Cooling system query

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Zelandeth
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Re: Cooling system query

Post by Zelandeth » Mon Jan 27, 2014 9:18 pm

From the description my gut feeling would be head gasket problems. Though that's just a guess - and it's kinda hard to diagnose remotely.

Are there any signs of bubbles in the coolant when the engine is running? Especially when the engine is revved.

I can't remember off the top of my head what the working pressures of the cooling system on the Ladas are, but I would have expected the hoses to be "firm" when the engine was up to normal temperature, but I wouldn't have said "hard" if everything was normal. Might be worth getting a "sniff" test done, which looks for signs of hydrocarbons in the coolant, or doing a compression test. If there are any signs of oily residue in the radiator or header tank that can be quite an obvious giveaway as well.

If the radiator cap isn't fitted, the coolant WILL tend to overflow when the engine warms up, just because of the coolant expanding. The fact that it will contract again when it cools though should normally mean that once everything cools down that the system will depressurise. If there's still pressure in there afterwards, that extra pressure has to have come from somewhere.

Usual candidates would be head gasket, or very occasionally a leak on the suction side of the water pump which can draw air into the system.
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Zelandeth
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Re: Cooling system query

Post by Zelandeth » Fri Feb 14, 2014 10:55 pm

Had something similar to this with my Suzuki Cappuccino a few years back. It was allowing water out into the expansion bottle, but wasn't then drawing anything back into the radiator when the system cooled.

Took a bit of head scratching initially to work out what was going on, but at least was easily and cheaply sorted in the end.
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Current fleet: 02 VW Caddy 1.9SDI, 90 Mercedes 208D Autotrail Navajo, 85 Sinclair C5, 78 Vauxhall Cavalier 1.6GL, 73 AC Model-70.

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