90hp Johnson wants to run hot??????

[wilsonjg]

Got a 4 year old Johnson 90 hp that's been a great engine. Did some cleaning today and ran the boat "in the yard" like I usually do if I don't plan on running it in the river or sound that week. About 4 to 5 minutes into running, hot alarm came on. Water was flowing from foot, so I assumed the thermostats were working properly. Any other suggestions. Boat hasn't been run in ocean in about 2 months, but I do run the engine weekly for a couple of minutes, so she will not get lazy on me. Thanks for any assistance.

 

[petryshyn]

Re: 90hp Johnson wants to run hot??????

Best to actually FEEL the head with your hand. If you can hold them comfortably, engine is not overheating. If you can't hold them, engine running hot...>bad thermostat, bad impellar, blockage, etc.<br /><br />Is there a good stream from the telltale?<br /><br />Good luck!

 

[jegervais]

Re: 90hp Johnson wants to run hot??????

Is this a "cross-flow" motor?? If you don't know what a cross-flow is, just post your model number, we'll figure it out.<br /><br />Little known fact, cross-flow do have a tendency to overheat when run on a flushing device, so don't worry just yet...<br /><br />-John

 

[wilsonjg]

Re: 90hp Johnson wants to run hot??????

Motor is 90 hp 1998 Johnson SP<br />number J90TSLEC

 

[jegervais]

Re: 90hp Johnson wants to run hot??????

Yup, its a cross-flow. When you get the opportunity, back the boat into the water (you can leave it on the trailer - as long as you've got the ramp to yourself that is) and start & run it for awhile. If the hot horn doesn't come on, chalk it up to one of those "crazy thangsss"...<br /><br />-John

 

[wilsonjg]

Re: 90hp Johnson wants to run hot??????

Thanks for your replys John....will try the "ramp test". Hopefully, it will get enought water to prove I just left it on the flush too long.

 

[wilsonjg]

Re: 90hp Johnson wants to run hot??????

Did the ramp test. Backed off trailer and idled down river for about 3 minutes......and warning buzzer went off. Floated back to trailer, hooked boat up to leave and thought, what the hell, run her on the trailer for a while. I backed it down in the water and fired her up. Let it idle for a minute or two then put her in reverse and let it sit there and run to see how long it would take to run hot. Well, it never did, so I took it off trailer and ran it up and down the river a few times and could not get the hot warning buzzer to come back on...What do you think? Therostats stuck?? Any suggestions would be great.

 

[DJ]

Re: 90hp Johnson wants to run hot??????

My guess is stuck thermostat(s). It's happened to me before.<br /><br />When you flush it after running it in saltwater, how long do you let it run? It has to get to operating temp. to do a thorough job.<br /><br />If not, the thermostat(s) turn into little white balls of salt.

 

[wilsonjg]

Re: 90hp Johnson wants to run hot??????

I usually let it run when flushing until I see water coming from my foot vents when the therostats open. Once they are open, I let it run 2 to 3 minutes tops...

 

[DJ]

Re: 90hp Johnson wants to run hot??????

Wilson,<br /><br />I assume you mean the two vents (exhaust reliefs) at the top of the leg? If so, that's a relatively good indication she's up to temp.<br /><br />I feel the telltale and the spray coming out of those vents to make sure it's nice and warm.<br /><br />Even at that, those stat's can be tempremental after sitting for a while. I'm working on an older 90 that would NOT warm up. One bank of cyl's was fine, the other stone cold. Duh, no wonder it didn't want to idle smooth. <br /><br />I think you're OK.