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Discussion Starter #1
After some search about the expansion tank caps.

Do pressure caps fail in both ways i.e. they don't allow the pressure to build up (1.4 bar) and this leads to overheating or they allow to much pressure to build up leading to coolant loss (marks of coolant around the cap).

Does this make any sense?

This is regarding a pressure build up in the cooling system of an 147 1.9 JTD 16V.
 
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The easiest thing is to change the cap they only cost £3/4 on eBay. See if it makes any difference.
As for the problem if you have pressure build up it might be a head gasket allowing air in the water way and pressurising it .
Has the car had a leak and been repaired and refilled at all recently. If so it could be trapped air that was stuck.
 

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Discussion Starter #3
thanks for the answer!

I will try to find a cap locally to see it today.
Like you say there might be some bigger trouble in the way. I explain what happened:

Arriving home after 500 km, the temperature rises quickly(2 marks above 90 ºC), the radiator fan in second speed, tried the heater and not heating! Quickly parked and turned off the engine. No coolant in the expansion tank!
On the next morning I do a better inspection, take the cam belt covers. There was coolant dropping behind the water pump pulley.
Next, I send the 147 to the workshop (AR dealer) telling them what happened. I also ask that they change the pump and the timing belt (don't have 60000 mile yet but I just noticed on car maintenance book that they have 7,5 years).
After the job is done, the mechanic told me that I should take a good look on the temperature gauge. They noticed some marks of coolant around the expansion tank cap, meaning that the cap is not good (they didn't had caps) or, there is to much pressure building up in the cooling system, due to a possible head gasket leak and it could have been the major culprit of the coolant loss.

driving home (50 km):
- no overheating
- no white smoke
- the oil color is OK

Going to find a cap first. If it doesn't work, going to ask for a compression test on the cylinders.
 
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It maybe you have been lucky but watch the water level for the next couple of weeks to be sure it's ok . :)
 
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On here they recommend new belt at 50,000miles or 5 years on the diesels just to avoid problems like you have had .
Petrols 36,000 miles 3/4 years.
 

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Discussion Starter #6
The recommendations here are more or less the same. When I bought the car I only looked at the millage of the last timing belt change, forgot the how long it was :cry:

The new cap is on and there is still much pressure built up and signs of coolant loss around the cap. Going to buy an Universal Block tester on eBay before doing a compression test.
 

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i am looking for a place where i can buy EXPANSION TANK and a Radiator for an Alfa Romeo 156 Sportswagon in south africa, Gauteng or pretoria. can you please help.
 
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