Overheating still possible on muffs 71 Johnson 50

[Jconnell43]

I have replaced the water pump impeller (which was good anyway ) and the thermostat but I am still getting the overheating siren.

I am running it on muffs and do detect some water coming from the upper unit, no pee hole apparently on these.
I'm also getting some water coming out from the propeller.

I have the muffs attached to a garden hose which is not on full force.

Did I miss something or will an old engine still overheat on muffs only after 5 minutes of running (siren is loud).

Any ideas will be appreciated.

Jim

 

[F_R]

Re: Overheating still possible on muffs 71 Johnson 50

You cannot test the water pump by running on muffs. It is being force-fed by the hose, so the water pump is not doing anything but letting the water pass through. So, is your motor overheating? I dunno. You will have to put it in the lake to determine that.

 

[emoney]

Re: Overheating still possible on muffs 71 Johnson 50

If you can't get it to the lake, a 50hp should fit in a good sized outdoor trashcan full of water. Might have to put the can up on blocks, depending on how high it is, but much better test of waterflow. Just keep the hose near the bucket for the water that gets expelled. If you have a Harbor Freight nearby, they sell an Infrared Digital Thermometer than is just point and shoot to get a real reading on the heads. Best way to confirm the T-stat is opening as well.

 

[boobie]

Re: Overheating still possible on muffs 71 Johnson 50

As said above muffs are no true test for overheat probs. Get it in the water and make sure the l/u is deep enough in the water.