Pump is not timed to the engine.

 

This is my first TDI, and I might have read something wrong... So, remove the belt and replace it? Sounds good to me.

 

Correct. Common rail pumps aren't timed, all they do is create the high pressures. The ecu controls the timing by telling the injector when to open.

 

Awesome, thank you!

 

This has me curious as to what sort of conditions this car was subjected to that the belts are bad like this

 

10 years and 130,000M of high heat will do that.

 

This is the only reference I can find to changing the V6 or V8 TDI HPFP belt and tensioner. These are not listed as a service item by VW but they clearly have a finite life due to belt wear and aging and the bearing in the tensioner pulley wearing out. What experience do people have of these failing and needing to change these apart from this single post ?

cheers
Rohan

 

This is the only reference I can find to changing the V6 or V8 TDI HPFP belt and tensioner. These are not listed as a service item by VW but they clearly have a finite life due to belt wear and aging and the bearing in the tensioner pulley wearing out. What experience do people have of these failing and needing to change these apart from this single post ? cheers Rohan

2012 Touareg CATA 192k,. Im fixing to change the timing belt on the pump myself before 200k .. I ordered the lockout tools off amazon which included Im assuming some others for different models.. Still trying to find a procedure on locking the system and changing the belt and tensioners.

 

erWin has all the service information you need. If you don't want to pay, use the search function and find gifts from others, both on here and many other (typically russian) sites.

 

Yes I have the Erwin download and unfortunately there is no data in either the engine or fuel system or maintenance sections on the HPFP tooth belt drive life and recommended maintenance. There is also apart from this one thread nothing I can find on peoples experience with any HPFP drive belt failures and maintenance. Fortunately my Treg has only done 100k kms but it is now 10 years old. I am trying to put together the maintenance plan for the next 10 years and i am struggling to find information I can rely on around this item.

The lack of data suggests the belt and tensioners have a very long life normally and that failures despite no maintenance are very rare

If the pump and belt system was easily accessible I would just replace the belt and tensioner pulley now but its buried up against the firewall at the rear of the engine on the V8 TDI and under a lot of Air Con system piping so it not a trvial exercise to do the job

 

Well, if it were mine, I'd treat it just like a timing belt. It is essentially the equivalent of one, and if it goes to crap, it does significant damage. Remember that belt degrade, and over down under you probably have lots of heat and stuff so you may want to bite the bullet and do it as PM instead of waiting for the big bang.

 

Significant damage?

 

Guess not. Just wait till it lets go and simply replace it.

 

Just curious what damage there would be? It would simply stop running.

Not saying I wouldn't replace it, just that it isn't going to cause catastrophic damage, and it is a lot harder than on an old V6, as it's on the back of the engine.

 

FWIW, I'm on my second 2008 3.0 TDI, and I have replaced the toothed belt on both.

The first one I purchased in 2010 (@53K) and replaced the toothed belt at 106K kms / 5 years of age, purchased the second one in 2018 (@90K) and replaced belt at 138K kms both as preventative maintenance.

I really look at a belt the same way as SaVAGeSoot, a belt is a belt....

TonyB

 

Because you've called me out on it, I would actually have to look into how it's driven and what it can get tangled up in and such. (but honestly, I don't care that much to argue about it) We don't have that engine here, so I know roughly where it is from seeing an SSP on the engine, but I don't know what is all around it and all that. There have been many examples on various engines where simple belts, anything from accessory or whatever have been ignored and when they let go, they tear up other stuff, get tangled, rip wires, lines, sensors or whatever.....

Lastly, I don't know the OPs use patterns or what a tow cost would be to retrieve his rig if it leaves him stranded 5min or 5hrs from his home, so there's a lot to factor in if one wants to minimize the potential risk.

At the end of the day it's up to the owner to decide what headaches he wants.

 

There is nothing to get tangled. You guys have them over there in boats 😉. Generally when a toothed belt like a timing belt fails, the teeth are ripped off the belt, the belt doesn't flail around wildly like a failing ribbed belt can, there is also a guard over the whole lot. You normally.enjoy a good argument 😔

 

I promise we can argue about anything in the near future... I was having a day with other life junk and couldn't get in the mood 😜

 

I discovered the fp belt while doing my recent intake de carb and was surprised to know it existed. I did ask my concierge Porsche tech and IIRC there is a process involved that was more technical than I expected. That and the $8x cost of the belt made it a PASS til later. The good news is it's very accessible (once you know where it is).

 

I would like to see some actual data on wear from a used belt vs. a new one.

There are a couple 3.0 TDI's in Canada that have gone over 500,000 kms and afaik, they never changed that belt.

Obviously different environments and usage can affect something like this.

Sent from my SM-S906W using Tapatalk

 

You can't see the wear on a toothed belt, they are working one minute, have no teeth the next minute.

 

I'm not even sure the belt would be the root cause of a failure. The idler/tensioner is more likely to crap out no?

 

Yes I agree the tensioner bearing is probably going to fail first. The tooth belt is relatively lightly loaded and runs at a relatively low speed compared to cam timing belts. My guess is that a 150k to 200k km replacement of belt and tensioner is reasonable preventitive maintenance. If the belt fails you will get no warning and the car should just stop due to lack of fuel from the HPFP not great if your in Australia and in the middle of nowhere. If the bearing goes out then you will get a warning as it starts to whine well before it will fail totally.

 

FWIW I have a 2004 Audi A6 with a BMK engine. (3.0 L TDI). The recommended change interval is 120K Km (80K miles) and the tensioner every 240K Km.

 

I wonder why Audi have a recommended HPFP belt and tensioner change interval but VW dont ? Just something they missed maybe. Given the difficulty on doing it on the V8 I think i will do belt and tensioner at 120k km which will come up in about 12 to 18 months

 

Replaced, make marks and count teeth.. Make sure you adjust the tension on the tensioner correctly..
With nearly 200k on the original it was time to have some more piece of mind.
Make sure you do the hardware pullies and all.
No sense in being cheap over parts that have gone 12yr and 200k miles in my opinion.

 

You don't need to make marks or count teeth, the high pressure fuel pump is not timed.

 

Did you miss the "it must be timed" part?
I've also included an extract from the manual for his exact engine "implying" that it must be timed due to the use of lock tools\pins and the setting the engine to TDC........

I don't have the exact info, but I believe that on systems with 8 injectors, they actually need to be timed to coincide with the firing events, or there would be potential for insufficient pressure........ when the same CP4.2 is used on a 6 banger, there's not enough injectors to "deplete" the rail, so it doesn't matter.... but if you look at the 4 bangers using the CP4.1, they must once again be timed.....

I'll agree that they will run even if not timed, but I suspect that they would not sustain redline rpm and\or optimal output if not timed.

 

Having just read the factory service book regarding the belt on CATA engines I will say it is rather a complicated collection of locking pins, pretensioning and warnings about only turning pulleys in 1 direction.

while I did not see anything specific to "timing" this is not as simple as changing a drive belt and is something I would not personally under take without a way better understanding of the process and risks.

 

It sounds like it's not that the belt is timed, but that it can possibly damage something if either of the sprockets are rotated backwards on accident?

I tried to do some searching, and couldn't find a single instance of this belt ever failing... but I did find a few instances of the tensioner or bearings starting to make noise. I'd guess it's pretty safe to just replace it together with those parts when they start making noise.

 

I think that's a reasonable assessment and sound logic. I'll add that my concierge tech says they are a 10 year service item...keeping in mind that he gets paid to do these jobs unlike us, who pay to have them done

 

Yes, I know this is an old thread but there was no conclusion. I recently had to replace my HPFP. My conclusion is that the HPFP isn't timed, and couldn't be timed if you wanted.
1) logically it doesn't seem there would be any need to time the HPFP on the V6 TDI common rail: The pump is a 90 degree V2 driven by a double sided cam, so there is a pressure pulse every (90 degrees of pump rotation. the pump turns at crankshaft speed. so there is one pressure pulse every of 90 degrees, or 4 pulses/crankshaft rotation. So, for each crankshaft revolution, there are 4 HPFP pulses, and three cylinders fire. That seems to indicate there is no timing on the V6 TDI since the pulses, and cylinders firing are not evenly divisible.
2) VW does specify locking the cam and HPFP cog when putting on the HPFP belt which implies that they are timed but it doesn't make sense.

As far as wear, I replaced my belt at 145K miles, after the HPFP that ground itself to bits. The belt look great, and all the idler bearings were all smooth. The issue I ran into was that the belt tensioner pully wasn't tensioning the belt correctly, so I just replaced everything since the kit wasn't much more than just the tensioner pully.