Timing Belt Inspection

[Ski in NC]

Hi all. A friend has a 2010 JSW with CR TDI, it has about 100k miles on it. She knows she needs to get the TB done soon, but has to take a couple long-ish trips before she can get it done.

I'm a long time ALH owner, and I do my timing belts usually at 110k each. Towards the tail end of it's interval, and before a trip, I pop the cover off and check tension, tensioner tabs and watch the belt run a bit and make sure it all looks ok.

I looked at her engine, and it seems to have similar snaps holding the cover over the belt. I had no tools and was in a parking lot, so I did not want to mess with it then.

Is it easy to pop this cover off for a look like it is on an ALH? She's freaking a bit about going on these trips with old belt, and it would ease her mind some if I looked at it and it appeared ok.

If it is easy, I'll get her to come to my shop for a look-see.

Tks..

 

[BleachedBora]

A timing belt inspection is like inspecting a light bulb to see when it's going to go...
It's fine until it isn't...

That said she's almost certainly fine. The interval on CR's is 120k. We recommend 100k as its a easy to remember number and because the PD's started at 100k and later were lowered to 80k; we might see something similar with the common rails.

Regardless a couple more thousand miles will be fine.

-BB

 

[Ski in NC]

Thanks. I'll pass that on.

I know the insp is not going to tell 100%, but if something is amiss, that would be good to pick up early.

Is the plastic cover a PITA to pull off?

 

[meerschm]

you can look.

I think you can unhook part of the cover, but to get it off, you need to unplug and lift out the intermediate fuel pump to get enough room to pull the top of the cover off.

http://pics.tdiclub.com/data/500/CR_Timing_belt_procedure_Rev2.pdf

will give you some idea.

the interval is 120k, and a couple years later, they raised it to 130k.

so I would advise just keeping an eye on it.

you are more likely to get something misplaced or misaligned trying to see something in the timing belt area than you would be likely to see any issues

you should, however, give a close look at the accessory belt, while the engine is running, to verify that the accessory belt tensioneer is not bouncing around from a locked up alternator pulley.

you can look at it when stopped also.

all the covers and such under the engine should be in place as well.

a few folks have had the accessory belt shred and take out the timing belt.

 

[Ski in NC]

Thanks. I'll not bother with the cover. And let her know 120k.

 

[CNGVW]

I to tell my customer at 100k start to think hard on it.

It is funny how the same product timing belts system can grow in a longer life span!!

VW and Audi can grow the number from 80K to 100K -120K it is more to do with lowing the cost of ownership . Most are out of warranty so it dos not hurt them!

 

[turbobrick240]

I to tell my customer at 100k start to think hard on it.

It is funny how the same product timing belts system can grow in a longer life span!!

VW and Audi can grow the number from 80K to 100K -120K it is more to do with lowing the cost of ownership . Most are out of warranty so it dos not hurt them!

It's called engineering. Sort of like how engines once needed full rebuilds before 100k miles. Things change as designs improve.

 

[meerschm]

I to tell my customer at 100k start to think hard on it.

It is funny how the same product timing belts system can grow in a longer life span!!

VW and Audi can grow the number from 80K to 100K -120K it is more to do with lowing the cost of ownership . Most are out of warranty so it dos not hurt them!

it is not the same product at all.

does the same function, but the parts, stresses, and materials are different.

 

[ksing44]

ha, ha, ha, timing belt inspection! Everyone, and I mean everyone, says there is now way to tell by inspection. That is unless it's obviously messed up which it never is unless it just failed.

I'm a dumb noob and I already know that!

Funny too about people going by old specs. That's like changing your synthetic oil at 3K miles like the good old days, so stupid. The new oils last a very long time, much longer than the recommended intervals. It's proven by science and actual diagnostic analysis. This isn't like praying.

 

[Ol'Rattler]

ha, ha, ha, timing belt inspection! Everyone, and I mean everyone, says there is now way to tell by inspection. That is unless it's obviously messed up which it never is unless it just failed.

I'm a dumb noob and I already know that!

Funny too about people going by old specs. That's like changing your synthetic oil at 3K miles like the good old days, so stupid. The new oils last a very long time, much longer than the recommended intervals. It's proven by science and actual diagnostic analysis. This isn't like praying.

Your first paragraph is correct, your second paragraph is a little confusing.

For the BRM, the original spec was 100K miles which VW later changed to 80K miles. Same exact T/B. I changed my T/B at 88K miles.

There still are folks around the swear by the 3K mile OCI. There was this guy that argued and argued that 3K miles was "cheap insurance"and no one could convince him otherwise.

 

[nord]

I believe the stated belt intervals err on the safe side by a considerable margin. This isn't to say that there are no early failures but rather to say that 120k miles is a good baseline. Change the belt somewhere around that mark. Have a reputable tech do the job and drive on.

As to a physical check of the belt, I won't say you can't. The problem, though, is usually a catastrophic failure rather than a failure over time. Timing belts don't fail the same way as does a serpentine. Often a belt that suddenly has two ends or one with missing teeth.

 

[oilhammer]

I never ever look at a belt until it is being replaced at the specified interval.

And truthfully, 120k miles is probably conservative for these, but I still recommend doing them then by the book. Although I've seen some at 180k miles still working fine.

 

[CNGVW]

When it comes to timing belts Some weeks I have done as many as 7 jobs most being TDI . So I have been keeping a eye on where that old adjuster is . IS it still tight or is it so far back that the adjust is just a roller in the system at this point!
On VW engine 4 cyl engine every thing is very close to the same position and the cam,crank, water pump are the same size and location. On a CR engine 2009+ you have the HPF in the mix and a very tight roller next to it. And the belt is wider.
What makes a belt fail over time is the torque to rotate the head components, the fuel pump load, the water pump load small but is there. How tight of a reverse bend on the back side rollers. Ad how well the adjuster works then temp big player here.
Then engine speed and torque and what the belt is made of there is more to.
So when I see CR engine at 100K with the adjuster all the way backed off so it is just a roller now I feel it is time to get ready to change the complete Timing belt package.
I have not had one come in broken on a CR I think it is best to play it safe.
If you wish to do a inspection you should take note where is the adjuster?

 

[oilhammer]

The adjuster position is only relevant if you have the engine block/head assembly at the exact same temp when comparing. Because it moves from thermal expansion.

That is why you never want to tension a new belt if the engine is at either extremes of temp. The thermal expansion of the block and head from bitter cold to operating temp will cause the cam and crank to be further apart, and thus the indicator will move a cm or so.

Out of the service manual, verbatim:

"Requirements

¤ Ignition is turned off.
¤ Engine must be cold.
¤ Adjustments to the toothed belt may generally only be performed when the engine is cold, because the indicator position of the tensioning element changes depending on engine temperature.
¤ The engine mount bracket must be removed to remove/install the belt tensioner. Refer to => [ Engine Mount and Bracket ] See: Engine Mount\Service and Repair\Engine Mount and Bracket."

 

[gmcjetpilot]

Hi all. A friend has a 2010 JSW with CR TDI, it has about 100k miles on it.
If it is easy, I'll get her to come to my shop for a look-see.Tks..

HAVE A GOOD LOOK AT THE SERPENTINE BELT. People have had those fail
at 60K to 80K.... they have a bad habit of jamming up the timing belt
which is bad.. You might say no chance the timing belt is covered by
plastic. Well this is a real crappy design; the crank shaft that drives both
the timing belt and serpentine belt have a LARGE GAP OPENING which
easily lets the serpentine belt migrate into the timing belt and foul it.
Timing can then shift and valve piston contact is likely. I would have a
good look at it.

 

[Ol'Rattler]

The adjuster position is only relevant if you have the engine block/head assembly at the exact same temp when comparing. Because it moves from thermal expansion.

That is why you never want to tension a new belt if the engine is at either extremes of temp. The thermal expansion of the block and head from bitter cold to operating temp will cause the cam and crank to be further apart, and thus the indicator will move a cm or so.

Out of the service manual, verbatim:

"Requirements

¤ Ignition is turned off.
¤ Engine must be cold.
¤ Adjustments to the toothed belt may generally only be performed when the engine is cold, because the indicator position of the tensioning element changes depending on engine temperature.
¤ The engine mount bracket must be removed to remove/install the belt tensioner. Refer to => [ Engine Mount and Bracket ] See: Engine Mount\Service and Repair\Engine Mount and Bracket."

Couldn't agree more. Your posts, as usual are ALWAYS spot on........

Also, I would add that you need to turn the engine some in the direction of rotation with a socket on the crank before you check tension. What that does is makes sure that the belt's slack is on the tensioner side of the belt.

What it boils down to is you are tensioning essentially a rubber band and for the indication to be valid you have to use a very specific procedure.

 

[CNGVW]

I see what you are saying about the install and adjustment of a belt.
My post is that I have been tracking how far the adjuster has undone its self over time!! Due to the belt wearing /stretching at a 100K they have been backed off to a point of being just a roller in the package. These are for the most part are cold engines.

The adjuster position is only relevant if you have the engine block/head assembly at the exact same temp when comparing. Because it moves from thermal expansion.
That is why you never want to tension a new belt if the engine is at either extremes of temp. The thermal expansion of the block and head from bitter cold to operating temp will cause the cam and crank to be further apart, and thus the indicator will move a cm or so.
Out of the service manual, verbatim:
"Requirements
¤ Ignition is turned off.
¤ Engine must be cold.
¤ Adjustments to the toothed belt may generally only be performed when the engine is cold, because the indicator position of the tensioning element changes depending on engine temperature.
¤ The engine mount bracket must be removed to remove/install the belt tensioner. Refer to => [ Engine Mount and Bracket ] See: Engine Mount\Service and Repair\Engine Mount and Bracket."

 

[Ol'Rattler]

I see what you are saying about the install and adjustment of a belt.
My post is that I have been tracking how far the adjuster has undone its self over time!! Due to the belt wearing /stretching at a 100K they have been backed off to a point of being just a roller in the package. These are for the most part are cold engines.

Huh? What exactly are you talking about? Your post makes absolutely no sense.

 

[scdevon]

Huh? What exactly are you talking about? Your post makes absolutely no sense.

He was trying to say that as the timing belt wears, the tensioner "runs out" of movement all the way to its maximum range and no longer applies tension to the belt to the degree that it should. At that point, he was comparing the tensioner pulley to more of an idler pulley rather than the tensioner pulley that it once was when it had a meaningful range of motion under spring tension.

 

[oilhammer]

That never happens. The belts do not "stretch out" like that. If they did, they'd all fall off in short order, and the teeth would get torn up.

You can lay a used belt and a new belt side by side, and they will be the exact same length. If you get an old belt that you can still read the label on, you'll see that is the exact same too. It is not stretched out or anything.

There is a small amount of material on the toothed side that does, slowly over time, wear slightly away. So this could give the impression of belt stretching, but that is not exactly what is happening.

Chains DO stretch, although technically that is not the best description, as it implies elasticity. And that is not what is happening. With chains, all the individual joints (link pins and the holes in the links they go through) wear larger, and more into an oval shape. And THAT does indeed lengthen the chain.

This is why chains in OHC engines need oil pressure fed tensioners and guides to keep them all from flopping loose.

 

[CNGVW]

I am just telling you what I have been tracking. The adjuster is backing off a lot.
So it is stretching or it is wearing into the teeth.
And for inspection of the belt over time there is a lot more down there then just the belt.
case 2013 Passat with 78K on it, some one looked under the cover to find it wet!!
The wife had been driving it and did add antifreeze and did not think any thing of it and told no one.
We found the belly pan full of it and dripping out of the water pump and the pump was wobble and the adjust was backed up a lot. So inspection saved the car owner a big headache .
below is a write up on this site??
https://www.tdiclub.com/articles/A3-TimingBelt/
The finished product! I have found that after around 25,000 miles the timing needs to be checked again due to belt stretch. You will notice an increase in performance with a noticeable increase in smoke output and lower mileage around this time. Most people attribute this to the engine "breaking in" it's actually the belt stretching from normal wear.
In another post I'll put together a pictorial on setting the injection timing.
Thanks to drivbiwire for the writeup and pictures.

 

[scdevon]

Chains DO stretch

No they don't, but you covered that in the rest of your post about chain link wear adding up over the length of the chain making it APPEAR that the chain has
stretched. Metal used in chains doesn't stretch under the normal force of driving an overhead cam, but you're a service tech like me and I know you know the difference.
The inside diameter of a timing belt definitely does wear over time though and just because you can lay a new timing along side of a used timing belt and they are the same length on the outside diameter doesn't mean that the inside diameter isn't worn. An 1/8 of an inch of inside diameter wear on a timing belt is a lot when considering the useful range of a timing belt tensioner. Timing belts are fiberglass reinforced rubber and I agree that they don't stretch any significant amount at all as far as outside diameter is concerned.

 

[CNGVW]

I think we can relay on this from Jason

They are looking a bit wasted by 120K miles. I'd not go to 130K miles. The base of the teeth are usually starting to separate. I've done about 200 CR belts so far and they all needed it.
__________________
Jason, Service work available. www.jasonTDR.com
Give a hand,www.akitas.org

 

[turbobrick240]

I don't think I've heard of a single CR timing belt failure under 130k miles.

 

[meerschm]

has anyone heard of any CR timing belt failure? (except the couple done in by a shredded accessory belt)

 

[scdevon]

has anyone heard of any CR timing belt failure? (except the couple done in by a shredded accessory belt)

I haven't heard of them routinely failing prior to the recommended replacement interval. Generally speaking, stop and go driving is harder on them than steady highway cruising. Generally speaking, manual transmission "up and down rpm shifitng" is harder on belts than the more stable shifting of automatic transmissions.
The accessory belt failing and getting under the timing belt cover causing the timing belt to fail is a bit disturbing, though. This was a sloppy design oversight on VW's part.

 

[A5INKY]

I never ever look at a belt until it is being replaced at the specified interval.
And truthfully, 120k miles is probably conservative for these, but I still recommend doing them then by the book. Although I've seen some at 180k miles still working fine.

X2

I've had CRs come in with as many as 171K on the original belt and have yet to see a CR TB failure. I don't recommend going past 120K, but VWs interval is just fine on them.