Airlock or stuffed Waterpump?

[bigbofo]

2003 147 TS: thermostat stuck in open, then engine overheated. Replace the stat, but now the engine is still overheating...

I havent touched the plastic bleed valve on the radiator yet, since many other alfa forum members advise against it - but what would be the correct way to bleed the coolant system?

also, what indicates a stuffed water pump, since the coolant seems not so circulate: as engines warms up, new stat now opens, but radiator stays cool.

Any ideas?

[colcol]

You mean thermostat stuck shut and engine overheated?, the water pump usually gets noisy, due to bearing and or it leaks, although you could have the fan with broken blades or the fan cracked and spinning on the shaft, the water pump should be replaced every second cam belt change, that is 6 years or 100,000klms, didn't know there was a bleed valve on the radiator, [learn things all the time on this forum], this is how i fill the cooling system in mine to avoid air locks, make sure heater is on max heat, as it is part of the cooling system, have all the raditor and heater hoses off and disconected, start filling the reservoir tank with red or pink coolant slowly, and when it starts to dribble out of a lower hose, connect that lower hose up and continue filling reservoir until the next highest hose starts to have coolant dribbling out, then connect it up, continue doing this until you reach the highest hose, and this will help elliminate air locks, as the air has no escape, so the water won't flow through, when full, start engine, with pressure cap off the reservoir, and as the coolant level drops in the reservoir, keep topping it up, and keep an eye on the temperature gauge, while listening for any boiling sounds coming from the engine, see how you go with this, Colin.

[bigbofo]

yup... pretty much what I did.... also squeezed the radiator hoses...

but I start to believe it is the pump! there should be a constant coolant exchange while engine is idling, right?

now, if i start the engine it heats up to 90, thermostat opens, fan comes on and a minute later temperature keeps rising while radiator stays cold and there is no circulation in the reservoir happening...

[Mick A]

It does sound as though it will be either a blocked radiator or shagged water pump. The latter more likely.

[bigbofo]

Well, on the positive side - now I got a good reason to change this pesky variator while i am at it... the diesel sound was driving me insane!

[colcol]

And as you do the 'diesel' variator do the cam belt and balance belt while you are doing your variator and water pump, and take off the pulleys and idlers and check them for wear, you may want to squirt a hose through the inlet on the radiator and see if it comes out of the exit, seeing if it is blocked or not, and if it is, take it to a radiator repair place and get it power flushed, Colin.

[bigbofo]

Ok - the root problem was a faulty water pump! There were no leaks, no squeak, no nothing that could have visually indicated the failure... the impeller simply rotated on the drive shaft and lost its connection. Since I was in there, I also changed the Variator, pulleys and belts. The Alfa manual states that this should be a 3hr job...  Gee, it took me a little longer than that! But worse, I got sent the incorrect timing belt (for 1.6l TS, not 2.0l TS) which is shorter... So I had an opportunity to DO IT ALL OVER AGAIN. Much quicker second time around....

[colcol]

The V-6's suffer from the plastic water pump impellar syndrome, but i didn't know the 4 cylinder did as well, i know the 4's have a plastic fan, but have never heard of them spinning on the shaft, my genuine original pump was plastic as was the replacement pump [Quinton Hazleton] was also plastic, what brand of water pump did you use, and was it plastic?, see what we mean!,  change the water pump every second cam belt change, that is 6 years or 100,000klms, or whatever comes first, Colin.

[Steve S]

Yeah even the older twin sparks did it as well. The first one I came accross was in a 164. It had me fooled for a while.

[Evan Bottcher]

I got a little cross-eyed reading that. You must mean in NZ where there were twin spark 164s?

[Steve S]

Yep, that was many years ago in NZ.