2000 Johnson 115 still running hot at low speed

bullgator99

Seaman Apprentice
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Aug 30, 2004
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My Johnson 115 warms up to 155-160 at idle. Above 1500-2000 rpm the temp comes down below 120.<br /><br />Last season it never went above 140.<br /><br />So far I've replaced the water pump, thermostats, and t-stat seals. It's still getting hot at idle.<br /><br />Any suggestions?
 

bullgator99

Seaman Apprentice
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Aug 30, 2004
Messages
43
Re: 2000 Johnson 115 still running hot at low speed

Does anyone know of a way to tell if there's an obstruction somewhere in the motor? Does this unit have deflectors (they are not mentioned in the manual or parts list)?
 

ezeke

Supreme Mariner
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Sep 19, 2003
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12,532
Re: 2000 Johnson 115 still running hot at low speed

No deflectors on the loopers.
 

mike481050

Cadet
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Jun 1, 2004
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Re: 2000 Johnson 115 still running hot at low speed

1997 90hp Evinrude looper. <br /><br />Since new idled at around 160f and ran between 120 and 140 depending on if it was Summer or winter.<br /><br />530 hours and no problems<br /><br />Cheers!
 

bullgator99

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Re: 2000 Johnson 115 still running hot at low speed

Thanks for the info!<br /><br />I just got back from the lake and at 1500 rpm the gauge went one mark past 160 which I guess is 170. Got it up to 1800 rpm and I guess the water pump pushed the stats open and she cooled down to 130-140.<br /><br />When I got back to the dock I pulled the thermostats and found some very fine gravel just inside the starboard thermostat seal.<br /><br />I went back out and ran her without the stats for 15-20 minutes, hoping to flush her out.<br /><br />Went back to the dock and put the stats back in, and she promptly went back up to between 160 and 170 at idle.<br /><br />I'm concerned that there still may be some gravel in my water jacket. Will running without thermostats flush it out or is there a better way?
 

seahorse5

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Jan 24, 2002
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Re: 2000 Johnson 115 still running hot at low speed

Originally posted by 99fourwinns:<br /> My Johnson 115 warms up to 155-160 at idle. Above 1500-2000 rpm the temp comes down below 120.<br /><br />Last season it never went above 140.<br />
The first things to realize are that the dash temp gauges are not that accurate, and they are not taking the water's temperature, but reporting the metal temp at some area of the cylinder head.<br /><br />The idle specs for a Johnson 115 and almost everyother traditional 2-stroke is 145 degress, plus or minus 15°.<br /><br />The only true way to see the engine temp is to use an infrared gun or a TempStick on the top of the cylinder head by the thermostat cavity, or if different location is mentioned in the factory service manual.
 

bullgator99

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Aug 30, 2004
Messages
43
Re: 2000 Johnson 115 still running hot at low speed

Update:

I finally got around to measuring the temp with an infrared thermometer.

It reads 163-164 on the starboard head and 87 on the port head.

This doesn't seem right to me. Any ideas?
 

Solittle

Fleet Admiral
Joined
Apr 28, 2002
Messages
7,518
Re: 2000 Johnson 115 still running hot at low speed

163-164 & 87 makes no sense at all. If you touch both heads after the engine is up to operating temp they should feel roughly the same - hot but can touch for a few seconds. You could also check the temp with temperature sticks as Seahorse advises.

If that does not add anything you might want to pull the heads & check for crud.
 

Fl_Richard

Lieutenant
Joined
Jan 21, 2005
Messages
1,428
Re: 2000 Johnson 115 still running hot at low speed

Ezeke,

I tried your link for "looper Idle temp". It seems the new board has broken all the old threads.....

I've searched for the thread you mentioned, any clue how I can find it? I'm interested to read it.

Many thanks,

Richard
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: 2000 Johnson 115 still running hot at low speed

The 143 thermostat is designed to open at 143, which means it will normally run hotter. The 163 sounds OK at idle. The 130-140 also is normal once you are at running speed. The 87 is not. I know you replaced the thermostats, but it sounds like one is sticking open. Either it is defective or has some debris in it, holding it open. Running cold is not good for the combustion process.
 

clanton

Rear Admiral
Joined
Jul 9, 2001
Messages
4,876
Re: 2000 Johnson 115 still running hot at low speed

Very easy to have the wrong water pump housing in this engine.
 

seahorse5

Rear Admiral
Joined
Jan 24, 2002
Messages
4,698
Re: 2000 Johnson 115 still running hot at low speed

Just to make sure that you have a looper 115, the motor mounted trim button is on the port side of the motor, correct? If it is on the stb. side you have a crossflow engine with a completely different cooling system.

Because of the difference in temp on the heads its time for some detective work. Are the thermostat springs a red color? If not they have to be changed. Look inside the t'stat cavity at the round rubber seat that the t'stats seal against. If they are distorted and not perfectly round, they can cause both sticking and un-sealed problems with your motor. The head had to come off to replace the seal. A severe overheat condition can distort those round seals.
 
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