454 DP-C Trying check for blockage in line while in driveway

[92sx]

I have a 1992 Chaparral with a Volva Penta 454, no heat exchanger or through hull exhuast installed, mounted to a DP-C outdrive. I have recently found the motor overheating after taking it out the third time. I changed the impeller in the saltwater pump and am not familiar where I need to make sure there is water traveling through the motor so that I can run her in my driveway.
I mounted a set of rabbit ears to the v drive after rigging them so the they fit to the front v where the inlet is. I also noticed from the outside there is two holes at the bottom of the I/O drive backside of boat hull that apear inside to lead to the pump. Do I need to mount a hose to one of these holes. Im not sure even if this boat can be run out of the water.

 

[Don S]

Re: 454 DP-C Trying check for blockage in line while in driveway

Those holes in the bottom of the drive are exhaust reliefs and will do nothing to put water to them.
You need to concentrate on the intake side of the pump. You said you replace the impeller, did you replace the gaskets? If not, you are probably sucking air (not water) and it will cause an overheat. Same with any loose hoses from the drive to the pump.
Could even be the hose connection on the drive is cracked or leaking. Your's has a plastic fitting, unlike the older models that the hose end would corrode off of. Any of those hoses or fittings could be plugged, even on the output side of the pump. Any clogs in coolers or manifolds will cause overheat.
What is the model number of your 454?

 

[92sx]

Re: 454 DP-C Trying check for blockage in line while in driveway

my 454 is a 740A. I put a new gasket when installing the impeller. I also lubed the impeller up with 24c lubricant. I had water coming out of a hole at the bottome of the v-drive when I had rabbit ears hooked up before the change. I just dont want to hurt the impeller by running it dry after changing it. Nobody locally wants to tell me how this motor sucks its water in and dishcharges it out. It may be very simple and im making it very difficult. I just find it hard to believe that 2inch spot of fins on the front of v-drive is where the motor gets all its water from. How will I know it is cycling all the way through the motor and that parts of the impeller are not stuck somewhere is in the system.

 

[Don S]

Re: 454 DP-C Trying check for blockage in line while in driveway

Trust me, those to opening on the drive let plenty of water through, and have for years on those engines.
You also don't have a V-Drive, you have an outdrive. VERY BIG difference.
Here is the OEM service manual for the 740A, it has a diagram of the water flow in it.
Turns out I don't have it uploaded. Give me 20 minutes or so, and it will be.

 

[Don S]

Re: 454 DP-C Trying check for blockage in line while in driveway

Here ya go.

http://www.4shared.com/file/128755761/747d3326/7733187--740A-B.html

 

[rodbolt]

Re: 454 DP-C Trying check for blockage in line while in driveway

also be aware that a lot of larger hulls used a thru hull fitting and not the drive fitting for water intake.
trace your seawater intake line from the pump back and see where it goes.
like DonS reccomended,if your drawing water from the drive carefully inspect the plastic fitting at the drive for cracks or distortion.