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Triumph TR3 - Thewrmostats

Has anyone had experience with the original style thermostat for a TR3A. I understand that they had a sleeve to blank off the by-pass hose when the thermostat opened. Thermostats sold today don't have this sleeve and so I would think that a significant portion of the coolant would not go via the radiator and hence the engine would tend to run hotter than desirable. Is there a solution or a source for the original style thermostats at a reasonable cost?
Tom Addison

Tom - I did the following when I restored my TR3A from 1987 to 1990. I drilled and tapped pipe threads into the top end of the casting which connects to the famous "by-pass hose". Then I drilled a 1/8" diameter hole in the brass pipe plug I used. I threaded in the plug with the drilled hole and tightened the plug into the casting. This reduces the flow through the "by-pass hose when you don't have the original "shrouded thermostat". But I use a shrouded one.

It has been said that doing this will cause your TR to take longer to heat up to operating temperature on a cold winter day. But who would drive a TR these days in the winter ?

The small hole is to allow air bubbles to come up and out the cooling system just after you have re-filled it. I use 50/50 water/antifreeze even though I only drive in the summer. Mine has been like this for more than 70,000 miles and the only thing that I noticed is when I removed the by-pass hose after about 50,000 miles, the small hole I drilled in the plug was full of beige coloured sandy crud. It was easy to clean out.

You will get all the details from TeriAnn Wakeman in Southern California. Click on her wensite:-

http://www.cruzers.com/~twakeman/TR/#article

Then scroll down to the 2nd item from the bottom.

On the last line, she says to drill a 3/8" hole. I don't know why the difference.

Don Elliott, 1958 TR3A
Don Elliott

Tom-I noticed that Moss has the original type thermostats for about $37. The plugged bypass is probably just as effective. I just used a piece of metal that was a comfortable fit in the bypass hose.
Berry

Hi Tom:
Chuck

Hi Tom:
These new fangled machines often confuse us old-timers.
What I wanted to say was---I have 2 buddies who installed the standard thermostat (as used in Chevs and Pontiacs) without mods and and noticed no difference whatever.As a result I put an ordinary one in my '58 this winter.The begining of the driving season will settle the question in my mind once and for all.
Chuck

Don:- Thanks for the info. I should tell you that I use my TR practically very week out here. What is "winter"?
Tom Addison

I'm holding one of the "sleeved" thermostats I ordered from Moss for $37. Other than it's round, it bears no resemblance in form or apparent function to the original sleeved thermostat I removed from my car. I spoke to Moss's technical staff yesterday and they confirmed I have the right part listed in their catalog as "sleeved", but they did not quite understand its operation.

The so-called "sleeve" on the Moss unit is apparently the fixed collar, or body, that extends from the mating surface of the thermostat housing approximately 3/8" into the throat. It does not move. By my estimation it would partially impede the flow through the bypass.

I'd love to hear if anyone has obtained the correct sleeved thermostat from the good folks as Moss.

Bill Stagg
1961 TR3A
Bill Stagg

Further investigation and discussion with the Moss folks has determined that the Moss skirted thermostat works in reverse fashion to the original one for the TR. The "skirt" or sleeve starts out tight up against the mating collar of the thermostat and then "pushes out" to cover the bypass hole as it warms up. The original thermo collar "pulls back" to cover the bypass. The only disadvantage I can discern to the Moss unit is that its sleeve partially blocks the opening to the bypass when it is in the "cold" starting position. The original thermostat leaves the opening to the bypass wide open.

Bill Stagg
1961 TR3A

Bill Stagg

When our sidescreen TR's left the factory, they had radiator caps with a 4 psi rating. This was because if you overheat a bit, the cap will let out the pressure above 4 psi. If you are using one of the original bellows style thermostats with the moving sleeve, make sure your rad cap is 4 psi. The bellows on the sleeve type thermostats will fail if you put on a rad cap with a higher rating.

Don Elliott, 1958 TR3A
Don elliott

This thread was discussed between 23/02/2003 and 06/03/2003

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