thermostat quqliaty

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dalebrignall
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thermostat quqliaty

Post by dalebrignall »

yesterday i had yet another thermostat fail on me , they seem to last 2000 miles , i would rather pay more for something that works , so annoying
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MikeNash
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Re: thermostat quqliaty

Post by MikeNash »

What temperature do you want? I've got few that are ages old but all work. Could find you one.
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dalebrignall
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Re: thermostat quqliaty

Post by dalebrignall »

many thanks ive fitted my spare one and ordered another just frustrated they dont last
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bmcecosse
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Re: thermostat quqliaty

Post by bmcecosse »

What happens to them? Usually extremely reliable and no reports of problems that I have seen. You sure that's the problem?
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Monty-4
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Re: thermostat quqliaty

Post by Monty-4 »

I've had a new one fail too. Two examples doesn't really equal data or a trend though. :)
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dalebrignall
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Re: thermostat quqliaty

Post by dalebrignall »

they just fail to open , i back flushed the rad thats 2 years old and was clean as a whistle tha water pump is 4 years old , coolant was 4 months old so the cooling system is good , they just seem to jam shut dont know why
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bmcecosse
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Re: thermostat quqliaty

Post by bmcecosse »

And does the engine boil up? I've never know a stat to jam shut - maybe had one in all my years that stayed open - but that's all.
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amgrave
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Re: thermostat quqliaty

Post by amgrave »

I find when they fail they stick open but not fully so it takes the engine a while longer than usual to warm up and because it's not fully open can over heat when pushed hard or in hot weather. Never had one fail to open though. It is in the right way round ?

oliver90owner
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Re: thermostat quqliaty

Post by oliver90owner »

I've never know a stat to jam shut

I have. Not a moggy. I've experienced, first hand, both part open and non-opening failure in my 50 years driving experience.

The vehicle in question was a Ford P100 diesel pick up, while towing a fairly heavy load. The fault initially appeared intermittent, or at least I got it home after losing coolant through boiling, allowing some time to cool before filling. I was expecting a head gasket failure, but it survived with no more than a thermostat change by the owner. The truck went on to do another 50k miles, at least.

Open modern stats were more obviously 'jammed', as the spring should close it, but failing to open is not necessarily a 'jamming' situation, but if it did jam, the likelihood would be seal failure. The old 'bellows type' could jam open due to crud building up between the bellows. One I have (that was permanently part-open) is still working perfectly over 60 years after fitting, after cleaning. I would estimate the thermostat was fitted in about '53 or '54 as I cannot recall the actual modification ... but I still have the original manifold, which was removed.

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bmcecosse
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Re: thermostat quqliaty

Post by bmcecosse »

Are you sure the problem isn't in fact an over heating engine? When you take out a stat it is always 'closed' - it should open if you boil it up in a pan of water.
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Monty-4
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Re: thermostat quqliaty

Post by Monty-4 »

My new one that failed did indeed fail open. It took an age to warm up.

The old/original one has a 3-4mm hole drilled in the flat rim, I imagine this one done by the previous owner to get the heater going faster or to keep things flowing on short journeys?
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oliver90owner
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Re: thermostat quqliaty

Post by oliver90owner »

Overheating engines (for other reasons) generally don't respond to a simple thermostat change! Other signs are no circulation through a known clean radiator, or electric fan (if fitted) not called for operation if the sensor is fitted in the bottom hose. 'Stats stuck open at cold are obvious failures and are clearly not closed. One sign is that of needing the choke to keep an engine running on a cold day (and a mediocre heater, of course).

One way to reduce the effects of a non-opening 'stat is to put the heater full on with maximum fan speed - and likely open the car windows. That reminds me that my wife's Volvo 2 litre suffered a poorly opening 'stat. Eighteen years ago, that one.

'Stats are cheap, so no reason to risk 'cooking' an engine, once the symptoms are recognised. No need for boiling water, the opening temperature should be marked on the thermostat.
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Re: thermostat quqliaty

Post by bmcecosse »

The hole is drilled to allow a small flow of water when the bypass hose has been eliminated. This does indeed make for faster/better heater operation, and ensures full flow of cooling water round the back of the engine block and head until the stat begins to open. It's not essential to do this - but the heater tap should then be left open at all times.
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oliver90owner
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Re: thermostat quqliaty

Post by oliver90owner »

And I thought the small hole was there to avoid 'air-locking' when fitting, or refilling the radiator! It lets air through to avoid a part- filled water jacket and a potentially cooked head before the operator had any idea....
amgrave
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Re: thermostat quqliaty

Post by amgrave »

Yes your right, BMC was describing a mod :roll:

dalebrignall
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Re: thermostat quqliaty

Post by dalebrignall »

well ive been up north this week and since the thermostat change ive had no more problems did 800 miles last week and did not miss a beat .
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