Do I use existing/stock thermostat or a new style one?

[pleask]

Okay all you guru's... I am finishing off rebuilding my motor (TD block mix of TC/TD stuff). The thermostat in the housing is the the original, it appears to be in good shape, seats well and so forth.

I read somewhere that a modern type thermostat could be used in place of the stock style.

I'm not sure which way to go.. thoughts please?
Thanks, Pat

[Steve Simmons]

If the original works, I would definitely use it. Modern ones (to my knowledge) lack the sliding bypass sleeve.

[pleask]

Thanks Steve , but as I bought my car in box's I have no idea if it works or not.
Pat

[Steve Simmons]

Put it into a pot of boiling water. If the sleeve moves down then it works! Just remember to wash the pot before anyone tries to cook dinner in it.

[Duncan M]

What Steve said. You do need to test it in a pan of water gradually heated to boil on the stove, with thermometers accurate in the 160 to 190F range. Use distilled water and some anti freeze to lube the water pump, and change it every two years. Use the cheap old fashioned kind anti freeze available everywhere. Not the extended stay kind, as it can react badly with the different metals in the system of the T-Types, especially if you have original solder in the radiator. You can now buy replacement, original style bellows thermostats. Most people suggest you actually restrict the bypass hose, otherwise the thermostat rarely opens and crud can settle in boas of radiator.

[pleask]

Duncan, when you say to use distilled water is this just for the test or the entire car cooling system?

I've never heard of the "Extended stay" type anti freeze, what does "Extended stay" stand for any idea? Will test the stat tomorrow when my better half goes out
Pat

[frenchblatter]

Do not use OAT (Organic Antifreeze Technology) as it eats away old type solder as used in T type rads. Most OAT is used for 5 years in the cooling system of new cars. Use ordinary old fashioned Gycol AF. It will need changing every year (or used to)

I never realised you should wash the kitchen stuff after testing things. Like heating the head in the oven and freezing the guides in the freezer. I must remember to clean up next time

[Duncan M]

pleask-
you can use any water for the testing. Distilled water mixed with coolant-a/f in the cooling system. There is some debate on the amount of glycol a/f to use. Up to 50%. It also lubricates the thermostat mechanism somewhat when installed on the engine. The borate extended a/f has other problems in old car engines aside from eating old fashioned solder in radiators. My TC has always had fresh coolant and the original radiator is clean as a whistle, and the original thermostat works quite well. Really. The freeze plugs are also original, and this I know for a fact. Good water in N California.

[Tom Lange, MGT Repair]

You might also consider the stainless steel thermostat housing I have custom made and sell, with a modern, replaceable thermostat and ALL stainless parts. The original-style thermostat housing requires the whole unit to be replaced if there is a problem, although there is in formation on the 'net about modifying the original housing to accommodate a modern thermostat. The after-market aluminum ones are awful, Chinese products that start corroding almost immediately. My stainless steel ones will out-last you and your car!

See mgtrepair.net for information about what I sell.

Tom Lange