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david johnson

Bellows Thermostat

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Could anybody advise the best place to get the TR3 thermostat from. Moss I know ,but is anywhere cheaper. Thanks David.

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Hi Peter,

 

I have a number of N.O.S. thermostats.

 

Tried to send you a P.M. but your message box must be full...........!!!!!!

 

Regards, Richard

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When I was driving TS2 this past summer, I took it to the Newby Car Show in Yorkshire. At the huge autojumble, I saw two of these bellows thermostats still in boxes and I was floored when I asked the price. The chap replied "£2.00 each!". Needless to say, I bought them both.

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When I was driving TS2 this past summer, I took it to the Newby Car Show in Yorkshire. At the huge autojumble, I saw two of these bellows thermostats still in boxes and I was floored when I asked the price. The chap replied "£2.00 each!". Needless to say, I bought them both.

 

Thats very true Don. I tend to pick them up when I see them at country shows/autojumbles/tractor fairs etc. They do fit a huge range of cars not just TR`s. ;)

Stuart.

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I'm beginning to wonder if they are necessary because my Bentley uses a similar design to do the same thing, but it's more complicated and they are £180 each! I've had troubles with my car getting too hot and my son has had customers the same, so out of desperation, I shelled out about £6 or so for two 75 degree jobs from an early nineties Peugot 504. Now both cars run at 75 as they should despite nothing to cover the bypass hose.

 

I have the correct type in the TR and it was about £20 I believe.

 

Ash

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The idea is that when the engine is cold the water comes out of the pump and straight back into the block through the by pass hose without going through the radiator. Once it's up to temperature, the thermostat opens and water goes through the radiator to be cooled.

 

With the correct thermostat, there is a ring at moves up at the same time to cover the outlet to the bypass hose. A cheap, modern one may open more accurately, but it won't have any means of covering the bypass hose outlet. I'm not sure that matters, but...

 

Ash

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To make sure all the water goes through the radiator and gets cooled properly. The bypass hose bypasses the radiator and heats the engine up quickly when it's cold, but you need the radiator to keep it cool once the engine is up to temperature.

 

What I'm saying is that my Bentley, which has the same arrangement, cools just as well with a cheap modern thermostat that doesn't prevent water going through the bypass hose when it's open. I have heard you can do the same with a TR, but I'd be interested to hear what Stewart thinks.

 

Ash

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What I have heard about modern thermostats, the TR will take longer to warm up on cold days because the bypass hose doesn't get blocked. That's why I have plugged my bypass hose with a threaded brass plug and I have a 3/16" diameter hole drilled length-wise through it to allow air bubbles to rise after changing the coolant.

 

Also many TR owners who install modern thermostats will remove that jiggly thingy in the large round plate and others have drilled a small hole there as well. I assume that's to allow the air bubbles to rise and get out the sytem after changing the coolant.

 

BTW, I have been using a 20% anti-freeze and 80% DI water mixture for the last 5 years or so. a 50/50 mixture is what I was using before but I rarely overheat with a 12" diameter Kenlowe fan when it's needed and the new mix will never freeze.. But then I never drive my TR3A in our cold Canadian winters. The TR lies stored in my warm (very dry) garage under covers where it never gets lower than 55 deg F (15 deg. C) all winter long.

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I have found that TR4/4a dont seem to mind a standard thermostat as opposed to a sleeve type but sidescreen cars really do prefer the sleeve type, Maybe due to better airflow/cooling on the later cars. But regular flushing of waterways and rads and a good inhibitor/antifreeze is essential on a 4 pot whatever model.

Stuart.

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......... I have plugged my bypass hose with a threaded brass plug and I have a 3/16" diameter hole drilled length-wise through it to allow air bubbles to rise after changing the coolant. Also many TR owners who install modern thermostats will remove that jiggly thingy in the large round plate and others have drilled a small hole there as well.

That's what I have done Don, although I used a washer with a 1/4" hole (GHF314 from Moss is ideal) in the bye-pass hose and I fitted second jubilee clip behind the washer to keep it in place and prevent it slipping down the hose under pressure.

 

This solution has been fitted to TuRK for almost 9 years now without any problems, unlike the several bellows type I tried and eventually dumped as they continually failed.

 

Cheers

Andrew

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I used a half length of wine bottle cork with a 3/16" hole drilled through it to block my bypass hose.

Has been there for some years but I still feel the original bellows thermostat with sleeve worked spendidly.

I do have a sleeve that replaces the thermostat and would blank the bypass, (C-AJJ4012 from Abingdon Special Tuning dept.) but have never been brave enough to use it.

 

What do wedge owners do for thermostats ?- The orig. had a sort of plunger thing on the end of it to block the bypass.

 

Cheers

Peter W

 

UKSPME-088.jpgAJJ4012 image from Moss Europe

 

GTS108.jpgGTS108 image from Rimmer Bros for TR7

Edited by BlueTR3A-5EKT

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A Jaguar XK120 owner..but these use the Smiths bellows sleeve thermostat, we are busy checking to see if the new Moss Europe  bellows sleeve thermostat that is spec for Triumph, Healy.,will fit, work in the XK,  It "fits" ,that is its outer dimensions fit..but..will the sleeve block the bypass.  There is a lot to this..I will summarize as I see some misconceptions. The thermostat's job is to warm the cold coolant to optimal engine operation temperature which is usually in a range of about 20 D., say 65C to 85C.  Its job is also to cool hot  coolant to that same range,. It does this by the top poppet valve closing the passage to radiator when cold, and the sleeve will be low on the thermostat out of the way of the passae to the block.,called the (radiator) bypass: .it bypasses the radiator,,..so the passage to the engine block direct is now open. Coolant is warmed more rapidly, lessens cold engine wear, the choke will cut out etc.  As the coolant warms, the thermostat starts to open and then becomes fully open at a specified temperature..different thermostats that fit and work ,,can have different full open temps.  So when open, now the thermostat has "said" warm enough! stop the warming, ! ,.now I need to cool the too warm coolant, and run all coolant thru the radiator, and shut off coolant thru the engine where it would have been warmed too much by now..,  so then the radiator cools the coolant..and soon the coolant is a bit too cool..so now the thermostat says,.,oh--too cool..and closes to the radiator while it opens to the engine,  It will cycle like this all the time..though on a hot day it will just stay open all the time if the radiator can not make the coolant too cool.   If you block off the bypass: ..warm up will be slow, the engine may run too cool all the time, and both are not the best for wear, fuel-air mix, combustion etc. Racers do this..but they run WOT..and have far fewer cold warmups than daily drivers.  Once the thermostat is wide open to radiator (and closed to engine ) .,.let's say at 80C, the radiator just cools..if the cooling system is in fine shape..it just stays a bit over and under 80, as the thermostat  cycles.  A colder temp thermostat will NOT make the car run cooler if it is running at a temp over the thermostat spec, say 85C..the stat is open at 80 anyway, all coolant to the radiator,  A lower temp stat may allow the enine to run at say 73C..and a benefit is 7 degrees of "room"  on a hot day,.but it won't take lon to reach 80C anyway..the hot day/traffic issue starts in anyway quite quickly and the 7 de won't save you.  The overheat issue is not the thermostat, but is the ability of the radiator to cool, and the internal condition of the cooling system. (crud, corrosion, debris, old rust and sludge etc). At this point..realize you enjoy a vintage car, as its vintage temp indicator  needle moves to the vintage 100C mark.  BTW..bellows sleeve thermostats will self destruct if more than a 4lb, (7lb absolute max maybe which only provides 3 d anyway) radiator cap is used.  Do not try to raise boil temp with a 13-15 lb cap.  Your old head gasket or core plugs and the thermostat will be your next repairs.  And..BTW..50 50 antifreeze provides about 107C boil..(at seal level--each 1000 ft takes away 3 de.)    Look us up at Jag-Lovers.com , thanks, Nick

smiths them w box.jpg

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