Over heat woes

[.44mag]

1996 mariner 200 efi sn. OG12989
Boat w as s running fine with no over heating issues until a moomba ski but came wot out of a cove and turned in front of me. I couldn't get off plane and slowed down enough before I hit his wake and went air born for about two foot. Everything seemed fine right after that. I made a long run to fish and on the way back got an over beat alarm. I came off plane to idle and watched the temperature gauge drop, cool down, so I shut down and trolled back to the ramp. Next day I put a new impeller in, went to the lake to test it and got an over heat alarm about the time I got on plane, shut down. Went to take the cowl off and noticed that the none functioning paralift jack plate was way up in the up position. Troled to ramp. I took the Paralift off putting the motor on the transom, can't afford to replace the motor and pump for it right now if I can find one to match up for the old jack plate. I put in a new water pump kit and another impeller. Stilling getting close to 200 on temp gauge. Took the thermostats out and it gets between the lowest hash mark and 200 degrees and I stop and idle until it cools down below 150 degrees and headband to the ramp.

Water pressure at idle is between 5 and 8 psi, in gear while idling water pressure is about 4 psi. Getting on plane the water pressure is almost pegged at 30 psi with the thermostats in or out????????????????????????

Thanks for any help.

[.44mag]

Oh prior to all this the engine would turn 6000 rpms and only get to 150 degrees on temp gauge with about 15 psi.

[Riccochet]

I'm no rocket surgeon, but it sounds like the poppet valve is stuck closed. Or whatever it's called on that particular motor.

[.44mag]

Will look into that.

[Riccochet]

Will look into that.

Just to expand. At least on my Pro XS. The thermostats are bypassed beyond a certain water pressure. That pressure opens the poppet value to allow a higher volume of water to flow through the block. So when you are at higher RPM's and water pressure your temps will come down below the thermostat operating temps. You come off throttle, pressure drops, poppet closes and then the thermostat open back up. If it gets stuck closed the thermostats simply don't allow enough volume of water to flow to keep temps low.

To me that's what it sounds like.

[.44mag]

Just to expand. At least on my Pro XS. The thermostats are bypassed beyond a certain water pressure. That pressure opens the poppet value to allow a higher volume of water to flow through the block. So when you are at higher RPM's and water pressure your temps will come down below the thermostat operating temps. You come off throttle, pressure drops, poppet closes and then the thermostat open back up. If it gets stuck closed the thermostats simply don't allow enough volume of water to flow to keep temps low.

To me that's what it sounds like.

Makes sense, I'm off tomorrow and will at least take it apart and give it a cleaning. When I replaced the water pump and impeller I noticed some sand in there. Hopefully that's all it is.

[.44mag]

Just to expand. At least on my Pro XS. The thermostats are bypassed beyond a certain water pressure. That pressure opens the poppet value to allow a higher volume of water to flow through the block. So when you are at higher RPM's and water pressure your temps will come down below the thermostat operating temps. You come off throttle, pressure drops, poppet closes and then the thermostat open back up. If it gets stuck closed the thermostats simply don't allow enough volume of water to flow to keep temps low.

To me that's what it sounds like.

Makes since, I'm off tomorrow and will at least take it apart and give it a cleaning. When I replaced the water pump and impeller I noticed some sand in there. Hopefully that's all it is.

[JOE54]

report back

[.44mag]

Took the poppet vavle off, the big disk/washer under the plastic disk didn't move when I worked the valve the first few times. It did have some gunk around it, wish I'd of took a picture but any way cleaned it with some dawn dish liquid. Headed to lake to test it. I will report back after that.

[.44mag]

report back

@Riccochet.
Ok guys ran her up to 5800 rpms several times with no over heat light/alarm. The temperature guage (yeah I know) showed between 170 and 200 degrees. Came off plane, took the cowl off and took a temp reading with a laser thermometer 120 on port and 125 on starboard t-stat housing. Put the laser about two inches from both. Idling in neutral my water pressure reads about 3.5 psi, idling in gear it's reading 5 psi, trimmed up about three bumps on plane at 5800 rpms water pressure is about 25 psi and it dropped with extra bump of the trim. Sorry didn't look at it at that speed just enough to tell that is was just below 20 psi but above 15 psi. Have new gaskets the rubber piece in hand, spring should be in Wednesday. So hopefully that solves that and I can get back to getting some seat time and catching more fish.

[Riccochet]

That's good to hear! Glad you got it figured out.

[.44mag]

Thanks!!!

[JOE54]