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crud in cooling system


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Hello experts...

My boat is an 88 Sunsetter with the 5.7l Mercruiser ski/ velvet drive.

I'm winterizing my boat right now and just went to drain the block and manifolds. When I pulled all the plugs, no water came out, and i had to dig in the drains with a screwdriver and clear them out. It seemed to me like there was an excessive amount of crud both in the block drains and the manifold drains. It appeared to me like it was a mix of sand/grit, flakes of rust, I even found a small piece of impeller. I understand that the drain plugs will be at the lowest point in the system so is this normal to have this crud collected around the drains. Should i be concerned or will just cleaning out what i can reach with a coat hanger around the drains be ok. I'm going to try running the flush pro with the drains open and see if more stuff comes out.

Any recommendations, should I start pulling apart manifolds etc to try and give them a proper clean out?

Thanks in advance. Ive been reading and absorbing tons of great info here since I picked up my Malibu this summer.

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I ran into the same thing when I winterized last month with my 350 Mag. I figured the prior owner didn't clean it out very well the prior year. After cleaning out the drains with a small screwdriver and then a wire, I pulled the hoses off of the thermostat housing and put the garden hose in them and flushed each line until the water was pouring out. Then I removed the thermostat housing and did the same with the block. I flushed a lot of junk out until it finally started to come out clean.

The inside of the block is raw cast steel and will rust as soon as it is exposed to the water. I would like to know if there is a product out there that can be put in the engine to coat the inside to prevent the rust.

Lastly, I have always flushed the engine in the driveway to clean out all the grit and sand.

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Well I ran water through the system with all the drains open and cleaned out the drains with a screwdriver/wire also. Seems better but I think in the spring i will try and do a more thorough cleaning by pulling all the hoses etc. I was rushing to finish yesterday as I ran out of daylight and working in the rain under a tarp sucks.

Winterizing went good mostly, with the standard few parts and tools lost in the bilge. (My extendable magnet is probably the best tool I own)

Took me all day as this is the first time I've done any maintenance on my Malibu and there was lots of tinkering and discovering.

Aside from not being able to get all the oil out of the engine, which i know I've read about here.... I filled the cooling system with antifreeze which siphoned flawlessly through the flush pro, fogged it up and she's tucked away sadly awaiting the spring.

Thanks again for all the great info I've read here, and the excellent winterizing document.

Rock On

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i always coat hanger the block plugs

the impeller piece is not good to find

if you want the right way to winterize boats, shoot me an email with serial number

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