6A12 MIVEC TIMING BELT CONFUSION?

[mela!]

Hi all

I'm trying to get the timing belt done on my '98 GPX but we're having a bit of trouble sorting out the timing belt. Had everything lined up as per normal, put it all back together and started it up to find it had a huugeeee knock i.e. timing was out.

Pulled it apart again, everything is right.
BUT
We noticed in the manual that it tells you to wind the crankshaft pulley COUNTERCLOCKWISE by 1 tooth (i.e. 1 tooth back from top dead centre). THEN to put on the belt with other pulleys lined correctly to their timing marks, tension the belt, wind the crankshaft pulley back a quarter turn and then wind it forward until it lines up it's own timing marks.

Can someone please clarify firstly why we need to wind the crankshaft pulley BACK from it's timing mark, then secure it in the wrong timing position with a tensioned belt.

Can someone please clarify for me ASAP as I need to get this car running in the next 2 days because we're moving and I need to sell it!

Thanks guys!

Mel

[ZFL45H1]

I have come across this when I did my engine rebuild and to tell u the truth I didn't turn it back at all just lined up all cams with the corresponding marks and it's been fine ever since prob about 15000-20000kms

[mela!]

Yeah that's what we did the first time, we just lined it all up like you would a normal car. The strange part is, after we noticed the knock and pulled it apart again with the intent of now redoing it with the crankshaft pulley a tooth counter clockwise, it now looks like the crankshaft pulley IS a tooth to the left of the timing mark, which has confused us more. We set it up straight and now it is a tooth to the left? For everything to be correctly timed I would have though I'd have to be moving it a tooth CLOCKWISE if anything...
It's getting very confusing -_-'

[ZFL45H1]

yeah it's a bastard of a job that about as much as I can help good luck let us know how u go

[Shane001]

Best way to change your belt is to get a white paint texta, mark the old belt at the cam timing marks and a bottom tooth on the crank before you remove it, then transfer these marks over to the new belt, then put it back on the same.

The reason they suggest to do it one tooth out on the crank pulley is that once you tension it all up you will find it will now be correct.

Also you should always spin it by hand a few times and double check that the timing points are lining up correctly before you start putting it all back together ready to start the engine. If you had done this than regardless of what method you used to put the belt on you would have identified if there was a problem before starting the engine.

And very important to get the belt tension right.

[silverGPX]

What happens if the timing belt is too tight? Does it become noisy?

[Shane001]

I'm guessing, but I would think increased wear on the belt and bearings leading to premature failure.

What I was more referring to was not enough tension causing the belt to jump teeth.

[PHIL069]

The reason they suggest to do it one tooth out on the crank pulley is that once you tension it all up you will find it will now be correct.

This^, put your belt on the camshaft sprockets first.
Turn the crankshaft sprocket one tooth counterclockwise, put the belt on, turn the crankshaft back one tooth without moving the camshaft sprockets to hold some tension towards the camshaft sprockets and some looseness toward the tension pulley. The belt will then have the correct number of teeth inbetween the cam/crank.
If you tension the belt too tight your tension pulley will start making a loud noise very quickly, I know because I did it with my old belt.

[mela!]

One more thing, have you needed to run in the tappets after adjusting? Ours are really noisy, after adjusting them. Just want to know if you guys have had to ware them in first, before i pull it apart again

[mela!]

actually, come to think of it, they will be out, as timing was out a tooth

[PHIL069]

timing was out a tooth

That will make your tappets noisey

[mela!]

actually, come to think of it, they will be out, as timing was out a tooth

[PHIL069]

It won't hurt to go back over and check tappet gaps.

BTW, I visually position the cam lobes to adjust tappets, this way I don't rely on belt/sprocket positions.

[payaya]

Without getting into detail, the workshop guide is stupid. If I gave that guide to a pro, they will get it wrong usually as well.

It's not a whole tooth!!! It's just enough for the belt teeth properly line up with the teeth on the crank!

[Bennoz]

Agreed ^

[payaya]

I've got a timing belt bible at work for mechanics. It makes so much more sense and they state to start off crank a 1/4 a tooth anticlockwise.

Ill get a photocopy of it.

[PHIL069]

I just held the belt against the crank pulley, turned it counterclock until the belt dropped in. I didn't take note on how far it turned.

[payaya]

Here you go!

A guide for mechanics for the 6A12 that has been written by people who speak english and not roughly translated from Japanese to english! Such a handy book, its got instructions for every engine out there.

It's basic but boy does it give you a better guide on how to change the belt!!! One tooth anti clock is a load of rubbish! Just like a lot of crap in the workshop manual.

[payaya]

Dunno how to un side ways the photo!!

[Sahin]

Dunno how to un side ways the photo!!

Rotate would've sufficed! Lol