I have started my boat with the fresh water flush connection. Never had any problems such as pressure or over heating.

Went to winterize it with anti freeze in two 5 gallon buckets. Ran the hose from the fresh water connection into the bucket and it would not suck.

Connected "ear muffs" to the drive pick ups and then put the hose in the bucket. No problems. It sucked fine.

Why would the fresh water conection not suck??

I USE A SMALL PUMP IN THE BUCKET WORKS FINE.

Ditto

Well, if you have a pressure check valve in the flush system, it won't pull threw to the pump. It would have to be pressurized. It draws from the pick up because the flush is probably blocked off by a valve of sorts. If you take duct tape or shrinkwrap tape and tape off the water pickups on the drive, all of them, it might pickup. Depending on what the pressure setting is on the flush. Also if you have a sea strainer, take the lid off and put it in that way will work good too.

John S.

I agree, you need to tape off the holes on the outdrive as the pump will find it easier to suck air from another inlet rather than heavier fluid from another entry point.

I also winterize with a bilge pump mounted in a bucket and connected to the flush connection and I tape off the lower unit intake holes, this way all the pressure gets directed to the raw water pump rather than the outdrive water pickups....

Do you guys have yours on a valve where you can switch the connection from the drive intake to the hose intake? If not, I can understand why you have to seal off the drive intake. If you do have a valve - doesn't the valve seal off the drive intakes?

I don't have a valve. When I put pressure to the flush connection under my swimdeck, the water or antifreeze backflushes and empties out the drive holes. By taping off the drive holes, the water or antifreeze will then be pushed to the raw water pump.

At first, I get some blow by on the tape on the drive, but once the engine starts, the tape sucks tight and nothing comes out.

You have to mix the anti-freeze with water or a small pump will not pump it. Sounds stupid....but the same thing happened to me.