[KarensCamry]

Hi guys:

I have been trying to install my timing belt and get my car to run. The first time it ran fine for about 30 minutes and then the belt slipped. I put it back on again twice and it slipped both times and a lot -- in each case, the belt slipped and the cam gear rotated about 180 degrees off top dead center in relation to the crankshaft pulley at top dead center. I had gotten the belt on reasonably tight -- I think -- so I just can't figure what is wrong.

I don't have the bottom belt cover off right now and I'm wondering if that is where the slack is -- between the water pump and the crank shaft.

I think I have the right timing belt. It's a Mitsuboshi CD138. I bought a kit that included this belt.

Thank you for your help in advance!

Karen

 

[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 It's superseded by T199.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.

 

[KarensCamry]

John:
Thanks very much for your reply. The tensioner didn't come loose, but I will get a new spring and a new belt and see if that makes a difference. I appreciate your suggestions on the make of the belt.

I do tension the belt with both pulley's aligned to TDC, but why does that matter?

I'll let you know what happens!

Karen:Bruce:

 

[WaxonWaxStillOn]

With it slipping that many times, I'd wonder if it has damaged some belt teeth if not stretched it, both perhaps making it slip easier.

When I put my new belt on, there wasn't much play in the belt with the tensioner untightened but spring on, and I rotated the engine numerous times to let the belt's tension sync throughout it's complete path before torquing. Then I torqued the pulley when there was already proper equal tension all the way each pulley. That seemed to work well in my circumstance, so far atleast.

 

[KarensCamry]

Hi John:

I got the new timing belt you suggested. I tried one last time to get the old belt on tight and then rotate the engine a few times. With the lower cover still on, I got the belt seemingly tight -- at least it was tight between the water pump gear and the cam. I then released the tensioner pulley and rotated the engine. I rotated it once, and I heard the belt slip. It slipped two teeth.


I am going to pull the bottom cover off and put the new belt on and see if I can get it on tight all the way around. I'll let you know how that turns out!


Thanks for your help on this and pointing me in the right direction.


Karen :Bruce:

 

[KarensCamry]

John:

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 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.

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

Karen :Bruce:

PS: thank you again for your help.

 

[Perkins]

Rotate your camshaft pulley counter clockwise (towards the rear of the car) Until the belt between the camshaft pulley and the Water pump is tight. Tighten your Manual adjusting nut down, and crank the car over. the reason your supposed to rotate two revolutions is to make sure that the belt is guided properly over the camshaft and crankshaft. If you have about 1/8" Gap between the belt and the edge of the pulley on the camshaft pulley your belt will be ok.

 

[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:

 

[KarensCamry]

John:


Thank you so much for your reply. I have the tensioner bolt tightened right now. Are you saying I should loosen it and turn the engine four times? Should I loosen the bolt just enough that the tensioner pulley is free to move?


Do you think the Toyota dealer would have a spring?

Karen:Bruce:

 

[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?)

 

[KarensCamry]

John: I did replace the water pump. When I took out the defective belt (the one that seems to long), the belt did not show any wear at all. I will let you know how it goes when I get this back together and start it. I appreciate your help so much!

Karen

:Bruce:

PS: the new pulleys are NTN and the water pump is GMB. I didn't use the NTN tensioner pulley because the slot is shorter.

 

[KarensCamry]

John:

I really thought I had it this time, but when I started the car, it was hard to start and then it finally started, but at low rpms it hesitated when I gave it gas. It ran for a while and then the engine quit.

I pulled the top cover back and I can see that the belt has skipped quite a bit.

What do you think I am doing wrong? The belt seemed really tight this time. Could the tensioner spring be at fault somehow? I ordered a new one.

Can I retension the belt without remiving the bottom cover?

Thanks!

Karen :Bruce:

 

[nitronate33]

maybe this is stating the obvious, but is there a possibility that something out of whack is causing so much resistance against the belt that it is forcing it to slip? does the crank and cams turn easily? if it has a hard time turning over something could be frozen up or binding. with the belt being the weakest chain in the link so to speak, it is going to give first.

 

[WaxonWaxStillOn]

Someone can correct me if I'm wrong, but once the tensioner pulley is torqued to 31 lbs. (iirc), the tension spring is irrelevant, since it's not going to move the pulley's position if that level of torque on it's mounting bolt is achieved. And if you inspected the belt's tension and found it rather snug around all the pulleys before torquing the tensioner pulley, the spring wouldn't be a factor imo.

I would be concerned with what nitonate33 said. The water pump, oil pump, tensioner pulley, and idler pulley should all spin easily by hand.

The crankshaft is generating the belt's movement, so that's not likely going to be the cause. The camshaft is turning because the engine is starting, albeit briefly, so it's definitely not frozen atleast. So I would probably make sure the other 4 items don't have any noticeable resistance when turning by hand.

(another thought would be making sure the belt is installed properly, over and under the pulleys in the proper sequence according to the diagram. There probably aren't many ways one could get it wrong and still get the right tension, but I almost did before I double checked it.)

 

[KarensCamry]

You guys are wonderful. The cam slipped 180 degrees from dead center.

I will check everything that rotates and see if there is a problem. 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. 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. 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.

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

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

When the engine was idling, it was initially smooth and everything in the timing box was quiet.
Thanks!!!!! :Bruce:
Karen

 

[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.

 

[WaxonWaxStillOn]

In addition to what's been mentioned I'd also check each pulley to make sure there is no wiggle in them. Everything should be snug on it's axis and rotate like you mentioned your water pump does, but have no play side-to-side play at the same time. It's not something you'd expect from new parts, but new parts can be defective too.

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.

Maybe others would have more insight on this one, but could the oil pump be so worn that the driven rotor doesn't rotate freely, or rubs against the housing quite a bit? I had a bit of housing-wear on mine, altho don't know if the parts could wear enough to cause enough resistance and make the timing belt slip.

A side note, I'm also wondering what precipitated the need to do this timing belt job in the first place, ie. if it's possible the thing you're trying to solve now is what created the problem in the very beginning, causing you to start this repair project.

 

[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.

 

[KarensCamry]

Hi there. I pulled everything off to check it out. The oil pump gear turns freely along with the new water pump gear. The idler pulley turns well, the tensioner pulley doesn't turn as freely as the idler pulley, but it turns. BTW, the slot on the new tensioner pulley is just as long on the lower side of the pulley as it is on the old one. So it does come up just as far as the old one when the spring snaps it up. But I can't push it down as far as when I want to remove the belt from the tensioner pulley.

When I release the tensioner and tighten it down, I notice that the belt gets tighter when the engine rotates and it stays tight. I really thought I had it tight enough today. I guess not.

John, you said this:

"When doing the tensioning the instruction is to loosen by 1/2 turn. But I'd make sure the tensioner can move freely and is not bottomed out in the shorter slot as you mentioned."

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?

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.

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.

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.

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.

Thank you so much!!!

Karen :Bruce: