Timing belt question

[Ahimsa]

So I am replacing the timing belt on an 2001 LC. While I am at it I am doing the radiator, water pump, and related pulleys (tensioner). I set the crank past TDC at ATDC per manual. What I notice is the crankshaft mark, and Left cam (bank 1) is dead on but the right cam is off by about 1/2 to 1 tooth. I read on one forum that this is normal due to the old belt stretching.

My question is do I move the right cam back into alignment before putting new belt on? Or, keep it just as it was when I removed the old belt. Silly question, I know, but I cant find anything that says to move the cam back. Instead everything I found says don't move things. I really want to make sure its right or is there a way to check the timing to be sure its all lined up when running (its all reassembled at this point) or will that kill the engine, hah! I don't look forward to tearing it all apart again, but if I need to I will.

Slow (in the head) but steadily persevering.......

Thanks!

 

[LBridges]

Well, for me I did not move the crank past TDC - that way I knew all markings should be aligned.

Not seeing your case in person I would have voted for moving the right cam back into position.

Not easy, but not too difficult, I would pull both cam upper covers so you can see the marks. Then as a check rotate the engine by hand two times to make sure the marks come back to where they should be. In my case the belt slipped on one cam gear and I had to re-accomplish using the "clamp the belt to the cam pulley" method while setting the tensioner. If you should have moved the gear before reassembly it will be apparent after the two times rotation.

 

[Sandroad]

Like @LBridges I can't be sure without seeing the case in person. However, if there was any "belt stretch" in the old belt, it would have been eliminated by the tensioner. So, the forum where you read that a cam can normally be one tooth off due to belt stretch is likely not correct. Go for the 2 crank rotation by hand test noted above just to be absolutely sure before you light it up.

 

[Ahimsa]

I did the two crank rotation it came back to the same places each time with the left cam centered the crank centered the right cam one to a half tooth off. Will disassemble unless Toyota can tell me they have a diagnostic test to see the wave patterns of the firing to confirm if they are not firing at (or near TDC).

 

[BillZ260]

I did my belt this past weekend. I noticed that passenger side cam sprocket rotated clockwise, maybe 1 degree or very little, when I pulled the old timing belt OFF. I was able to re-align the marks. It's like the cam it's right at the end or beginning of a lobe engaging and would move off the mark if I bumped it at all.

So when I reassembled, I lined the sprocket mark with the one on the head, then I lined up the belt marks to the sprockets, all 3, 2-Cam, 1-Crank with all the marks lined up. When I got it all back together, it started right up and have had no issues. Maybe mark where it is now, and try to rotate the sprocket to match the mark on the head, see if you are having the same issue, should be a bit of pressure rotating to where the marks line up, mine would stay once lined up, unless like I said, I bumped it. Good luck.

 

[nissanh]

Do you get all the marks to match at TDC? I did it at TDC and all went smooth.

 

[Ahimsa]

It was off by the same amount both at TDC and ATDC. So I will check the timing if it is out of the range of the service manual I'll go in and manually realign it.

 

[Ahimsa]

yep....timing is off. will tear down this friday

 

[vipergrhd]

If you have a Toyota TB or Aisin belt is marked for both cams and crank so no chance of mis alignment.

 

[nissanh]

^^^ Even Mitsuboshi (Made in USA) timing belt has all the marks to line up with cams and crank.

 

[Ahimsa]

This was the amount that the Right cam was off.....a whole tooth.

Crank and left cam were dead on.



After adjustment made (Left cam and Crank also dead on, see below).

So this is set as per manual to the "T" which takes pressure off the cams.

Just as an aside, I found that taking the bottom bolt out then the top for the air conditioning unit then reverse than on installation was the easiest. I used this set up from below:

I only show it cuz I tried several set ups to try to get it and thought it might help someone save a bit of time. The rest was just moving through the paces!!!

All is back together and running just fine. I tried to check the timing using a timing light, as per service manual but don't feel I am doing it right. The light has a dial on it so if I advance it to about 22 degrees it shows the timing is right. Dunno need to research it more. Service manual says 5-15 BTDC if I am reading it right.

Thanks for the help though guys.

 

[nissanh]

I did the cams at TDC and there was NO pressure on both cams. None of those turned.

Yeah, your second set of pictures is the way to go. I had the same exact positions.

 

[Ahimsa]

It can be done either way imho, on my old Taco I did it at TDC. I just followed the manual this time. I think the crucial piece is alignment and not cranking things counterclockwise

 

[Astralplane]

Shouldn't it be lining it up to the vertical line, not the "T" ?

 

[Ali FJ80]

The T is not TDC its the line thats to the left of it.

 

[Ahimsa]

Not to confuse anyone, but here is the relevant section of the FSM that I was referring to earlier. Step 17 you set the crankshaft pulley to "0" check that the marks all line up ( on the line next to the T) and mark your old belt. Step 17c when you move the pulley to approx. 50 degrees clockwise the cams will then both be set directly on the mark T. when you remove the crankshaft pulley and cover you will see a little stud sticking out of the block that is the mark for the ATDC 50 degrees advanced. Once you reinstall the belt and to the two revolutions it will line all back up on 0 degrees for the crank, and on the lines (not the T) for right and left cams.

But as I said I've done it both ways successfully.