Re: 1934 1104 running hot

Posted by 32model901 On 2010/5/3 19:16:39

Tom,

One suggestion, you may want to check the clearance between the pump impeller and the casting in the block. An easy way to do this is to stick three small pieces of clay to the back of the impeller equally spaced around the diameter that is facing the block.

Maybe you can ask one of you "helpers" to donate some. Playdough will work fine also.

After you attach the three pieces of clay to the impeller bolt the pump back in, then remove it and check the thickness of the clay. What you're tying doing is measure the clearance between the impeller and the block. If this clearance is to large you're going to reduce the flow of the pump.

I did this on a '32 which had .110 clearance. most modern water pumps are designed for .035 - .055 clearance between the impeller and block. I removed the impeller from the pump and machined a large copper disk which I soldered to the back of the impeller after machining it flat. I used .062 thick copper which gave a working clearance of .048, after the pump was bolted it.

I took temp. readings before and after I did this and saw a 15 degree drop in the coolant temp. under identical test conditions.

The impeller clearance is critical because as this clearance increases the coolant circulates from the center of the impeller to the outside of the impeller through this gap, instead of flowing through the block and radiator.

I've also had good luck using a wetting agent, which reduced the surface tension of the coolant. Most parts stores carry this, one trade name is hyperkool.

Regards,

Dave