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TR2/3/3A 3A Thermostat Housing

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M_Pied_Lourd

M_Pied_Lourd

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Evening All,

Another question for the experts.
Started re-assembling the engine after painting and came across another curious difference between my two cars.
Thermostat housings are different. I only discoverd this after I tried to use the mounting bolts from one type to secure the other type to the block.....too short, as the flange for the type that came off my parts car is higher.

Here are a few pics.

P1060644.jpg


P1060641.jpg


P1060639.jpg



Can anyone tell me which one is orginal to the car.
Are there issues using either one?
Cheers,
M. Pied Lourd
 
The one on the right is from a TR4 or 4A (not sure offhand exactly when the change occurred). The one on the left looks original for a TR3A (but sure is in good condition for being some 50 years old!)

Either one should work fine, but with the one on the left, you may want to either restrict the thermostat bypass; or use a sleeved thermostat. That said, I got by just fine for many years without doing either one.
 
Yes, the one on the right appears to be the same as the unit on my late TR4.

Randall -- wouldn't the caution to restrict the bypass or use a sleeved tsat apply to either example?

I too drove for years w/o such a restriction until Bob Schaller suggested I block the bypass. I now use a 3/4" Cu pipe cap with a 3/16" hole in it to partially block the bypass hose.
 
Agree with Randall as to the unit on the left being from a TR3, it's like the two I have...not a TR4 guy so can't talk to the other.
It does look excellent tho (TR3).
 
Geo Hahn said:
Randall -- wouldn't the caution to restrict the bypass or use a sleeved tsat apply to either example?
Click to expand...
I suppose so, but the later housing already has a smaller opening than the earlier one; and was used without the sleeve (or a block) by the factory.

Another way to go, for maximum cooling, is to block the bypass completely and drill a 3/16" hole through the thermostat backing plate. But it does make the engine slow to warm up and it may never get completely warm in cold weather, so this mod is suitable only for warmer climates.
 
Thanks guys,

One more quick question. It is regarding the orientation of the rad hose connection.

The TR4/4A one intially had the connection up the other way....I turned it around to match the one from the 3.

Was curious though, which is correct.

Cheers,
M. Pied Lourd
 
TR3driver said:
Another way to go, for maximum cooling, is to block the bypass completely and drill a 3/16" hole through the thermostat backing plate. But it does make the engine slow to warm up and it may never get completely warm in cold weather, so this mod is suitable only for warmer climates.
Click to expand...

Shouldn't be much of an issue for you Pied? Right about now maybe? <grin>
 
Wasn't aware the factory modified the TR4 housing. Can you take a pic of the two bypass openings side by side? Or, what size is the TR4 opening?
The TR4 used a normal non bellows sleeved type of thermostat?
Interesting.
 
I can take another pic and post tomorrow.

Skip, brutal up here this evening. Very cold, snowy and extremely windy tonight. Just went out to pick up a pizza for dinner..thank god for big trucks and 4 wheel drive!

Cheers,
M. Pied Lourd
 
Couldn't get it to show up very well, but this photo should give you an idea of the difference. I added the black bar to indicate the bottom of the slot.

The non-sleeved thermostat was even listed as a factory-approved supercession for the original sleeved type.
 
M_Pied_Lourd said:
Was curious though, which is correct.
Click to expand...
AFAIK, it was always the way you show, Pied. At least that's what it shows in my TR4A factory parts catalogue.
 
Here is the original one that came on my 1958 TR3A when new.

I have seen some later castings where the corners had sharper edges. Possibly for the TR4 or as repro for any 4-cyl TR engine.
 

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Don,
You always make me mad...I know you drive your car a lot and it's always so damned shiny!!!
What's the special lever on the housing (Nice tool mod btw).
 
I've heard of the 3/4 copper cap with hole referenced more than once before. I finally think I understand it. Does the cap with a small hole go inside the bypass hose? I kept trying to get it inside the pump or t-stat housing, but it will not fit.

"TrailerBrite" aluminum cleaner can make the one one the right look like new -except for the pitting and worn away sections (which on mine are mostly on the inside or covered by the hoses).
 
The copper cap fits nicely inside the rubber hose.

I just installed mine a couple months ago; can't vouch for how well it works since we've had no hot weather since then.
 
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