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Cooling and Thermostat


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Hi all

Please excuse my ignorance on what I guess is simple mechanics.

I found my engine to take ages to warm up so bought a new thermostat.  I went to do a replacement and found my dear TR to be missing a thermo all together (is there a reason for this?).  I put in my new thermo and watched in concern as my temp gauge went up and up almost to red, then I switched engine off.  I did notice on replacement, a dirty foam and fluid around where the thermo would go but as I did a full flush some months ago so dismissed this concern.   It seems the thermo is simply not opening so is the thermo faulty or did previous owner know something I do not? 

Thanks for help

Rich

 

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Hi Rich,

sorry for asking, but is the thermostat installed the right way around? the spring should be at the bottom (facing down).

Another possibility is a faulty temperature. measurement, it may indicate too high. 

A 3rd possibility is air in the system after replacing the stat.

 

Regards,

Waldi

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Hi Waldi

Yes, did consider if I put in upside down but was right!  I removed the thermo and nice hot warmth came from the housing to the radiator (which did not happen before).  Do you think its air in the system?

Rich

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Airlocks can send the temp gauge into the red very quickly, and potentially cause damage including head gasket failure.

Try jacking the front of the car as high as possible when filling and remove the temp gauge sender from the thermostat housing. Fill with coolant through the radiator cap until the radiator appears full then refit the temp sender. Refit the radiator cap, and try squeezing the top and bottom hoses to push the coolant around inside the engine and radiator. Remove the cap, top up again, squeeze the hoses again and keep repeating until you cannot get any more coolant into the radiator.

Try running the engine up to temp. If it quickly goes to the red on the gauge again, you need to consider:

- Faulty gauge reading. Look at sender, instrument voltage regulator, and the gauge itself, in that order.

- Blocked radiator or corrosion/silt in internal waterways of the block. Try a flushing compound first, but a new radiator or removal of cylinder head to clean waterways may be required.

Most likely you have an airlock or a gauge sender problem. Good luck.

Nigel

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My guess is an airlock but check the opening temperature stamped into the thermostat body.

I like to use thermostats with an air vent hole, often they are fitted with a tiny ball check valve. If you haven't got an air vent I'd drill a 2mm dia hole in the thermostat.

If you have an overflow bottle fitted a few operating  cycles (warm up /cool down) in the garage will soon blow out the air and suck coolant back in -just keep an eye on the level in the overflow bottle.

Of course there's always the chance  a previous owner might have taken the thermostat out to mask a duff water pump.

 

 

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11 hours ago, AarhusTr6 said:

Hi Waldi

Yes, did consider if I put in upside down but was right!  I removed the thermo and nice hot warmth came from the housing to the radiator (which did not happen before).  Do you think its air in the system?

Rich

Rich,

as Nigel and Mike also point out, and after your additional testing, my bet is on air in the system.

Pump is probably ok, since you had more than enough circulation without a stat.

The above recommendations from Nigel and Mike cover it all so hope it will be resolved when doing all this.

Good luck,

Waldi

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Hi guys

I will give those tips a go.  I removed the thermo and the car eventually runs up to mid range temp so fluid is getting around, but seems thermo is not opening for some odd reason.

Thanks for help

Rich

 

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6 minutes ago, Mike C said:

If  the engine  runs up to mid range on the gauge without a thermostat , your cooling system's not in real good shape. 

Hi Mike?  Why so?  How can I check?

Rich

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Rich

Test the thermostat in a sauce pan of water on the cooker if has not got the air bleed hole, drill one in the flange (no bigger then 2mm)

Then fill the system through the thermostat housing and replace the thermostat. Remove the rad cap and start the engine and allow to tick over untill no more air comes out, this is known as burbing the system this should cure your problem

A nice little mod is to fit the thermostat housing from a mg midget 1500, this has a filler plug and is a straight swap

 

George

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21 minutes ago, Mike C said:

If  the engine  runs up to mid range on the gauge without a thermostat , your cooling system's not in real good shape. 

"Hi Mike?  Why so?  How can I check?"

 

The intention is that a cooling system should have capacity in hand so that it can cope when the engine is working in the worst conditions. That capacity is usually 'strangled' by the thermostat so that cooling is reduced to allow the proper engine temperature to be reached.  A car with good cooling capacity but no thermostat will not reach normal operating temperature on the road as it will be over-cooled most of the time.  If the engine gets up to normal temp when running on the road with no thermostat and without working hard, it shows the system hasn't got that spare cooling capacity and may be why someone removed the thermostat.

 

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Ok thanks

If the car is still, then it goes mid-way, once I start to blow cool Scandinavian air into the rad' the temp drop way down.

Why do some mention this little hole to be drilled?  Cant understand why.

Rich

 

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The little hole allows air to bleed through a closed thermostat and prevents airlock, it also allows water to circulate past the sensor element making it open.

If the thermostat sensor is surrounded by air or cod water it won't open. Most thermostats these days have a hole with a small ball check valve already fitted to it.

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Many of the thermostats I have seen have this small hole and usually a loose rivet (valve?). It is there to allow air to leak past the thermostat so that the system can be properly filled with water and so prevent air-locks.  Since the hole is very small it has no effect on water flow.

 

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Ok thanks

I put thermo in a pan and it opened up lovely.

So drilled a wee hole, double checked, spring down and ran engine....  watched as it crept up and almost to red and switched off.

So now drained fluids and will try Nigels recommendation,

Part two coming soon :-)

Edited by AarhusTr6
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When you run it up next time check if the top radiator hose gets hot. It should when the thermostat opens. If it doesn’t get hot when your temp gauge shows red then you have a flow problem or the gauge is telling lies, possibly the wrong sender. Does the heater work?

Edited by peejay4A
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Part two!

did a flush, jacked up front, filled up with fluids and kept squeezing hose and bubbles did come up.  Main hose at top goes got.  Gauge almost goes to red and stops and hot air comes out of vents (I had them open when filling).

The however, is I bough a temp sensor ray beam thing off eBay and its saying about 90 degrees on radiator and 100 on engine block so maybe sender is faulty???

Its cooling now and I will go do a check of sensor (I have a spare)

Rich

 

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Very good Rich, you are getting closer.

100 degrees on the thick cast iron block means the water temperature inside the block is higher, probably by 10-20 degrees, so it still appears the stat is opening too slow?? It may still be related to entrapped air. If you have a 14 psi radiator cap (hope so), you have been close to the boiling point at 14 psi(gage).

Safety:  Do not remove the cap when the engine is hot, but you could leave it off until the water reaches 95-100 degrees.

You can measure the water temperature in the rad when the cap is off, and can then also see more air escape, hopefully.

Waldi

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Part three!

I had a bottle stuck in radiator and warmed engine and pumped top pipe.  quite a lot of bubbles came up but gauge shows high.  After 15 mins + I basically tested water temp and its hovering about 60ish.  Tomorrow I try a new sender.  Learnt a lot.

Rich

 

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Sorry Rich,

what I miss on your post is "it get's hot while I drive the car".

Is your testing on ideling ?

Don't worry about air in the system, the water pump is a monster and strong enough to blow it with the coolant through the engine.

There is (and MUST be) a bypass in the TR6 water pump housing, diameter 8 mm. Is it blocked? Please look.

Ciao Marco 

 

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If the radiator temperature is indeed 90 degrees C then your sender's probably OK . I'd still change it for peace of mind or at least test its output. Make sure you have installed  the right sender , seems to be a problem with these:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&cad=rja&uact=8&ved=2ahUKEwidxbvoupPeAhVMU30KHXGMCVQQFjAFegQIBxAB&url=https%3A%2F%2Fwww.tr-register.co.uk%2Fforums%2Findex.php%3F%2Ftopic%2F40390-temperature-sender%2F&usg=AOvVaw3Y76w7KptlRvpj2IaDhZPf

Triumph water pumps are indeed flow monsters when they're working. Here's a video of a 4A pumping:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=video&cd=2&cad=rja&uact=8&ved=0ahUKEwjN8aGGupPeAhWRWX0KHXAyC3MQtwIIKjAB&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3D7Zw4Mj1JbVM&usg=AOvVaw1PqbhF_loO0Sak1rC2Q0-e

Good luck. I use the infra red gun to do a lot of radiator analysis- if it's reading roughly the same temperature on the block as on the radiator top header tank, like yours,  then the thermostat is almost certainly open.

Good luck for the weekend.

 

 

 

 

 

Edited by Mike C
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11 hours ago, AarhusTr6 said:

Hi Marco

I have never got that far yet (water pump).

Rich

Sorry Rich,

you have heat problems with your car ideling in your garage, you did not drive with the new thermostat yet?

Hi Mike,

very interesting, you found one of my videos on youtube...

I made them while checking the "story" of "air locked in the engine" that I have told so many times and wondered about.

You realised the engine is only running with about 1,000 revs?

Ciao Marco

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