How to test the coolant pump?

I've just rerouted incoming hose, and will check tomorrow if that helps. If not I'll replace evaporator with the other one I have.

And I now located temperature sensor at the evap return hose. We'll see tomorrow.

Yvan wrote on 21/01/2009 :

Check the evaporator is not blocked. Are the hoses feeding the evaporator hot? Not hot at both hoses would mean a blockage in either the evaporator or the hoses feeding it.

Duncan Wood laid this down on his screen :

The out pipe would only be much cooler if the flow were poor. Poor flow = all of the heat taken out of the coolant = low output temperature.

An, i had taken same to mean same but good point, Ivans probably not measuring it the way I do :-)

Nedavno Duncan Wood napisa:

I remember that last summer when I was driving up the mountain for a summer holiday (car fully loaded) the needle at the temp gauge did show a bit hotter than usual, but I thought that it was normal. I had no problems after that.

Nedavno Harry Bloomfield napisa:

I connected the LPG evaporator back to the hoses for heater (with tee-joints). I added some coolant, and now it is better, evaporator did not freeze when I tested it later.

Could be that coolant level was slightly low (I do not have expansion tank - coolant level is checked at the radiator - not easy to see there), so with low ambient temperature coolant might not be high enough to flow into evaporator "in" hose at the high point where I connected it (the highest coolant point at the engine).

When the engined warms up, coolant expands, and flow starts - no evaporator freezing. I might be wrong, just a thought.

Anyway, it looks that it is OK now, I'll post again if it is not. Thanks to all.

Ah well, good luck!

Detached impeller happened to me a few years ago. Mysteriously, the engine would run cool enough for several miles then suddenly overheat, but a spell of idling would cool it again, then it would run at normal temp for 20 or 30 miles. The cast impeller was a shrink fit onto the shaft and sporadically detaching and gripping, depending on heat.

Nedavno Duncan Wood napisa:

:-(

I started the car about an hour ago, and there was some crunching sound coming out of the area where the water pup is. I am not 100% sure that it is the pump as the fan makes a lot of noise. I do not think that the fan is touching the shroud, I checked, and as I can see it is not. Plus it did sound metallic. And engine rpm was constant, the sound was not.

Can the water pump do that? Impeller hitting something? Hire is my pump:

When I think about it I think that I heard this sound few times, but I always think I was imagining it. Now I am sure, my battery is bad, so I connected it to the charger, and while I was disconnecting the cables I could hear it quite good.

While I was looking and trying to pinpoint where it is coming from, it started to have more pause between the crunches, and than it stopped.

I guess it has something to do with the engine temperature going up.

What do you think, I probably have to remove the water pump, or perhaps something else can produce this sound?

You're never going to be happy till you take that pump to bits :-)

A collapsed water pump impeller will do that - hardly any coolant goes round the engine.

Seconded.

Having recently started to look at all the possible failure modes of BMWs, a plastic impeller on the water pump falling apart is one of them. Usually it just seems to be noticed as a rise in temperature rather than noises, but if you just catch it at the right moment I guess you'd hear it go...

Nedavno Duncan Wood napisa:

Are you trying to tell me that I am going to remove the pump unnecessarily or that I need to remove it and check?

And if it is not the water pump what can it be? Again, it is metallic sound, and the word that best describes it (well the one that I know in English :-) is crunching.

Take it off & check. You won't know otherwise.