TR2/3/3A TR3 water pump housing question.

[mallard]

I have two water pump housings and one is in much better condition than the other due to rust on the inside. My concern is about the bypass ports are not the same size and one is threaded and the small one is not. I think I read that it is good to reduce the size of the port to limit the amount of coolant entering the radiator so more of the cooled coolant goes to the engine. Also is one of the housings for a later car? I'm trying to keep the car as original as I can.

 

[Adrio]

An other way to tell if the pump housing is original is to look for the grease fitting on top. the replacement I have on my TR4 (same engine) does not have the fitting or the boss for the fitting.

 

[Tinkerman]

Adrio, I just took the hose off of mine (much twisting turning and etc.) and found that the hole on mine is similar to the on the right in your picture.
That is to say it is a large hole. Mine is a post 60000 car. This is the original water pump housing that came with the car.

Tinkerman

 

[PeterK]

The grease fitting is on the pump. not the housing.

On later cars (TR4A) the size of the bypass is restricted (photo left). It's a common trick to use a 3/4" copper pipe cap with a 3/16" hole on earlier cars (photo right) to restrict the bypass and hopefully improve cooling. Didn't work for me though.

 

[mallard]

Since both pumps look the same from the outside I will use the housing with the smaller hole. I just read an article today about the plug in the bypass port issue. They said to plug the hole all together then install the pipe over it to make it look like it was still working. That was written by a well known TR3 person from the south west back in the early eighties. Engine temp is a big concern for me living in AZ. (115 today) Thank goodness I have three sinks to install today, or I would be out in the garage working.