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derbydrifter
20-04-2008, 09:21 PM
Hi,

I recently bought a VW Transporter 2.5 TDI van. It's a 2002 with 168,000 miles on the clock - with mainly VW service history. Two days ago it developed an unusual imtermittent tapping noise coming from the top of the engine after being run for a few miles and getting hot. It is most noticeable while idling and comes and goes. Because of it's inconsistency, my mechanic is a bit puzzled and cannot make a positive diagnosis. The van runs beautifully without any trace of smoking or oil leaks, and other than the annoying tapping noise, a bit like somebody using one finger to write on a typewriter, the engine is as sweet as a nut. On a recent forum somebody suggested replacing the vacum pump, which drives off the cam. Has anyone come across the problem, or please have any advice?

Kurt.

robot
29-04-2008, 08:07 AM
glad to hear that someone else has the same problem. i have been told to do the same thing but also at the same time by my vw mechanic he said why bother its expensive to replace and the tapping is just a sound with no mechanical implications, so how many people out there have the same problem?

rayl
29-04-2008, 04:47 PM
Hi, i have a lt35 2003 model which i have had from new, this too had the same tapping noise , tapping there some days then not the next, was told by vw dealer it is most likely the vacum pump if it gets to bad pump will need changing (think about £150), vehicle has done over 340 thousand miles now and tapping noise has been gone for the last 100 plus thousand miles still have same pump on, Noise sounded like a dry tappet.

Rake
30-04-2008, 01:01 PM
Replace Vac pump push rod.

if this fails

Replace vac unit.

derbydrifter
30-04-2008, 06:52 PM
Hi,
the tapping noise I originally described comes and goes more infrequently now. When it does come, as I pull up sometimes and the engine is idling, I can stop it by depressing the brake pedal twice; which I assume points to the servo valve - although I still don't know what or where that is.

Now that it has been mentioned, I think that it sounds very much like the sound a vacuum pump push rod could make. But, I've just spent £400 on having the cam-belt and pump belt replaced, so I wont be splashing out just yet on a new vacuum pump and rod.

I am going to give my engine an oil and filter change though, and I really want to put in the best possible oil money can buy. Can anyone recommend the one, and would that be fully synthetic?

Kind regards to all,

Kurt

rayl
01-05-2008, 02:28 PM
Hi
see if you can get the push rod as rake has said, but as i mentioned mine tapped for quite a while time and mileage wise, vw said its the rod sticking now and again, so i take it that the rod has found its home now as not had a whisper from it.
The oil i have in is semi synthetic helix lubricant which vw put in every service and has had since new, hope this helps a little

derbydrifter
05-05-2008, 05:08 PM
Well, I've been hoping that my unusual tapping noise on my 2.5 TDI Transporter would go away, but if anything, I think it may have got worse. Or is it my imagination? But, it's driving me nuts, so, this week - taking into consideration all the advice about vacuum pumps and push rods - I'm going to get it sorted.
However, before I start, I'd like to know where the Vacuum pump is located, so can anyone tell me? (Oh by the way; that's the correct spelling for vacuum, so my spell check keeps telling me.)

All the best,

Kurt

kenney
05-05-2008, 06:49 PM
Hi The vacuum pump is bolted to the side of the cyl head

derbydrifter
06-05-2008, 06:59 PM
Hi,

thanks Kenny. I took my van to a new mechanic that I'm trying out, because I thought that the £406.00 for a cam belt and pump drive belt change that my old mechanic charged me was a little steep; and my new guy, Tim, immediately located the vacuum pump and discounted it because the, now distinctive and more regular, tapping noise is coming from the area around the servo. Gulp!

So, he's taking my van in on Thursday morning for further investigation. I guess the worse case scenario is that I need a new servo. Has anyone got any suggestions for getting one if I do? :1zhelp:

Regards to all,

Kurt

kenney
06-05-2008, 07:35 PM
Tapping noise from servo? thats somethig i have never heard of before

Freshup
07-05-2008, 07:08 AM
Don't rush into servo. replaced one vacuum pump at 100000k, started tapping again at 220000. Now done 660000k just put up with it. Noise disappears when brake pumped.

derbydrifter
07-05-2008, 06:25 PM
Me neither, but someone on the forum, in an earlier reply, said that it could be the servo-valve. Personaly, I don't think it is coming from the servo, but it is strange that the noise always temporarily stops when the brake pedal is pressed.

derbydrifter
07-05-2008, 06:32 PM
The tapping, which is now quite loud and a little embarrassing, definitely is not coming from the vacuum pump - which as far as we can make out is at the front of the engine. Sure it does stop when the brake pedal is pressed, but the worrying thing is that the noise is getting loulder.

kenney
07-05-2008, 06:58 PM
Hi (Sure it does stop when the brake pedal is pressed) this is typical of the vacuum pump,if it had of been any thing else then the noise would not have stopped by pressing the brake pedal.The valve is plastic and there is nothing in the servo that could make such an noise.Try removing the vacuum hose from the pump,see what happens.I had one ACV engine were the cam that operates the pump was completely worn ,but this resulted in the pump not producing enough vacuum.To check this you must remove the cylinder head cover

derbydrifter
08-05-2008, 09:34 PM
Hi Kenney,
I am going to have to investigate your diagnosis by suggesting that my mechanic takes of the cylinder head cover - because to me, that's where the noise appears to be coming from.
Would you believe, I took my van to the garage today to get this thing sorted once and for all, and the noise stopped. The mechanic managed to get it to do it occasionally, but not long enough to track it down. So, I'm going to take your advice and get him to take that cover off. Any idea what he's supposed to be looking for, and what new bits I had better order in preparation?
Thanks for your help,
Derbydrifter

kenney
09-05-2008, 10:09 AM
To diagnose the noise,if it is the pump,when the knocking is present,pull the vacuum hose of the pump,this releases the pressure on the pump and the noise should stop immediatly.I cant understand it can be anything else,a leaking valve lifter, can make the same noise,but applying the brake pedal,would not have any influence on it.

derbydrifter
09-05-2008, 07:04 PM
Kenney,

over the weekend I'll try pulling the hose off to see what happens. Thanks for the tip. Like you, I'm convinced it is the vacuum pump and its operating mechanism. I told my mechanic what you said, and he agreed also. So, we're on the case. I'll keep you posted how things go.

Thanks again...Kurt

diggerboy
19-04-2009, 06:15 PM
Hi folks,

I know I'm blowing the dust off this original post, but I've got the same problem - intermittent tapping from near the top of the engine on my LT35 109 5-cylinder diesel.

I've noticed it getting slightly louder over the last 1,000 miles. Ony happens when hot, and the tapping is slightly irregular.

I'm going to have it looked at as soon as I can, but assuming it is a vac-pump problem what are the potential running problems and how long can I run before any further damage is done?

Are there any other ideas about what the problem could be?

Thanks in advance.

rayl
21-04-2009, 02:14 PM
Hi Diggerboy, mine has gone on to do 400,000 plus miles and still taps now and again, first started taping around 150,000 miles or so, noise has not got any louder, engine oil and filter has been changed on or even before the 15,000 service time with out fail, hope this helps.
rayl

Walesy
23-04-2009, 07:16 PM
What a great thread! I have a 2002 2.5TDI which is just about to hit 140k, this noise appeared about 6 weeks ago and has been getting me progressively worried - I just went out and gave the old brake pedal to the floor twice trick and it worked! Its great to know it's not engine related and is something I can remedy as and when I find the time/money!

Thanks for the free info guys! :)

oblioi
17-01-2010, 01:48 AM
hate ta butt in but snap!!my engine with the pump n push rod disconected sounds like a bag of spanners,i still aint found the problem but susspect hydrolic cam follower,they use summit simala to the ford cvh,nuf said lol,like u the noise is going right trhough me:(

boisty
20-11-2012, 06:23 PM
A long time has passed since the last post on this thread but i would love to know whether this problem was ever sorted.

I have had a similar noise for some time and seems to be getting worse.

Changed the rocker cover gasket on mine yesterday as it was leaking and took a cursory glance at the cam while it was off. Considering the engine has done 200,000 miles all looks pretty good with only minor pitting of the vaccum pump lobe.

Before I go to the expense of replacing the vac pump or pushrod it would be great to know if this problem has been solved. Also, can the pushrod be replaced seperately or does it only come with the pump?

derbydrifter
20-11-2012, 09:52 PM
I have had a similar noise for some time and seems to be getting worse.

Before I go to the expense of replacing the vac pump or pushrod it would be great to know if this problem has been solved. Also, can the pushrod be replaced seperately or does it only come with the pump?[/QUOTE]

Hi, it is the vacuum pump pushrod, and a common problem on these engines - or so the VW specialist garage informed me at the time. I'd just bought the van back then and thought because of the horrible metalic knocking noise I'd been sold a duff one.
From my receipts I see that I had a new push rod fitted and then twenty days later had a new vacuum unit fitted. But I can't recall why the later job. All I remember is that the new push rod solved the problem. Perhaps there was still a littly noise so hence the new unit. But boy was I happy! So yes, as far as I can make out the push rod can be replaced on its own quite easily. I see that the fitting of the new vacuum unit was cheap on labour but the actual pump was expensive.

The garage that identified the problem immediately for me specialise in VW and a couple of their guys drive early transporters. They are in Lincoln and are pretty good with advice if you are too far off to pop in. MG RAW MOTOR ENGINEERS, tel; 01522 522539.

There's no reason why your engine with that mileage shouldn't be in really good shape. Mines done about the same now and is as sweet as the day I bought it six years ago. I know a guy locally who has a 1.9 Transporter with well over 300,000 on it which runs beautifully. And I hear stories of vans far in excess of this.

Anyway, I hope all this helps.

All the best,

Kurt

boisty
22-11-2012, 06:12 PM
Engine noise LT35 2.5TDI (http://www.vwaudiforum.co.uk/forum/showthread.php?139575-Engine-noise-LT35-2-5TDI&p=763417#post763417)

Hi DD

Thanks for the info but I've just tried the suggestion made by Zollaf in the above link and it seems to have worked, for the time being at least. Lets hope it's a permanent cure!