|The MGA With An Attitude
Water Pump BROKEN IMPELLER - CO-108A
On 7/20/2011, David Woods wrote::
"After taking it for a test drive I am finding that driving 55 for about 5 miles in this nice 90F weather I pretty much boil out all the water. [Using plain water for testing]. Proper long reach 7-psi pressure cap, felt pad on top of radiator, 4" air hoses in front of radiator, 160dF thermostat. When at idle the car sticks around 190-200 when driving pegs the needle at 235. I can leave the car idle for 20 minutes and the temp sits right around 180F everything looks fine. I can leave the car to idle longer and it hangs between 180-190F, and today it was about 90F outside no issue just sitting at idle. BUT as soon as I put the car on the road is when I overheat. Today I ran a few tests.
1. Double checked timing. Car is a 1600 and set at 10 degrees BTDC at idle of 700 and max advance is 25.
2. Double checked carb settings they seem great, in sync and adjusted jet so when piston is raised a bit get a slight raise in RPM then back down.
3. Verified with IR probe the temp gauge is correct which it is plus all the water boils out so can't really argue with the gauge. Temperature while cruising at 60 MPH jumps to 235F within 2 miles.
4. I borrowed a pressure checker and took it up to 10 psi no leaks. The engine did not have any external coolant leaks only boils off".
Well, David. If it holds pressure in the radiator,
and the cap also holds pressure, and the cap length matches the filler neck depth, then I think the next step is to pull the water pump and see if it still has an impeller on the back end. -- Barney
On 8/2/2011, David Woods wrote:
"Well mystery solved. I pulled the water pump off and my theory of the propeller free spinning was correct. I actually thought they were all metal I can't say I've seen a rubber propeller before".