interesting issues with a 940 turbo

[lixah]

Originally Posted by Laird Scooby

You may have something there Matt, perhaps the problem isn't just the cam timing is out although that could cause a lot of problems. Maybe the mechanic did it deliberately knowing it would still run but not be right then would make a silly-cheap offer to the owner to buy it. Then the owner decided to scrap it instead.

If the crank pulley has distorted, the only solution is to replace it, however you can determine if the piston is at TDC with a pencil in the spark plug hole - insert the pencil as you are approaching the TDC mark so it sits on top of the piston and observe it as you bring the crank pulley round. There will be a spot with no movement either side of it and that should be TDC - usually it is only a problem on high mileage cars though and 100k isn't high mileage really.

ok, so, maybe i need to remove my last statement, im not quite sure how i did it before, or maybe i dont understand how exactly it works.

when working from the crankshaft and checking the cam it seems to align accurately. as in, setting the crank to 0 (TDC i assume) the camshaft was accurately hitting it's marker. then two full turns of the crankshaft would see the camshaft again hit it's marker accurately. I assume this is how it's meant to be?

sorry if im making silly mistakes here, really want to make a reliable daily. I also might start a (minor) build / restoration thread, to document all the work being done, etc.







-Matt

[Laird Scooby]

Originally Posted by lixah

ok, so, maybe i need to remove my last statement, im not quite sure how i did it before, or maybe i dont understand how exactly it works.

when working from the crankshaft and checking the cam it seems to align accurately. as in, setting the crank to 0 (TDC i assume) the camshaft was accurately hitting it's marker. then two full turns of the crankshaft would see the camshaft again hit it's marker accurately. I assume this is how it's meant to be?

sorry if im making silly mistakes here, really want to make a reliable daily. I also might start a (minor) build / restoration thread, to document all the work being done, etc.







-Matt

That's pretty close there! As in you won't get any closer!

Once you've reached about 600 miles from when it was changed, get the engine into this posiition again, slacken the tensioner locknut and allow the tensioner to release a bit and make the timing belt tighter again - chances are that will take out the slight discrepancy that's showing there.

Before releasing the tensioner locknut to allow the tensioner to retension the belt, it needs to be in this position as this is where the timing belt is at its loosest. There is an inspection hole covered by a plug in the top front of the timing belt cover and also a grommet that covers the tensioner locknut which can save time on retensioning but as it sounds as if this is a new procedure for you, i'd suggest removing the cover as you've done this time so you can see what you're doing.

If you had turned the engine counter-clockwise on your earlier attempt, that could easily have resulted in getting the misaligned timing marks.

[360beast]

There is a rubber grommet in front of the tensioner but I've never seen an inspection hole for the cam before Dave, that's not to say they didn't do one just that I've never seen one on any of the red blocks I've worked on.

To get it in the position for redoing the tension just turn the crank so the marks line up and the cam will be in the correct position. I believe the torque is 50Nm for the tensioner nut.

[Laird Scooby]

Originally Posted by 360beast

There is a rubber grommet in front of the tensioner but I've never seen an inspection hole for the cam before Dave, that's not to say they didn't do one just that I've never seen one on any of the red blocks I've worked on.

To get it in the position for redoing the tension just turn the crank so the marks line up and the cam will be in the correct position. I believe the torque is 50Nm for the tensioner nut.

Good point Luke and thinking about it, you're correct.

It's a while since i've seen a red block in the flesh Luke and was about the same time as i last did the timing belt on a red block and also the 827 Coupe i used to own - that definitely has inspection holes so i obviously mixed the two memories from a similar time!

Sorry for any confusion Matt!

Yes, the tensioner locknut is 50Nm or 35lbft in old money.

[tofufi]

Is this one from down here in Bristol? I spotted it advertised at what seemed a very fair price and was rather tempted - glad it has gone to a good home as it looked a great buy

[lixah]

Originally Posted by tofufi

Is this one from down here in Bristol? I spotted it advertised at what seemed a very fair price and was rather tempted - glad it has gone to a good home as it looked a great buy

Indeed it was