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Engine Specific Info and Questions => TDI - VE Pump TDI Engines => Topic started by: Ibuprofen on December 24, 2018, 02:22:32 am

Title: Eating timing belts
Post by: Ibuprofen on December 24, 2018, 02:22:32 am
I have had one timing belt partially fail once already, though the belt didn't fully separate it did prevent the engine from starting. After retiming with a new belt and tensioner it fired up without issue. I've been keeping an eye on the new belt and it appears that it is also destined for the same fate. Attached is a photo of the current belt at the IP sprocket with around 1500 miles on it. This is a 50 degree mTDI in a Vanagon.

(https://i.imgur.com/IOq18E7.jpg)

I will pull the aux belt and covers and get a closer look at things but I wanted to get any opinions of folks that may have seen this before as I've not been able to find any obvious reason why the belt is trying to depart. My van has quite the arse sag and the engine tilts that way somewhat, but there are a lot of saggy Vanagons out there.


Any thoughts on why the belt wants to head away from the engine? Thanks
Title: Re: Eating timing belts
Post by: ORCoaster on December 24, 2018, 07:40:28 pm
Wow, way too much wear for 1500 miles unless it is on way too tight or rubbing on something.  I have seen less wear on some with ten times that mileage on them. Something is not right in Denmark.

Pulley alignment is generally the culprit for belts walking away from the intended direction.  Check the IP bracket bolts to see if they are good and tight under the IP.  Or just see if you can get the bracket to wiggle some with a long screwdriver between the engine block and the bracket.  I know it is a pain to get under and work on it but that might keep you from having to pull the IP just to see they bolts are indeed tight as need be.

Title: Re: Eating timing belts
Post by: libbydiesel on December 26, 2018, 12:54:11 am
That looks terrible.  How tight is the belt?  You can clearly see the tooth impressions in the belt which makes me think it is waaayyy too tight. 
Title: Re: Eating timing belts
Post by: Ibuprofen on December 28, 2018, 03:34:29 am
What makes this even more confusing for me is that I swapped the injection pump, ip sprocket, ip mounting bracket, and new tensioner when this new belt went on in replacement of the shredding belt. When I look at the belt with the engine running, the alignment seems fine to me.

The tensioner tightness is simply lining up the nub with the slot, yeah?
There isn't anything behind the tensioner aside from the metal tin? Tensioner -> Tin -> Engine

I will give it another hard look and probably take a video. The TDI has nice torque over the stock engine but leaving the belt behind is pretty extreme. :P
Title: Re: Eating timing belts
Post by: smutts on January 01, 2019, 02:10:14 pm
You will likely get a "whirring" sound with an over tight cambelt. They won't last long overtight, nor will the bush bearing in the injection pump. The teeth of the belt look to be shredding too, also likely to be overtight.

There are some crap tensioners out there, usually in a "GENUINE!" Gates, Dayco, or whatever timing kit box, slathered in Sellotape, filled with assorted no name ***e, bought on Fleabay. (Library image of course ::))

I've been screwed twice this way. ::)
Title: Re: Eating timing belts
Post by: Ibuprofen on January 03, 2019, 09:21:39 pm
Hrmf, bummer that there are bad tensioners out there. I got mine from IDParts. At ~$50 I'm not thrilled to swap it out again but beats a ruined engine.

Here's a short slow motion of the belts, it looks like it starts to move on the intermediate pulley. Cam and IP pulleys look okay to me.

https://www.youtube.com/watch?v=vwyr3ra-aAw (ignore the busted exhaust mount...)

cam: https://www.youtube.com/watch?v=nFMLdCpYs1g
IP: https://www.youtube.com/watch?v=WV__fjJ9K5I
Title: Re: Eating timing belts
Post by: libbydiesel on January 04, 2019, 01:34:49 am
Is the initial picture in this thread where the belt normally runs on the injection pump?
Title: Re: Eating timing belts
Post by: Ibuprofen on January 04, 2019, 04:33:35 am
Yup. There is a short video of the IP in my last post as well if you didn't see it.
Title: Re: Eating timing belts
Post by: libbydiesel on January 04, 2019, 07:28:53 pm
I missed the cam and injection pump videos.  I have never seen a belt get worn on the side like that unless it was walking off the injection pump.  What is the dust that is on the backing plate by the injection pump sprocket?  The tracking all looks fine.  Any chance one of the outer covers  or any other part is touching the timing belt when those parts are installed?   
Title: Re: Eating timing belts
Post by: ORCoaster on January 04, 2019, 08:16:54 pm
I watched the vids and I think I would be checking the belt tensioner bolt.  As the belt comes up from the crank it appears to rub on the tensioner and that is what we see as wear on the front of the IP.  I also hate to say it but you might need to check the crank pulley as well. 

A little wobble might be doing the belt in. 

First check the bolt in the block on the tensioner.  It may just be a tad loose. 
Title: Re: Eating timing belts
Post by: libbydiesel on January 05, 2019, 01:17:07 am
Have you removed the crank pulley and the lower cover and looked for any potential causes there?
Title: Re: Eating timing belts
Post by: Ibuprofen on January 05, 2019, 12:09:22 pm
Libby, the dust is belt material and I don't see anything obviously rubbing except for the tensioner.

I'll take a closer look at the tensioner bolt and lower pulleys. Here are a couple of pictures above the IP, I'm wondering if the sprocket I used sits too far from the IP bracket? It was cheaper for me to get a brand new sprocket than it was to find an ALH sprocket and get it machined, but I'm wondering if maybe I need a different sprocket. If someone with that setup, a machined ALH sprocket and land rover pump, doesn't mind eyeballing theirs for the bracket offset next time it's convenient I would very much appreciate it.

My engine:

(https://i.imgur.com/O8I0I3k.jpg)

(https://i.imgur.com/NlemSAi.jpg)


Image I found via google of someone else's ALH sprocket setup:

(https://i.imgur.com/1HNxYVs.jpg)


Thanks!
Title: Re: Eating timing belts
Post by: libbydiesel on January 05, 2019, 08:54:56 pm
That does look like an excessive gap between the injection pump sprocket and the pump bracket.  I hadn't noticed the offset before.  If that sprocket is out overly far, then the belt tracking as it does would be too far out and the mystery is solved.  What injection pump sprocket/hub setup are you using? 

Here is a very easy way to determine if the tracking is OK.  Remove the lower crank pulley and lower timing cover, leaving the crank sprocket and timing belt in place.  Rotate the crankshaft through a dozen revolutions or so by hand while looking at the belt tracking on the crank sprocket.  If it wanders to the outer edge or beyond the outer edge of the crank sprocket, the belt is tracking too far out and you will need to make adjustments. 
Title: Re: Eating timing belts
Post by: Ibuprofen on January 06, 2019, 02:12:59 am
I would love to know how many mm/inches it is from somewhere on the pump (interface with pump mount) to the edge of the ALH sprocket, then I can know if I'm way out or not.

The sprocket I'm using is 028130111F https://www.ecstuning.com/b-genuine-volkswagen-audi-parts/pulley/028130111f/, the hub is the stock one from the land rover pump.

Title: Re: Eating timing belts
Post by: libbydiesel on January 06, 2019, 06:27:44 pm
Hmmm, stock LR hub spaces the sprocket out farther than the VW ALH hub.  I believe that sprocket you have is the late AAZ sprocket and I would be amazed to find out that fitted to the LR hub arrived at the correct offset.  I have not used that sprocket, though, so I can't really say.  The distance from inner edge of the sprocket to face of injection pump (not bracket) is 13-14mm.  If the inner edge of the sprocket is farther than 14mm from the mounting edge of the injection pump then you have found your issue.
Title: Re: Eating timing belts
Post by: Ibuprofen on January 06, 2019, 09:00:36 pm
Thanks for measuring that, I'm getting 16-17mm:

(https://i.imgur.com/OZ53BnC.jpg)


Looks like it's time to track down the ALH hub/sprocket. Thanks.
Title: Re: Eating timing belts
Post by: libbydiesel on January 07, 2019, 12:36:37 am
That also means that you will need to adjust the belt tracking by rotating the injection pump mounting bracket.  You will need to rotate the sprocket side of the pump DOWN and the delivery valve side of the pump UP.  Pump will need to be removed to do that.

I want to reiterate what I said earlier.  The belt should *NOT* rub on the back of the crank pulley.  The best test for that, IMO, is to remove the crank pulley and lower timing cover and then run the crank through a bunch of revolutions by hand to see if the belt tracks off the front of the crank sprocket at all.  If it does, you need to adjust the injection pump bracket in order to get it to track closer to the engine. 
Title: Re: Eating timing belts
Post by: Ibuprofen on January 07, 2019, 02:27:27 am
I think I am understanding correctly, the idea being to change the angle of the IP sprocket so the lower half points more towards the engine, which should help correct the belt position on the intermediate shaft pulley?

I am already trying to track down the ALH hub and sprocket assuming that is the better long term solution. I still haven't pulled off the lower cover as it's been typically rainy here in the PNW but will do so soon. When you say crank pulley, you are referring to the harmonic balancer?


Thanks
Title: Re: Eating timing belts
Post by: libbydiesel on January 07, 2019, 11:34:33 am
Yes, when I say crank pulley I am referring to the harmonic balancer.  The belt should not be riding up against the back of it.  It is very common that it does due to bad belt tracking. 

The injection pump bracket has some play between the three mounting bolts and the holes they go through in the bracket.  Sprocket side DOWN injection line side UP makes the belt track closer to the engine.  If you don't have enough play in the bracket holes to get the belt to track so it doesn't rub on the back of the crank pulley, then you will need to enlarge those holes in the pump bracket so you can adjust the tracking further. 
Title: Re: Eating timing belts
Post by: Ibuprofen on January 16, 2019, 04:02:50 am
Are you referring to the holes at the IP/bracket interface or the bracket/block interface? Sounds like the IP/bracket interface.

I bought an ALH IP sprocket and compared with the current one I have, they're nearly identical spacing from the edge of the injection pump. The ALH sprocket is maybe half a mm closer to the pump, not much at all. The IP hub was ALH the whole time, forgot that I'd already swapped that on there and compared with a spare I have it appears to be the same size/width/etc.

I am thinking I can either:

1. Slot the holes in the bottom of the injection pump bracket such that it can slide further towards the flywheel side of the engine, concern being the bracket won't stay-put long term.
2. Add some sort of spacer(s)/washers between the injection pump body and the injection pump bracket, concern being this is too janky or not enough surface area connecting the two components. Writing this I recall having a sheet of stainless that I should measure the thickness of.
3. Machine the IP hub so it's thinner.

I am not too keen on setting anything at an unnatural angle by shimming one side of it.

Eyeballing the injection pump with everything mounted, regardless of sprocket, it really does seem like the whole assembly is too far to the pulley side of the engine, strange.
Title: Re: Eating timing belts
Post by: libbydiesel on January 16, 2019, 12:35:40 pm
Are you referring to the holes at the IP/bracket interface
No.

 
Quote
or the bracket/block interface?
Yes. 
Quote
Sounds like the IP/bracket interface.
  Nope.

Quote
I am thinking I can either:

1. Slot the holes in the bottom of the injection pump bracket such that it can slide further towards the flywheel side of the engine, concern being the bracket won't stay-put long term.
No, no, no...  Reread my posts.  You do *not* want the bracket to move toward the flywheel.  That will only change where the belt rides on the IP sprocket which is not the source of the belt wear.  You need the belt to track toward the engine at the CRANKSHAFT.  You need to ROTATE the bracket relative to the mounting surface of the block.  The sprocket side needs to go DOWN and the injection line side of the pump needs to move UP.  I'm not sure how to make that more clear. 

Quote
2. Add some sort of spacer(s)/washers between the injection pump body and the injection pump bracket, concern being this is too janky or not enough surface area connecting the two components. Writing this I recall having a sheet of stainless that I should measure the thickness of.
Nope.  Again that might could change the position of the belt on the IP sprocket but do nothing to address the actual issue that is chewing up the belt.

Quote
3. Machine the IP hub so it's thinner.
Same thing.  It won't help prevent the actual issue.

To be clear VW actually released a service bulletin specifically stating the procedure I have outlined for adjusting belt tracking.  Bad belt tracking so the belt rides off the front of the crankshaft and wears against the crank  pulley is a COMMON and well-known problem, and the cure is also well-known.  The belt tracking needs to be adjusted as I've outlined EVERY TIME the injection pump bracket is removed from the block or any time the tracking is off. 
Title: Re: Eating timing belts
Post by: Ibuprofen on January 16, 2019, 01:37:40 pm
This is apparently the bulletin: https://workshop-manuals.com/volkswagen/jetta/l4-1.9l_dsl_turbo_%28aaz%29/engine_cooling_and_exhaust/engine/drive_belts_mounts_brackets_and_accessories/ribbed_belt_-_drive_belt/component_information/technical_service_bulletins/all_technical_service_bulletins_for_ribbed_belt/1597-01/jun/97/mfi_pump_drive_belt_runs_towards_outside_wears_jumps/

I find it hard to believe simply pushing on one side of the bracket (no shims) and torquing the bolts is enough but I'll give it a go.


(https://i.imgur.com/FjPCOsi.png)
Title: Re: Eating timing belts
Post by: libbydiesel on January 16, 2019, 02:37:11 pm
You push DOWN on A and lift UP on B to get the belt to track closer to the engine.  I've adjusted belt tracking in this manner on ~10 1.6, 1.6TD, 1.9TD and 1.9TDI engines.  It certainly works.  It's a little bit weird, to have described exactly how to adjust the tracking multiple times and to have you come back and proclaim your disbelief that the adjustment in the manner described can work.  Great, use shims if you want.  I'm done. 
Title: Re: Eating timing belts
Post by: Ibuprofen on January 16, 2019, 02:56:04 pm
Yeah, I get it. I think my confusion was due to looking at the engine at 50 degrees, down and up being relative terms.

Thanks for the help.