Water Circulation Problems

Have a Gray Marine 327 with re

Have a Gray Marine 327 with reciculation system.

Inspected the Sherwood pump and vanes are ok. Water comes out of both outlets in spurts. Water is getting thru the oil cooler and exhaust manifold and into the front of the block on both port and starboard sides...again in spurts. Removed the relief valves and there is water in the head cavities.

Thermostats were removed and tested and were ok. But not getting any water at all not even the tiny stream they should provide when closed thus no water out the exhaust in 30 seconds as specified by the service manual. Shut her down it says or engine will be damaged. As long as I monitor the temp to < 160 can that be?

My gut says it's the pump not producing enough pressure... evidenced by spurting? The pump is such a simple design hard to imagine what the problem could be. How would you measure the pressure? What are the best tools to do it?

Im running test on trailer with fake a lake input which hasn't been a problem in the past.

Any suggestions would be appreciated.

"Could you be sucking air in t

"Could you be sucking air in the intake side somewhere? What condition is your supply hose to the pump. I use a plunger with a hose connection jammed up to the bottom intake while testing on the trailer, make sure your water supply is adiquate. The only other possibility I can think of at the moment would be the relief valves sticking. They are neoprene ball/spring pressure activated valves. They do have a tendance to get rust formed around them and stick open.
Cal"

Cal...Im using the same supply

Cal...Im using the same supply set up as u and believe ample water. Ill turn it up full blast and try again. Relief valves inspected and clear.

Pump is rated at 15GPM max at each outlet...don't think it is anywhere near that. The relief valves activate at 4-6 pounds. Im going to run the engine for a couple of minutes and see how much it will pump into the boat...will keep u posted. Thanks for the input.

"Jeff...I had problems with my

"Jeff...I had problems with my 327 also but she was overheating. It turned out the problem was in the heads where water flow was restricted. I ended up blowing a head gasket and the port head had a crack in it. Lucky for me the shop I deal with had another head. I'm currently having the heads redone and should have her running next week. I went through everything too, the pump, thermostats, all the hoses were removed and there was no blockage. The problem when working on this part of the engine is the exhaust manifolds. I was able to get mine off and save them for reassembly."

"Well I took off an outlet hos

"Well I took off an outlet hose...a fair amount of water was flowing so I reconnected the hose and ran the engine for about 5 minutes and finally got some exhaust flow. Keep running it until the temp leveled off @ 160...not overheating.

I guess it just needed some time to purge the air from the system.

Don where did your heads get plugged? Did your relief valve fail or thermostat? I know from servicing mine that there is rust in there and I suspect in the exhaust manifold also. While the water from the exhaust is clear I fear rusty water will, eventually screw something up. Anyone know if they can be cleaned and if so how?"

"check your intake hose to mak

"check your intake hose to make sure there are no vanes from a water pump impeller that was changed sometime ago if the vanes break off the hub of the impeller, they will lay in the intake suction hose. and when the pump is trying to pull water from the intake, it will starve the pump. Also you might try disconnecting the hose from the pump and lay it down in the bilge of the boat to see what kind of water flow you have. when the eng is running You should have a solid stream of water, coming out of the discharge side of the pump. check your impeller the vanes might be weak and need replacing. also check the cam in the pump it also might be distorted or grooved with wear. Also the intake hose might be colasping when the pump is running. the intake hose should be a wire reinforced hose 1" in diameter. hope this info helps you out
Fred Durbin
[email protected]"