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175 mercury outboard

M

mikestoke

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"I changed my water pump and b

"I changed my water pump and both of my thermostats and it seems to be running hotter than I expected. At 3/4 throttle it is a little over half way, at a idol it is almost all the way to the H. Before the tale-tail was barley spitting any water out , now it is pretty hard but it seems it should be running cooler. Any help will be great.

Mike"
 
"It maybe that the thermostats

"It maybe that the thermostats you replaced were not seating properly as over the years they can warp etc and will let a constant flow through. Now u have installed new ones they seal better and dont allow flow until temp is up, a cooler thermostat will open up earlier to keep engine temps down."
 
"Thanks for the reply,, should

"Thanks for the reply,, should I try putting the old ones back in? I bought the boat used about 6 months ago so I don't know when they were replaced last. Or should I buy some new ones?"
 
"depends? can u tell if the on

"depends? can u tell if the ones you purchased recently are the same temp rating as the old ones? do u have any part numbers? for peice of mind do an old trick, get a pot of water on the stove, from cold heat it up and have one new and one old thermostat in the pot as it heats up see which one opens first. then either use the colder one or take it down to get a similar temp thermostat."
 
"Thanks Brent, I sure will try

"Thanks Brent, I sure will try that.The new ones I bought at an auto parts store, they are 140 deg. Not sure what the old ones are.
thanks mike"
 
"Mike, do you know the model y

"Mike, do you know the model year or have the serial for your motor.

The 140's sound correct (actually I think the Merc branded are 143 degrees) - in any event most of the 6 cylinder Mercs are not considered to be running "hot" until 170+ if that helps..."
 
"when u say 140degrees, I bel

"when u say 140degrees, I believe u mean farenheit? sorry for the ignorance as we use celcius degrees over here in good old aussie land"
 
"Yes, I do mean 140 F, sorry,

"Yes, I do mean 140 F, sorry, we changed to Celcius in Canada when I was in high school and never really got the concept on that one. When it's 18C outside I have to convert it back to figure out whether I need a jacket or not


Anyhow, Mike, that model year would not considered to be running hot until above 170 degrees and not actually running hot enough to cause a warning until higher than 190 degrees (all in farenheit).

I suspect that you have got used to seeing the motor "run cold" on your gauge and it may be running "normal" now which seems high to you.

Or even alternately/coincidentally your temp sensor may be off a little/dying which is causing a higher reading that actual.

If your tell-tale stream is strong and feels nothing more than warm (no steam coming from the tube is another good sign), the motor is probably not overheating.

You should be able to put your hand as well on the head/waterjacket and keep it there for a couple of seconds without burning it.

Best to determine if there is an actual problem before you start tearing into something that may be "finally" working as it was designed..."
 
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