Can Outboard run without Thermostat?

92Evinrude200HP · Apr 24, 2006

I recently replaced the thermostat on my Evinrude 220 Looper with identical ones purchased from an online source. After installing them, I noticed that the temperature rose to 190 deg when idling. With the original thermostat, the temperature never rose pass 170 deg I cant replace the old ones because they are now burried in a land fill somewhere. I decided to remove the new thermostat all togethter and the tempertature now never rises above 120 deg. I am from the Southern California region so the cold temperature is not an issue. If I leave the thermostat off, will this cause any harm or performance to the outboard. Thanks

jfm1 · Apr 24, 2006

Re: Can Outboard run without Thermostat?

the t-stats are there for a reason" if it were mine I would replace them.

floatingwoody2006 · Apr 24, 2006

Re: Can Outboard run without Thermostat?

I don't run with a thermostat at all, and i live in maine, but i only have a little 18 horse. In fact, the mechanic took it out for me. Truly, i don't see how it could hurt running without one. Im sure someone will chime in and prove me wrong..

ezeke · Apr 24, 2006

Re: Can Outboard run without Thermostat?

Were the new thermostats the black ones and did you replace the cover gaskets with new ones? There are small holes in the cover gaskets that need to be open. The looper likes to run warm. Run cold, it gets excessive carbon and fouls plugs. I've been told that running a two stroke cold changes the shape and relationship between the piston and the cylinder and accelerates wear. I think your alarms would have gone off if you really hit 190 degrees - might want to check that with something a lttle more reliable than your dash gauge.

2even · Apr 24, 2006

Re: Can Outboard run without Thermostat?

92Evenrude200HP,I have a pair of 1989 225 rude's that I run without the thermustat guts, therefore creating an even flow with a slight restriction. The temp never goes over 160.

itstippy · Apr 24, 2006

Re: Can Outboard run without Thermostat?

Uh huh. No tstats. Why do you suppose the engineers at OMC designed it with tstats if it runs better without them? If you don't have a tstat the cooling water circulates unrestricted around the cylinders. So they stay nice and cool. But the pistons inside them still get hot. Nice hot expanding pistons in nice cool cylinders. Not a good idea at all.

red boat · Apr 25, 2006

Re: Can Outboard run without Thermostat?

IO have a 1990 Evinrude XP-200 I ran mine without t-stats and had to rebuild it because of cold siezing after only 20 hrs without them. How badly do you want to do a rebuild?

Saskatoon2005 · Apr 25, 2006

Re: Can Outboard run without Thermostat?

I agree that these outboards are built with t-stats for a reason...replace them and gaskets. The piston needs to be in a warm environment, if it is cold something will give and a rebuild will be necessary.

floatingwoody2006 · Apr 25, 2006

Re: Can Outboard run without Thermostat?

I stand corrected.. Hope my 18 hasn't been affected..Im assuming a mechanic that would remove it and say it was fine, i may not want to return to..

92Evinrude200HP · Apr 25, 2006

Re: Can Outboard run without Thermostat?

Thanks for all the great information. Time to replace the thermostat!

KYHunter2 · Apr 25, 2006

Re: Can Outboard run without Thermostat?

Hey Floatingwoody, Didn't I read in another post, about you being concerned with a breakdown . Where you run around. While your putting your thermostat, back . If you haven't done it in awhile , rebuild your waterpump. LOL, KYHunter

Oh, One more thing, Which tree was your "mechanic" sitting under ? ? LOL.

floatingwoody2006 · Apr 26, 2006

Re: Can Outboard run without Thermostat?

always wooried about the breakdown.. I put myself in places only black flies go..No one for many miles up in northern maine in the back side of baxter state park. Yeah.. I really dont know why the mechanic would have taken out my thermostat and said i dont need it.. He has a great reputation from all the local dealers up here. Probably just another old timer that hasn't seen too many issues while running without them. Im now trying to locate a thermostat for my 71 18 horse rude.. I did a fresh waterpump before my first time out this year.. Pumps like mad without the stat in..Motor runs sweet and pushes my 14 foot lund at around 21, 22 mph. After paint, i will post a before and after.. I really rescued one for sure.. This thing was under 4 feet of snow for years.

Can Outboard run without Thermostat?

Recruit

Petty Officer 1st Class

Chief Petty Officer

Supreme Mariner

Seaman

Chief Petty Officer

Petty Officer 2nd Class

Master Chief Petty Officer

Chief Petty Officer

Recruit

Chief Petty Officer

Chief Petty Officer