1992 431BDP Intermittent Overheating

"1992 Chaparral 28' with 4

"1992 Chaparral 28' with 431B and DP stern drive.

Rebuilt engine with all new water pumps, manifolds/risers, thermostat and a non professionally rebuilt carburetor and what I mean by non professional is it was just done by a normal mechanic and not tested on a test motor etc but rebuild kit was used.

Overheats randomly at both high throttle operation and when idling in gear for extended periods.

This is the motor with the power steering pump.

A little history. We put in a Jasper rebuilt motor after the original got hot and put a hole in the piston.

The out drives were rebuilt about 3 years ago.

The boat is raw water cooled and is in salt water.

Ideas???"

"Have you checked the raw wate

"Have you checked the raw water hose connector (part 25 in the exploded view)? They tend to get perforated with corrosion, in which case the raw water pump will suck air.

http://www.volvopentastore.com/INTERMEDIATE_HOUSING_DPA/dm/cart_id.449604471--se ssion_id.966025667--store_id.366--view_id.314173

If OK, then you will have to start troubleshooting by checking raw water pump impeller, thermostat, thermostat housing, hoses, exhaust manifolds and risers, and oil cooler if installed."

I will check that hose connect

I will check that hose connection part thank you. The rest of your suggestions are all new with the exception of the oil cooler which I will check as well. By the looks of the oil cooler it would appear that you could probably see through it if not at least check that fairly easily.

Is there anyway to check and or test the flow through the out drive? I have heard through someone I don't know very well that if seals in the out drive go bad it can cause exhaust to flow into the water system and cause issues as well.

"You can put a plastic hose be

"You can put a plastic hose before the raw water pump, and if you see bubbles you know you have a problem. Also, check inside the outdrive grids for potential marine growth (barnacles, mussels,e tc)."