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Re: Two TR3A radiator questions (correction)

To: triumphs@Autox.Team.Net
Subject: Re: Two TR3A radiator questions (correction)
From: AMfoto1@aol.com
Date: Tue, 25 Jan 2005 05:35:25 EST
Hi Carl and all,

First of all, let me correct one thing. I said in my earlier response that 
"overflow tanks" were a "one way" system. As some others have pointed out, 
that's not entirely true. It's a one way system only while the car is running 
and 
the cooling system is under pressure. But, once the car is shut off and the 
system cools down, with the right radiator cap, coolant will return to the 
radiator. Another response correctly pointed out that the "right cap" has a low 
pressure valve, opened by the vacuum created when the radiator cools, allowing 
coolant to return. 

True "header" tanks are a two way system all the time: catching overflow, 
eliminating air from the radiator/engine and returning coolant to the radiator 
as 
needed, while driving. 

Still, the mounting of an overflow tank is less critical than a true header 
tank. The former is usually below the level of the top of the radiator. The 
latter needs to be at a level slightly higher than the top of the radiator, 
which 
might mean installing it pretty far from the radiator in our cars. 

Carl, my understanding of 4 cylinder TR radiator caps is:

- TR2 through 3A use 4 psi cap with 1" length.
- TR4 up to CT9000 approx., with long neck rad\iator (same as TR3), use 7 psi 
cap with 1" length. My car happens to have this radiator, even thought it's a 
later car and should have a "no-neck" radiator. Tonight I measured the 
distance from the top rim of the filler to the lower rim and it's exactly 3/4". 
The 
spring in the cap compresses the remaining 1/4". 
- TR4 after CT9000 approx. and TR4A, all with "no-neck" radiators, use 7 psi 
cap, 3/4" length.

I mention the length of the radiator caps above, because they are incorrectly 
listed by many auto parts stores. One or more of the major manufacturers 
incorrectly specify a 3/4" length cap for the long neck radiators on early 
TR4s, 
possibly TR2 & 3 as well. I had an email exchange with John Swauger at The 
Roadster Factory this week and even they are having trouble getting the 
manufacturer to supply the right item. They just got a shipment of incorrectly 
sized 7 
psi caps. Using a 3/4" cap on a car needing 1" is a good way to cause heating 
problems and I've currently got the wrong cap on my car (which isn't going 
anywhere under it's own power for a while, anyway).  

Sorry for any confusion due to my earlier posting. I hope this clarifies.

Alan  Myers
San Jose, Calif. 

AMfoto1@aol.com
http://hometown.aol.com/amfoto1/amfoto1.htm

Date: Sun, 23 Jan 2005 19:14:51 EST
From: CarlSereda@aol.com
Subject: Re: Two TR3A radiator questions

Hi Alan,
Can't TR4s easily be made to draw radiator coolant back to the radiator from 
the catch tank when engine cools off - rather than the bottle simply being 
used as an overflow catcher?
I bought a NOS Stanpart TR4 spec'd radiator cap that has additional gasket to 
seal the top of neck (rather than just metal-to-metal neck connection) as 
well as the rubber seal for the inner filler hole plus a smaller built in 
'return' valve.
I assumed I could have a good "closed" 'back-and-forth' system..




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