Coolant CO2 test for car, cheap kit available?

[leebex]

Ive got some coolant issues on my car and trying to diagnose it is leading me nowhere.

The car is a cheap garage trade in, so I don't plan on spending much on it, but Im a glutton for an Italian car, so couldn't help myself but buy it. Its an Alfa 145 cloverleaf, but that's beside the point :p

Now, the car either has a huge airlock which Ive tried numerous times to shift, or a part time water pump that works when it feels like it (car sometimes runs too warm, but doesn't overheat) or the headgasket has/is failing.

Coolant is new and clean, Radiator has recently been changed, by previous owner, Ive fitted a new thermostat, but still the car runs too warm.

Is there a cheap CO2 test kit for the coolant available? the local garage want £20, but the Mr Tightwad in me says lets try a cheaper way if possible.

Lee

[DJ123]

I'm guessing with it being an Alfa it isn't a fully sealed coolant system with an expansion tank. Probably the standard system that allows feedback into the reservoir.
How is the water pump driven? Chain/belt/geared? My guess (as with most cars) the water pump is due to be changed when the timing belt/chain is as they tend to wear out.
Have you tried the standard air bleed techniques to relieve the air lock?

[leebex]

Ive bled it with the reservoir tank cap off and car running, Ive squeezed all the pipes, and Ive even unscrewed the water temp sensor a couple of turns, much like bleeding a radiator indoors.

The heater only puts out luke warm air at best.

As for the water pump, I can see coolant returning to the tank, but not continuesly, more spits and spurts. I took that pipe off the tank and blew down it hard, a jet of coolant came out the tank, so its not blocked either.

Drove a 150 mile round trip last weekend, and it ran at about 100degrees for a few mins, wasn't even in traffic. cooled itself back to just under 90 and didn't play up again. although the heater was cool sometimes, hot others on that journey

[embee]

I don't know anything about that car, but it's not unknown for some water pump impellers to become detached from the shaft, then they turn when they feel like it. Just a possible.

[SIII]

Had a similar sounding problem with the disco, had a sniffer test at the garage and it did not show anything!

Turned out the plastic dowels had sheared and the head had moved a couple of mm's, causing the coolant system to pressurise.

So even if you do a sniffer test it doesn't always prove one way or the other.