Touareg: 2007 V10 TDI
Join Date: Feb 2018
Location: Memphis, TN
Second Vehicle: Still looking
Thanked 2 Times in 2 Posts
Tandem Pump Rebuild/Replace
Just a few quick thoughts from completing a rebuild on the right/passenger side tandem pump - without engine removal. First and foremost, I have worked on many cars over the past 15 years which range from small stuff to full-on rebuilding engines and replacing transmissions and this was one would rank really high on my list of hard jobs. It's not for everyone, so if you do it just remember that it can be done without engine removal and I'd recommend having the help of someone that can at least take pictures of how things disassemble.
In no particular order, here are my thoughts on the job:
Step one. Ask your dealer what they will charge to do it before you start, that way you can feel good about all of the work you are about to do.
Everything is fragile. EVERYTHING.
The wiring that VW, Audi, and Porsche use are extremely fragile because it is made with soybean oil - I'm not joking. The Germans might be good at a lot of things, but automotive wiring is not on the list. Having said that, be careful with your wiring harness and the 4 or 5 things you will have to unplug.
The bolts are a steel composite and are designed for single use. So my advise would be to buy a couple intake manifold bolts and various other bolts to have on hand. Also, get acclimated with the ballpoint extra long metric allen wrenches. You might want to check out Northern Tool and get both the long and smaller set.
I ordered the rebuild kit on eBay and it came from Latvia and took 3 weeks to get. During the disappointing wait, I looked for the kit from an American seller and there weren't any.
If you do the rebuild which will save you about $500:
The internal T30 bolts on the fuel side of the pump were very hard to get off. I had to drill the heads off of two of the bolts, so if you struggle it's normal. The center seal that separates the vacuum side from the fuel side can be tapped out with a flat head screwdriver and the new pressed in with a same sized socket as the outer seal diameter and hammer. It would probably be wise to put a very small amount of grease on the center of the seal - I mean very very very light coat.
Don't ask me how I know, but do not get any cleaning solution, especially WD 40 on the rubber gasket on the tandem pump, because the rubber will stretch/expand and the gasket becomes useless.
There are only 3 bolts holding the pump on the head. Two 6 MM allen heads and one 10 MM bolt. Before installing aggressively clean the surface where the pump mounts. Use an endoscope or mirror to look at it before reinstalling.
Every surface that has a gasket should be cleaned to the point of looking new. You don't want to spend X number of hours to have to do the job again because of a leak. The safest way is cleaning solutions and terry cloths. If you have the experience you can use a solution and brass bristled brush, but be careful. On the intake manifold I used wire brushes and the 600 grit sandpaper, which made the surface look new, but if you overdo it you can cause serious damage with the brush or low grain sandpaper.
The bottom screws to the center EGR cooler hub are very hard to get out and equally hard on the reassembly. I used a small magnet and the really long (about 6 - 7 inches) 6mm ball ended allen wrench from Northen Tool and it took about 30 - 40 minutes to get all of them in.
On the tandem pump, the center key that mates with the camshaft have to line up or the pump will NOT go back on. I think I have read somewhere that you should mark or make note of where it was upon removal, which is a complete joke. I put blue paint on mine and it was not helpful for this reason: the center bar has to line up exactly with the camshaft because it's square in shape and cannot correct itself if your a little off. Basically, you either have it lined up or you don't. Also, you are leaned over the motor and cannot see anything so you are relying on whatever you can feel. Even with the paint, I had to turn the key on the pump fractions of an mm to get it perfect and it took about an hour.
All of the gaskets are single uses which aren't unusual. On just the Tandem pump job you will at minimum need: the pump or rebuild kit, the EGR to throttle o ring, the throttle to intake manifold o ring, intake manifold gasket, the EGR hub gasket, and I would strongly recommend new bolts for the EGR hub and the intake manifold.
While I'm sure it was more specific to my case the engine will need to turn over a lot to prime the pumps. The reason my case was different was that I replaced all the seals on the oil cooler so I had to take the fuel rails off which means the pumps it has to fill the rails up before you get your diesel rumble. While I didn't time it, the engine turned over for a solid 40-50 seconds before it started.
If you decide to do it, good luck and be prepared to have two days to work on it. If you break something and have to go to the dealer, the chances are slim that they have it in stock and you might have to wait a few days for gaskets, bolts or whatever. In my case, the dealer can get your parts the next day (depending on the part) if ordered before 1 PM Monday through Friday. If on Saturday you have to wait until Tuesday.