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2003 50Gxi overheating

B

bcarr

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"I ran into a problem last tim

"I ran into a problem last time out when the engine suddenly overheated after getting up on plane. I checked the usual suspects (raw water pump, intake hose and outdrive, thermostat, etc.). Nothing jumped out at me as looking suspicious. I replaced both risers, circulation pump, thermostat, and water temp sensors. I put it back in the water this past weekend and it did the same thing. While I was flushing the engine, I felt both risers and the starboard riser was noticeably hotter than the port, The port one felt almost cool to the touch. I believe I have narrowed down my problem, but what would cause one side to run hotter than the the other? Any help you can provide would be greatly appreciated."
 
"I had this condition last yea

"I had this condition last year,,,It was a bad dash gauge....I tested the motor with a external laser tester and all was fine..Replaced the gauge"
 
"Thanks for the response, but

"Thanks for the response, but I'm still curious as to why one riser would be noticeably hotter than the other. I'm beginning to suspect that I may be getting exhaust gases into the riser through the gasket sealing area.
When I replaced the riser, it came with a new style metal gasket. It required that I grind the mating surface of the manifold flat. I used a belt sander to perform this and I noticed that there was one area that would not 'shine up' like the others; no matter how much I sanded. I put a straight edge on it and there was no dip, so I put it together. I thought I had it licked since I wasn't getting any water into the exhaust manifold, so I let it ride.
Just to be on the safe side, I'm ordering a fresh set of manifolds. I'm afraid if I don't, that problem will continue to haunt me."
 
"Brian,
On the port side of

"Brian,
On the port side of your drive on the intermediate housing there is a grease fitting, it is there to lubricate an o ring that supplies water to the engine via the pick up tube, I had the same problem myself once, and the engine would be just fine while not on plane, and overheat while on plane, the problem was the o ring, after time this o ring if not properly greased will rupture, thus letting the engines water pump suck air, therefore making the engine overheat while on plane, it is an easy fix, and I suggest you check here before spending any more money on parts you may not need. Good luck.
Michael"
 
"That makes sense Michael, but

"That makes sense Michael, but if that was the case, wouldn't it suck air if I was running it with muffs? The o-ring would be exposed, so if it was sucking air, I should be able to see it if I replace one of the hoses with a clear plastic one. If that's the case, where is this o-ring located and is there a good parts breakdown so I can see how it ties into the grease fitting? I've got a manual, so I plan on taking a closer look at this tonight. Thanks for your help."
 
"Brian,
The O ring is locate

"Brian,
The O ring is located in between the lower unit, and the intermediate housing, you will have to remove the lower unit to see this o ring, it is lubed via the grease fitting on the left side of the drive.
Checking the water flow with a clear pipe is a great idea, this will let you know if that is the problem.
Does your engine over heat while on muffs? Also not, that you probley are not running the engine near as hard while on the muffs, so you may not be over heating , however while running on plane, if this o ring is at fault, you will for sure know it, just a thought, Good luck.
Michael"
 
"Thanks, I'll check it out

"Thanks, I'll check it out. The only thing I noticed while running it on muffs is that it warmed up quicker than usual (didn't overheat)and the starboard riser was quite a bit warmer than the port. I disconnected the sensor on that riser and it appeared that the temperature dropped back some. The temperature never exceeded 170 deg.
Loaded with this new information, I'll do some more diagnostic work this weekend. Thanks again for your help."
 
"Brian,
Some times we find t

"Brian,
Some times we find that the raw water pump pushes more water to port side than starbord, this is most common to a bad impeller, or leakage of some sort, and often found while running on muffs. Check your impeller for starters, i know you just replaced it, but I have had the same problem, what happens is that the raw water on port side is closer to the pump discharge, and most of the water is going to go there first, instead of going up that line to starbord, and dumping into exhaust.
My first thought is that you have a bad o ring, second is that you may have installed the impeller wrong, (and its easy to do) done it myself, but dont tell anyone please! But anyway, if the impeller is installed with the fins in the wrong direction, you can bet it is shot all to hell.So check these couple of items out, and see what you find. Good luck.
Michael"
 
"Brian, I agree with Michael.

"Brian, I agree with Michael. Check the impeller, or leakage of some sort...Air is not your friend. I replaced a bad impeller and had a air leak that made me go crazy..The next time I replaced it I took my time and did it right the first time. Take your time be a detective before you jump to anything on replacement parts...My port side is 4 degree cooler...Good luck..."
 
Brain
Just had the same probl

Brain
Just had the same problem w/ my 5.7 GXI. I had a air leak on the intake side of the pump. You can cut in a clear plastic hose to see if your pulling air in the intake side of the water pump. Retorque or replace intake hose to pump.
 
"Thanks for all the tips guys.

"Thanks for all the tips guys. From my observations and what I've read in these posts, I'm convinced it's an air leak on the intake side of the raw water pump. When I hook the muffs up to the lower unit, I noticed water coming from a fitting connected to the 'S' hose coming out of the pivot housing.
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Pivot Housing"">I'm thinking that either the tube (23) is cracked, nut (27) is loose, or the o-ring (24) is blown. Either way, looks like the lower unit is coming off to repair it. Guess I'll be taking this opportunity to replace the bellows as well. Thanks again for all your help."
 
"Removed the stern drive Frida

"Removed the stern drive Friday evening and found a severed tube (23) (broke in two when I removed it). Replaced the tube and took her out on the water today for Mothers day, everything worked perfectly."
 
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