flushing cooling system

[Ray IN]

I tried to drain, flush, and replace coolant in a Kubota M100 tractor today. Drained it at the lower radiator hose, with cap removed. Ran garden hose in radiator and up the radiator hose toward engine. But filling back up it would only take about 1 1/2 gallon and its supposed to hold 2 1/2. So how do I get the last gallon to drain out if I try again? Or maybe just call it good enough, after all, the radiator was flushed out and most of the coolant is new. Or maybe it will hold more after I run it some warm to get the air out. Ill try that and see what happens.

 

[Pete in Holland MI]

Look up in the maintenance manual about re-filling the system. May be an air bleed hidden some place.

Idling it with the cap off the radiator, eventually the thermostat will open up and allow fluid to flow thru. At that point, slowly pour water into the radiator, a little bit at a time, so as not to shock the block with cold water.

 

[Steve@Advance]

There should be a drain plug on the side of the block.

It may be hard to get out, and if it's never been drained may be clogged behind it with sediment.

But that is the only way to get all the old coolant out.

Problem is, flushing it likely displaced all the old antifreeze, leaving only water in the block. If you refilled with full strength anti freeze, it's probably OK. If you used pre diluted it may be too weak. You best test it to find out.

To do a proper flush, the thermostat needs to be removed, or the bypass hose removed, something to let the water pump vigorously circulate through the block instead of being restricted by an always cold/closed thermostat. if you reflush, be sure it gets a good flow through the block, especially if it was rusty.

Then with clear water flowing, drain the radiator and block. Refill with premix or straight antifreeze and distilled water. I have been using premix, just easier and already has the correct ratio.

And always let it run until the thermostat opens. It may be air locked, and will take a considerable amount more once it is open and circulating.

 

[Texasmark1]

My 2007 Branson 6530 solves the get the last gallon out of the block without having to find the block key and once found realizing that it is frozen up......they have a drain plug on the side of the frame with 2 hoses connected...one from the radiator and one from the block.

 

[Ray IN]

thanks I did find the drain plug, and it is located below where the radiator hose connects, so there is prob. a gallon in the block. I dont want to mess with the thermostadt right now, so maybe do it again this fall and do a complete job. Thanks for the info