Johnson 110 running hot- no alarm

M

Mercboy

Seaman Apprentice
Joined
Sep 17, 2001
Messages
40
Just got off the lake tonight after testing an SE 300 hydrofoil that I installed on my bassboat. I ran the boat wide open (5800 rpm) for a good while immediately before trailering it. When I was putting the transom straps on and the motor toter, I felt some heat coming off the motor. I pulled the hood and the powerhead was VERY hot. It wasn't bubbling paint, but it was too hot to touch for more than a second or 2 everywhere, not just the heads. I have 23 PSI of water pressure at wide open throttle and a strong tell-tale stream. Water temp in the lake was probably around 80-82 degrees. Is this normal on a V4 crossflow motor? The motor was running great.
 
H

Hooty

Rear Admiral
Joined
Oct 2, 2001
Messages
4,496
Re: Johnson 110 running hot- no alarm

Probably residual heat and didn't hurt anything. A couple of things you can do though. First is, with the switch in the "on" position, ground the tan wires coming from the temp switches and be sure the warning horn works. Then, if you want to test the temp switches themselves, remove them from the heads and, using an ohm meter, heat the switches in a pan of water. They should close at 200*F.<br /><br />g'luck & c/6<br /><br />Hooty
 
M

Mercboy

Seaman Apprentice
Joined
Sep 17, 2001
Messages
40
Re: Johnson 110 running hot- no alarm

Thanks hooty, I'll check those. I assume at 5800 rpm alot of heat is generated!
 
L

ledgefinder

Ensign
Joined
May 2, 2002
Messages
916
Re: Johnson 110 running hot- no alarm

The thermostats on the later-model V4s START opening at 143 degrees. That feels pretty hot to me, & I can leave my fingers on for only a couple seconds. The factory manual says you have a problem if the cylinder surfaces melt a 170 degree heat stick. I believe the earlier V4s (1977 and older) opened at something like 105 or 120, and those I can leave my fingers on for 4-5 seconds.
 
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