Waterpump Working?

[Woz]

Hi All

A right puzzler!! (for me anyway)

I have a B5 A4 1.9 TDi 90bhp (AHU). My problem is that occasionally it loses coolant, didnt think much of it until this latest cold snap and was a bit concerned that I was diluting the coolant too much.

So I investigated a bit further. Top hose gets hot, bottom hose stays cold, slightly warm the other side of the thermostat housing, even after a run, get plenty heat out of the heater. Circulation problems I thought.

This is what I did today:

1. Removed thermostat, 1 side was nice and clean other side was covered in rust, tested it in a pan of boiling water and it works fine.

2. flushed out radiator to see if it was blocked, it wasn't but lots and lots of brown rusty water was flushed out. Running clear eventually.

3. Removed top hose flushed the block out rusty water again but was flowing, clear eventually.

4. Put it all back together but filled areas independantly i.e. block, rad, hoses. runs fine plenty of heat from the heater.

I dont think the coolant is circulating. I think the coolant loss is the water getting hot, building pressure and blowing out of the cap because the coolant in the header tank was coolant coloured and the water from the rad & block was brown, is there anyway of testing that the waterpump is working.
Should i be getting heat if it isnt circulating. Judging by the colour of the water I think this problem has been there for a long time, years possibly, but the car has never missed a beat, 1 other problem is that the temp guage doesnt work so I cant tell if it is getting too hot.

Any sugestions gratefully received.

Thanks

Warren

[phil miller]

it could be the water pump, i think if it was me id take the water pump off and make sure the impeller is ok, it is known that the impellers come loose and therefore dont spin, but i would have thought it would boil if it wasnt working, what you have done and checked so far is a good place to start, but like i said if in doubt about the pump take it off and check it mate

[Woz]

Thanks for the reply Phil, hadnt thought about the boiling thing but now you mention it, you would think it would boil up.

Cheers

Warren

[burkey1]

I would get the temp guage fixed whatever you do.

Are you sure the coolant loss blowing out the cap isn't the head gasket leaking???

You can get these sniffed quite easily..

[Woz]

I agree the temp guage needs sorting, have put a new sender in a while ago but it didnt fix it so I sort of gave up, 1 of them jobs that you know that needs sorting but never get round to it

Not 100% sure its blowing through the cap to be honest and i have thought about the H/G. Oil is fine now mayo but I know it could be going the other way into the cylinders but no steam coming out of the exhaust. H/G is the worst case senario. That was my next check (sniff test) but was wondering if you can do a test when the engine is running to check if the water pump is working.

Thanks for the reply.

[burkey1]

I was thinking the gasses are leaking into the cooling system, not the other way around. Thus increasing cooling system pressure.

With the issues you are having, not to have a working guage is very risky.

Is you fan coming on a lot??

Can you get someone with VAG-COM or VCDS diag tool to take a temp reading and do an output test on the dials.

You could try this link for ideas on how to test your pump.
http://www.ehow.com/how_4829065_test-water-pump.html

[Woz]

I see, didn't know that could happen. Unfortunatly I do not know anyone with vagcom etc. Will defo try to get the guage working tomorrow though.
I'll see if the top hose pressurizes tomorrow if it does I'll release the pressure then see if it does it again then i suppose that way it will be 1 less thing to check out. Thanks for the link.