thermostat

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hookedonjc

Petty Officer 2nd Class
Joined
Dec 27, 2003
Messages
156
Hey guys (1990 120 evinrude) Is it ok to run with thermostat removed allowing full waterflow all the time? I have heard of this being done<br />Thanks<br />Hooked
 
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ob

Admiral
Joined
Aug 16, 2002
Messages
6,992
Re: thermostat

I don't advise it as the engine never reaches its designed operating temp.Also makes for difficult warmup at cold starts.In some applications and depending upon the health and efficiency of your waterpump the lack of back pressure from the T/stat assys. will not allow adequate engine water jacket squeeze which can result in cylinder hot spots.
 
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hookedonjc

Petty Officer 2nd Class
Joined
Dec 27, 2003
Messages
156
Re: thermostat

Thanks for the reply I have taken the thermostats out and I took them apart and the brass looking piece has a pin that seems to be stuck out not allowing the tstat to fully close is the brass piece what actually opens and closes ? I was confused when I first pulled them out for inspection not understanding why it wasent fully closed. I thought the spring that is seperate done the work.
 
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ledgefinder

Ensign
Joined
May 2, 2002
Messages
916
Re: thermostat

Probably a 1/4 of the older OMCs I see up here (New England salt) have the thermostats removed, and some of them have been running that way for years. So, yes it is done. Further, Mercs didn't have thermostats at all until the mid-1980s. <br /><br />That said, your motor will have a shorter lifetime, use more fuel, and may idle way worse if you pull them. Most modern internal combustion engines run a higher temp thermostat, on purpose, than they ran "in the good old days". As long as it doesn't get TOO hot, a good warm/hot engine runs more efficiently (thermodynamically), & burns off water vapor easily so it stays clean inside. I'd leave them in there for sure.
 
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ob

Admiral
Joined
Aug 16, 2002
Messages
6,992
Re: thermostat

The brass bullet shaped piece is indeed the thermo actuating component of the T/stat assy.The large spring under the T/stat cover that contains the valve portion acts as the pressure bypass at higher engine speeds.
 
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rodbolt

Supreme Mariner
Joined
Sep 1, 2003
Messages
20,066
Re: thermostat

hello<br /> just put new thermos and diaphrams in it and engoy life. my 85 120 eats plugs and idles nasty when they stick open. the v-4 and v-6 looopers dont like to run cold.<br /> good luck and keep posting
 
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hookedonjc

Petty Officer 2nd Class
Joined
Dec 27, 2003
Messages
156
Re: thermostat

Thanks I just rebuilt this thing and I have new ones on order but I was wanting to run it a little for break in do you think this would be ok to do? By the way I apperciate all of your advice from the beginning when she first broke down on me. I figure I saved about $700 doing the rebuild myself. Boy what a sweet sound when it fired off yesterday<br />Hooked
 
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Hooty

Rear Admiral
Joined
Oct 2, 2001
Messages
4,496
Re: thermostat

Seven hundred bones? That's enough to take us all out to supper.<br /><br />c/6<br />Hooty
 
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