Leaking injection pump

bryancald · #1 03-12-2011, 08:47 AM

OK, I searched the forums for posts relating to leaky injection pumps and couldn't find the same symptom. I have a N/A D24, it has progressively become harder to start (irregardless of temperature). It's now having a hard time idling, and has started to stall. This morning I popped the hood and noticed fuel leaking from the injection pump to block junction (I think). Is it possible that the injection pump is just loose, or is it more likely a seal issue? I recently started running B99 biodiesel with the understanding that the pump seals were replaced shortly before I purchased the car a year ago. Are the pump bolts easy to access?

Thanks for your help!

Bryan

Jason · #2 03-14-2011, 08:07 AM

Its a seal issue, probably leaking at the pump head or the front shaft. A leaking pump head really wont affect how it runs all that much, however a leaking shaft seal will really mess with it, by alowing air to get into the pump and turning the fuel to a frothy mix. Try running the pump from a jar of diesel fuel held above the pump so it gravity feeds it. If it smooths out, you know the pump seal is sucking air and thats your problem. Also check or replace your fuel filter if it hasn't been done recently, a partially clogged fuel filter will also lead to poor performance. I would try those and get back to us.

Jason

casioqv · #3 03-14-2011, 01:27 PM

Sometimes installing a cheap 12v fuel pump to provide positive pressure to the IP can buy you some time before re-sealing the pump. It will still leak (perhaps worse than before) but should run ok.

mtb.rxstar · #4 03-17-2011, 05:25 AM

I think I'm having a problem similar to Bryanclad's although not dealing with the injector seals but I was thinking it was a shaft seal. I'll try the gravity feed pump test before going ahead with the VE rebuild!! Although I was considering the auxiliary inline fuel pump as a stop gap measure...

casioqv · #5 03-17-2011, 05:47 PM

Quote:

Originally Posted by Jason

Try running the pump from a jar of diesel fuel held above the pump so it gravity feeds it.

Haha.... your post just reminded me of a Mercedes 240D I saw on the road the other day which had a 3 gallon can of diesel duct-taped to the roof, and a fuel line running down to the engine.

Jason · #6 03-18-2011, 05:52 AM

The lift pump will do the same thing, but I realize not everyone has a electric pump laying around, so holding the jar above the pump is a good test. I think it even says to do so in the greenbook.

Jason

bryancald · #7 03-18-2011, 09:51 PM

OK, so the IP is leaking so bad that a puddle forms on the ground below the engine.
I have to depress the gas pedal at lights to keep from stalling, and I have to rev the engine before I shut it off to keep fuel available for the next start.

It seems that the leak is from the front shaft seal.
Is it possible to replace without removing the pump? I don't have any timing tools.
Can anyone tell me if it's a 17mm or 20mm.
How about the seal kit part number?
Is there truly a Viton seal kit for biodiesel?

Here's some interesting info from the EBay seller of the seal kit:

Hi - According to the girl at Bosch, this VW kit will also work on that pump.
The VW Kit I sell comes with a 17mm front seal and she told me that your pump could carry a 20mm seal. The book doesn't say which size front seal is on your pump.
If you don't have your pump off yet and you don't know which size front seal you have, then I can just include both sizes for an extra $5.00 if you want.

I talked to some people at Bosch about the Viton seal Kits awhile back and they told me that Bosch doesn't offer any Kits with Viton seals. They said that all Bosch kits made since around 1995 are bio-diesel compatible, though.
Regular diesel fuel and Biodiesel tend to swell the seals and ULSD shrinks them, so as long as you pick one type fuel and stick with it as much as possible most experts say you should have no problems.
Most of the leaking problems seem to happen to those that go back and forth with the different type fuels. The seals don't seem to like the constant sweeling and shrinking.

Thanks, Sam.

bryancald · #8 06-06-2011, 07:21 AM

I am in the process of resealing the injection pump. Is there a trick to getting the 3 sided bolts out? Do I need to remove the governor shaft at all? I also remember reading that 25mpg (which is what I'm getting) on a N/A D24 is pretty bad. Since the pump is off, should I replace the injectors or at least the nozzles?

Thanks,
Bryan

ngoma · #9 06-06-2011, 09:19 AM

After a few experimental prototypes (the sockets I started with were too weak), I made a good tool to remove the three-sided bolts out. It was a beefy 1/2" drive 1/2" 6-sided socket. I ground reliefs in three of the walls with a small grinding stone in a dremel tool. The reliefs allow space for the three "points" of the triangle bolts so the remaining three sides of the socket wall can grab the three flat sides of the triangle bolts. The earlier prototypes were 1/2" drive cheap sockets, and their walls were too thin/ material too weak, so they deformed too much to grip the bolts well.

Unless you are positive those seals were leaking you might want to leave them alone. Those bolts are the pivot for the governor lever, which is under strong spring pressure. Which means removing one bolt at a time, and finding some way (clean screwdriver or small prybar) to force governor lever back into position for reinserting the pivot bolts.

One other warning: When replacing the IP cover (removed for replacing the accel. shaft o-ring) be careful the governor spring cage is properly connected to the governor lever and positioned correctly. My car wouldn't start after its reseal and removing its cover showed that the governor cage was disconnected and the cage (lobster claws) was bent, as well as the thin shaft. It is fiddly to get the cover back on, and I still have not figured out how to successfully get the cover back on without damaging anything.

Injectors may or may not need replacing. What other symptoms other than 25 MPG? "OK, so the IP is leaking so bad that a puddle forms on the ground below the engine." <== This could be enough of a leak to noticeably affect MPG.

bryancald · #10 06-06-2011, 09:29 AM

I'm not sure where the pump was leaking from, it was pretty bad though. Are there seals for the governor shaft and hinge bolts? I'd rather not disassemble the pump anymore than I have to to reseal it. Because I'm not sure where it was leaking from, I'm a little paranoid about leaving old seals in. So your saying you got a 6 point socket to work? Interesting.

The car ran beautifully prior to the leak, it just sounded like everybody else were getting between 27-32 mpg.