The Stovebolt Site Forums The Shop Area Engine Shop Engine Coolant Capacity

I flushed Ol'Roy's cooling system today after effecting a nicer looking, cleaner, Marine Tex epoxy repair in the standard water jacket crack on the driver side of the engine.

After finishing the flush, clean, refill, etc, I was only able to add 12qts of coolant to the system.

The manual says it holds 15qts, 16qts with a heater. Where is/was the extra water that never drained out? I drained the block at the driver side petcock , which I thought was the lowest point of thew system.

I even did this on a hill so water would flow to the rear of the block. I even blew air into the radiator and got air and spatter blowing out of the petcock. It seemed pretty empty to me.

Engine had been running for a couple hours during the flushing procedure and was at full operating temperature so I know the T stat was open.

What gives?

The heater is a bit of a high point in the system and may be part of the problem.

Also, as soon as your pour cool coolant into the system, the thermostat will slam shut, so unless you preheated the coolant, that's going to prevent coolant from getting back up thru the thermostat into the top tank of the radiator. Just run it a bit till the thermostat opens and refill as needed.

The engine was run for some time after refilling to clear air bubbles or whatever and the dash gauge said 180 so it seems like the T stat would have been open.

I'll see what happens when it cools down and if it draws the small amount of coolant in the overflow tank back into the engine. That is part of the 12 qts, though.