Mercruiser 470 antifreeze levels

[kevinstan]

Took off the antifreeze cap to test my mixture before winterizing and noticed the coolant was at least 2 or 3 inches from the top. Is this normal ? I don't see a resavoir anywhere with a fill limit for it. How do I know how full it is suppose to be to make sure it's good for winter and next spring use ?

 

[wrestling coach]

First and foremost check the antifreeze in the reservoir using an antifreeze tester to see the level of protection your coolant has. Be sure it is adequate. Next you should have a coolant recovery tank or any coolant that is being discharged is going to your bilge. On the neck of your filler cap should be a black hose attached to a nipple coming from the filler neck. Follow that hose it should be attached to a coolant recovery tank. You can't miss it if you have one. If that hose has nothing at the end then all your coolant that is being expelled during heating and cooling is going to your bilge.

 

[kevinstan]

I noticed the recovery tank, but on the top is a connector with nothing connected to it. I didn't see an empty hose that wasn't connected but I will need to look again to be sure. It should come from the top under where the coolant cap is ?

 

[wrestling coach]

Correct. That hose goes to the BOTTOM of the coolant recovery tank NOT the cap of the recovery tank. As the coolant expands under heating some may be pushed past your pressure cap into that overflow hose just below your cap. The coolant would then travel to the recovery tank. As the engine cools your coolant will be drawn back into your engines reservoir thus keeping the coolant in the engine at a consistent level. When you take your pressure cap off the engine coolant may not be right up the neck and right at the cap. Mine never is. It should be close however. You can use a 50/50 automotive antifreeze to top it off. Available pre mixed at any auto parts store. Be sure to drain your heat exchanger by removing the very rear (aft) plug on the bottom of the exchanger. If you are not clear on that procedure let us know. You HAVE to do this.

 

[wrestling coach]

I noticed the recovery tank, but on the top is a connector with nothing connected to it. I didn't see an empty hose that wasn't connected but I will need to look again to be sure. It should come from the top under where the coolant cap is ?

Post some pictures so we can see what you have.

 

[stonyloam]

Yeah, the coach is right on. Make sure the hose is in good shape, and top off the reservoir then fill the tank to the "fill" line, or about half way.