[balders]

I really need some help, please guys, before I douse the inside with a gallon of petrol and throw a match in!! I am sick of staring into the engine bay and trying to work this one out.
My problem is over heating and venting coolant at the expansion bottle. I have replaced the water pump, the expansion tank cap and today the thermostat housing,and STILL she is blowing off coolant and over heating, we limped back from town today with the heating on max and the blowers on full wack!

I keep finding after these episodes that the rad is very hot at the top and cold at the bottom, I would expect that a car that is overheating would have a red hot rad?? The heater matrix hoses are equally hot, the top of the thermostat housing very hot but the bottom of it cold!
The wife and I filled the rad with hot water tonight and it took about 3 litres to fill and it appears to be flowing ok.
Have I picked up a faulty stat?
Dose anybody know the coolent flow direction? I assume its in via the bottom and out through the top?
I would be really gratful for any input on this before I do something reckless like buying a Ford Galaxy or something equally sensible!!!

Regards
Mark

 

[keithdixon]

Check that it is has all air removed from the engine and burped properly.

 

[Rich998a]

Is the radiator blocked? :think:

That could be the reason the water pump finally packed up as it tried to pump water around a blocked system.

 

[kmagnuss]

Burp it.

 

[balders]

Thanks for the replys

I don't think the rad is blocked. We flowed water from a garden hose through very easily this evening,the other pump gave out whilst I was rebuilding the engine recently(think the ceramic seals dried out whilst off the engine for 3 months).
I will try refilling tomorrow and giving it a good burp!! then cross everything and go for a drive.
Thinking about it I am wondering if it is air locked because we drove for about 20 miles at about 40-50 mph with the temperature gauge at 12 o clock then very quickly the the temperature shot up.I have found this evening though search that the pump actually sucks the coolant down through the rad(I think!) so could the air be collecting under the stat and causing a cool spot or air lock?
Regards
Mark

 

[TehPriest]

Hot water rises, cold falls. the water enters the engine cool at the bottom and as it cools the engine takes on heat and rises up. The thermostat opens and the water flows into the top of the rad. The pump forces the water into the rad and down. As it cools it falls to the bottom and re enters the engine. This would happen without the pump but the pump makes it many times more efficient.

4 things can cause overheating.
1. too lean a mixture (unlikely)
2. low coolant lever (sounds like you had this one)
3. Failed head gasket/slipped liner or cracks. (this could be what is causing your water level to fall)
4. badly sealing reservoir cap/split or loose hose. This one would be obvious if it were the case.

My guess would be #3

ray:

 

[kmagnuss]

...we drove for about 20 miles at about 40-50 mph with the temperature gauge at 12 o clock then very quickly the the temperature shot up....

Telltale signs of an airlock. Time for a good belching.

 

[balders]

Thanks for that info Tehpriest
Hope your wrong about the head gaskets because this engine has only done about 200 miles since full rebuild including new gaskets and skim.
I hedging my bets on a good belching,as I know these engines are notorious for being problematic but I have never had trouble before!!
Cheers

Mark

 

[kmagnuss]

I've never in my life seen an engine so prone to air locks in the cooling system. If one of us was smart we'd design a filler cap higher than the rest of the system.