Change throttle shaft seal

[ian2000t]

The throttle shaft seal on my pump is leaking. First it started weping when I started it up after 2 weeks of standing still (when the headgasket went), but on revving the engine it stopped weeping and hasn't really given me an issue since.

Few thousand miles later and it seems it's puddling often when idling now. Also when engine switched off after running, you can hear a little noise coming from the throttle shaft, like it's slowly sucking air into the pump, which is made worse if you rock the throttle shaft slightly.


Is the throttle shaft seal something that can be easily done with the pump in the car? I am no diesel expert and have never taken a pump apart before, but will give most things a try - so far have done headgasket, cambelt, IP timing, injectors on it... so if it's no more complex than those I'll give it a try.

[ngoma]

Possible, yes, probably one of the easier IP seals to replace with the IP installed. If you have successfully done headgasket, cambelt, IP timing, and injectors, you have proven your abilities. IP throttle shaft seal is similar skill level, but more like working on a sewing machine.

I thought I had bookmarked some pictorials but cannot find them, here is a link that has helpful photos and descriptions (note the bracketry and springs are different, as are some of the pieces in the governor spring assembly):
http://www.vwdiesel.net/forum/index.php?topic=24323.0

Ball-end long allen wrench (5? or 6mm?) is strongly suggested to remove the IP cover screws.

Some important points:
1. Clean area as best as possible, leave IP full of fuel (don't drain) so dirt on the edges will tend to spill out rather than fall into the IP.
2. Mark (scribe) position of accelerator lever on splined throttle shaft before removing.
3. Recommend removing fuel screw before removing IP cover. Makes reassembly easier. Count turns to full seating, to arrive at same position on reassembly.
4. Note orientation of gov. assy. (where the elbow is pointing) in underside of IP cover. You will need to repeat this orientation on reassembly.
5. Throttle shaft may need some sharp hammer taps to convince it to slide out of the bushing.
6. If you remove the gov. assy. from the fulcrum lever, make sure you get it connected up correctly when replacing the cover.
7. Might as well replace the IP cover seal while you have the cover off. Also the fuel screw o-ring.
8. Reinstalling the IP cover can be bunglesome. Need to worry about orientation of gov. assy. and matchup of fuel shutoff lever to corresponding piece in IP cover. Cover should drop into place with no forcing. IP cover screw torque is not that high; it is the rubber seal that does the sealing, not metal to metal.

[v8volvo]

Ball-end long allen wrench (5? or 6mm?) is strongly suggested to remove the IP cover screws.


I think it was a 5mm. The ball end does make the job much easier.

You may as well get a complete seal kit, Bosch part # DGK-121, rather than buying the seals individually. It doesn't cost much. That way you are sure to have a selection of seals to choose the right one, and if you need to replace other seals in the future, you have them already on the shelf.

The trickiest part of this job, when working on a turbo pump, is getting the whole upper assembly to sit back down onto the lower pump body. The upper assembly has a jumble of appendages sticking down out of it that need to fit properly into the bottom section, and they tend to want to jam on bits below when installing. One trick we tried that might help, was lightly pressurizing the charge air inlet nipple on top of the boost enrichment (aneroid) device. This depresses the aneroid diaphragm and allows the lever that the aneroid pin acts against to be backed off into a position where it's easier to slip down into the pump body without hitting on the top of the main governor lever.

And to reiterate the above -- removing the fuel ("smoke") screw first and installing it last is a key step, since it will hit things on the way down during reinstall if it is not removed. Mark its position carefully! We found that noting/marking the original orientation and then turning it *inward* until its stop while counting the fractions of a turn it took to get there was easier than counting the number of turns to remove it.

You may also have to remove the low idle stop screw to get access to one of the pump top cover screws -- if so, remember to make marks and count turns with it as well so it goes back together in the same place.

If any dirt does get into the pump, flush with clean fuel and then remove with a cleaned-off suction hose from a fluid evacuator tool. Carefully wipe clean the mating surfaces of the pump body and the upper cover and, as ngoma mentioned, use a new top seal. (It's the big round-looking one with nubs, not the thicker formed rubber one that is also in the kit.) Then, assemble the pump with the main cavity as full of fuel as you can get it without having it spill out everywhere during installation, to make the system easier to bleed when you are starting it. Once everything is together, be sure to wash off any fuel that leaked or spilled onto the heater hoses down near the fuel filter head. If they show signs of deterioration from contact with fuel (swelling, bulging, flaring), replace them.

It's a finicky job, but not hard. If you work slowly, make your marks carefully and get everything back together in the same place, the car will start up and run just as it did before, and you will smile. :)

[ian2000t]

Cheers for your replies guys - a lot of help, thanks! Sounds fiddly, but managed 5 and 6 glowplugs, so how hard can it be..? ;)

Is this the right seal kit?
http://www.ebay.co.uk/itm/BOSCH-VE-Turbodiesel-INJECTION-PUMP-SEAL-KIT-/270812081679?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item3f0da86e0f

Will also get a set of ball end allen keys.

Also - now is the time to shim the govenor slightly if I'm going to do it then?

[ngoma]

Seal kit appears correct, judging by the applications listed. To be sure, ask the seller if it is the Bosch part # DGK-121, as v8volvo listed above. The mainshaft seal will be incorrect size, 19mm. For that you will need to get the 17mm seal separately. That one probably needs the IP on the bench for replacement, but stay tuned, we're going to give it a try in-car.

Shim the governor? I've never tried it; apparently it removes the rev-limit. Careful about runaway! But as long as you have the IP cover off, yes that is the time to shim the governor. Maybe after you cable up a remote fuel shutoff, like this:
http://www.dieseltruckresource.com/dev/showthread.php?t=211283

Warning: There is at least one IP failure mode that can cause runaway that cannot be stopped by engaging the manual fuel shutoff.

[ian2000t]

Will I actually be replacing the main shaft seal? Which seal is this?

I'm just looking to fix the leak on the throttle shaft (and any others I need to when taking the top of the pump off to change the throttle shaft seal).

[ngoma]

Not unless it is leaking. It is the one on the driveshaft that the cog pulley bolts to. Hard, maybe impossible to do in-car. For throttle shaft leak you want to replace throttle shaft o-ring, and since you will remove the fuel screw, that one, and since you will remove the IP cover, that one.