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Old 13th March 2019, 22:18   #31
Hawkesman
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Cheers John.

"Norwegian Blue", ha ha! "Joined the choir invisibule." Blimey, that takes me back!

No idea on the stat. Take it out to find out? Where is it? I guess I should buy a Haines manual before I give up. Got quite a collection of these now. The Hillman, of course, and Renault 5, Toyota Starlet, Metro, Montego, Peugeot 309, Cavalier, etc.

Happier days when it didn't hurt so much to get out from under the car to find my 10mm socket!
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Old 14th March 2019, 23:20   #32
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OK – I’ve been mulling this over today, and thinking about all the excellent help and advice I’ve been given here. This is my conclusion thus far (sorry if it’s a bit long, but I wanted to be clear so that the wise souls out there can correct my logic if it is flawed)…

The gas that escapes from the expansion chamber does not seem to smell of exhaust, although it does have a faint smell of petrol to it. So, if we assume, for the moment, that it isn’t the HG then it seems to follow that it may be the thermostat. If it was the water pump then presumably I’d see evidence of water seepage, which I can’t, though I’ll double check that tomorrow, but either way the pump would still be working. Also, the amount of coolant I lose seems consistent with the amount that comes out when I loosen the filler cap, which seems to imply that I’m not losing significant amounts from anywhere else.

If it is a failed thermostat then the coolant locked in the jacket would presumably boil, creating over-pressure. This would account for the water bursting from the expansion tank, and the also fact that it is cold because it is not circulating.

With regard to the blackened new plug in no. 4 then perhaps this is just because the extreme over-pressure has caused the new IMG to fail again at its weakest point, so letting coolant into the cylinder once more. This also kind of makes sense as the vacuum in the inlet manifold would draw coolant in (in a way that a HGF might not) and could also leave the top of the piston damp (which it is).

So, stat is my next target.

Well, that’s my thinking at the moment!
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Old 15th March 2019, 00:38   #33
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That's a good idea. Usually when I open a cap slowly when hot, it does exactly as you say. It releases the pressure gently and you can open it a little more over time until you can take it off with no overspill or drama. When it's cold, nothng happens. I'll try what you've suggested.
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Old 15th March 2019, 10:45   #34
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Pressure in a cold system points to exhaust gases in the coolant system - i would as suggested above leave over night after giving your car a decent thrash at motorway speed for 10 miles or so - but in addition to listening for a clearly audible hiss of escaping gas when you open the cap - stick your nose near the coolant tank to see if you can smell exhaust gas as well.
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Old 15th March 2019, 15:45   #35
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Don't let too much coolant get into the cylinder. I have a friend who bent a conrod because of water in the cylinder.
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Old 15th March 2019, 16:35   #36
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1.6 k series in a 2002 TF. Plastic inlet manifold. Leak into number 1 cylinder.
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Old 19th March 2019, 22:34   #37
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Quote:
Originally Posted by stevestrat View Post
The mid point on the gauge covers too great a temp range (75°C to 115°C) to be of any real use. The onboard diagnostic is more reliable.

Start the engine, press and hold the trip reset button until the display shows "test 1". Release the button then immediately press again and keep pressing repeatedly until it shows "test 19", release the button. The display will alternate between "Log 1 -on" & "Log 1 -off". While it is showing "Log 1 -off" press the button and press repeatedly until it shows "7" then release the button. This will give a live and accurate reading of the coolant temperature.
OK, even more confused now. Ran the engine (stationary) up to about 80 degrees, then took it for a run. The temp then fluctuated between 97 and 104 degrees, averaging around 99.

Switched off and checked the top hose and it was rock hard. Left it for 6 hours then opened expansion tank. Slight hiss then nothing. No coolant left in tank though. Sniffed expansion tank and could smell petrol but not exhaust.

Like I said, I'm perplexed.
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