Cooling system winterizing

[Jim.B.MacK]

I was looking at the flow diagram on the late model A4 I have a raw water cooled engine. Over last several years I have removed the thermostat before sucking in the pink juice. Other A4 chum leaves his in. I may not understand flow pattern with Tstat closed vs open but thought I’d have more effective circulation of antifreeze with Tstat removed.

So help me understand flow with Tstat closed vs open and why or why not to remove Tstat during winterizing.

Thank you forum!!!

Jim
1978 C&C 34

[sastanley]

If you are sucking in pink stuff with the engine cold, the t-stat will be closed and limit the amount of pink stuff getting past the t-stat and into the block. However, if you do not have any restrictions/valve on the bypass, that will allow some mixing of the pink stuff in with the raw water in the block even if the t-stat is closed, but, it will be diluted as compared to removing the t-stat, which should give a more thorough flooding of the block.

My $0.02.

[ndutton]

The MMI recommendations for winterizing* mention removing the thermostat and pinching the bypass hose closed to be certain antifreeze gets into the block thoroughly.


*The recommendations are found in the General Maintenance forum category, "Winterizing your Atomic 4" sticky thread, post #1. The note I'm referring to is found under "Cooling System", the Note following Step 2.

[Jim.B.MacK]

Originally Posted by ndutton

The MMI recommendations for winterizing* mention removing the thermostat and pinching the bypass hose closed to be certain antifreeze gets into the block thoroughly.


*The recommendations are found in the General Maintenance forum category, "Winterizing your Atomic 4" sticky thread, post #1. The note I'm referring to is found under "Cooling System", the Note following Step 2.

Now which is the bypass hose is it the short one coming out of thermostat housing. That would seem to be the one.

Thanks!

[ndutton]

Originally Posted by Jim.B.MacK

Now which is the bypass hose is it the short one coming out of thermostat housing. That would seem to be the one.

No. It's the hose between the sideplate Tee (behind and slightly above the starter) that turns up to the thermostat housing.

[Jim.B.MacK]

Originally Posted by ndutton

No. It's the hose between the sideplate Tee (behind and slightly above the starter) that turns up to the thermostat housing.

Ok I have a ball valve installed there so thats an easy one. If that is off or pinched all the antifreeze is forced into the side of engine yes?

Cheers Jim

[sastanley]

Yes, closing the ball valve is the same as pinching the hose.

[zellerj]

Best to drain the water out of the block first before antifreeze. On my engine ( and I think most engines) there is a capped off tube just behind the alternator belt. I connect a piece of plastic tubing to this tube and blow in it periodically to allow all the water to get past rust and other particles that tend to block off the flow. I keep draining until I hear gurgling during a blow. I then suck in a gallon or so of antifreeze (via the hose that connects to the cooling through hull) so that it pushes out the water in the water lift muffler and replaces any water in low points of the exhaust hose. I kill the engine by pouring Marvel Mystery Oil into the flame arrestor on the carb just before I get to the bottom of the antifreeze bottle.

This procedure assures that only full strength antifreeze is in the block and not diluted antifreeze.