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 Overheating or not? Baffling!
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bigt80

United Kingdom
979 Posts

Posted - 07 Jan 2018 :  16:29:14  Show Profile  Reply with Quote
I would just endorse Panky's comments. Running w/o a stat is for emergency use only and not prolonged periods or 'normal' running. If you have to do this to achieve proper running temp then something else must be wrong; starting with the stat itself of course . G
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Panky

United Kingdom
25 Posts

Posted - 29 Dec 2017 :  16:47:16  Show Profile  Visit Panky's Homepage  Send Panky an AOL message  Reply with Quote
I respect the knowledge your two mechanics have but I've got to disagree on this. I've no Personal experience on the damage it can do but I never run without a stat for log enough to find out. If you look at it this way I think it is well known that the main cause of engine wear takes place during start up and warm up, a thermostat will help the engine reach the temperature it is meant to run at as quickly as possible so running tolerances and oil performance are as close as it can get to design. Without a stat the temperature is constantly changing and as a result the oil has to work much harder and tolerances are all over the place. Wear on the engine will increase but not noticeable immediately but will take a while- but much faster than an engine that isn't subjected to the extra stresses caused by constant temperature swings.
I would advise you try a new stat and if you are still having temperature issues then there is a problem elsewhere, but hopefully not.
Did you try putting the old stat into a pan of boiling water to test it? would be good to know if it was at fault.
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Sunbeam Tommy

United Kingdom
7 Posts

Posted - 29 Dec 2017 :  13:01:45  Show Profile  Reply with Quote
The advice here is most welcome. However, I am baffled by the advice about NOT running the engine without a thermostat.

I have spoken to 2 professional mechanics, one with 40 years experience, and they both say that they have NEVER known running an engine without a thermostat to cause ANY damage whatsoever.

They say it might result in poorer fuel consumption but no damage.

What is the evidence you have that damage could be caused please?
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pruyter

Netherlands
214 Posts

Posted - 29 Dec 2017 :  10:50:58  Show Profile  Reply with Quote
I certainly should not advise to run the engine without a thermostat, so I should start with trying out a new theromostat.
And yes this engines are prone to leak with among others culprit candidates like the timing cover, sump pan, side cover and rocker cover.

Regards,

Peter
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Panky

United Kingdom
25 Posts

Posted - 25 Dec 2017 :  22:09:27  Show Profile  Visit Panky's Homepage  Send Panky an AOL message  Reply with Quote
Good news but I wouldn't run it for too long without a stat as the you will get preferential flow through certain parts of the engine and others will be starved. The stat is there to keep things at a constant temperature and running without one will mean the temperature fluctuates up and down, dependent on conditions, which will eventually accelerate wear on internal components.
Putting a new stat in will also make sure running without one isn't masking some other problem.
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Sunbeam Tommy

United Kingdom
7 Posts

Posted - 25 Dec 2017 :  15:44:54  Show Profile  Reply with Quote
Problem solved!
I have given the car a 50 mile run with the thermostat removed and it ran cool as a cucumber with the gauge not moving above about 150f. I assume there is not a problem with it running too cool?

Thanks forum for your advice.

Generally, are Audax Rapiers prone to engine oil leaks by the way? I seem to have developed 2 minor ones but until I get underneath it is difficult to know what it is.
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Sunbeam Tommy

United Kingdom
7 Posts

Posted - 20 Dec 2017 :  18:35:01  Show Profile  Reply with Quote
Thanks for this helpful advice.

Thermostat has now been removed, and car now awaits a test drive.
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Panky

United Kingdom
25 Posts

Posted - 20 Dec 2017 :  17:56:04  Show Profile  Visit Panky's Homepage  Send Panky an AOL message  Reply with Quote
Thermostat is a good place to start but I would get one of these and check around the system to see what the temperature actually is

https://www.ebay.co.uk/itm/Temperature-Gun-Non-contact-Infrared-IR-Laser-Digital-Thermometer-FDA-Approve-EP/263394678056?hash=item3d538bd528:m:msXtW_auzGH8meG7heix1yg

I got a similar one to check one of my Commers as the gauge was reading high, in my case it was a sender/gauge miss match and the temp was fine. Great piece of kit and cheap as chips.
Couple of questions though - does the car get regular use? Have you worked on the cooling system recently? Does the heater work OK.
Just trying to nail down the possibilities of what is happening - hopefully nothing major.
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Sunbeam-mike

United Kingdom
81 Posts

Posted - 20 Dec 2017 :  13:07:57  Show Profile  Reply with Quote
Thermostat stuck?

Mike Hooper
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Sunbeam Tommy

United Kingdom
7 Posts

Posted - 20 Dec 2017 :  10:38:09  Show Profile  Reply with Quote
I have a 1961 Mark IIIA Rapier.

On a recent journey of 100 miles, for the first 60 miles the temperature guage was sitting just above the midway position. Then it started to creep up and went to the extreme right position, indicating that the water was virtually boiling.

I stopped. The fanbelt was OK, oil level OK and when I carefully removed the radiator cap, I could see the radiator was full and the waterwas very hot but not boiling. The engine started first time, oil pressure good and engine ran perfectly but that temperature gauge crept up to the far right again.

Anyone know what is going on here? Could it be the gauge has developed a fault or could it be something more serious?
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