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Penta drive overheating under gear

E

emac

Regular Contributor
Hi, just bought a new (for me) boat, with volvo penta powered by a chevy 305, mercury i think. Problem old owner had, under power engine bogs down and over heats. Whats been done is pretty much a complete engine overhaul, new elbows and risers, new heads, all new hoses, new thermostat, new carb, upgraded to electonic ignition. Nothing has been done to the outdrive though. Engine runs and purrs real pretty. real pretty. I'm thinking there might be a blockage in the intake on the outdrive, or I need to bust out the freeze plugs and flush the thiing out. My last boat was a complete inboard, so i have l little learning curve to deal with. Any thoughts or suggestions would be greatly appreciated.
 
There have been a number of threads on this forum about overheating. The big culprit are the raw water pump impeller (mounted on the front of the engine just like a straight inboard) and the neck or elbow fitting on the drive that the raw water hose attaches to.
This latter fitting tends to develop pinholes and allows air to be sucked into the water line "at speed". This is not a particularly expensive part (replace gasket/seal while you are at it) and if you don't mind getting very wet, replaceable while the boat is in the water. If you haul the boat, its replaceable without pulling the drive.

If you are pulling the boat, I'd suggest pulling the drive (or at least the transmission... the top 1/3 of the drive) and replacing the top boot. Inspect the U joints while you are at it. Save big bucks and aggravation in the future.

Also... check the dip stick (not normally checkable when boat is in the water) to make sure the oil isn't milky.

Volvo drives of this series (I assuming a 280?... please give more info!!) are about as bullet proof as any stern drive can be, but they DO have some areas that need attention.
1) Water elbow/ hose
2) Shifter seal
3) Top boot /U joints
4) Prop shaft seal.

I've avoided the whole water elbow / sucking up sand into my engine issued by converting to a thru hull pickup, just like a straight inboard.
 
Hey Capt Bob, thanks, oil looks great, boat is out and going to bring it down to my house where i can get some good time poking around on it. Changing the water intake to a through hull pickup is an interesting idea. The old owner he checked the raw water pump, but planned on double checking that anyway. I'll post back with update and more details on the engine.
 
The classic diagnostic test for water intake problems related to the drive...
Disconnect either end of the line from the inlet of the raw water pump to the fitting on the transom collar. Inset a short section of transparent hose.
If you see bubbles, you have a vacuum leak ( hose, elbow, seal..)

Re: checked out the raw water pump.

I don't bother checking them, if I suspect them, I just replace the impeller. "Checking it" entails the same labor as replacing the impeller.
 
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