[tmcalabro]

I have to replace my timing belt. When I set the engine to TDC at the flywheel, the mark at the distributor looks to be slightly off (see attachment) to the left. Do I have to go through and check the cam timing?

Some background - The water pump seized, stripping off the rubber on the back of the belt down to the cord. I believe it also stretched the belt, as the hydraulic tensioner did not reach the tensioning pulley. When I install the new belt, the tensioner works fine. although there seems to be a bit more play in the upper side of the belt compared to the lower (water pump side).

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[oppositelock]

Best solution is to start at the very basics: #1 at TDC and set the cam timing. You have had a serious problem, but maybe not a catastrophic problem. This looks too far off in my opinion, but you may be ok with piston/valve interference. You can turn the engine over by hand and if there is no resistance, run the car. This may not be the optimal timing, but you will not have to set cam timing. No matter what you do, alway rotate the engine over by hand at lest a couple revolutions jut to make sure there are no problems. Mitch

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[tmcalabro]

Thanks Mitch! I did rotate the engine a couple of times setting TDC. Before I start the car I will rotate it a few times to "set" the belts, then I'll check the marks once more.

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[Lear35A]

It looks one whole tooth off to me. It will probably run without the pistons and valves fighting, but something isn't right.

Edit: Let me expand. When putting on a new belt it is easy to get too many belt teeth between the cam sprocket and the crank sprocket. The tensioner does not take care of this, and you get what you are seeing on your car. Make sure you're at TDC on #1 by some method besides the flywheel mark (like a long thin screw driver down the spark plug hole). Once that is certain, get your flywheel lock in place. Compress and pin the tensioner and take the belt off. Rotate the cam sprocket so that the marks line up. Now get the belt on there so that when it is tight between the cam and crank sprockets, the marks still line up. When you release the tensioner, these positions won't move. If you have the belt tension measuring tool 9201, it should read 4.0 +-.3 with a new belt.

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[Ryan]

When I did my belts the mark started out to be lined up, but did the same thing you are showing in the photo when I let the tensioner out. I had to go back and correct the problem as this is off one tooth.

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[tmcalabro]

Mine didn't move, this is where it landed when setting the flywheel to TDC. I am thinking that the belt stretched when the water pump stopped turning, and this is the result. My plan is to make sure the #1 piston is at TDC, the flywheel is at the proper mark, then move the cam slightly.

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[Ryan]

That sounds like a plan. Cam timing could have been set wrong by the past mechanic or owner. This could mean better performance if timing has been off for some time.

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[tmcalabro]

Got my fingers crossed!

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[Lear35A]

Just for kicks, before you take the old belt off, count the number of belt teeth from the cam sprocket to the crank sprocket. Put a little paint dot on the sprocket teeth you use for this count, so you don't loose track of which you used. After you get done installing the new belt and the cam sprocket mark lines up where it should, count the number of belt teeth between the marked teeth on the sprockets.



I'll bet you discover that in fact the old belt was one tooth off - not stretched.

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[tmcalabro]

Yep, I thought of doing this as well, right after I took the old belt off. <img src="/forum/images/smilies/968/ohmy.gif" class="smilie" alt="" />

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[earossi]

When installing the new timng belt, you may find it easier to rotate the cam sprocket just a little bit clockwise (one to two teeth) and then install the timing belt on the cam gear. Do this after you have installed the timing belt completely except for slipping the belt onto the cam gear. Once the belt is slipped onto the cam gear put tension on the upper leg of the belt (from the cam gear to the crank sprocket) by rotating the cam sprocket counter clockwise to take up the slack in that upper leg. You may have to experiment with this a little bit, but when you take up the slack using the above technique, the marks should line up between the cam gear and the notch in the cam gear housing. Once you have everything lined up, install the belt tensioner. Installation of the tensioner should not change the alignment mentioned above. If the alignment does change after installing the tensioner, you had some slack in the timing belt (between cam gear and crank pulley).

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[kwikt]

Exactly, just went through this last week.

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