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Choice of thermostat


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I've now had my TR4 for about 15 months and have never experienced any overheating issues even though I have been stuck in stationary traffic in hot weather. It has a mechanical fan only. It always seems to hover on the line just below the 70 mark. However, in this cold weather it isn't rising much above the 30 (maybe up to 40) though the heater is functioning (though I can't say it is toasty warm in there).

I haven't checked the thermostat (perhaps there isn't one) and I don't want to go down the road of switching between winter and summer ones as there isn't always a lot of difference up here in Cumbria.

I would like advice on the best all round choice of thermostat for north of England conditions

Thoughts anyone?

BTW. The bellows type that are a tad under £100 are just way too dear

Andy

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Edited by Ocheye
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You may have a faulty/incorrect temerature sender, giving a falsely low reading.

before foing to the trouble and expense of a new thermostat perhaps check the actual engine temp ?

steve

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You dont need a bellows type for a TR4 as the changed the size of the waterpump housing, I would fit an 82C one.

Stuart.

(waits for all the smart comments about fitting a restrictor in the bypass{unnecessary in my opinion})

Stuart.

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3 hours ago, Steves_TR6 said:

You may have a faulty/incorrect temerature sender, giving a falsely low reading.

before foing to the trouble and expense of a new thermostat perhaps check the actual engine temp ?

steve

That may be the case but it is a significantly lower reading in the cold weather

Andy

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I have seen several NOS bellows type thermostats for sale. They are marked TF4.

Is this the correct one for a TR4 or is the google/eBay search misreadiing my TR4 reference?

Maybe it is just coincidental that it has a similar designation.

Hope that makes sense to someone

Andy

s-l1600.jpg

Edited by Ocheye
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Its not the bellows type thats expensive its the "Shrouded" bellows type. IMHO you dont need a shrouded one on a TR4 engine as I stated before they changed the water pump housing and so they can happily run on standard type thermostats.

Stuart.

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In my opionion a bellows thermostat is mainly a horrible plug for the coolant flow.

The shroud is only a nice wish of what could happen, it does not work like a valve because there is a wide gap to the thermostst housing.

"The plug" forces lots of coolant anyway through the bypass.

In your case I would kick it out and spend no money on that.

post-13222-0-45958200-1528409364_thumb.jpg  post-13222-0-80922800-1528409377_thumb.jpg  post-13222-0-53955200-1528409387_thumb.jpg

 

Edited by Z320
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On 1/18/2021 at 8:05 PM, Lebro said:

I use an 88 degree shielded bellows type all year round with no problems.

Bob

Luckily he cooling system of our 4 cylinders is totally oversized and even forgives us the use of a bellows thermostat.

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The radiator on the TR4A is wider than that used on TR2/3/4, so greater capacity and cooling. 

Although the TR4A radiator may be adequate (I don't know because I've never had and would not want A TR4A), I consider that the radiator on a TR4 with modern petrol is inadequate.  The more so because summers are getting warmer, and, in my case, the engine is larger (2238) and modified.

After trying every other fix to try and get my TR4 to run cooler in hot weather, I installed a larger capacity alloy radiator.  However, there was no real opportunity to test this in 2020, as everyone will know!

Ian Cornish

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1 hour ago, Z320 said:

In my opionion a bellows thermostat is mainly a horrible plug for the coolant flow.

The shroud is only a nice wish of what could happen, it does not work like a valve because there is a wide gap to the thermostat housing.

"The plug" forces lots of coolant anyway through the bypass.

In your case I would kick it out and spend no money on that.

post-13222-0-45958200-1528409364_thumb.jpg  post-13222-0-80922800-1528409377_thumb.jpg  post-13222-0-53955200-1528409387_thumb.jpg

 

Land Rover had the same problems with bellows thermostats and produced a wax-stat type item to replace the bellows type.  The Land Rover item has a moving sleeve connected to the opening valve to blank the bypass just the same as a TR.

 

Edited by BlueTR3A-5EKT
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Hi Andy,

It is my understanding that the type of thermostat required is dependent upon the Water Pump Housing which is fitted to the car.

Originally the TR4 was fitted with a Housing which had a by-pass opening of approximately 9/16” diameter and was originally fitted with an AC Bellows sleeved thermostat.

The various manuals state that a TF1 - 72 degree was the Summer fitment and a TF4 - 86 degree to be used during the winter.

With the introduction of the TR4A the water pump housing was modified and the by-pass opening was reduced to an approximate diameter of 5/16” with a recommended thermostat of the wax pellet type and same temperature ratings.

Importantly the period AC technical literature states that if a Bellows thermostat (sleeved or un-sleeved) should fail in use it would do so in the open position and thus not compromise the cooling system.

Whereas wax pellet type thermostats fail in the closed position and thus could lead to the overheating of the engine and possible subsequent damage.

Regards, Richard

(Amended 15.23 20-01-2021)

Edited by RAHTR4
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10 minutes ago, RAHTR4 said:

Hi Andy,

It is my understanding that the type of thermostat required is dependent upon the Water Pump Housing which is fitted to the car.

Originally the TR4 was fitted with a Housing which had a by-pass opening of approximately 5/16” diameter and was originally fitted with an AC Bellows sleeved thermostat.

The various manuals state that a TF1 - 72 degree was the Summer fitment and a TF4 - 86 degree to be used during the winter.

With the introduction of the TR4A the water pump housing was modified and the by-pass opening increased to an approximate diameter of 9/16” with a recommended thermostat of the wax pellet type and same temperature ratings.

Whereas wax pellet type thermostats fail in the closed position and thus could lead to the overheating of the engine and possible subsequent damage.

Regards, Richard

My observation is that the earlier version had the bigger hole and that was reduced in size when the wax-stat thermostat replaced the bellows item.  That follows with the fitting of a restrictor in the bypass, which is the most commonly suggested modification when a wax-stat thermostat is fitted.

Marco did a whole series of tests on this and posted his results some time ago.

https://www.tr-register.co.uk/forums/index.php?/topic/73273-overheating/page/2/&tab=comments#comment-679208

 

image.png.358f9528d3aa0ea8d289870f22b8de89.png

Cheers

Peter W

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Hi Andy,

Just a thought... based on what you have is actually an ‘luxury problem’ (in that overheating in the summer is the real concern that can lead to serious damage and expense).

You are fine in hot weather driving, why not simply do What all our practical Dad’s and Grandpas(?) did back in the day....... and Simply place the ‘correct’ sized piece of cardboard in front of the radiator to restrict the cold air passing in winter?

However tough up North you are bet the majority of your TR driving is done in the summer months.... I doubt you even need to be pulling the (efficiently working cooling) system apart!.......... Only my tuppence worth and meant in the best possible way

 

Cheers

Tony

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I would concur with Tony's advice. I installed a grille cover once upon a time on a Series II Land Rover that worked quite well in some very low temps (-10deg F). Mind you I still had to wear a heavy parka when driving the thing in the depths of a northern Ohio winter.

 

Seeing the 30-70-100 gauge ( I have the same in my car)  reminded me of the attached Service Bulletin issued by the Western Zone of Triumph  back in late 1965. I wonder if they had complaints from worried customers when the gauge when past 70C before the thermostat opened.

triumph-service-bulletin-1965-59-638.jpg

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Thanks to all for your input. Initially, I am going to check engine temperatures with my i/r thermometer and take appropriate action. Perhaps all I need to do is blank of part of the radiator 'old school' style until the spring.

Andy

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On 1/20/2021 at 5:00 PM, Tony_C said:

Hi Andy,

Just a thought... based on what you have is actually an ‘luxury problem’ (in that overheating in the summer is the real concern that can lead to serious damage and expense).

You are fine in hot weather driving, why not simply do What all our practical Dad’s and Grandpas(?) did back in the day....... and Simply place the ‘correct’ sized piece of cardboard in front of the radiator to restrict the cold air passing in winter?

However tough up North you are bet the majority of your TR driving is done in the summer months.... I doubt you even need to be pulling the (efficiently working cooling) system apart!.......... Only my tuppence worth and meant in the best possible way

 

Cheers

Tony

Hi Tony

For some reason your post didn't appear before my last posting. Just in case you thought I was being a bit stupid. In fact, yours', Peters' and Andy303s' didn't appear until now.

Cardboard is what I'm going to do - and well within a pensioner's budget!

Andy

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Hi Andy,

Thanks but not necessary.... Definitely don’t think you are being‘stupid’, this is the smartest approach imo; not necessary to start by pulling system apart, sheared studs and all sorts of unnecessary grief can often follow for no benefit gained.

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49 minutes ago, Ocheye said:

Hi Tony

For some reason your post didn't appear before my last posting. Just in case you thought I was being a bit stupid. In fact, yours', Peters' and Andy303s' didn't appear until now.

Cardboard is what I'm going to do - and well within a pensioner's budget!

Andy

Roger explored this.

Peter W

 

https://www.tr-register.co.uk/forums/index.php?/topic/64438-thermostatic-radiator-blind/

 

 

 

 

Edited by BlueTR3A-5EKT
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Gotta love your approach Roger .... and the broad church that TR ownership has Increasingly become over the years...

When I was first led into 4-pot TR ownership as a penniless teenager (actually I was never penniless, just had competing priorities to spend my money on B)) way, way back in the day..... Despite the exotica that has come and gone in the meantime, my first love for the TR has never waived... This remains firmly based on how the initial concept was so beautifully basic, rugged and simple with all the key components over engineered almost to the point of being ‘bullet proof’ whatever bodging and abuse some of us owners throw at the over the years.

 

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