I didn't do this post originally, It's was done by another forum member sometime ago, It's disappeared from the forum for some reason so I am simply reposting it for the benefit of others. I don't know specifics so I can't answer questions for you.
original post.The atmospheric bleed is a common source of leakage from the TD pump. Allowing it to leak can ruin the aneroid diaphragm, hurt fuel economy and cause a terrible mess. Although it is a very small o-ring that leaks, the replacement of that o-ring is not nearly so small of a task. If taken step by step, though, it is not particularly difficult. Pictured here I am pointing at the atmospheric bleed with an awl.
If fuel is leaking from that odd rubber boot, then the following procedure should be followed to remedy the situation. Although the pump does not need to be removed from the vehicle, the pump top must be removed and disassembled in order to replace that o-ring. The o-ring itself is part #1 460 210 347. It is included in the seal kit DGK 121. IIRC it is NOT included in the seal kit DGK 126 (n/a pump seal kit). Although not strictly necessary, I would recommend getting the whole seal kit as it will include the accelerator shaft o-ring along with the other metal sealing washers that should be replaced on reassembly. It will also include replacements for any other seals that might leak on that pump in the future and so the remaining seals can be saved for a later date. Note that the main shaft seal included in the kit will not fit the smaller VW shaft, tho.
Cleanliness is of utmost importance. Any grit getting into the fuel system can seriously damage the pump or injectors. Clean the exterior of the pump prior to attempting to work on it. A car wash with a pressure washer is one method.
The accelerator lever, max rpm screw and the residual fuel/idle screw all need to be removed in order to access the (4)5mm allen head bolts that hold the pump top to the pump body. They all also need to be returned to their original position on reassembly. To that end, find two extra m6 nuts to use as lock nuts and thread them all the way onto the max rpm screw and the residual fuel/idle screw until they bottom out on the existing lock nut. Loosen the existing lock nut slightly and using two wrenches tighten the two lock nuts together on the screw to maintain the position of the original lock nut on the screw.
Remove the max rpm and residual fuel/idle screws, label them as to which is which and set them aside.
Use a utility blade to scribe a mark on the throttle levers that aligns with the groove in the top of the accelerator lever shaft.
It's also wise to take a picture of the accelerator lever spring assembly as some are complicated and can be difficult to replace. Having a picture to reference can be helpful. Remove the accelerator lever nut, the lever itself and the return spring(s).
Remove the four (usually) slotted screws that hold the lid on the aneroid.
Those screws can be very tight. I like to use a screwdriver that accepts a bit along with the most tightly fitting bit I can find along with a 6 pt 1/4" wrench (available from craftsman - great investment). I place the bit in the screwdriver and place the wrench around the bit. Then I press firmly down with the screwdriver to keep the bit from slipping out of the screw head while I turn the screw using the wrench. Using the wrench can exert incredible torque.
Once the lid is removed, note or mark how the dimple in the metal diaphragm plate lines up with the aneroid body.
Remove the diaphragm, pin, nylon stop washer and spring and set them aside.
Remove the four allen head bolts that mount the pump lid to the pump body.
In the picture you can see another excellent tool. It accepts typical 1/4" hex bits and yet is a very small ratchet. Another alternative is to use the aforementioned 6pt 1/4" wrench around the body of a bit to loosen those bolts.
When all four bolts are out, press down on the accelerator lever shaft while lifting up on the lid.
There is a shaft o-ring and so the shaft can be fairly difficult to remove. I would recommend replacing the shaft o-ring on reassembly. Avoid buggering the threads of the shaft or the bushing during removal if any tool is used to push down on the shaft..
With the top off the pump you can see the aneroid lever underneath.
That lever needs to be removed in order to remove the feeler pin in order to replace the offensive o-ring. There is a rod on which the lever pivots. That rod is held in one of two ways. Earlier pumps tend to have a flat head screw on either side of the rod preventing the rod from coming out of the pump. The screws are sealed by copper washers that should be replaced on reassembly. Newer pumps tend to have the rod held in place by a ball bearing pressed in on either side of the rod. If the aneroid has the screws, then using the same technique used on the aneroid lid screws, remove each of the flat head screws that hold the rod in place.
If the aneroid has the ball bearings, then it is necessary to appropriately support the aneroid and use a punch and hammer to tap on one of the ball bearings until it pushes the rod far enough to push out the opposite ball bearing. Then flip the aneroid over and use the punch on the rod to tap out the remaining ball bearing and the rod itself. The ball bearings can be hammered back into place on reassembly or the holes can be tapped to 1/16 npt and allen head plugs used instead. http://fittingsandadapters.stores.yahoo.net/pipthreadcou.html]
With the two screws removed, support the aneroid appropriately (I usually place it over the open jaws of my vice) and use a punch and hammer to tap the rod out far enough to remove the lever.
Next, remove the 5mm allen plug that is pictured here:
That plug is also sealed by a copper washer which should be replaced on reassembly.
With the plug removed the feeler pin can now be removed using needle nose pliers. With the feeler pin removed, the o-ring keeper can now be accessed. I've seen two different styles. One was slotted and the other was an allen head style. Use the appropriate bit through the opening to loosen and remove the o-ring keeper.
With the keeper removed the o-ring can now be accessed (woohoo).
Use a pick or other appropriate tool to remove the o-ring. The new o-ring is usually green. Here they are are side by side.
Lube the new o-ring (I use vaseline) and replace it. Assemble the rest of the aneroid and install it back on the pump.
