M20 multiple tdc points?

[bostonvert]

I have tried the search function before starting a new tread and I tried a local forum but no luck. Basically I want to be 200% certain that the TB belt is being replaced the correct way.

I really lucked out because about 9 or 10 tooth where missing from the belt, thank god I haven't drove it yet! The upper mark is at TDC.

My question is that in some DIY video's and manuals state that you have to align the mark on the bottom half on the timing cover with a groove on the pulley, these 2 :



But the Haynes manual I am using states that you have to align the groove in the crankshaft with the notch in the front inner cover, as the following photo shows.


Is this the correct way or if these marks lign up does the pulley line up as well? I think it does, I know there have been millions of TB treads but you can't blame anyone for double checking right?

m20b20
01-01-1985 ( I lucked out with the production date I guess )

[E30-325iS]

I've done my TB a few times and always used the notch on the crankshaft.
Missing teeth on the belt is indicative that something is wrong, at least turn the engine by hand before you start it.
It also looks like you have the stamped intermediate shaft gear, replace it with a sintered one before it self districts.

[3vilE30]

The correct way is, put on the lower timing cover and the crank pully and use the notch on the back side of the crank pully. That's how I've done it. I can't remeber but the notch in the last picture isn't correct for some reason.
Use the lower timing cover and the upper cam gear notch to determine TDC for the block and head together.

[digger]

use the gear and lower timing cover as a first instance because you cant get the belt on once the vibration damper is put on. you can easily check they give same position

[bostonvert]

use the gear and lower timing cover as a first instance because you cant get the belt on once the vibration damper is put on. you can easily check they give same position

Thanks, so basically if the notch in the crank and the inner cover line up the outer cover and pulley will also line up? So its safe to put on the new belt now? And I am definitely turning the belt a couple times before starting it!

This job is pretty stressfull, pretty nervous about starting it for the first time already.

[bostonvert]

So as it is right now I'm not good the install the TB yet? The old belt is already off

[AndrewBird]

Put a wood dowel or something through the #1 spark plug hole and rotate the crank back and forth slightly. You will be able to see where TDC is. The marks should line up as well.

[digger]

Thanks, so basically if the notch in the crank and the inner cover line up the outer cover and pulley will also line up? So its safe to put on the new belt now? And I am definitely turning the belt a couple times before starting it!

This job is pretty stressfull, pretty nervous about starting it for the first time already.

yes both sets of marks tell you the same thing i just mocked it up to verify. the marks on the gear and lower timing cover notch are a little more prone introducing a bit of parallax error especially if the engine is in the car compared to the vibration damper markings and lower covering. its not difficult to temporarily add the cover and vibration damper to double check if youre concerned (it doesnt need to be fully assembled to do the check)

[bostonvert]

yes both sets of marks tell you the same thing i just mocked it up to verify. the marks on the gear and lower timing cover notch are a little more prone introducing a bit of parallax error especially if the engine is in the car compared to the vibration damper markings and lower covering. its not difficult to temporarily add the cover and vibration damper to double check if youre concerned (it doesnt need to be fully assembled to do the check)

Thanks a lot to clarify this! I'd send you a beer but shipping would be a bitch

[Seawolf]

Take note of the comment from e30-325iS:

"It also looks like you have the stamped intermediate shaft gear, replace it with a sintered one before it self districts."

If your upper cam timing gear is also stamped then replace it before you go any further, stamped gears are dangerous, if you continue to run them you risk failure and engine destruction if you don't replace them.

[digger]

also the crank gear teeth look to have some debris in there so id clean that out properly to.