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1987 VP 290 cooling problem

A

aspidal

New member
I have a 1987 Sunrunner cuddy cab with a VP 290 outdrive. I got the boat with a Mercruiser 305 engine with a cracked block. I am replacing the engine with a Chevy 350. It has the water pickup pump on the front of the engine. I started the engine with the outdrive in a tub of water covering the intake over 6” after a few minutes the exhaust manifold was getting hot so I shut it off. I put muffs on the intake clamped tight with a extra spring clamp same problem. I pulled water pump impeller out and turned hose on very little water flow. I pulled the water pickup hose at the outdrive turned on water on no flow coming from fitting on top of outdrive. I put externa hose on outdrive water pickup water flows good out of water pickup, I noticed a large hole in bottom of outdrive water pickup should I try to find a plug for this when using muffs? I ran water through the hose to the water pump, good water flow. I put everything back together not much water flowing to the pump housing. I will try to find a plug for the hole in the bottom of the outdrive and try again. Do I need to pull hoses off exhaust manifold to allow air out when I first run after changing water pump impeller?
 
That hole needs to be plugged when running on muffs. No you don't have to pull those hoses.
If you have the gills underwater by 6" , that hole is not your problem. Running on muffs without plugging that bottom hole is a NO NO,
The fact that your manifold gets that hot indicates that you have a problem with the engine.,
 
sandkicker said:
That hole needs to be plugged when running on muffs. No you don't have to pull those hoses.
If you have the gills underwater by 6" , that hole is not your problem. Running on muffs without plugging that bottom hole is a NO NO,
The fact that your manifold gets that hot indicates that you have a problem with the engine.,
Click to expand...
I am not getting water to the water pump intake hose with muffs clamped on and drain hole plugged. I pulled the hose at the outdrive water flow is good to pump with impeller pulled and good going down to water intake with muffs removed. I put muffs back on and no water flow out of elbow going to the boat. Looking at diagram it should be a tube running from water intake straight up about a foot to a 90 degree fitting. It should flow water with hose connected. I will pull the lower part of the outdrive to check the water path. It acts like there is a check valve in backwards but I don’t see one on exploded parts diagram.
 
No check valve. BTW... problems with that water path is one of the reasons I went thru hull with an external wedge strainer. This also afforded me the opportunity to put in a T at the thru hull and a hose bib for flushing.
 
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