Volvo Penta 501A Raw water issue - Overheating

[the zigman]

Hi Everyone..

Been working on my brothers boat forever, seems like something is always amiss.. Discovered it had a cooling issue and in dianosing that we discovered that the fork was cracked... replaced that and re assembled everything tonight.

Initially the boat was overheating... Got hot on Muffs, and in the lake too. Discovered the cracked fork, and replaced it, thought maybe the steering pin was cocked and creating a leak.. reassembled everything, and still gets hot.

Replaced the impeller in the raw water pump.
it appears that the raw water pick up is not working.

Is there some way to diagnose this?
A way to find out if the raw water pump is working?

This has the crank mounted raw water pump, from what i can tell the top hose is the output, and bottom hose is the inlet. thats how it is assembled.


If I run the boat, and remove the raw water hose at the transom, should I be able to feel suction on that hose with the engine running?

Is there some trick to replacing the impeller?

Everything appears to be fine.
All the suspect components are new.

New impeller,
New thermostat.
Replaced the gaskets and O-Rings in the outdrive.


this is a 91 Volvo 501A with a DPA-1 Drive.

Any suggestions would be very well appreciated.

thanks!!

 

[captmello]

Re: Volvo Penta 501A Raw water issue - Overheating

The water intake fitting and gasket are always suspect. Its the fitting just under the ujoint bellows that the intake hose attaches to. Have you checked that fitting for corrosion?

To check the water pump, pull the hose from the thermo housing to the raw water pump, stick it in a bucket, start the engine, and see if its pumping or not.

Can you confirm the temp gauge is working correctly?

 

[the zigman]

Re: Volvo Penta 501A Raw water issue - Overheating

Just replaced that gasket during the rebuild..
I am pretty confident in the seal at that point.

A am also sure the temp gauge is correct since the engine shut down last time it happened.

 

[captmello]

Re: Volvo Penta 501A Raw water issue - Overheating

Well, its either not getting enough water, or not getting rid of the water quick enough.

Is this a fresh or salt water boat? Have you had the risers off? What is the condition of the exhaust manifolds?