AQ225"E"/270 Overheating

[Fire Escape]

Last time out I "toasted" my exhaust hoses. Replaced them and the riser gaskets, (exhaust manifold and risers are clear, barely any interior passage surface rust). I suspected a sea water pump problem, removed and examined impeller, looks good. Replaced and sealed cover with RTV. I also put 2 clear hoses on the thermostat housing to exhaust manifolds so I could verify the water flow. At idle, the hoses were half full of water and I could hold my hand on the risers, engine temperature was normal, 160, (I had previously tested the thermostat in a pan of water on the stove). After a half hour of idleing at the dock, I went for a quick spin and then looked back to see that the hoses were completely dry! Let everything cool down at the dock, restarted the engine and got NO flow to the exhaust manifolds. Could I have enough suction at the pump to collapse the "S" hose from the outdrive to the transom shield? Or an impeller that is freewheeling on the shaft? I can't see anything on the inlet of the outdrive, (plastic or seaweed) and am looking for an air tank to blow out the line from the pump intake to the outdrive to verify that it's not obstructed. Any ideas? HELP!

 

[Don S]

Re: AQ225"E"/270 Overheating

Check the hose connection where the water intake hose hooks to the outdrive. One of the most common problems with the older Volvo drive was that connection corroding away inside the hose. The engine will run fine and not over heat when going slow, but when you start to get on plane, the connection comes out of the water and sucks air, asnd you get an overheat.

 

[Fire Escape]

Re: AQ225"E"/270 Overheating

Thanks Don, I'm going to order a new impeller and the "S" hose and check that housing when I change the hose. What do you think about backflushing from the pump input with some compressed air to verify that I didn't suck up a partial obstruction?

 

[Don S]

Re: AQ225"E"/270 Overheating

What do you think about backflushing from the pump input with some compressed air to verify that I didn't suck up a partial obstruction?

Waste of time.
There would be enough air moving past any obstruction that you wouldn't notice the difference.