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175hp Yamahaoverheating

papas

New member
"Hi,
I have a 1992 Yamaha 175


"Hi,
I have a 1992 Yamaha 175hp outboard motor, the alarm sounds that is in the control box. The motor runs well without any issue until you exceed 4000rpm for a period of time. The bottom left indicator on the tacho light ups indicating a temperature problem. Leave the motor running in neutral for approx. 15 to 30 seconds ceases the alarm. (also keeping the engine revs below 3500 revs will not activate the alarm).
I have changed the impeller and the thermostats and I still have the problem.
Any ideas as to the cause of the alarm?"
 
"#48
[url=""]http://www.yamah


"#48
http://www.yamaha-motor.com/outboard/parts/home.aspx
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that will b $5 please, lol"
 
"Hi, found the poppit valve lo

"Hi, found the poppit valve looked in good condition cleaned and replaced it, took the boat for a run and the overheat alarm sounded again when travelling at 4000rpm (below 4000rpm no issues). Removed the cover from the motor and felt the temperature of both heads with my hand, I was able to keep my hand on the heads while the motor was running. Based on this do you think that I may have a faulty heat sensor (swith) on the motor or could it be something else?"
 
"I have a 98 150 VMAX with the

"I have a 98 150 VMAX with the same issue. I have done all of what you have and just finished the PRV replacement. Still overheating at about 3500 to 4000 RPM. I gained a few RPMs before overheating, but I think that is just due to the water temperature being cooler than the last time I was out. Thermo switch is about the only thing left other than the water jackets. Also your water jackets may be causing the overheating in a location that would not be evident by just touch alone. Let me know how you fair after testing the switch."
 
best is to use a infa-red temp

best is to use a infa-red temp gun
around 30 from harbour frieght

running lean also would mae you run hot
 
"Andrew, if the engine is in f

"Andrew, if the engine is in fact running hotter than designed it will start steaming from the exhaust. If you don't see any steam and the heads are only warm to the touch look for a faulty sensor...any discolouring/browning of the paint on the heads?...a sure sign that overheating has occured I beleive the so called poppet valve is a preasure releif valve and only dumps off excess water when the pump is pushing more water than the block can handle....ie high rpm"
 
"Dave, I usually run about 420

"Dave, I usually run about 4200 at about 30 mph..I think I can get down below 3000 and still keep it on plane..just. I'm running a 22ft Seasport"
 
"used an infra red gun and tou

"used an infra red gun and touch thermometer, confirmed heads are overheating.
Checked thero switches, both are fine (activate at 87 degrees C).
Before I remove the water jackets for inspection do you think it mat be something else ie timing, fuel mixture etc??"
 
"Update.
Finally bit the bull


"Update.
Finally bit the bullet and removed water jackets, both were found to have a salt build up inside restricting water flow (right side was worse). Cleaned water jackets and replaced. Motor is running well with no overheating problems. Ran motor at 4500 to 5000 revs for 10 mins no problems. Ran motor continuously for 9 hrs offshore, no problems.
Hope this information is of use to someone else.
Thanks for your help."
 
Friend has same problem....how

Friend has same problem....how big of a hastle was it to get to the water jackets? And how did you clean them?
 
Not a big job actually very ea

Not a big job actually very easy removing covers. The only way to clean is to scrap off the salt build up. Will need new gasgets at $35 each.
Also a low torque wrench range 20 to 200 cm.kg.
 
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