timing marks

[htown318is]

so Im replacing the timing belt on this car I bought..

before I take the belt off, Im trying to align the marks at TDC.

but, after many rotations and rechecks, Im finding that the bottom mark O|T is always about an inch behind the indentation when the top mark is aligned.

can I just remove the belt and turn the crank bolt forward an inch to independently align these marks?

btw: first m20, sounded fine when I was driving it, a little loud maybe but I assumed it was normal.

[LJ851]

NO!

You must be looking at the wrong marks.

[N2MYE30]

this is what you match up.


and...

[htown318is]

http://e30world.com/engine/BMW-E30-timing-belt-and-water-pump

based on this, I am fairly sure (99.9%) that I am looking at the correct marks.

they do not align. crank mark is about an inch, or 3 teeth behind the lower timing indentation.

edit: thanks for the replies, gonna go out real quick to make that extra .01% sure im checking the right mark.

[N2MYE30]

When you take the bottom pully off, do you see this?

[htown318is]

no this is what I see after multiple rotations

[N2MYE30]

Stupid question, but did the car run? That is very odd.

[LJ851]

It's hard to believe it could run with the cam advanced that far and not be having valve to piston contact. But maybe.

How loud did you say it sounded? Did it idle smoothly?


EDIT, looking at your last pic i think it might be only one, maybe two teeth off.

[htown318is]

it cranked and ran, though if it ran like a good m20 or not I couldnt tell you. the car has been parked for at least 5 years with a bad auto transmission. so I threw one on there, fixed the vac leaks and it idled smoothly.

took it for a few test drives before this and it was pretty good. I just couldnt get it to rise above 60 mph quickly.

I assumed it had something to do with cable adjustments.

so should I just do the belt change in the position it is in? would hate to take it back off if its not optimal lol.

[htown318is]

kinda sounded like a ford super duty diesel truck. LOL

[LJ851]

I would put the new belt on by lining the marks up (properly) and turn the motor over very gently by hand with no plugs in it to feel for valve contact. If the motor spins freely put it all together and probably enjoy a massive bump in HP.

Your could also do a compression test the way it is now and see if the numbers are wrong indicating bad cam timing. Or bent valves.

[LJ851]

The pulleys on the cam and crank can't be on wrong in relation to their shafts unless their locating pins/keys are missing.

[htown318is]

so would it be okay to turn the crank clockwise that last bit to get it on the mark?

[LJ851]

so would it be okay to turn the crank clockwise that last bit to get it on the mark?

My crystal ball is acting up so i can't say for sure.


I would do what i said in the first part of post #11 if i was in your shoes.

The chances of someone for some reason putting a pulley on wrong and compensating for it by shifting the timing belt and not making a new mark would be very, very small in my book.

Someone prob put the belt on wrong, it wouldn't be the first time. A leakdown test will tell you if your valves are still sealing (not bent).

[jlevie]

Remove the pulleys and harmonic balancer. Then rotate the engine until the mark on the crank hub lines up with the notch in the lower inner timing cover (see post #5) when the mark on the cam sprocket is close to the mark on the head. If the belt was installed incorrectly the cam sprocket may not be lined up. Remove the belt and rotate the cam until the marks are lined up and install the belt, starting on the load (left side). With the belt and the tensioner free to move, rotate the engine through two revolutions stopping when the crank marks line up and then check the cam/head marks.

The cam rotates at half crank speed, so rotation is done until the crank lines up. Then one looks at the cam sprocket marks.