Engine Cooling

artificer · Post by **artificer** » Mon Sep 19, 2011 3:07 pm

The radiator never boils over. I have removed the thermostat, the radiator has been cleaned and tested, all new hoses, water pump rebuilt, new temperature gauge. Has anyone else experienced this problem?

Going back to the beginning Wes & any number of others have told y'all to check a number of things....there is no indication any of this has been done.

started it up and the lower hose again begain to get hot right near the pump. I stopped it before it overflowed again. could a complete pump failure cause this?

Water pumps may leak & don't just fail like you are suggesting.

Systems that have been overfilled will always overflow when they heat up the first time....then they will maintain the level after overflowing unless folk insist on topping up all the time.

The lower part of the cooling system including hose will get warm/hot before the thermostat opens & allows flow.
One must understand coolant flows by convection [even without a pump] from the normally coldest part of the system [bottom radiator tank] through the engine block, through the thermostat [if it is open] out through the top hose & into the radiator again [top tank].

The coolant cools & flows through the radiator to the bottom tank then the cycle starts all over again.

You tell us what happens to the coolant when the thermostat is closed?

First thing to do is check the gauge is reading correctly & that was what I am sure was recommended back @ the beginning of the thread.

One suggestion here is to post what y'all did, with the results as done, then no one needs to go round in circles.

randall1234500 · Post by **randall1234500** » Mon Oct 10, 2011 12:03 pm

wesk wrote:The first step when troubleshooting an indicated problem (one displayed on an instrument) is to check the accuracy of the instrument. Replacement does not guarantee it is correct. For the coolant temp gauge you remove the sender from the block. With it's wire connected immerse it in a pan of water sitting on the fender or head. Keep it from touching the pan itself. Place a jumper wire on the body of the sender and ground it to the body. Suspend a thermometer in the water keeping it away from the pan. Now with the master switch on, monitor the gauge as you heat the water with a propane torch. The temps shown on the thermometer and the gauge should remain within 2 or 3 degrees of each other all the way to the boiling point of the water.

Next thing to check while you still have the pan out is the thermostat. Again replacement does not mean it opens fully or at the correct temp. Suspend the thermostat in the pan. Heat the water and watch the thermostat and the thermometer. The thermostat should start to open at it's specified temp and be full open at it's operating temp and as it cools down it should close fully. Do this test on any new thermostat before you install it in any engine.

randall1234500 · Post by **randall1234500** » Mon Oct 10, 2011 12:06 pm

Thanks to ALL who replied about my cooling problem.
I have found the problem after removing the water pump. I exhausted all suggestions and decided to remove the water pump. To my surprise, the impeller was loose on the shaft. This is why it would cool better in idle than at normal driving RPM's. The impeller was not damaged at all, it just turns on the shaft, I will buy a new pump.
Thanks to all, again,
Randall

artificer · Post by **artificer** » Mon Oct 10, 2011 2:09 pm

Why not just replace the impeller or the bearing?
...whichever of the two is worn.