timing belt broke

[Joe Z]

Are you asking if you need to turn the crank after installing the timing belt to recheck your timing marks?

I was just having severe brain fog for a second..... each revolution of the crank with the belt off would bring the #1 piston to TDC.....
Then i would line up the cam marks and put the belt on.
Why i would think the piston would be down on one revolution was just shear fog ...i screwd up on that question

 

[stir_fry_boy]

Durk.... I was thinking about this last night.....
Timing belt off.... Every one revolution of the crankshaft the #1 piston would be TDC.
Then line up the cams timing marks?_____

It's much easier to get the engine to TDC before pulling the old belt off, remove old belt, do your WP etc, then put the new belt on all without turning (or minimal turning) of the pulleys.

Every single revolution of the crank the #1 piston would be TDC.

 

[Joe Z]

Thanks stirfryboy
I haven't finished my first cup of coffee yet this morning.....
thanks for the replies.
Get ready for the heat today..... triple digits again

 

[JRZEE2000TR4LTD]

Weird that this is so confusing given all the writeups out there and Durk's corrects info in this thread.
The timing marks imprinted on the belt are practically useless. The timing marks above each cam and on the cam pulleys (little dimples) need to be lined up along with the crankshaft pulley timing mark ( a little groove which may still have red in it) at TDC (lined up with the "0" on the timing indicator) . Once you get the belt on, which requires a little finese, the 3 timing marks will ALWAYS line up every 2 turns (720 degress) of crankshaft revolution. The belt is pretty snug so you should be able to turn the crankshaft 2 turns without pulling the tensioner pin. If you do have it off by a tooth, then you need to start all over.

 

[nobb]

No need to overthink it, positioning the timing belt is actually pretty straightforward once you see it. The hard part is getting all the tensioners in place without skipping teeth on the belt. But it's pretty obvious when it's not aligned even if it's only one teeth off.

1. Align camshafts so the arrow is at the very top (pointing to the top notch, TDC).
2. Align crankshaft so the arrow points at 0 degrees
3. Install belt. Optional: use the markings on the belt such that the arrows on the belt point to the arrows on the camshaft and crankshaft pulleys.
4. Install tensioners. Pull the pin on the hydraulic tensioner ONLY when you are confident the belt is aligned and secure. Remember, the crankshaft spins clockwise.
5. Turn crankshaft clockwise a few times and make sure on every second crankshaft rotation, that at 0 degree alignment of the crankshaft pulley, that the camshaft pulley arrow points straight up at TDC. Ignore belt markings, they won't line up after the first few rotations.

 

[stir_fry_boy]

5. Turn crankshaft clockwise a few times and make sure on every second crankshaft rotation, that at 0 degree alignment of the crankshaft pulley, that the camshaft pulley arrow points straight up at TDC. Ignore belt markings, they won't line up after the first few rotations.

This you could skip. Once the belt is lined up with the pulleys and the tensioner is pulled you are done.

 

[TheDurk]

Durk.... I was thinking about this last night.....
Timing belt off.... Every one revolution of the crankshaft the #1 piston would be TDC.
Then line up the cams timing marks?_____

Yeah, with the belt off, the crank does not know whether it is at Compression/Power TDC or Exhaust/Intake TDC. You just set the crank at TDC and then adjust the cams so they are at their TDC.

That said, best practice is to set the crank to TDC (0° on timing arrow on crank pulley) BEFORE you take everything apart and just fine tune when you install the belt trying not to move the pulleys in the meantime. This will save you messing stuff up when you eventually work on an interference engine or one with a distributor, neither of which applies to the 5VZ-FE.

 

[TheDurk]

This you could skip. Once the belt is lined up with the pulleys and the tensioner is pulled you are done.

In theory. Most of the time. It's easy to be a tooth off on the initial install and not realize it until tension is applied and the shafts are revolved a full cycle. I've had belts where the markings weren't precisely in register with the teeth leaving me even more nervous than normal about a critical step. I would NEVER skip this step--although I only do it once and then call it good. I sleep better that way. I like the satisfaction seeing them come up spot on. It just feels good.

 

[stir_fry_boy]

Most of the time. It's easy to be a tooth off on the initial install and not realize it until tension is applied and the shafts are revolved a full cycle. I've had belts where the markings weren't precisely in register with the teeth leaving me even more nervous than normal about a critical step. I would NEVER skip this step--although I only do it once and then call it good. I sleep better that way.

Interesting. I've now done 3 timing belts all with lining up the marks on the belt with the pulleys, pulled the tensioner without turning the engine to verify marks and no issues. 2 were OEM belts, one was Mitsuboshi. If the marks on the belt are lined up with just the pulleys after tension is applied, you can't be a tooth off after turning the engine.

If the belt is not well marked, yes I would double check it too.

 

[JRZEE2000TR4LTD]

No need to overthink it, positioning the timing belt is actually pretty straightforward once you see it. The hard part is getting all the tensioners in place without skipping teeth on the belt. But it's pretty obvious when it's not aligned even if it's only one teeth off.

1. Align camshafts so the arrow is at the very top (pointing to the top notch, TDC).
2. Align crankshaft so the arrow points at 0 degrees
3. Install belt. Optional: use the markings on the belt such that the arrows on the belt point to the arrows on the camshaft and crankshaft pulleys.
4. Install tensioners. Pull the pin on the hydraulic tensioner ONLY when you are confident the belt is aligned and secure. Remember, the crankshaft spins clockwise.
5. Turn crankshaft clockwise a few times and make sure on every second crankshaft rotation, that at 0 degree alignment of the crankshaft pulley, that the camshaft pulley arrow points straight up at TDC. Ignore belt markings, they won't line up after the first few rotations.

This is good except don't pull the pin on the tensioner until after you do a couple of CS revolutions. Also, to help with the belt install, it seems to help if you barely thread in the top middle idler pulley and make sure the whole time that none of your pulleys move. I kept getting it off by a tooth in the same direction so i moved the CS pulley back in that direction and got it on that way.

 

[TheDurk]

Interesting. I've now done 3 timing belts all with lining up the marks on the belt with the pulleys, pulled the tensioner without turning the engine to verify marks and no issues. 2 were OEM belts, one was Mitsuboshi. If the marks on the belt are lined up with just the pulleys after tension is applied, you can't be a tooth off after turning the engine.

If the belt is not well marked, yes I would double check it too.

Also, see Step 10 on page EM-21 of the attached. The people that built the thing think it's a good idea. It's also nice to be able to confirm that the tensioner has taken up the slack and placed appropriate tension on the belt, whether you are reusing an old one or it is new out of the box and untested. It takes less than a minute to do it, why not?

[EDIT] ....forgot the link...

http://tacoma.site40.net/4Runner_96-02_Repair&Wiring/techinfo.toyota.com/ileaf/02toyrm/02toypdf/02rmsour/2002/024runne/em5vzfe/timbel/inst.pdf

 

[stir_fry_boy]

Also, see Step 10 on page EM-21 of the attached. The people that built the thing think it's a good idea. It's also nice to be able to confirm that the tensioner has taken up the slack and placed appropriate tension on the belt, whether you are reusing an old one or it is new out of the box and untested. It takes less than a minute to do it, why not?

Well, I'll be doing it from now on. Thanks.