Coolant System Problem Options

[80gumdrops]

Howdy. Got a UK '96 ST202 3S-GE.

Firstly, when I start the engine I can hear air bubbles circulating around the cooling system (happens about 3 seconds from ignition).

I've checked that the coolant is fully topped up.

On two occasions I haven't heard any bubbles.. when that happens, no hot air comes in and the engine temp rises above normal. When this has happened I've felt the pipes and found that the top pipe and top of the radiator is hot and the bottom pipe and bottom of radiator is cold.

First time it happened I decided to get the thermostat replaced.

Second time, I added coolant and gave the pipes a squeeze, which must've dislodged some air, because it started working again.

Last night, I heard a few bubbles as usual and had heat as usual, but about 5 mins into the journey I gave it some welly up a hill, lost hot air and the engine started to overheat again.

After a 5 min rest, I started the engine and heard LOADS of air bubbles circulate.

Any ideas folks?

Cheers.

[trdproven]

with a radiator cap off, a good sign its a hg is when you can also the bubbles are pretty extreme and never stop. but you would already probably see a lot of exhaust smoke, mixed oil or coolant, overheating if at this point. thermostat is between what hoses are hot and cold on the lower and upper. radiator cap is the cheapest to test, borrow a good one, or see if your old gasket feels a bit thin, i just did one 2 weeks ago, and it was the radiator cap on an integra. but for your issue just check for all signs.