[Vwdiesel] Water pump not pumping

[Chris Geiser]

Run the car with expansion tank cap off, and look for bubbles coming
through the coolant. That would confirm compression gases in there -
usually don't need a tester to tell with these engines, as you'll see
bubbles when running.  That would narrow it to head gasket or more likely
with that mileage, cracked head...

CG
**sent with mobile device
 On Feb 15, 2014 1:15 PM, "Erik Lane" <eriklane at gmail.com> wrote:

> Hello all,
>
> I'm looking for some ideas. I've run out, at least for the moment. This is
> on a 1981 Jetta with a 1.6NA diesel. No modifications to the system - I
> just replace parts when they wear out with the stock replacements.
>
> Driving home from work one day, that also happened to be about the coldest
> day around here, I had no heat and the temperature gauge was getting
> uncomfortably high as I was getting close to home. I was worried that I had
> lost all my coolant or something, but I was close enough to home and it was
> rising slowly enough that I was able to make it without getting anything
> into danger zones. (Plus it was cold and snowing with no good spot to leave
> it.) Though I live near Portland, OR, so our cold is not like most of you.
> It was probably mid 20s.
>
> I got home and checked it, and it was full of coolant. After puzzling over
> it and letting it cool I took everything apart, thinking that maybe the
> impeller had come off the shaft. That wasn't the case, and even using those
> rubber band strap wrenches to get a really good grip, I couldn't budge it.
> I tried tapping with a punch and hammer to see if the impeller would move
> at all on the shaft in or out, and it wouldn't.
>
> I replaced the thermostat, cause I had one on the shelf, and it seemed like
> a long shot, but I was running out of ideas. I drove it around a bit after
> putting it back together, and it acted up again. I looked at it, and the
> coolant bottle was completely full, but it still hadn't even sucked down
> any coolant into the radiator. In the past I've always been able to fill
> these cars by only putting coolant in the fill bottle and running the
> engine a bit to pump it around the system.
>
> I've got it apart again, and I've put the exhaust from a shop vac up to the
> hole in the block to see if there were any restrictions, and coolant came
> shooting out of every hose that I had open. When I go to drain the system,
> I open all three hoses down at the water pump, and water comes out of them
> just fine. I also have an inline tee in the hose to the heater core that a
> previous owner installed - it's one of those that comes with a radiator
> flush kit and has a screw on cap to be able to purge the system. So using
> that I know that I have water to the heater core.
>
> I've stood there and watched while the engine was running, and the water
> pump spun just fine. (Well, the system was full of coolant, so I only know
> that the pulley was spinning. I wasn't directly watching the impeller.) I
> revved it up, and there was no hesitation or slipping of the pulley.
>
> I've read an idea about a hose collapsing on the input side of the pump and
> restricting the flow, but since there are three of them, I find it hard to
> believe that they would all fail at the same time.
>
> My dad has suggested a head gasket failure and air lock that is stopping it
> from pumping, which seems possible, but I want to remove all other credible
> possibilities before removing the head. I've also dealt with a couple of
> these before that had blown head gaskets, and I've never had one stop
> pumping like this.
>
> The coolant that came out was pretty ugly black, but not oily. So that
> would seem to give some credibility to a head gasket. I've never noticed it
> look anything other than green before, but it's been so reliable that I
> haven't had to mess with it much lately.
>
> So I think that's all the relevant facts. I'm hoping to learn/benefit from
> the combined experience and knowledge of this list. I'm kind of at my wits
> end, and with this engine having unknown miles, but I suspect in the
> ballpark of 400k, I might get in there and decide it needs to be rebuilt.
> With where I am in my life right now, it would be best to be able to wait 6
> months or a year before having to tackle such a big job. So even if I open
> it up, I'm going to want to do the bare minimum to get by until I have the
> time to really do it right, if it gets to that.
>
> Thank you everyone!
> Erik
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