running out of water

[firehog6305]

Hey guys, I just picked up a new project boat (82 bayliner 23ft montery) it has a chev 350 w/volvo 280 drive. The boat has a closed water system on it. I picked the boat up really cheap, and the old owner said that the engine was knocking really bad before he shut it off and used his kicker to get back to shore. After a quick inspection of the motor I could not find any damage to the outside of block, or under the valve covers, so I asume it is enternal (rod,piston, ect.) I wanted to hear the knock for myself, so I started the engine just for a second to hear it, it purred like a kitten with no knock Now I do understand that it might come back with the engine warming up, or when ever, but my question is, with a closed water system, how long can or should you run your motor out of water with or without a flush kit without doing damage?

 

[Maclin]

Re: running out of water

The impeller in the raw water pump can't last very long without water, 30 seconds would be long enough to hurt it. That is the part of the system that keeps the antifreeze "side" cooled down thru the heat exchanger.

The engine can run a lot longer with no real damage to itself, but too long without water coming into the raw water side will ruin the large diameter exhaust hoses that run from the exhaust manifold risers to the exhaust tubes.

So, you did not hurt the engine but the raw water pump impeller is probably compromised. But, it may have been toast when you bought it. And do not run it long without water hooked up or you will burn up those exhaust hoses.

Did you check the oil first

 

[firehog6305]

Re: running out of water

yes of course I checked the oil first, thanks for the info

 

[Maclin]

Re: running out of water

I would check the impeller, I bet it is bad, and probably not just from your doing. I bet the engine overheated on him and that is why it was knocking, etc. Got any pics? Sounds like an interesting boat.

 

[Maclin]

Re: running out of water

yes of course I checked the oil first, thanks for the info

I figured you did! Some would not, though, and they might search thru and see that sentence about checking the oil and go "Doh! guess I better do that first...."

 

[firehog6305]

Re: running out of water

I dont have any pics yet, but I did pull the impellar and it looked fine so I ran it out of water for about 5 mins with water, and sure enough the knock returned ha ha, it sounds like the rod, so I shut her down and going to pull it out, I even thought about pulling off the pan, and removing the bad rod that way, but the boats hr meter reads 857hrs, so its about time for a complete overhaul, I will post pics soon

 

[Maclin]

Re: running out of water

Sounds like a pretty good find for mechanically inclined person such as yourself, good luck!

ps don't forget the pics!