90 Johnson Overheating Issues

[SCMarine]

My 2000 Johnson 90 got the last time I had it out and went to shut down mode. I turned it off immediately and got a tow home.
When I got back I checked the compression and it looked good all 120 or+5. Rebuilt the water pump, new thermostats, and installed a tempature gauge.
When I run it now it climbs to 155 degrees real quick and will stay there at idle. If I give it a little gas It will go above 160. I haven't run it under load yet, but 160 seems a little hot and the guage jumps quick when you give it some gas. Is 160 O.K or is it still overheating?

 

[Rancherlee]

Re: 90 Johnson Overheating Issues

possibly a blown head gasket which will push water out of the head in which its blown. Do the "thumb" check on both cylinders at idle and see if one is hotter then the other as you should be able to get a good 2-3 second count before it gets too hot to hold your thumb on the head.

 

[SCMarine]

Re: 90 Johnson Overheating Issues

I'm going to put a temperature gun on it and look for hot spots.

 

[emdsapmgr]

Re: 90 Johnson Overheating Issues

The thermostat opens at 143, which means it wil probably run hotter, when operating normally. Your guage may have some variance also. 160 is not high. It should not have gone into slow mode at that temp. Did you check to see if you ran over a plastic bag?

 

[SCMarine]

Re: 90 Johnson Overheating Issues

I was thinking something like that happened because the engine got hot suddenly. Didn't see a plastic bag or anything when it shut down. I'm going to confirm that it is actually 160 and then try and run it.