I have an older evinrude 88hp 2 stroke and will sometimes idle it in the driveway with the muffs, and the water hose turned all the way up on high. I do this just to run it when I can't get to the lake for awhile. Anyhow, The overheat alarm will come on after a few minutes. I had the impellar and Tstat changed recently and I never get that alarm when out on the lake, only on the water muffs at idle. The tell tale is peeing and everything seems normal. Is this normal due to the engine not being submerged with back pressure? Thanks.

Very possible. I wouldn't worry about it if it runs fine on the lake. Does the alarm go off if you're sitting on the lake at idle?

No, only in the driveway. Thanks for the reply.

I think your fine but I would stop running in the drive with muffs. Submerge it in a barrel of water if you must run it at home. 

If you turn up the water pressure too high the muffs can't stay tight to the engine intake ports.

You only need about 10 psi of water flow to cool the outboard engine at idle without introducing air into the water flow.

Water coming out the pee port doesn't indicate water is circulating through the engine power head. Water coming out the exhaust discharge indicates the thermostate has reached it's pre set temp and circulating water.

Tom

Thanks guys, I will try it next time with less water pressure and see if that helps. I normally don't like to run it at home, noise, smoke, etc. But it is a pretty good trip to the lake and if I do not have time I still like to run her just to keep everything in shape. These old engines like to be run and do much better if used more than just sitting around.