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Overheat Issue
1998 v4 115 HP two cycle not injected. Changed impeller plus housing and hose checked ok. Six weeks later put it in saltwater and after pulling boat off trailer the overheat light came on and with little to no water coming out of motor. Checked impeller and it was ok. changed out head thermostats on both sides as well as cleaned water channels and ports and installed all new gaskets. Hose run check gave overheat light and horn. Pulled heads off both sides and removed sand and debris, clean water channels and installed new gaskets. Hooked water directly up into water pipe after removing lower unit. Motor ran 118 degrees on both sides. Reinstalled lower unit with new impeller and motor gave overheat light and horn with left at 140 degrees and right at 190 degrees. I am out of things to check. Should I install a complete water pump and all new hardware? Could it be losing water before it can be pumped into engine? The direct hose hookup implies it is not getting water up there unless it is connected directly by passing pump. Could it be cavitating losing water in the pump somehow?
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did you look at or change the PRV and grommet?
It will dump too much water at low RPMs if stuck open and cause overheat -
No I haven't checked the PRV but will check it today.Comment
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The PRV was checked and it looked good. After removing the lower unit again to examine the pump I discovered the lower stainless plate below the impeller was with wear circle-cut just inside the o-ring fit point and also at the small hole beyond the center point of the impeller. Installed a new plate and put all the other new pump-parts back together and this time the pump moved water uphill and the engine did not overheat at idle. Left and right sides ran at 118-119 degrees. So overheat issue solved after a better inspection of parts I don't normally replace or inspect. Don't know what caused the circular cut into the plate yet but I will examine it closely in the future. Thanks 99Yam40 for your help.Comment
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If you buy the kit instead of just the impeller, it comes with the wear plate and cup along with impeller, bolts, o rings and gaskets and does not cost much more than impeller itself. Just does not come with housingComment
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I'm OMC tech from way back before they did fuel injection...
I recommend the full waterpump kit every few years because the sand in the water wears the groove in the plate and SS cup. Especially if you do a lot of operating in the shallows.
ChaChing, two cents please.....If its got teats or tires, you bound to have trouble with it....Comment
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Had a similar issue found that the impeller housing was not sealing to the plate needed to Sand down pump housing. Take a sheet of sandpaper on a flat surface and work the housing back-and-forth motions Evenly,when you put the O-ring in the housing the O-ring should protrudes outside the housing Groove I've had no more issues since then Hope this helpsComment
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I believe it was the lower SS plate that caused my problem. The grooves cut into it did not allow the new impeller to create effective water pressure and thus the engine overheated in idle. I have learned that the grooves were probably made by sand and/or shell sucked up into the water pump. Once it cut in grooves, the new o-rings did not cover the grooves-gap and I loss water pressure. Good advice about sanding the housing to ensure the o-rings protrudes beyond the grooves. In my case, I replaced the housing so it was good. I will look at this every time I change the impeller. I will replace SS plate every other year as well as check the o-ring housing for effective sealing capability. I am learning albeit slowly. Thanks.Comment
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the cup will groove just like the plate, but the housing will not need replacing unless there is a problem from overheating and melting. The housing does not come in the kit.
Just put the kit in every time and inspect the housing and all will be goodComment
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