there is no compression). The lack of compression gives you the ability to feel any resistance in the crank pulley; that resistance is either valve-to-piston contact or just the pressure of the cams turning over. If you pop the belt off the top pulleys then it must be valve-to-piston contact so stop turning the crank!!

Put a long tie wrap or wooden BBQ skewer down each plug hole. These will bottom out on the piston crowns. Now you have a visualization of where the pistons are. You must turn the crank so that the pistons that are up come down and the ones that are down come up, i.e. away from TDC WITHOUT PASSING THROUGH TDC.

Cheers,
Robin

[campbell]

Robin and I have just been working on my C Service and hence cambelt change.

To prove I was listening to what he said, I'll try to recount it here...but you should check first before proceeding!

The crank pulley has a couple of teeth with wee dots on. When a faint line on the engine block shows between these two dotted teeth, I believe this means the crank is at EDIT: 90BTDC. With your cam pulleys aligned across all 4 timing marks - use a straight edge across them to ensure you are not 1 tooth out with the belt, which can happen - and this crank pulley reference point set, this means the relative timing is all set.

You have to be careful when tightening the crank pulley bolt though, to ensure you lock the engine in place either with something jammed through the flywheel or with car in 5th gear (latter is Robin's preferred method). Otherwise you may be able to crank the engine part way, slip the belt around the crank pulley, and end up with screwed timing shortly followed by bent valves upon startup.

Robin will be along in a minute to fill in the bits I missed...

Campbell

PS - bravo for self-maintaining, no shame in that whatsoever. And even better to take time out to ask advice before proceeding.

ETA - aha, he's here already !!

(Campbell: I edited out a potentially misleading mistake in your post - it's not BDC (which is the same as TDC on the other two pistons) but 90BTDC (90 before top dead centre).)

[robin]

P.S. The 90BTDC marks are on the alternator drive pulley and timing cover along with some other marks. I find all these marks useless as I can never remember which is which and they are very hard to see in the limited light there is available.

I usually rely on spotting the two dimples in the lower timing gear straddling the vertical mark cast in the oil pump housing.

That said, if you're confident of your lining up abilities, you might also get there with just the BBQ skewers - they must all be at exactly the same height. At that point (knowing you are now close to right) you might be able to see the timing mark on the alternator drive pulley and lower timing belt cover and then tweak the crank angle so these line up perfectly.

Cheers,
Robin

[m400kay]

many thx i have down this on old foden diesels with fuel pumps so spill timing is kind of same except we used depth guages so seems straight forward - i think i am possibly two teeth out as one cam shaft jumped so will now find barbeque skewers on a holiday week end, tipex form office and lap top to hand for advise, god i hate cars!!!!!!!!! although could just crank it and say to wife cheaper to go down honda route.

[robin]

Use your imagination - I'm sure you have something that you could make 4 equal length rods out of ... doesn't have to be BBQ skewers, just something that is rigid enough and won't mash the piston if you drop it into the bore.

Cheers,
Robin

[m400kay]

yes i will sorry was just being sarccy thx for advice will try tonight as always SE comes to rescue.

[Ferg]

Not sure if this is any help, but I had my bottom pulley slip a few teeth in the cold weather in 2009. I have this picture showing the change in timing. What it does show you are the timing marks quite clearly. Note that this was before I re-timed the car so the marking on the pulley should be at the vertical marking visible just under the right bolt in the picture.



HTH

[campbell]

I had my bottom pulley slip a few teeth in the cold weather in 2009

How did you manage to avoid that being terminal to the top end of the engine?

[Ferg]

I didn't run well at all but fortunately I realised something was wrong and didn't try and accelerate through the problem. After researching the issue I found several people to whom it had happened, caused by small amount of ice build up around the pulley which subsequently slips the belt if the engine is jolted. In my case I started up after leaving the car over cold ground after a short run in wet and subsequently freezing conditions, and then the wheels slipped and jolted the engine trying to get it out from it's snow bound parking spot. Lesson learned and no ill effects thank goodness. Dodged a bullet on that one for sure

[robin]

When the cam pulleys are like the top picture the bottom pulley SHOULD NOT BE AT TDC. Please edit your post as this mis-information could cost somebody a lot of money ...

Here are the correct drawings from the manual ... note the upper and lower timing marks that I have highlighted.

Click on it for bigger picture.

Cheers,
Robin

[Rich H]

I can confirm that a tooth out will not hurt the engine but will impede performance significantly!
I had verniers fitted and neglected (In my haste/panic to get it running) to mark the timing marks.
So I guessed using the marks that were avaialble and was a tooth out on both cams
I ended up having to use DTIs and start again.

[Ferg]

When the cam pulleys are like the top picture the bottom pulley SHOULD NOT BE AT TDC. Please edit your post as this mis-information could cost somebody a lot of money ...

Here are the correct drawings from the manual ... note the upper and lower timing marks that I have highlighted.

Click on it for bigger picture.

Cheers,
Robin

sh*t...doh. apologies... forgot to which I had aligned.... post updated and before anyone does anything based on things said on a forum they should check the manual.

[m400kay]

Well i think i am clear on this and i my cams are not far off position shown so pulley wheel should be around position shown i will look tonight and now have a perfect excuse to avoid royal wedding invitation and fix elise ready for summer, i did not realise what a popular little topic this would turn into. Many thx to all i will keep you posted once i have done this. Just for info i had silver s1 that got a lot of moisture in its rotor arm cover and it back fired badly two or three times during start up this also caused one cam shaft to jump 2 teeth did not touch but scary moment as power was down above 5,000 and scratched head for a while- falkland performance found it straight away and said it was not uncommon to see.