Timing belt replacement interval

NoSmoke

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The topic of when the timing belt and associated hardware should be replaced, over and above the recommended mileage limit, has arisen here from time to time. My particular case might prove to be instructive for those maybe wishing to push their luck a bit i.e.drive over the limit and hope nothing breaks.

My 02 Golf has around 475,000 kms and is getting a bit on the tattered side although it still runs well. My timing belt came due about a year ago and, since I was going to replace the car with an electric vehicle in the not too distant future, I decided to forego spending the about $1K it would cost to have the belt replaced and hope nothing happened until I sold the car. As it turned out, the elect vehicle I was planning on, the VW ID3, will apparently not be available in North America for while, if at all, so I decided to keep the 02 another few years or so and spring for the belt replacement.

At that point I was about 30,000 Km over the recommended limit. I just had it done and asked the mechanic to keep the old parts as I was very curious as to what kind of shape they would be in. My observations are a bit subjective as I have no real basis of comparison except for the new parts.

Anyhow, what I found was that the belt itself appeared pristine with no signs of wear or cracking at all. The tensioner, large roller and one of the small rollers all appeared to be fine with no discernable rotation roughness, shaft play or friction.

One of the small rollers however had discernable shaft play (or wobble). Not a whole lot but enough to be felt when the shaft was wiggled. The water pump shaft had no wobble or roughness but more rotational friction than the new pump.

I don't really know how all that shakes out as to whether or not the overhaul was required at the time I did it but the wobble in the small roller and tightness in the water pump kinda makes me feel it was past its time(??).

I also suppose that when I sell the car a couple or so years from now, the new belt will increase the resale value somewhat and I won't have to worry about the thing cratering (at least from a broken belt mechanism) so I guess it's all good in the end. :) YMMV.
 

Mongler98

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Because its VW. And parts are hit and miss. Plenty of cases where just sitting for 5 years leads to total destruction.
Also 1 grand for a 125$ kit? You need to find a better mechanic. It's a 4 hour job just for the belt by the book. So 500 in labor really.
I can change these belts in about 45 minutes. If you do all the work yea it's a full day to diy.

Most belts go a long time if they remain dry from oil. It's a gamble. There are by far more cars that make it well into 4x the service limit but then again there are plenty of cases where it's been a major issue
 

Carlos_TJ

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Since:
A) the timing belt components cannot be inspected while installed on the car( belt roller tensioner water pump)
B) the failure of ANY timing belt component may yield to engine failure and a possible safety hazzard (dead engine without warning at 80mph?)

Vw gathered data for the mean time between failures for each component and set the replacement interval of the failure of the weakest component with generous margin. This is for legal liability issues etc.

So you should see your used components in good shape as they did its job

Remember the goal is to replace them while they are good not when they fail because that is a more complex expensive job...if you follow vag service interval you are almost guaranteed to avoid tb failure as long as you use reputable parts and follow the service procedure as designed by the manufacturer.

Of course there are parts that have their quality issues (like seizing water pumps?) But those should be the exception not the rule..
 

NoSmoke

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Location
Calgary, Alberta
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2K2 Golf
Thanks all for your comments. Whether or not the timing stuff needed changing, it's been a few days now and the car runs exactly as before so so far so good.

I was a bit miffed though to see paint marks on the old belt which indicate the mechanic (a small indy who has a good rep) used M&P instead of the factory prescribed procedure. So, looked up an old thread about M&P (mark & pray) and, after thinking about it a bit, have concluded that if M&P is done carefully, the resultant timing with the new belt will be the same as it was with the old when it was new and is therefore acceptable as long as the old belt timing was correct in the first place and, neither the cam or inj'n pump sprockets have shifted somehow on their respective drive shafts.

I realize this is quite the controversial topic here and don't wish to resurrect an argument but if anyone has definitive information otherwise, I would be pleased to hear it - just sayin'.

BTW, from what I have read here, it seems some of the difference in opinion on the matter lies in not fully realizing that the timing belt is a toothed belt rather than a friction belt and, as a result, if timing is out at all (and assuming the sprockets haven't slipped), it can only be out by exactly one tooth pitch (or two tooth pitches etc if it's really out) and nothing in between. So, if the timing was good before the belt change and the M&P was done carefully, the timing will be just as good after. Or so it seem to me anyhow...
 
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STDOUBT

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Portland, effing Oregon
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dos jettas
NoSmoke, how many years were on that old belt?
This topic is ever-fascinating.
Right now, I'm 42,750 miles into a 5 year old belt. I daily drive it too.
I'm considering giving it another year, as the belt itself looks fine,
and I understand it's generally not the belt that fails out, but rather
the metal bits. I know I'm playing with fire, but dang. 42k.
 

Nuje

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Island near Vancouver
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have concluded that if M&P is done carefully, the resultant timing with the new belt will be the same as it was with the old when it was new and is therefore acceptable as long as the old belt timing was correct in the first place and, neither the cam or inj'n pump sprockets have shifted somehow on their respective drive shafts...
My understanding is that it's pretty easy to get the teeth lined up correctly, but that the issue with M&P is that it's impossible with that method to get the tension on the belt equal around the full pathway of the belt. This causes more tension (and thus faster wear) on one part of the system compared to the other, and thus, something is more likely to fail well ahead of its spec'd service interval.

As suggested above, VW engineer build in a lot of safety margin, so sometimes you get lucky with the M&P method...but lots of times, you don't.
 

keaton85

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Camden, ME
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It won’t be perfect but it will run. As long as the tech adjusted the IP after, as that is important.

As for tension, doesn’t matter how you do it, the tensioner doesn’t care as long it it’s set in its window. As soon as you start, the tension is even on everything so there is no way one part would receive more tension from pain and pray.

But for $1k bucks! I would want to see it perfect with new everything.
 

NoSmoke

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Location
Calgary, Alberta
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2K2 Golf
NoSmoke, how many years were on that old belt?
This topic is ever-fascinating.
Right now, I'm 42,750 miles into a 5 year old belt. I daily drive it too.
I'm considering giving it another year, as the belt itself looks fine,
and I understand it's generally not the belt that fails out, but rather
the metal bits. I know I'm playing with fire, but dang. 42k.
My belt was last changed on June 2013 so about 6 years ago.

You are right - it is an interesting topic alright - kinda reminds me of the old "which is best, Ford or Chevy" debates. A little good info interspersed with a lot of questionable theories and hand waving. :)

Anyhow, I feel your concern but, as I understand things, the age issue affects usually only the belt as wear on the other mechanical bits is unlikely to be age related (unless there is some sort of ongoing corrosion thing going on because of water leaking in through the cover or some-such thing). OTOH though maybe the lube in the roller & tensioner bearings tends to dry out or degrade with time - I dunno.

As I mentioned, my belt looks pristine so the 6 years seem to have had little effect. Since you have only 43K miles on it and your belt looks good, I would
leave it and keep going until you reach the 100K mark or the belt starts showing signs of deterioration.
 

NoSmoke

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It won’t be perfect but it will run. As long as the tech adjusted the IP after, as that is important.
As for tension, doesn’t matter how you do it, the tensioner doesn’t care as long it it’s set in its window. As soon as you start, the tension is even on everything so there is no way one part would receive more tension from pain and pray.
But for $1k bucks! I would want to see it perfect with new everything.
It still seems to me that, assuming the cam sprocket has not slipped or been maladjusted in the past, putting on a new belt, even using M&P, should result in cam timing that is identical to when the car left the factory. I think that would also apply to the mechanical timing of the IP. Assuming no screw ups, I don't see how it could be otherwise but I'm certainly willing to be shown if incorrect.

Agreed on the tension - it evens up automatically.

As for the $1k, I'm in Canada so it's Canadian bucks which would be about $750 US. And, everything here costs more in any case. :) The stealers here would charge about $1,500 :mad:
 

Nuje

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How does the tension "even out automatically"? The distance between the cam and injection pump is fixed, so when you tighten the belt, that cannot and will not change. With those two cogs unable to move or adjust their relative position, the tension of the belt between them can't change.

Imagine you have string around four nails in the shape of a square. Now, you pick up one corner and move it toward the middle of the square. If the string is locked to the other three nails, is the tension going to be even?

No - it's going to be tightest around the nail the you moved. Similar with the timing belt. It's going to be (and stay) tightest around the tensioner.
 

AndyBees

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Southeast Kentucky
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Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
I've owned VW diesels since 1980. Back in those early days, proper tools were not readily available in my neck of the woods. I made those tools with my limited abilities and things to work from. So, all of my TB changes (my vehicles) were done by the Mark & Pray method, however, I never used paint. Not a single disaster...... period.;)

Fast forward to my first TDI.... yep, did that first TB by the M&P method without loosening the Cam Cog ... and, I only changed the Belt and Tensioner (yes it was a knuckle skinning procedure). Then, I purchased VCDS and checked everything... best I remember, the timing was okay, but I did do another TB job at 67k miles in. Thus, all the rollers and WP went for 167k miles with no problems.

I have seen without any doubt the OE belt and components go:
-152k miles and break on a 2003 Jetta automatic
-149k miles on an 01 Jetta, no issues
-105k miles on a 98 Beetle with the 60k mile original belt... teeth ripped off at 45 mph (dealer told the buyer that the TB had been changed at 65k, wow)
-119k miles on an 03 JSW, no issues
-100k to 110k miles on several others with no issues

Aftermarket TB kit:
-142k miles, no issues, 01 Jetta
-138k miles, no issues, same vehicle as above
-110k miles presently on my 03 Jetta which was installed in July of 2012
-100k to 110k miles on several others with no issues

The Water Pump seized on the ALH engine in my Vanagon at about 50k miles ... The Belt took a beating but did not jump teeth.

Below is a pic of the WP failure (tells me the TB is probably the strongest component).

Interestingly, after shutting down the engine, I re-started it to move the vehicle to a safer spot beside the road...:D



 

NoSmoke

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How does the tension "even out automatically"? The distance between the cam and injection pump is fixed, so when you tighten the belt, that cannot and will not change. With those two cogs unable to move or adjust their relative position, the tension of the belt between them can't change.

Imagine you have string around four nails in the shape of a square. Now, you pick up one corner and move it toward the middle of the square. If the string is locked to the other three nails, is the tension going to be even?

No - it's going to be tightest around the nail the you moved. Similar with the timing belt. It's going to be (and stay) tightest around the tensioner.
Hey Nuje, think of it this way, everything connected to the t-belt rotates and, that rotation is independent of each other component other than within the confines of the teeth on the belt and the cogs on the sprockets. So, when the belt is tightened, all those individual components will rotate a bit independently to relieve any of (or at least most of) the unbalanced tension in the belt i.e. they haven't changed their relative position to each other but they have changed their relative rotation. IOWs if the belt is significantly tighter between two components (such as the cam and pump in your example) than it is between the others, either or both of the can and pump sprockets will rotate slightly towards one another thus relieving tension in that part of the belt and, increasing it slightly in the other belt sections. The tension won't equalize completely due to static friction in the cam and pump and other components but it will equalize sufficiently to avert any problems.

In your example of the strings on a board, if the string is fixed solidly to the nails, yes, the tension will increase when you move one of the nails. However, if the string is free to slide one direction or the other around the nails (analogous to the sprockets rotating a bit with a cogged belt), the tension will m/l equalize depending on the actual degree of static friction between the string surface and the nails.
 

NoSmoke

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Andy, so all that crude abraded from the inside of the belt as it was dragged over the seized water pump sprocket without snapping? That's quite a testament to the otherwise durability and strength of the belt alright!

As I mentioned in my OP, my old water pump was a little hard to rotate so I wonder if it too was ready to have a "seizure"?
 
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AndyBees

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Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
When the Water Pump seized the shaft was cocked about 1 degree, give or take. Thus, the seal was compromised resulting in loss of coolant. So, the shreds from the belt also consisted of dust and coolant.

A new water pump is quite stiff. I've changed numerous TBs on ALH engines and 1.8T gasser engines. Most of the WPs are fairly stiff. So, I doubt "feel" is going to tell you very much.
 

Mongler98

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98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
there is a reason some TDI's go for 500K plus miles and then there are most that only go for about 200K, the difference is care and maintenance. dont cry when the car is totaled due to neglect.
 

jettawreck

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Bought the '03 jetta TDI with 165k miles on it. This was in May 2010 and I believe the belt issue had happened in the fall of 2009. TB was sheared and owner had a shop remove the head for a repair quote. My forensics seem to indicate the tensioner failed at that point and allowed the loose belt to slip/shear the teeth off until it got stuck on something and snapped (it was all disassembled upon my purchase/inspection). Head repaired by Franko6 and installed with his TB kit and install parts. Still fine today, engine living in a different 2003 (gasser) chassis after a rear ended totaling event. The donor chassis from a 2003 1.8T also had a broken/sheared TB at aprox the same mileage 160kish miles. Waterpump was seized.
 

AndyBees

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Never neglected and always cared for............ but *hit does happen out of the blue occasionally.







 

johnboy00

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Bridgewater,Ma.,USA
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I spoke to a guy in 2010 or so who just got a new Jetta. He finally junked his old one after Jiffy Lube screwed up an oil change. Sounded like they might have stripped the oil pan and the oil leaked out.

Anyway this guy had a 2000(?) Jetta that he drove for 225,000 miles with no timing belt change, EVER ..... and brought to jiffy lube for 3k mile oil changes IIRC. :eek:
 

Mongler98

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98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
3000 mile oil change? Oh lord.
Some people just insist on getting suckered into bad info from crappy shops.
It's not the belt. It's everything around it to a certain point.
 

AndyBees

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Yep! Those who extremely over torque oil drain plugs never ceases to amaze me. The oil plug bolt head should look pristine with no rounded off corners. I've seen them mangled really bad and extremely hard to break loose!

As Mongler stated, 3000 mile oil change, Oh lord.................... 10k miles is the interval and no sooner unless you are planning to head out on a long road trip! And, of course, use the oil that is spec to the engine!
 

Mongler98

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COLORADO (SE of Denver)
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98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
So for the last 35K miles on my ford escape, i have had a stripped out drain bolt. i was able to tighten it down to 8ft lbs and never had an issue until it just gave out, i has a spare oversizeed with the tap ready in the glove box for when i did my next change and fixed it properly in the end but you have to imagine, those plastic crush washers dont hold much. whats spec on spark plugs on most cars, like 15 ft lbs? pisses me off how people have to gorilla arm the heck out of things for no reason.

this entire thread is just trying to excuse lazy and cheep behavior.
 
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