How to test the coolant pump?

Yvan gurgled happily, sounding much like they were saying:

The water pump will either be working fine or pissing water out of the seal onto the floor. There's really not another failure mode for them.

Go through the rest of the cooling system, and make sure it's all good - might as well just chuck a new thermostat in, they're usually cheap enough. Make sure the hoses are all good, the rad warms up evenly, and change the coolant. If it's not been done for a while, flush it through with clean water before putting the new in.

Drive it up a hill when it's hot:-) Have you changed the thermostat?

Nedavno Adrian napisa:

It's this one:

What if impeller loses few fins? I flushed coolant system last summer, and added fresh Castrol coolant. I did not see any parts going out, or rust, sludge... Just clean water.

Thermostat can not be the cause of my problem, as the radiator is still cold (and the hoses going in and out of it) when evaporator temp is going down.

You've never seen one where the impeller has corroded away to the point of barely stirring the coolant? Or where the impeller is loose on the shaft, so it circulates at tick over, but not sufficiently at speed?

Only I've had both of those failure modes over the years on my own cars...

Chris

Nedavno Duncan Wood napisa:

I did, nothing wrong in this cold weather. Only last summer while I was driving up the mountain road. But I guess that it is normal. I go that way few times a year, but I did not pay much attention at the temp gauge, as it is twisty road with a busy traffic.

Nedavno Chris Whelan napisa:

So I guess that I have to pull it out to check? Do I need to change the pump gasket before I put the pump back?

Yes and Yes.

If the pump is old, and a replacement not too expensive, why not just replace it if you are planning on keeping the car?

Chris

Yvan gurgled happily, sounding much like they were saying:

It won't have.

I've had one where the impeller wasn't doing what it should be doing.

Ended up doing 2 cambelt changes in 2 months because I was too tight to replace it first time around.

If the pump was faulty the engine would overheat. You appear to be saying the engine coolant is staying too cold not too hot. That's either the thermostat or there is so much engine heat radiation in cold weather you need to blank off part of the radiator to help it warm up.

Well if the radiators cold then your engine's just too effecient :-)

Actually there is - disintegrated or detached impellor. It can spin like there's nowt wrong, unless you take it out to check, but there's no pumping action happening. Convection makes it look like water is still flowing but it isn't anywhere near the flow rate it should be.

And your basis for this statement is?

So far everyone except you thinks it's a possibility.

Nedavno Chris Whelan napisa:

Yes, the pump is old, but the car did only ~40k miles (in 20 years :-)

I plan to keep the car, but the pump is expensive (where I am) for me to change it if I am not sure that it is bad. But it looks that it is very easy to change it.

Nedavno Dave Baker napisa:

No, engine coolant is not too cold, the needle at the temp gauge is where it's suppose to be, and is going there at the reasonable speed, but it looks to me that coolant flow rate is to low, and not transferring heat at the LPG evaporator enough for it not to freeze during the warm-up (as it should).

Radiator and in and out hoses are cold during this period.

With my 325i when the pump wore out it didn't leak, it just didn't cool the car at idle properly.

If Yvan's car is icing the evaporator the pump is working fine, but the thermostat is possibly sticking open.

Nedavno Pete M napisa:

No it's not. If the thermostat is sticking open then the radiator would be warm, but as I wrote, both the radiator and its connecting hoses are cold.

Does the heater work?