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Hi Im curious of anyone makes a bolt on T belt guide that will keep Belt from walking off the end of Cam sprocket? I'll be on the road for a few days (with this 89 TD Van) Been having the usual Belt probs....loose or tight it keeps wanting to walk off the edge away from eng....(its currently a lil loose but not flapping too much, but can push belt over with hand). ...fun times. I would think a bolt on guide would while you figure out whats really wrong. THX!
 

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The very early cam sprockets had a guide, but they would be all square tooth design, so that won't help you. A guide will pretty much just tear up the timing belt if you have any real alignment problems. Are you aware that the tensioners are different for early and CB's? The CB tensioners are a bit longer than the square tooth tensioners. Are you having any problems with acc. belt alignment? The reason I ask is if the crank sprocket is not bottomed out on crankshaft, this will cause timing belt and all acc. belt alignment problems. Here is picture of difference in length of tensioners. Careful not to tighten belt too much. Be aware that a timing belt will tighten up as it heats up. Putting an early tensioner on your CB will make it run more on the inboard side, but perhaps too much.
 

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You definitely have an issue if the belt walks off the sprocket.
I have been driving without an upper timing cover for years, have replaced the belt 3 times, tensioner once and the front crank seal once in 30 years and have never encountered this issue.
I even removed the belt from the Cam Sprocket by hand and put it back by hand to replace the Front Cam Seal on the road and had no issues so something is definitely wrong.

I would suggest you remove the timing covers and take some pics if you cannot spot the issue.


Engine Compartment Right Side-2014.JPG
 

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Discussion Starter #5
The very early cam sprockets had a guide, but they would be all square tooth design, so that won't help you. A guide will pretty much just tear up the timing belt if you have any real alignment problems. Are you aware that the tensioners are different for early and CB's? The CB tensioners are a bit longer than the square tooth tensioners. Are you having any problems with acc. belt alignment? The reason I ask is if the crank sprocket is not bottomed out on crankshaft, this will cause timing belt and all acc. belt alignment problems. Here is picture of difference in length of tensioners. Careful not to tighten belt too much. Be aware that a timing belt will tighten up as it heats up. Putting an early tensioner on your CB will make it run more on the inboard side, but perhaps too much.
Hi I have a square cam sprocket. I measured the last (but same Gates tensioner as whats on there now) Tensioner...Looks like i have the longer tensioner. Yes having alignment prob with ALT belt, but not Power steering belt. Maybe in this case i should go with a shorter tensioner to compensate (maybe shim it for best sprocket placement?) P.S. The belt is now not walking around & lives on the outter edge of the cam sprocket, has not shredded any more....Just drove the van 1500 miles....I know the belt is a bit loose (set it that way on purpose), its flapping slightly still. THX! T
 

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Discussion Starter #6
You definitely have an issue if the belt walks off the sprocket.
I have been driving without an upper timing cover for years, have replaced the belt 3 times, tensioner once and the front crank seal once in 30 years and have never encountered this issue.
I even removed the belt from the Cam Sprocket by hand and put it back by hand to replace the Front Cam Seal on the road and had no issues so something is definitely wrong.

I would suggest you remove the timing covers and take some pics if you cannot spot the issue.


View attachment 270717
Im near a TD guy here in MA, he had a few of these TD vans. ill have him do whatever work you tell him to (i have MS, cant turn wrenches too much anymore). This fresh rebuilt short block is a 91 2.5 N/A conversion with all the old stock 89 2.5 Turbo externals (including head) btw THX!
 

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Confused by your last post, exactly what info/ advice do you need?
 

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My first concern would be why you have a square tooth cam sprocket when all 89 up were round tooth sprockets.
I cannot look at any part details until I return home on Monday.
Also, what type of alignment issues are you having with the Alternator?
The biggest issues with alternator mounting is the stationary bracket bushings wear or the lower isolator, both will cause the alternator to cock as the belt is tightened.


 

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Discussion Starter #12
My first concern would be why you have a square tooth cam sprocket when all 89 up were round tooth sprockets.
I cannot look at any part details until I return home on Monday.
Also, what type of alignment issues are you having with the Alternator?
The biggest issues with alternator mounting is the stationary bracket bushings wear or the lower isolator, both will cause the alternator to cock as the belt is tightened.


Maybe my van is an early 89? idk. Back then of coarse car makers werent very organized compared to today lol. ALT belt refuses to live in the proper place on WP pulley its hanging off the inside edge of that pulley a bit but still functions ok... for now. Changed to poly ALT bushings but didnt change the belt position (old bushings looked still "good"). I cant comment on the isolator as i didnt do the job. If its something i can tell by looking at i can check saturday
 

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The concern is that you have a square tooth cam sprocket and a round tooth crank and intermidiate sprocket since the block is a 91.
The issue with the isolator is the rubber cracks or comes loose from the bracket, since it is bolted to the tensioner...
 

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Hi I have a square cam sprocket. I measured the last (but same Gates tensioner as whats on there now) Tensioner...Looks like i have the longer tensioner. Yes having alignment prob with ALT belt, but not Power steering belt. Maybe in this case i should go with a shorter tensioner to compensate (maybe shim it for best sprocket placement?) P.S. The belt is now not walking around & lives on the outter edge of the cam sprocket, has not shredded any more....Just drove the van 1500 miles....I know the belt is a bit loose (set it that way on purpose), its flapping slightly still. THX! T
The concern is that you have a square tooth cam sprocket and a round tooth crank and intermidiate sprocket since the block is a 91.
The issue with the isolator is the rubber cracks or comes loose from the bracket, since it is bolted to the tensioner...
I too am confused and concerned you have a square tooth cam pulley with a round tooth crank and aux. shaft pulley. That won't last for long! I am not aware of any 89 production cars (Maserati TC excluded) coming with 88 engines in them. Many early 89 blocks were cast in mid to late 1988. The 88 year used a unique crank sprocket mated with a unique crank pulley. The hub center changed on these pulleys to prevent using the wrong pulley on the wrong sprocket. The crank snout and corresponding sprocket is also larger on the CB vs. the 88 and earlier cranks. Hope you don't have some mismatched parts going on here, but sounds like you could have. That could explain why your having the issues you're having with belt alignment. To complicate matters more, the 86-88 2.5 tall deck block used a unique crank sprocket snout and sprocket. Let hope you don't have TD 2.5 parts thrown in the mix.
Here is a picture of the 88 and 89 SOHC crank sprocket. So for the record you have a NA 2.5 in the vehicle now. Non turbocharged? Or you have a turbocharged 2.5 that was once a NA 2.5 block?
 

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I would recommend you check all parts cam, intermediate and crank sprockets.
It is difficult to say what any previous owners did.
My 88 Shelby Z when I purchased had a CB installed BUT had 88 square sprockets.
as another example what previous owners do.
When I bought my 87 CSX it ran terrible, then I look at the Cam sprocket and someone replaced the turbo 557 for the EFI 690. Yes someone switched the engine to CB. On 30+ year old cars it is difficult what previous owner have done.
 

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Discussion Starter #16
I would recommend you check all parts cam, intermediate and crank sprockets.
It is difficult to say what any previous owners did.
My 88 Shelby Z when I purchased had a CB installed BUT had 88 square sprockets.
as another example what previous owners do.
When I bought my 87 CSX it ran terrible, then I look at the Cam sprocket and someone replaced the turbo 557 for the EFI 690. Yes someone switched the engine to CB. On 30+ year old cars it is difficult what previous owner have done.
Well since i owned van 4 years now the van ran great (no belts probs) 40K miles on orig 2.5T, then i blew eng... Van has a rebuilt 2.5 Turbo eng now, so it def would have all the externals from the old eng....
 

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I too am confused and concerned you have a square tooth cam pulley with a round tooth crank and aux. shaft pulley. That won't last for long! I am not aware of any 89 production cars (Maserati TC excluded) coming with 88 engines in them. Many early 89 blocks were cast in mid to late 1988. The 88 year used a unique crank sprocket mated with a unique crank pulley. The hub center changed on these pulleys to prevent using the wrong pulley on the wrong sprocket. The crank snout and corresponding sprocket is also larger on the CB vs. the 88 and earlier cranks. Hope you don't have some mismatched parts going on here, but sounds like you could have. That could explain why your having the issues you're having with belt alignment. To complicate matters more, the 86-88 2.5 tall deck block used a unique crank sprocket snout and sprocket. Let hope you don't have TD 2.5 parts thrown in the mix.
Here is a picture of the 88 and 89 SOHC crank sprocket. So for the record you have a NA 2.5 in the vehicle now. Non turbocharged? Or you have a turbocharged 2.5 that was once a NA 2.5 block?
Looking closer at your pics it does look like i have the correct "round tooth sproket" but its hard to tell...maybe you can confirm? As stated the eng is a 91 NA (non Turbo) 2.5 eng converted to Turbo eng. All the extrernals (including the head) are from the original 89 2.5 Turbo eng
 

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The best thing to do is remove the timing covers and verify what type sprockets are on the block.
 

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Did not see your other post, enlarge this pic and compare the teeth with your sprocket.
74873-56d915ba6543cdf5f8f501f7811ff964.jpg
If you have a round tooth cam sprocket I would again suggest removing the timing covers and posting pics of the spockets and belt alignment.
 

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Yes definitely has round tooth cam pulley on it. Perhaps your crank sprocket didn't get installed quite all the way. I've seen that before. Some press on fairly easy, while others are pretty tight. I always use STP when pressing parts together. Makes the job of pressing interference parts a bit easier.
So assuming if you tighten the timing belt further, the belt will want to walk right off the cam pulley? If that is the case, I would suspect the crank sprocket isn't pressed on all the way.
Here are a couple pictures of my Masi engine's crank sprocket. The sprocket is a bit different than yours, but notice how close the inboard part of the sprocket is the the aluminum seal retainer? Yours should be that close too.
 

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