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1G New timing belt disintegrating after fewer than 18000 km - WHY?

sacrileger

Proven Member
288
40
Jun 26, 2016
Orillia, ON_Canada
After installing a brand new timing belt and putting on about 18000km, i noticed the timing belt started making rhythmic 'swooshing' sounds as if the belt was flapping and rubbing against 'something' so i took the timing belt cover off to examine the belt and instantly noticed irregular shallow marks on the belt:
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the first thing i thought of wearing belt in such a way were bolts on the oil pan flange not being in their proper place, i.e.one or two bolts were too long and making contact with the belt. no such luck. i removed the two bolts right underneath the pulley and nothing changed. the swooshing sound continued.

continuing with my investigation, i noticed that some of the teeth on the timing belt, the opposite side of where the belt made contact with 'something', were partially broken off and some of them were in the process of breaking off; however, none of the teeth broke off completely... and what i meant by 'partially' is that only about 1/2 of the tooth was broken off:

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upon further investigation, i wondered if perhaps i put on the wrong timing belt cover as i wondered why is there a gap of about 1/2" between the oil pan flange and the plastic cover itself:

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this is a 1992 6-bolt 4g63 and the cover part number is MD141459 S / MD141461 B:
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Any thoughts as to what could have possibly caused this damage to the timing belt after only 18000 km?
 

sacrileger

Proven Member
288
40
Jun 26, 2016
Orillia, ON_Canada
The only thing I see that looks a bit odd is the discoloration of the tensioner pulley on the back edge. I screen shot it and circled the discolored area, not that it has anything to do with it, but mine are usually just silver from the belt going around it. Maybe my old eyes are just "seeing" things too.

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your eyes are not 'seeing' things... the pulleys had belt shavings stuck to it and i did not wipe all of it off; plus when i looked at the pic at original resolution, the light from the top and bottom blends into a shadow at that spot as well.

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make sure you follow this method when doing the belt, check the tension.
thanks for the vid... what a neat little gadget to lock the cam shaft gears! i wish i had this thing right now! i tried to ram a piece of wood in between to lock the gears in place the last time but it didnt work... bc it was not hourglass shaped
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1990TSIAWDTALON

Moderator
9,698
5,537
Nov 14, 2013
Independence, Kansas
The "proper" tools to hold the gears, compress the tensioner and the small tensioning tool with 2 pegs on it are invaluable when doing this job. Do you have to have them, NO. Do they make things easier, YES. :thumb:
 

sacrileger

Proven Member
288
40
Jun 26, 2016
Orillia, ON_Canada
The "proper" tools to hold the gears, compress the tensioner and the small tensioning tool with 2 pegs on it are invaluable when doing this job. Do you have to have them, NO. Do they make things easier, YES. :thumb:
i dont follow^... the "tensioner" you referred to, is that the hydraulic tensioner? and what is the tool with 2 pegs on it? is there a pic on this forum? i am asking bc i am experiencing a serious counterclockwise force on the exhaust cam when i try to line up the timing marks. @pauleyman suggested i look into checking the condition of the sprocket dowels and holes... so i am searching up what that's all about bc it's the same issue i was faced with 18000km ago and then ended up with a partially shredded belt. except i did not know it was an issue back then. i have a serious feeling the counterclockwise force/torque was the primary reason why i am replacing the belt again and i dont wish to repeat the same thing this time and end up with the same problem as the last time.
 

1990TSIAWDTALON

Moderator
9,698
5,537
Nov 14, 2013
Independence, Kansas
I pulled this picture from ExtremePSI's website. It includes all of the tools that I use when I do a rebuild or timing job. I made my own threaded rod for the tensioner out of metric allthread and some coupling nuts (extra long nuts) but this shows the tools that make the job easier.
A picture is worth a 1000 words so here ya go!
Marty

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Tyeler18

10+ Year Contributor
2,475
205
Dec 16, 2008
Casa Grande, Arizona
39 teeth from the mark above the 9 o clock position on the exhaust cam to the 3 o clock position on the intake cam this is an easy check to make sure you have cam timing set where it needs to be for those not comfortable with the gear alignment. On a 2.0 if you have 39 teeth cam timing is right. If you have 39 teeth there then youre cam marks should be dead nuts on. Thread the oil pump, back the crank off half a tooth so you can thread the belt on the crank sprocket and then spin it the half turn clock wise to TDC, throw the belt over the tensioner pulley and set hydraulic tension.

If that belt actually has 18k on it I agree that belt tension wore that thing out if youre pulleys are all spinning fine. It looks like it was rubbing hard on the back side and as mentioned there's only 2 smooth pulleys for it to rub on.
 

1990TSIAWDTALON

Moderator
9,698
5,537
Nov 14, 2013
Independence, Kansas
I am only guessing here, but in the pictures of the outside of the belt, it looks like a hot rubber tooth got onto the tensioner pulley and stuck, producing the gouges we see on the outside of the belt. I am left wondering if one of the rubber teeth that fell out when you pulled the cover would mate up to those gouges........:hmm::idontknow:
 

sacrileger

Proven Member
288
40
Jun 26, 2016
Orillia, ON_Canada
I pulled this picture from ExtremePSI's website. It includes all of the tools that I use when I do a rebuild or timing job. I made my own threaded rod for the tensioner out of metric allthread and some coupling nuts (extra long nuts) but this shows the tools that make the job easier.
A picture is worth a 1000 words so here ya go!
Marty
thank you... now i get it. the two peg "preload eccentric pulley" would be very helpful since i use pliers for that and it is very awkward. i am especially impressed with the cam gear positioning tool. i will have to look for something like that here in canada. with all the shipping delays to canada, i would not get it until end of summer.

I am only guessing here, but in the pictures of the outside of the belt, it looks like a hot rubber tooth got onto the tensioner pulley and stuck, producing the gouges we see on the outside of the belt. I am left wondering if one of the rubber teeth that fell out when you pulled the cover would mate up to those gouges........:hmm::idontknow:
yes.. i am thinking that as well... and the mark on the bottom of the belt cover would support the theory that a piece of the broken off tooth got wedged b/w the cover and moving belt and then the loose tooth would vibrate/chatter and put those gouges into the belt.
 

1990TSIAWDTALON

Moderator
9,698
5,537
Nov 14, 2013
Independence, Kansas
Zip ties work very effectively. The handy item is that small 2 peg eccentric pulley tool and the tensioner compressor (the threaded rod). I got a piece of metric all thread at our local Fastenal store and welded a nut on the end and ground the other end to a rounded tip.
Cost = $5-8 dollars US and I made 5 of them out of that. You could do the same, I bet that in Canada, the all thread you find at a hardware store is metric to begin with.
 

pauleyman

DSM Wiseman
8,307
2,852
Nov 19, 2011
oklahoma city, Oklahoma
i dont follow^... the "tensioner" you referred to, is that the hydraulic tensioner? and what is the tool with 2 pegs on it? is there a pic on this forum? i am asking bc i am experiencing a serious counterclockwise force on the exhaust cam when i try to line up the timing marks. @pauleyman suggested i look into checking the condition of the sprocket dowels and holes... so i am searching up what that's all about bc it's the same issue i was faced with 18000km ago and then ended up with a partially shredded belt. except i did not know it was an issue back then. i have a serious feeling the counterclockwise force/torque was the primary reason why i am replacing the belt again and i dont wish to repeat the same thing this time and end up with the same problem as the last time.
The tension is both items but I was more thinking if the pulley as it is the component that takes up the slack...adds tension.
At this point I would back the crank away from the mark 90 degrees. The pistons are then in the middle and you can spin the cams as you see fit. I'm wondering if you're not aware just how much force a cam exerts. Spin the gears and find out. They will fight you then snap forward as you reach the other side of a cam lobe. They do not spin easily but it's not so difficult a wrench couldn't turn it with average force and no struggle.
 

sacrileger

Proven Member
288
40
Jun 26, 2016
Orillia, ON_Canada
The tension is both items but I was more thinking if the pulley as it is the component that takes up the slack...adds tension.
At this point I would back the crank away from the mark 90 degrees. The pistons are thrn in the middle and you can spin the cams as you see fit. I'm wondering if you're not aware just how much force a cam exerts. Spin the gears and find out. They will fight you then snap forward as you reach the other side of a cam lobe. They do not spin easily but it's not so difficult a wrench couldn't turn it with average force and no struggle.

i put a torque wrench on the exhaust cam gear and i get 21 ft lb push back in the counter clockwise direction if i want the valves timed correctly based on these recipes:



as you suggested earlier, i am researching your idea to check into 'the condition of the sprocket dowels and holes' ... i am not sure what that's about just yet but i think 21 ft.lb is excessive and i might end up with exactly the same problem if i dont address it now... what do you think? is 21ft lb pull too much for the belt b/w the cam gears?
 

pauleyman

DSM Wiseman
8,307
2,852
Nov 19, 2011
oklahoma city, Oklahoma
21 lbs is not excessive. Think how much spring pressure is on the cam lobes. I would spin each cam all the way around. I doubt you'll find anything as with that much motion I would suspect other problems. Remove, spin, and inspect all the pulleys. I concur with other poster any hot spots are not normal. Same for oil pump. Spin it a bunch and feel. Ignore your statement the pulleys were new. Check them anyway. Did you buy oem? Reputable known brand? Timken. NSK etc? Or a no name?
Given the backside belt damage it almost has to be that hotspot idler pulley
 

Dericsh

Supporting Member
1,463
694
Nov 25, 2002
Pearl River, Louisiana
thank you... now i get it. the two peg "preload eccentric pulley" would be very helpful since i use pliers for that and it is very awkward. i am especially impressed with the cam gear positioning tool. i will have to look for something like that here in canada. with all the shipping delays to canada, i would not get it until end of summer.
RTM is a Canadian company that is a contributing vendor on this site. It looks like they have the cam lock and the tensioner tool in stock, but not the bolt, which is really the least important I would guess, if you have access to a vise at least.

RTM timing tools page
 

sacrileger

Proven Member
288
40
Jun 26, 2016
Orillia, ON_Canada
RTM is a Canadian company that is a contributing vendor on this site. It looks like they have the cam lock and the tensioner tool in stock, but not the bolt, which is really the least important I would guess, if you have access to a vise at least.

RTM timing tools page
thank you... i'll check their inventory and shipping policy

21 lbs is not excessive. Think how much spring pressure is on the cam lobes. I would spin each cam all the way around. I doubt you'll find anything as with that much motion I would suspect other problems. Remove, spin, and inspect all the pulleys. I concur with other poster any hot spots are not normal. Same for pil pump. Spin it a bunch and feel. Ignore your statement the pulleys were new. Check them anyway. Did you buy oem? Reputable known brand? Timken. Nsk etc? Or a no name?
Given the backside belt damage it almost has to be that hotspot idler pulley
the two pulleys were made by GMB.
part no.
GMB E62/28RTN Double Row Ball Bearing

GMB TIMING BELT IDLER PULLEY # EGT602733RVN

i took the pulleys out... they spin freely and without any noise other than smooth hum of balls gliding in grease. when i spun the pulleys, they rotated without any change in speed and came to stop smoothly and gradually, i.e. they did not stop abruptly when slowing down at lower and lower speed. i did a visual inspection and the only thing i noticed is marked with two arrows = thin and wide shiny track around the circumference. i dont know if it means anything.

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just for clarity, the 21 ft lb is put on the belt teeth b/w the cam gears. if i ever so slightly push on the belt in the middle, even if i test a section of the belt w/ healthy teeth, the belt jumps and the exhaust cam goes back, counter clockwise, to its resting position. if that is fine and common, then the problem is elsewhere, perhaps the pulleys. i have two pairs of old pulleys and they are not as smooth as the new ones... it sounds like the grease packed inside the ball bearings partially dried out and now they make a slight grinding and rattling noise inside.

the belt was made in germany by CONTITECH. perhaps the belt was of low quality??
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sacrileger

Proven Member
288
40
Jun 26, 2016
Orillia, ON_Canada
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make sure you follow this method when doing the belt, check the tension.
just a quick comment re the vid^ you posted: the majority of guys, including the author of this vid, starts putting the timing belt over the camshaft sprockets. for some reason i have not been able to master this technique. i find it much easier for me to start from the bottom up.

this is the procedure and justification for why i prefer to start the belt installation on the bottom rather than at the top:
1/ the crankshaft has the least allowable play (0.002") so i find the TDC with a dial indicator (see pic) and secure the timing belt to the crank sprocket with clips. after that,..
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2/ i move to the oil pump sprocket and make sure the timing belt is taut which happens when i dont see more than 9 teeth on the timing belt:
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3/ then i pull the timing belt up passed guide pulley to intake cam and secure the belt with a clip and
4/ after that i put the belt over the exhaust cam gear, rotate the exhaust camshaft clockwise to line up timing marks while making sure i have 15 belt teeth b/w the cam sprockets and secure it with a clip:
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5/ then i drop to belt down passed the tensioner pulley. at this point i have all the slack in the belt b/w the exhaust camshaft sprocket and the crankshaft sprocket. this is the only way i can securely eliminate all play on the non-tensioner side.
6/ then i push the tensioner pulley by rotating it clockwise against the belt and i usually end up with the two pin holes on the tensioner pulley some place between 10 and 12 o'clock with 2 lb ft torque. the dude in the posted vid had the pin holes at 6 o'clock which would likely make the belt rub against the tensioner arm pivot or not being tight enough.
7/ after that i tighten the tensioner pulley
8/ and the last thing i do is adjust the hydraulic tensioner to 0.150" protrusion.

anyway, i am not sure what the advantage of starting at top rather than at the bottom is but the procedure i outlined above works for me quite well because that way i end up with all the slack on the belt on the tensioner side.
 

1990TSIAWDTALON

Moderator
9,698
5,537
Nov 14, 2013
Independence, Kansas
If you were to ziptie the belt to the gears when in alignment, they wont/cant jump.
 

Tigerinstincts

Proven Member
198
20
Mar 1, 2015
Sacramento, California
You're too focused on the torque between the cam sprockets. Use zip-ties around the 11 and 6 o'clock position for the exhaust cam to hold it in place, regardless of how difficult it seems. This effectively wraps the teeth of the belt around the gear and keeps it there. You can do the same to the intake sprocket if you'd like but I find it doesn't slip like the exhaust sprocket.

You seem to be forgetting that once your belt is on, you will be moving any tension or slack to where the auto-tensioner is. That is the whole point of turning the crankshaft 1/4 turn counter-clockwise, then clockwise til the timing marks align again, as seen in section C of the service manual.
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AWD-Tony

Supporting Member
6,802
3,690
Sep 11, 2017
Cincinnati, Ohio
I find it much easier to start from the exhaust cam. Zip tie it at the 10 o’clock position, get the belt onto the intake cam. Make sure the marks line up even with the top of the head, then zip tie at 2 o’clock position. Having the cam lock tool makes this part easier. Then over the oil pump and crank. If it’s loose, rotate the crank 1 tooth counter clockwise (possibly the oil pump sprocket as well). You always want the slack on the tensioner side.
 

1990TSIAWDTALON

Moderator
9,698
5,537
Nov 14, 2013
Independence, Kansas
You can browse this for a little different method but what the guys are saying here is all on the up and up. I have just found, (after many rebuilds) a way that seemed easier for me in THIS thread.
Marty
 

Dericsh

Supporting Member
1,463
694
Nov 25, 2002
Pearl River, Louisiana
I have a thought to run by everyone,

the hydraulic tensioners make a divet at the contact point with the tensioner arm, I assume will affect protrusion measurements?

I would think anything coming from the service manual might be assuming that you’re starting from a nice new flat tensioner arm surface, not one that’s diveted or used and been ground flat.

This could be why you’re finding yourself putting excess force on the belt with the pulley while trying to meet a certain measurement of protrusion instead of the pin alignment method, possibly?
 

pauleyman

DSM Wiseman
8,307
2,852
Nov 19, 2011
oklahoma city, Oklahoma
I have a thought to run by everyone,

the hydraulic tensioners make a divet at the contact point with the tensioner arm, I assume will affect protrusion measurements?

I would think anything coming from the service manual might be assuming that you’re starting from a nice new flat tensioner arm surface, not one that’s diveted or used and been ground flat.

This could be why you’re finding yourself putting excess force on the belt with the pulley while trying to meet a certain measurement of protrusion instead of the pin alignment method, possibly?
Yes. This has been discussed before and I agree yes it should be ground flat. Others have even filled the hole and ground it flat again but I never saw the need. All a little material removal would do it make it necessary to rotate the eccentric just a smidge more in order to get it right.
 

sacrileger

Proven Member
288
40
Jun 26, 2016
Orillia, ON_Canada
I have a thought to run by everyone,

the hydraulic tensioners make a divet at the contact point with the tensioner arm, I assume will affect protrusion measurements?

I would think anything coming from the service manual might be assuming that you’re starting from a nice new flat tensioner arm surface, not one that’s diveted or used and been ground flat.

This could be why you’re finding yourself putting excess force on the belt with the pulley while trying to meet a certain measurement of protrusion instead of the pin alignment method, possibly?
now that i have the belt cover off, i have been experimenting with the relationship between the pin hole alignment and how far the tensioner pulley is rotated clockwise.

i jammed a 5/32" drill bit b/w the hydraulic body tensioner and the tensioner arm, rotated the tensioner pulley clockwise and positioned the two pinholes on the tensioner pulley into 12 o'clock position, pulled the grenade pin out and the shaft retracted into the hydraulic body tensioner so that instead of 5/32" gap i ended up with 0.071" gap. incidentally, this gap, at least on my setup, corresponds to a near alignment with the two holes into which the grenade pin fits. i am using a finishing nail as my grenade pin and i can almost slide it back,.. not quite though, just the sharp tip.

i discussed this type of alignment with @1990TSIAWDTALON at the thread he provided above and we agreed that for as long as the tensioner is engaged and the shaft is not at or close to the end of its travel, it should be fine... especially for my non-turbo setup. so it would appear that there is an equilibrium between the hydraulic force and the tension on the belt and for as long
as the tensioner is engaged and in the vicinity of the hole alignment, it should be fine for most applications.
 

sacrileger

Proven Member
288
40
Jun 26, 2016
Orillia, ON_Canada
You're too focused on the torque between the cam sprockets. Use zip-ties around the 11 and 6 o'clock position for the exhaust cam to hold it in place, regardless of how difficult it seems. This effectively wraps the teeth of the belt around the gear and keeps it there. You can do the same to the intake sprocket if you'd like but I find it doesn't slip like the exhaust sprocket.

You seem to be forgetting that once your belt is on, you will be moving any tension or slack to where the auto-tensioner is. That is the whole point of turning the crankshaft 1/4 turn counter-clockwise, then clockwise til the timing marks align again, as seen in section C of the service manual.
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the reason why i have been obsessing over the torque b/w the cam sprockets is that i have run out of ideas as to what caused the damage to the belt. i am dealing with some serious drag on the belt and the crankshaft sprocket is pulling really hard on the belt to move all the moving parts above it. while only six belt teeth were ripped out, every tooth on the belt, every.single.tooth, was about to be cut off. using clock analogy, the cuts are on the AM side, it's the side with the most stress on it given the crankshaft rotates in the clockwise direction. the exhaust sprocket puts the pressure also on the AM side of the teeth... see pic below.. every.single.tooth looks that way:

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1990TSIAWDTALON

Moderator
9,698
5,537
Nov 14, 2013
Independence, Kansas
Did you install the belt or can you confirm its manufacturer or did you get the car this way. It almost looks like its just a shitty belt if the teeth are ripping off and dam glad you found it NOW. Good catch.
 

Dericsh

Supporting Member
1,463
694
Nov 25, 2002
Pearl River, Louisiana
Did you install the belt or can you confirm its manufacturer or did you get the car this way. It almost looks like its just a shitty belt if the teeth are ripping off and dam glad you found it NOW. Good catch.
I think he said earlier it’s CONTITECH. I looked it up and they are a oem supplier for some german manufacturers.
 

Tigerinstincts

Proven Member
198
20
Mar 1, 2015
Sacramento, California
the reason why i have been obsessing over the torque b/w the cam sprockets is that i have run out of ideas as to what caused the damage to the belt. i am dealing with some serious drag on the belt and the crankshaft sprocket is pulling really hard on the belt to move all the moving parts above it. while only six belt teeth were ripped out, every tooth on the belt, every.single.tooth, was about to be cut off. using clock analogy, the cuts are on the AM side, it's the side with the most stress on it given the crankshaft rotates in the clockwise direction. the exhaust sprocket puts the pressure also on the AM side of the teeth... see pic below.. every.single.tooth looks that way:
Hmm interesting. Is it possible you have the incorrect timing components for your N/T? Idk if any of the sprockets are interchangeable between turbo and N/T ( I assumed they were), but maybe you received parts for the wrong year DSM?

If this turns out to be just a belt issue, I'll have to rethink keeping my Contitech belt as a spare...
 
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