Vacuum/Fuel Tandem Pump Issues

[grandmasterorge]

Hi Chaps,

I am new to the forum having just got a Passat in the last couple of months and have searched for similar issues and found a number of threads with similar symptoms but none which detailed resolving the issue so...

Yesterday I discovered my brakes (2001 Passat TDi 130, engine must be AVF or AWX) were solid underfoot, still stopped the car and no softness like with air in the system but significantly less powerful than they should have been, felt as is they were all of a sudden non-servo assisted so I looked under the bonnet and the most obvious thing was that the EGR vacuum hose on the top of the engine was for some reason not connected. I plugged it back on and this seemed to fix the issue, but to be on the safe side I drove to the nearest VW dealer and asked if they'd be able to have a look at it for me. Fair play to them, free of charge they had a look over it there and then and made me a really nice hot chocolate.

The mechanic came back and said my vacuum tandem pump is leaking air and needs to be replaced, they didn't have one in stock so couldn't do it. VW charge £450 for a pump, GSF is £360 and ebay brand new is £260, ebay used are sub £100. I believe it is a combined vacuum and fuel pump.

Has anyone else had this issue? How difficult is changing the pump yourself and does anybody know where to find the OEM part number so I can make sure I order the correct one? I believe this issue is causing a few other symptoms on the car like sub-standard fuel economy (33 mpg) which will hopefully be fixed once I sort the pump and split hoses out.

Thanks in advance for any help/advice on this issue.

Cheers,

George.

VW.jpg

[aks1989]

Hey bud
I brought my passat last year, and like you the "actuator" vacuum pipe for the egr on mine had rotted through big hole in t side etc etc, I hadnt noticed anything off with the car except when I turned it off it liked to run over a few chugs, so when I changed that pipe and gave it a good service (there were a couple of other vac pipes too now I think about it) overrun stopped and haven't actually had another issue with it.
I say haven't had a problem, haven't identified one yet aside from a leaky egr and hissing turbo anyway haha.
I have however noticed a certain surprise with the brakes, soft then solid, barely on then BOOM you've got a skid, in a 4motion! pads fine, disks fine, calipers fine pistons nice an smooth, wondering if it might be lacking the vacuum from the servo, hmmmmm let me know how you get one, I'ma keep an eye on this

[mickeybo]

This is a common fault on these tandem pumps you will find where the vac pipe comes out of the pump is loose (slack) Put a sealer around the pipe at the pump entry. I have cured this problem on a few occasions using this methoid Hth Regards Mickeybo

[grandmasterorge]

This is a common fault on these tandem pumps you will find where the vac pipe comes out of the pump is loose (slack) Put a sealer around the pipe at the pump entry. I have cured this problem on a few occasions using this methoid Hth Regards Mickeybo

Hi mate, thanks for the reply.

The part of the pump which the hose mounts to (not the hose itself) seems to be loose inside the pump, is this what you mean? What sort of sealer do you mean?

Cheers.

George.

[grandmasterorge]

Tdi pump loose fitting - YouTube

I only got a quick look as the mechanic in the dealer showed me, but I'm pretty sure mine was loose like the one in the video.

On the plus side there seems to be plenty of used ones on ebay for around £60 or a new one from Poland for £180 - has anyone done this themselves at home? Is it a home mechanic job?

[grandmasterorge]

Just an update...

New pump arrived (£240 from darksidedevelopments.co.uk, cheapest I could find a genuine new one for), got the Haynes manual out and had a crack at changing it the other day, all went well but I thought I'd share my tips.

1. Accessing the lower mounting bolt with a normal Allen key/socket is nigh on impossible. I took a ball ended 5mm Allen key and cut it in half keeping about 3" and throwing away the L-shaped part. I then mounted this in a 5mm socket and used it as an extended ratchet Allen key, this did the job easy. (Haynes helpfully says "remove the 4 mounting bolts" and neglects to mention how hard this is).

2. The charge air pipe is best completely removed as it gives you much better access to everything (Haynes says unclip the one end and lay the pipe to one side).

3. When repriming the system (apply vacuum to the fuel return line on the fuel filter) I messed about trying to make a vacuum pump from a bike pump but ended up getting a 70 cL syringe from the local vets for £1.50, which was not only really cheap but extremely effective and did the job straight off - car started after 10-15 seconds of turning over.

Hope that helps someone doing the same job.

Cheers,

George.

[caldirun]

Thats a lot of money for a loose fitting, I would try Araldite first!

[Cavanmick]

I have done them with tec7 before and it worked fine, cable tie it in one spot and put a bead of sealer around the seam and it has held vacuum no bother.

Mick

[grandmasterorge]

Thats a lot of money for a loose fitting, I would try Araldite first!

Well the VW dealer wanted £450 plus labour and told me there were no serviceable parts in the pump or a kit available to fix it, so £240 all in seemed pretty good. Yes I could have tried araldite but seeing as the vacuum system powers the brake servo assist it seemed worthwhile fixing it properly.

On another note this has not fixed my low mpg issues (around 30-35 mpg on a motorway run driving gently) - any ideas? Boost leak? MAF?

[pjlouhisalo]

unnamed.jpgSounds like you got it fixed easy. Just replaced tandem pump and tried to start her up but with no success, seems I missed the point that the system needs priming. On the attached photo could you explain which hose to connect syringe/pump to. Any help at all much appreciated.