Injection pump leaking, any ideas?

Syncronaut · Post by **Syncronaut** » Sat Jun 24, 2006 12:10 pm

I just gave the 91 Jetta 1.6 normally aspirated diesel some love with new conti belts and a polish and wax. As I backed the car out of the garage last night, I noticed a trail of fluid on the ground. Turns out the injection pump appears to be leaking badly. When you look down over the engine from the front of the car, it seems to be leaking on the bottom side of the pump towards the front of the cylinder head. If you look between the head and the pump you can see the fuel squirting out.

Any ideas what may have come loose there? Has the pump failed or is there a fitting there that I am missing?

Help!

Thanks,

Brett
Delaware, Ohio

tylernt · Post by **tylernt** » Sat Jun 24, 2006 2:06 pm

There should be a little rubber or plastic hose in between each injector, then a line from the passenger side injector to the injection pump. There should also be two bigger hoses going to and from the fuel filter area. I'd make sure that all of these are not leaking as they are cheap and easy to replace, before blaming the expensive injection pump itself.

That said, the cold start advance mechanism is near where you describe, and those seals have been known to leak. They can be replaced, but most of the work is getting the pump in and out of the car.

Syncronaut · Post by **Syncronaut** » Mon Jun 26, 2006 1:46 pm

Thanks for the tips!

I confirmed that all the lines are dry and connected. I chatted with my parts guy, a long time veteran of the industry. He suggested I check the main shaft seal behind the pulley. Said it was a common failure point and a cheap fix. Mentioned a weep hole behind the seal that gets clogged, pressurizing the housing and blowing the seal out the front.

I'll check it out and follow up with the list.

Thanks,

Brett

Asymtave · Post by **Asymtave** » Mon Jun 26, 2006 2:21 pm

My experience is with a pump some 10 years older than yours, but I'm not sure what he's talking about. On my pump there is an oil seal that seals to that shaft but there was no weep hole.

The shaft bushings are lubricated by the fuel. If there was a weep hole I would think that the fuel would just leak out. Maybe he's talking about a channel internal to the pump that supplies said fuel to the bushings? If that hole is plugged then the inside of the pump must be filthy.

At any rate, the pump has to come out to replace that seal. Tough to do without scratching up the shaft. Search around some more. I think Coke or Fatmobile has a way of pulling the old seal out.

My bet would be that it's the cold start advance shaft or cover as Tyler suggested - much more common. According to research done by Hagar, these O-rings see 60 to 80 PSI of pressure, I believe. Much easier to change once the pump is out.

Eric

Syncronaut · Post by **Syncronaut** » Tue Jun 27, 2006 3:39 pm

From where it's leaking I suspect the cold start valve too. I will try to get the pump out this weekend and see what I find.

Thanks to all for the solid advice!

Brett

tylernt · Post by **tylernt** » Tue Jun 27, 2006 3:51 pm

From where it's leaking I suspect the cold start valve too. I will try to get the pump out this weekend and see what I find.

If you do not have the injection pump timing gauge tools, scribe a mark on the pump and pump bracket so you can reinstall it in precisely the same position. The pump is designed to tilt away from or toward the engine to adjust the timing (like turning the distributor on a gasoline engine, only more so). If you are off even a tiny amount, it will throw your injection timing way off.

Not trying to scare you -- just be aware of it and take precautions.

Syncronaut · Post by **Syncronaut** » Tue Jun 27, 2006 4:34 pm

Great call out. I will scribe a line for sure. I am borrowing the tools to set from a fellow VW diesel enthusiast, but it would be nice to have a reference for sure. I guess I should check the timing before I take the pump out to see where I'm at.

I read through the big Fatmobile post on pumps and a bunch of other links, but I'm not sure that I understand if you can change the advance seals without disassembling the pump. I don't think I wanna get that deep. Can I get to those seals externally?

Thanks,

Brett

libbybapa · Post by **libbybapa** » Tue Jun 27, 2006 8:20 pm

New belts are fine, washing is okay, but waxing is right out... Always causes problems.

Andrew

Asymtave · Post by **Asymtave** » Wed Jun 28, 2006 6:58 am

Yes, the cold start lever and timing advance piston cover O-rings are a snap to change on the bench. Just remove the screws (Allen head or Torx?) and take the covers off.

Be careful as there is spring pressure in there. Also, if you take the foreward cover off (Opposite side from the motor) there are shims in there that must be put back.

Also, as always with these, keep your bench immaculate clean and don't allow even a speck of dust inside the pump.

In all likely hood you're leaking at the small O-ring that seals the shaft of the cold start lever.

Easy on the torque putting the screws back in. (Torque specs for these pumps are the Holy Grail. A million dollars to the first person that coughs them up.) The housing is aluminum and the threads will easily strip.

Eric

Post by **Fatmobile** » Wed Jun 28, 2006 1:45 pm

I always wonder how the cold start lever is supposed to go back on.
Try marking it before you remove it.

Syncronaut · Post by **Syncronaut** » Fri Jun 30, 2006 4:51 pm

Thanks for all the solid advice. Does anyone have the correct size of the o-rings I'll need handy? Do I need a specific composition of o-ring, or will a generic hardware store variety work? Just has to be compatible with diesel and bio-diesel?

Thanks!

Brett

tylernt · Post by **tylernt** » Fri Jun 30, 2006 5:25 pm

TDoes anyone have the correct size of the o-rings I'll need handy?

See viewtopic.php?t=4996 for the main seal. Not sure about the cold start seal.

Syncronaut · Post by **Syncronaut** » Tue Jul 04, 2006 6:16 pm

A mechanic friend dropped by today and we took a look at my leaking pump. It appears to be leaking between the high pressure distribution block on the end of the pump and the pump housing. I did some digging through the files, and the only mention I found was about a "precision fit" between the two parts. Is there an O-ring in that junction that I can replace? If so, is this something I can do with the pump in the car? The exploded diagrams and photos I've seen don't look so promising.

Thanks in advance,

Brett

libbybapa · Post by **libbybapa** » Tue Jul 04, 2006 9:51 pm

There is an o-ring there and you *Might* be able to replace it on the car. I heard someone metnion how they removed the lines, and loosened that portion of the pump. Then picked the old o-ring out of it's channel, snipped it and slid/stretched a new one over the pump head and tightened it down. That being said, it will be risky, and not my fault if the pump gets messed up.

Andrew

Post by **Fatmobile** » Wed Jul 05, 2006 2:10 am

I think all the guts would fall out when you pulled the head, if you did it with the pump on the car and the car on it's wheels. Car on it's side might work

.
I think I put a link to a thread about changing this seal, in the FAQs at the top of the general fora.
Only thing I can think to add to it, is hagar suggests glueing the springs in place with wax before you try putting the head back on. I can see how this would really save some time and hassle. Setting the head back on with all the springs in place is the real hard part to this seal swap.
As for where to get seals. I send people to the bosch service center site and hope they find somewhere close by. The site was down just now when I went to it but it might be back up soon:
http://www.boschservice.com/public/serv ... otive.html

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Injection pump leaking, any ideas?

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