2000 Johnson 90 overheat alarm

[aacopd05]

My 2000 180cc is pushed along by a 2000 90hp Johnson two stroke.  All had been fine until recently during a trip back to shore in some rough water.  My hot alarm went off and the motor went into limp mode.  I got home, checked it later and found water was coming out the spout as it appeared it should.  I ran it in neutral for a while and the alarm never went off.  So I went for a ride and about 5 minutes in the hot alarm went off again and it was back to limp mode.  Where to start?  I know it has two thermostats and two temp sensors.  Before I start replacing stuff are there suggestions on what is the most likely culprit?  Any trouble shooting I can try? Thanks!

[gtightline]

My first guess would be the impeller. It could very well be shooting water out in neutral while sitting in your driveway, but putting it under a load could be a horse of a different color. When was the last time you changed the impeller?...If you are mechanically inclined it is no big deal to change, if it has never been done that you know of, changing it wouldn't be a bad idea....That's where I would start. When changing the impeller I personally would change the cup and the bottom plate while I'm in there...Here is a short video so you can get an idea. Good luck and keep us posted.

[Juan]

I agree with gtightline. Impeller first, thermostats second. If it's not the impeller, the thermostats may not be opening all the way thus preventing proper cooling. You can pull and check the thermostats to see if they are opening fully by holding a lighter under them.

[Juan]

Sept 1, 2016 17:30:58 GMT -6 @poerover said:

I agree with you Juan on checking a thermostat with a lighter but you have to careful with it. You can get a false postive because you can't control temperature or know how hot. Best way is to just put in a pot of water with a thermometer to make sure.

Agreed,,, Not as accurate, but much faster to use a lighter. They're not expensive, probably best to just replace em to be sure.

[freezerfiller]

Yep Impeller is likely your problem. I had the same issue once and it only happened when I was trolling. I thought my Johnson was peeing good, but when I put in the new impeller, it was so much stronger and the issue went away. Usually the t-stat will cause an alarm at idle or any speed, but why not go ahead and change them? Having to cut a trip short isn't worth it to me.

[aacopd05]

Thank you all for the responses.  I'm not sure if the impeller has ever been changed, I just bought the boat earlier this year.  I did notice that it was "peeing" (lol I'm sure there's a correct term for that) while in neutral and under load, but it may not be enough to cool the motor.  I appreciate the video and it looks like something I should be able to tackle.  I keep the boat on a lift and do have access to a floating pier, is that sufficient or should I trailer it to remove that lower unit?  Thanks again everyone!

[gtightline]

Not sure what you mean by floating pier, but if is over water I would suggest taking the boat to an area where you could be on solid ground and have access to some type of vice or cradle where you can rest the lower unit once you get it off. It makes it much easier to work on....let us know how it works out. Remember your learning experiences are also a learning experience for us all....Keep us posted.

[aacopd05]

Gotcha, I'll trailer it. Any brand better than another when it comes to parts? My research brings up Sierra most of the time.  Also where can I find the torque specs for the housing and the lower unit bolts.  If anyone has them for my motor that would be awesome, its OMC model number J90VLSSS if that is helpful.

[gtightline]

I purchased the impeller as a kit at Boat Owners Warehouse here in Fort Lauderdale Florida. It was an aftermarket kit specifically for my 1997 115 Yamaha, It came with a new cup housing and seals and bottom plate. I suggest when you do the job that you replace everything, no shortcuts, your in there, might as well do it right....Sierra, when I think of that name I think of thermostats...I can't remember who manufactured the impeller kit.As for torque specs on that I haven't a clue. When I did mine I just tightened it down until I felt it was tight enough, that's all.Just don't over tighten it to the point where you split or break the housing, it is plastic, although thick, still plastic, as for the torque specs on the lower unit, again I just tightened it until I felt it was tight, I did it by feel, what ever you do don't tighten to the point where you strip or break a bolt, cause then a simple fix turns into a pain in the you know what....Good Luck and let us know how it turns out.

[aacopd05]

Thanks again for all the info and tips. I found a Johnson/Evinrude brand pump kit from a local dealer so I'm going to pick that up today and dive into this tomorrow. The OEM kit was a bit more expensive then the aftermarket but I figure this was the better route to take and I like to stick with original parts. Hope to have an update/good news tomorrow.

[freezerfiller]

You are taking the right route. Once you get into it you will be happy you got her off the water, it complicates the process, particularly when you drop something. The brand name kit will last for years so the additional cost is minimal. To me it's worth the peace of mind. Sierra seems to make a good product however. Pm me your email address and I'll see if I can get you that info on the torque specs.

[aacopd05]

PM sent.

[freezerfiller]

You have mail

[aacopd05]

Thanks for all the assistance. I did change out the pump today. I think the hardest part was disconnecting the shift rod, but once it was off it was a breeze. I put everything back together and didn't notice a ton of difference in the amount it "peed". But the old wear plates did have some grooves. While the cover was off I decided to check the thermostats to make sure they were operational. I took the housing covers off only to find that neither side had thermostats in them. I guess the previous owner took them out for one reason or another. But I did drop her in the water and ran her for a while at full throttle and no over heat alarm. So it appears mission was accomplished.

[gtightline]

Great news!

[Juan]

Sept 6, 2016 19:14:51 GMT -6 aacopd05 said:

I took the housing covers off only to find that neither side had thermostats in them. I guess the previous owner took them out for one reason or another.

You might want to consider replacing those missing thermostats especially if you use your boat during the winter or in cold water. Running an engine hard or at high rpms before it's warmed up to operating temperature can cause serious problems. I've heard of outboards locking up when the cylinder walls have heated up and the water running through the cooling ports hasn't had time to warm up and running without thermostats, the water cooling your engine is the temp of the water it's picking up. It's not uncommon to remove the thermostats in southern waters but could be a serious problem in cooler waters.

[aacopd05]

Thanks for the info, I don't plan on using it during the winter and will winterize it. I'm not sure why the thermostats were removed, I was surprised when I found they weren't in there. I don't want to chance ruining anything by any means. Obviously its designed to run with thermostats so I probably will replace them, just makes me wonder why they aren't in there now. Its easy enough to get to so why not right.

[Juan]

I'll bet it ran hot with the previous owner too and instead of changing the water pump, he removed the thermostats thinking that was the problem.

[aacopd05]

I was kinda thinking along the same lines. Good news is I went out for another run today, a longer run this time, and still no alarm. So far so good.

[aacopd05]

Things are still going well. I ordered and just got in two new OEM thermostats and springs. They will be going in this weekend. Hopefully there will be no over heating after they go in. More to come.