Timing belt seems off by a tooth on Volvo 240

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Starting a timing belt change on this '86. It was running fine as far as I could could tell in the few miles I've driven it. With crank at TDC:

IMG_0562.JPG


The cam looks to be a tooth off:

IMG_0566.JPG


Any idea why? Assume when I put the new one on I should line up the marks as they are supposed to be.
 
It's probably going to "run"....but is it correct? Seems like an easy fix as it's a tooth-off. There's a direct relationship with this procedure and if I were you, I'd go back and adjust it.
 
Seems like the crank pulley timing marks shift over time due to the rubber between the inner and outer part loosening. The crank sprocket is off too.

IMG_0579.JPG
 
Two sets of marks - on the v belt pulley - that’s your ignition timing mark, and the molded line in the timing cover is 0 degrees BTDC.

On the crank pulley itself, that drives the timing gear - that’s your cam timing mark. Line it up with the cast mark on the block. Line up the cam with the cast in mark in the head. Don’t worry about the ignition timing relationship. Worry only about the relative position of the crank pulley and cam pulley.

Line those up. Install and tension the belt. Turn the engine over with a wrench, 720 degrees at the crank. Recheck your marks.

Then button it all back up, including the timing cover, and double check your ignition timing, using the mark on the harmonic balancer/pulley and the mark on the plastic timing cover.
 
You dremeled grooves into the pulley!!??

Why??!!

You clearly don’t understand how this engine is timed, even after I explained it, and now, you’re just butchering it.

Get the proper service information before you do any more damage to this poor victim.

Here are the timing belt marks


Nowhere does it say that this happens at TDC.

Your “new” timing marks on the pulley are hopelessly, hilariously, wrong.
 
Because the rubber inside the pulley deteriorates over time and the outer ring with the timing marks gets shifted. I dremeled new grooves into the pulley where TDC is now so I can check and adjust ignition timing later.
 
Because the rubber inside the pulley deteriorates over time and the outer ring with the timing marks gets shifted. I dremeled new grooves into the pulley where TDC is now so I can check and adjust ignition timing later.
How much is a new pulley (assuming that is the proper fix)?
 
And the poor victim as you put it is now running fine
How much is a new pulley (assuming that is the proper fix)?
I saved this car from the junkyard. I replaced the timing belt, spark plugs, plug wires, starter, alternator, all with name brand parts. I'm not doing a Pebble Beach restoration. If you want to replace a pulley on your car, go ahead, but if it runs fine with it now I'll leave it there.
 
Because the rubber inside the pulley deteriorates over time and the outer ring with the timing marks gets shifted. I dremeled new grooves into the pulley where TDC is now so I can check and adjust ignition timing later.
How did you verify TDC?
 
And the poor victim as you put it is now running fine

I saved this car from the junkyard. I replaced the timing belt, spark plugs, plug wires, starter, alternator, all with name brand parts. I'm not doing a Pebble Beach restoration. If you want to replace a pulley on your car, go ahead, but if it runs fine with it now I'll leave it there.
I haven’t had time to look it up, but if TDC is, in fact, when the crank pulley is aligned to that casting mark, and if, as you’ve determined, the v belt pulley is shifting because the vulcanization has failed, then the fix is to replace that pulley.

If the relationship between the v belt pulley and crank pulley is changing due to failed rubber, your dremel grooves will not remain accurate. A new pulley/balancer is $85.


This is a buggered fix. A hack mechanic move. Guaranteed to fail.

You‘re right, this car is not the victim.

The victim in this case is the poor fool who buys a car from you.
 
For the purpose of spark timing, you'd want to remove the #1 spark plug and probe the top of the piston while turning the crank through where the mark on the pulley is at zero. If the piston is not all the way up at the zero mark, the mark on the pulley is wrong.

In a few cases, the timing belt marks are not at TDC. It's easier to time an interference engine that way since the cam(s) can be rotated freely while none of the pistons are all the way up.
 
In a few cases, the timing belt marks are not at TDC. It's easier to time an interference engine that way since the cam(s) can be rotated freely while none of the pistons are all the way up.
This is how I time pretty much everything, let the cam spin on the valve springs. Typically its "Three teeth past TDC" and as long as I can count to three on both top and bottom, I'm good.

Notably this probably only applies to Inline-4, SOHCs, the simplest setup.
 
I've done many timing belts on my Miata over the years along with a few other cars. One thing is for sure... One MUST align everything to the factory marks and follow the manual. Sure... a "tooth off" and it'll still run... but is that correct??? NOPE. I've learned that if you follow the correct procedure, it usually works out that all the "marks" line-up correctly. "Belt Tension" is also a huge factor in the longevity of the system.

My Miata (I understand this is a Volvo) was very easy to do. An aftermarket company (Flying Miata) actually made great little tools that actually helped hold the cams in place while replacing the belt. I guess my point is.... If YOU'RE GOING TO DO IT - DO IT RIGHT.

That's all! :)
 
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