[JohnGD]

That's too loose. Did you torque down the idler pulley and tensioner pulley? Did they come loose? I wonder if the belt's damaged and was stretching like a rubber band.

If the torques check out then I'd get a new tensioner spring (~$5 or so) and a new T199 timing belt from NAPA or O'Reilly (that should be a Gates belt but I'll take an Italian Dayco too). Gen 3 is tensioned at TDC. Manually rotate the engine 4 revs after torquing and double check the marks. Yeah, these manually tensioned engines aren't the easiest to set properly, but they cost less to make than using automatic tensioners.

T138 belt is for the older Gen 3 engines. It's superseded by T199. T138 uses a cheaper rubber (neoprene? nitrile? not sure) and T199 uses highly saturated nitrile rubber (or HNBR, Hydrogenated Nitrile Butadiene Rubber) that can stand higher temps better. But I'd still change both of them at 5yr/60K miles.

 

[JohnGD]

I put the new belt on and got it pretty tight on the front and the back. I rotated the engine twice slowly and the belt did not slip. The timing marks are pefect. I don't know whether I should really give it a quick turnover with my wrench or not.

I'd think you're doing fine this time. Give it a few more turns.

The recommendation is to (slowly but no instruction mentions it) turn the crank two turns during the tensioning step (tensioner bolt 1/2 turn loose). I'd give it 4 turns (the belt has a tendency to jump teeth during this stage because of valve spring action). The marks should line up. It would be so much easier with an automatic tensioner.

And after tightening down the tensioner bolt, I'd give it 4 more turns and make sure the marks still line up. The engine should seem to run quieter, smoother, and more powerful than with an old belt and pulleys. Turning the crank slowly is fine, no need to turn fast.

I tried to get a new tensioner spring, but two NAPA stores didn't have them. My spring seems okay. One thing I did notice and this could have been causing me a problem: I put a new tensioner pulley on and it has a shorter slot in the middle of the pulley where the bolt passes through -- shorter than the original tensioner pulley. When you release the bolt on the new pullley, it didn't rise as far as the old pulley. So I put the old pulley back on -- with the longer slot -- and it does seem tighter.

I should have mentioned it's a dealer item. However, Dayco does include two in some of their timing kits, but no guarantee that they still do. The Gen 3 silver one is the older one and the timing belt is tightened at TDC; the green one is the newer one and the belt is tightened at 45 BTDC. The Gen 4 one (all silver) is slightly shorter and tightened at 45 BTDC because they had some defective timing belts stretching and tensioning problems too. That's another reason why I recommended a new belt and a new spring.

I'm not sure about the tensioner pulley slot. Maybe it's another Gen3/4 difference that I think shouldn't exist. I would think if the pulley didn't bottom then the belt would still have the proper tension set by the spring. Dunno. What brand was the tensioner? I see Koyo but more and more GMB tensioners in various Gates and Dayco timing kits.

BTW, the new Gates belt is about 1/4 inch shorter than the Mitsuboshi belt. That must make a difference in the slippage.

The specification of both belts are the same. I think the Mitsuboshi belt is defective. Again, I prefer Gates belts (and hoses), but will take a Dayco over other belts.

Hopefully this new belt solves the problem. Let us know. :thumbsup:

 

[JohnGD]

If it's already done then no need to repeat the work. I think the problem may be the belt, but the question would be why. Also, it would be nice if a correct, new tensioner pulley is installed too. Usually by 60K miles the grease is dry (clicking when you shake it), and by 90-100K they can be really noisy or even wobble a bit.

Maybe just run the engine until the cooling fan comes on once or twice. And then double check again the timing marks on the cam sprocket with the crank at TDC. You wouldn't want to drive 30 minute and then the engine quits.

(Quickly browsing through old threads I see that you took out the distributor and valve cover etc, but did you replace the water pump? I hope the pump isn't seizing. Did you see glazing on the back of this Mitsuboshi belt?)

 

[JohnGD]

Something is definitely not right. Usually it's the water pump seizing, that why I was asking about it and the pulleys. But as others said, double check the belt routing. Did you use a torque wrench to tighten the pulleys? How did you tighten the pulleys? Check Autozone's free loaner program for torque wrenches if you don't already have them. Harbor Freight also has good prices when on sale.

I'd remove the belt and check the crank, cam, oil pump, water pump and the two pulleys for turning resistance. I'd remove the spark plugs after blowing clean the tubes with compressed air to reduce crank turning resistance.

You should be able to turn the crank with fingers on a standard length ratchet. The oil pump sprocket should turn easily and smoothly. Same with water pump and the two belt pulleys. You will feel the valve spring pressure at various points, so the cam will take some effort but shouldn't need to exert to turn it.

If the teeth of the timing belt remain intact and show no wear and the back of the belt show no wear then I'd double check the routing.

Yes, you can retension without removing the crank. NTN pulleys are decent. Koyo and NTN are OEM parts. GMB pumps typically use rubber seals that can't handle silicates. I'd use OEM Aisin or Bosch aftermarket. I'll also be looking at the new Gates pump lineup in the future.

Maybe post some pictures or even videos on how the pulleys turn?

 

[JohnGD]

The cam is a bit stiff, but I can rotate it with the wrench. It seems like a vacumm is holding it back and then it lurches forward.

That's primary the valve spring pressure working against turning at various points. If it's all smooth otherwise and you don't intend to remove the crank pulley, then I wouldn't worry about it.

But if you do remove the crank then I'd pull the plugs give give both some good turns just to check.

The water pump is new and spins freely (the old water pump seized and that ruined the timing belt). I have replaced the two pulleys. They are made by NTN.

NTN are decent OEM pulleys. The other commonly seen is Koyo. There are many GMB in aftermarket kits. They perform about the same.

So double check the belt routing.

The tensioner pulley is a little stiff in turning compared with the old one, but I figured that's because it is new. I will check the oil pump gear to make sure it turns freely.

New pulleys are stiffer (but very smooth) because of the new grease. The grease gets used up by 50-60K miles and if you shake the pulleys they make some clicking noise. Usually the tensioner gets noisy first and the idler may still be smooth and quiet at 50-60K.

I was thinking maybe the tensioner spring was weak and not snapping the pulley all the way up.

It's a possibility. After you tightened the tensioner and go through rotating the crank you should be able to see if the belt gets a bit looser. I wonder if the dealer is selling the 1.65" one instead of the 1.81" one for the Gen 3. (Gen 4 uses the shorter one).

Can I tension the belt without removing the bottom cover and the crank shaft pulley?

When doing then tensioning the instruction is to loosen by 1/2 turn. But I'd make sure the tensioner can move freely (so it can tension properly by the spring) and is not bottomed out in the shorter slot as you mentioned. But with a new belt the tensioner should be closer to the MIN side (tensioner pulley nearer to the left).

When the engine was idling, it was initially smooth and everything in the timing box was quiet.

When everything is working it should be quiet and smooth and may even a little more powerful than with old parts.

 

[JohnGD]

Good point. This can happen if the key fell off. The key or the key way should point to the TDC mark on the block. So this is a way to double check. Similarly with the cam.

The idea is to use the pin/key on the cam/crankshaft to double check with the marks on the block/cylinder head, not just by the marks on the pulley and sprocket.

Another [low-probability?] issue could be if the crankshaft key, which the crankshaft pulley is held into place by, could be damaged or worn down, or if the pulley's inner diameter slot is damaged, either or both allowing this pulley to slip when the motor is running.

The camshaft pulley has a hole that sits on a solid pin on the camshaft, so it would probably be hard to imagine that pulley slipping as long as the pin it sits on is still in place and not damaged.

 

[JohnGD]

John, as to the above quote, I haven't loosened the tensioner 1/2 when I tension it. I just tensioned it with the tensioner tightened down. 1/2 turn looser from what? Full torque down?

Well, I think we may have found the problem. When a manual tensioner is tightened down it acts like like an idler pulley (the other pulley). The spring no longer has any function.

When the tensioner bolt is loosened 1/2 turn from fully tightened down, you'll see that the tensioner can remove freely in its slot. This is how the spring can apply it's tension to the belt.

The problem is when you rotate the crank 2 times with the bolt 1/2-turn loose, the belt has the tendency to jump teeth. But it can be done if you rotate slowly. That's a reason I prefer not to work on these cheap designs.

I don't have a torque wrench. I tightened the pulleys with my ratchet wrench. Should I get a torque wrench that clicks? Being a woman, I am not that strong, but the bolts seem pretty tight. My neighbor has volunteered to tighten anything down for me that i can't get tight enough. If they aren't torqued down could that cause a slip of the belt. The bolt seems tight on the tensioner when I go to remove the belt and have to loosen it and push it down.

Is that a standard 3/8" drive ratchet about 8" long? As mentioned above the problem may be the tensioning with the bolt tightened down. However, I'd still borrow a free loaner 3/8"-drive 80 lb/ft Autozone torque wrench to tightened down the bolt if possible.

The cam does take an effort to turn, and then it will suddenly lurch forward. I will do what you suggested and take the spark plugs out and make sure the cam turns smoothly.

I wouldn't worry about this step at present time. I think the problem may be the tensioning step.

The timing belt seems fine. No damage. How do I know if I have the right belt? Napa sold me a Napa belt made by Gates. The model number is 250199. It is slightly shorter than the Mitsiboshi belt.

That's the right belt. 250199 is NAPA's numbering system, it is T199. Redo the tensioning step. Use the Gates belt. IME Gates belts hold up quite well over time.

I will double check the routing, but it really only goes on one way. I have a picture of how it is supposed to look.

We are just turning the box upside down and making sure no stones are unturned.

 

[JohnGD]

The Gen 3 with green spring is tensioned at 45 BTDC. Gen 4 with the 1.65" spring (measured inside of hooks) is also at 45 BTDC. And yes given all the work done so far use a new tensioner spring from the dealer. Let us know what length/color spring they give you (I would think all are updated to the 1.65" silver one? Dunno).

The only thing I'm not sure about is if OP's Gen 3 lower timing cover has the 45 BTDC mark. But there is nothing a protractor can't solve.

The 1/2" tools or even the 3/8" standard ratchet should allow OP to sufficiently torque down the bolts, but as mentioned, a free loaner torque wrench from Autozone should be fine if it's not abused.

1/2"-drive 150 lb/ft on sale $14.99:
http://www.harborfreight.com/1-2-half-inch-drive-click-stop-torque-wrench-239.html

3/8"-drive 80 lb/ft on sale at $17.99 (!!):
http://www.harborfreight.com/3-8-eighth-inch-drive-click-stop-torque-wrench-807.html