ALH Injection Pump Head still leaking after Seal Replacement

loewenwolf

Well-known member
Joined
Mar 22, 2021
Location
Victoria, BC
TDI
2003 Jetta Wagon - Manual Trans
Thursday I replaced just the head seal as I don't have VCDS for timing. Leak stops, Hallelujah.

Saturday, friend from nearby brings VCDS and we do up the other two top seals. Good test drive, got the car up to temp, and no leak. No leak the next day either at temp.

(both with Diesel Geek Kit)

Today I look 48 hours after our job on Saturday and Head appears to be leaking even worse than what is was before. But now it appears the leak is on the backside of the pump off the bracket (initially it just slow dripped on the front side), as well as the front. Photo showing where the leaks are coming from.


With a light and a mirror, it doesn't appear the leak is coming from the big triangular seal in the middle of the 4 lines, but other than that because of where it is I can't really see where it originates, only where it drips.

Right away, any takers on "you pinched the head seal on first attempt?" Just curious why it wouldn't leak right away if that was the case.

All thoughts and wisdom welcome as I maintain being cool while totally annoyed.
 
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Windex

Top Post Dawg
Joined
Apr 1, 2006
Location
Cambridge
TDI
05 B5V 01E FRF
Did you take the pump out or do the head seal with the pump installed?

If installed, it is not uncommon for there to be a ring of corrosion on the aluminum, where it meets the head, as they are dissimilar metals.

Not gonna lie, I never do the head seals in the car for exactly that reason - too much risk that the head seal with get kinked, or chafed dragging across the corrosion you just cant see when the pump is still in the car.
 

loewenwolf

Well-known member
Joined
Mar 22, 2021
Location
Victoria, BC
TDI
2003 Jetta Wagon - Manual Trans
Did you take the pump out or do the head seal with the pump installed?

If installed, it is not uncommon for there to be a ring of corrosion on the aluminum, where it meets the head, as they are dissimilar metals.

Not gonna lie, I never do the head seals in the car for exactly that reason - too much risk that the head seal with get kinked, or chafed dragging across the corrosion you just cant see when the pump is still in the car.
It was left in the car and you might be right.

Any idea why it wouldn't leak the first two days of driving, and then starts leaking today, tho?
 

STDOUBT

Veteran Member
Joined
Jul 30, 2007
Location
Portland, effing Oregon
TDI
dos jettas
^For sure you have to have a really clean outside of the pump, and the gap between the iron head and the aluminum body is considered outside (on my cars they don't actually touch). IIRC, the times I have done this, I blast the gap with air. Might have even sprayed the gap with something, de-greaser probably.
If debris was caught in the o-ring seat, it could possibly over a short amount of heat cycles kinda slowly cut through the seal I suppose.
@loewenwolf, once you solve this leak, make sure and clean that black wire jacket you can see close to your lower left red circle. That fuel will eat it until it shorts out.
This is why the Dieselgeek kit comes with two o-rings :)
 

loewenwolf

Well-known member
Joined
Mar 22, 2021
Location
Victoria, BC
TDI
2003 Jetta Wagon - Manual Trans
^For sure you have to have a really clean outside of the pump, and the gap between the iron head and the aluminum body is considered outside (on my cars they don't actually touch). IIRC, the times I have done this, I blast the gap with air. Might have even sprayed the gap with something, de-greaser probably.
If debris was caught in the o-ring seat, it could possibly over a short amount of heat cycles kinda slowly cut through the seal I suppose.
@loewenwolf, once you solve this leak, make sure and clean that black wire jacket you can see close to your lower left red circle. That fuel will eat it until it shorts out.
This is why the Dieselgeek kit comes with two o-rings :)
Alright, thanks so much, this is why I figured it does come with two rings, but man I really thought I was careful, but obviously not careful enough.

Appreciate both of these tips and ya will, again, clean that electrical connector really well once it is solved.
 

fatmobile

Veteran Member
Joined
Jul 16, 2019
Location
north iowa
TDI
an ALH M-TDI in a MK2, a 2000 Jetta, 2003 wagon
I run a pipe cleaner around the o-ring slot to clean it out.
I suppose a proper piece of string would work.
Wrap it around and pull each end.
Spray it down good.

I lube the o-ring with vasoline.

Also if you are sliding the o-ring over the head,
put a cup over it, for the o-ring to slide up on.
I get no kickback from Caseys for posting this pic. Not even a pizza.
injectionpumpheadoring by vwfatmobile, on Flickr
 
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loewenwolf

Well-known member
Joined
Mar 22, 2021
Location
Victoria, BC
TDI
2003 Jetta Wagon - Manual Trans
I run a pipe cleaner around the o-ring slot to clean it out.
I suppose a proper piece of string would work.
Wrap it around and pull each end.
Spray it down good.

I lube the o-ring with vasoline.

Also if you are sliding the o-ring over the head,
put a cup over it, for the o-ring to slide up on.
injectionpumpheadoring by vwfatmobile, on Flickr
This is a great idea with the cup. And good point on the pipe cleaner.

When you say spray it down good, you mean the outside of the pump, or do you mean the slot where the ring goes? What's the choice of spray here?

Thanks
 

fatmobile

Veteran Member
Joined
Jul 16, 2019
Location
north iowa
TDI
an ALH M-TDI in a MK2, a 2000 Jetta, 2003 wagon
I mean spray down the area the pipe cleaner is scrubbing, with,...
I'd use brake cleaner.
I put the pipe cleaner around the pump then pull each end back and forth.

On the old 1.6s, when you remove the small (12mm?) bolt in the center of the head the hole goes down to the piston.
Some folks would put a longer bolt in there to push the piston in as the head was moved away from the body.
To keep the guts from falling.
With the TDI, that hole might narrow down and need a skinny shaft to do this.
 
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