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Thermostat & Winterization Question
Just read the MMI write-up on the A4 cooling system and realized I hadn’t really understood how it works, and still have some questions...
This has raised a few concerns about my winterizing approach.
For the last 3 seasons I’ve been winterizing my late model A4 from MoyerMarine with raw water cooling by:
- driving the engine for about an hour to warm it up
- closing the raw water intake seacock and racing the engine for 2 seconds before shutting it off to evacuate as much water as safely possible
- pulling the 3 drain plugs and draining the raw water strainer, then reinstalling the plugs
- drawing in a gallon of antifreeze - closing the bypass off for about half the gallon to force glycol through the block
- once again pulling all 3 plugs to check for solid pink
- then drawing in a second gallon of antifreeze, also half straight through and half with the bypass closed off
Based on my newfound understanding of the cooling system, is there a risk with this approach that an insufficient amount of antifreeze will make it into the bypass section of the cooling system (between the thermostat and the T-fitting)? My thinking is that with the warm engine, the thermostat would be open forcing antifreeze to pass though the engine block, limiting flow through the initial part of the bypass loop, and possibly trapping some water.
This leads me to a second question - if the engine is cold and I close the bypass hose valve (right before the thermostat), would this stop the flow of cooling water entirely, or would the thermostat still allow water to flow through it from the block?
Lastly, how is this linked with the MMI A4 manual recommendation to remove the thermostat during winterizing, and in particular, is it really needed when you can close off the bypass loop and force antifreeze through the block?
This has raised a few concerns about my winterizing approach.
For the last 3 seasons I’ve been winterizing my late model A4 from MoyerMarine with raw water cooling by:
- driving the engine for about an hour to warm it up
- closing the raw water intake seacock and racing the engine for 2 seconds before shutting it off to evacuate as much water as safely possible
- pulling the 3 drain plugs and draining the raw water strainer, then reinstalling the plugs
- drawing in a gallon of antifreeze - closing the bypass off for about half the gallon to force glycol through the block
- once again pulling all 3 plugs to check for solid pink
- then drawing in a second gallon of antifreeze, also half straight through and half with the bypass closed off
Based on my newfound understanding of the cooling system, is there a risk with this approach that an insufficient amount of antifreeze will make it into the bypass section of the cooling system (between the thermostat and the T-fitting)? My thinking is that with the warm engine, the thermostat would be open forcing antifreeze to pass though the engine block, limiting flow through the initial part of the bypass loop, and possibly trapping some water.
This leads me to a second question - if the engine is cold and I close the bypass hose valve (right before the thermostat), would this stop the flow of cooling water entirely, or would the thermostat still allow water to flow through it from the block?
Lastly, how is this linked with the MMI A4 manual recommendation to remove the thermostat during winterizing, and in particular, is it really needed when you can close off the bypass loop and force antifreeze through the block?
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