I've just had the cambelt kit and water pump replaced on my Mk 1 Mondeo. The system was refilled with 50/50 antifreeze, which is about what it had before.
I noticed on the way home that it runs hotter now than it did before - the gauge is on the R-M of 'NORMAL' instead of N-O. Not a huge difference, I know, but I'm curious.
I would have thought a new pump would have made it run slightly cooler.
Any ideas?
I would wonder if the system has been bled properly. Mike.
So its actually running where its supposed to now instead of too low which was what it was doing?
Nothing to see here, move along.
lol.
PCPaul gurgled happily, sounding much like they were saying:
Thermostat replaced with a slightly higher temp one?
Thermostat too?
If so, then it is now running exactly where Ford intended it to- was running too cool before..
Tim..
Oh, I know that, I'm just curious as to what could cause it to run hotter with a (presumably) higher flow pump than before.
I replaced the stat myself a month or so back, so that hasn't been touched.
If it has increased the flow it could be that the hot coolant is getting to the sensor quicker so it hasn't had a chance to cool so much. Maybe the fresh coolant has a better heat transfer ability but I would have expected that to transfer heat to the thermostat better, maybe it's just transferring heat to the sensor better. You can probably guess that I have no idea :-)
The reason I'm replying though is that I'm not sure why there should be a difference to the flow rate. Do the blades wear in time? On my car it has metal pump blades and it's driven by the aux belt so it won't go any quicker. I replace the pump with the timing belt because the timing belt has to come off to replace the pump so it's easier to do at the same time. The reason I replace the pump is because of possible bearing wear, the pump isn't running any slower.
I believe the impeller blades can wear (or even chip) in time, although this is more likely on a boat engine where the pump handles canal/river water which is more likely to have abrasive particles in. Usually in a car it would be bearing troubles.
I do know that if I take off the expansion chamber top (while unpressurised...) and run the engine to warm, the return flow is noticeably stronger now than it was before.
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