How To Change An Outboard Thermostat

This is how you change an Evinrude or Johnson outboard thermostat. This is an 1986 Evinrude 150XP. If your outboard is overheating, hard to start, or not running properly your thermostats could be to blame. They are not hard to test or replace. I show you EXACTLY how to replace these things quickly and easily! SUBSCRIBE! LINKS TO NEW THERMOSTAT KITS BELOW!: READ MORE:
This motor is a 1986 Evinrude 150XP V6. This is the same motor as a Johnson 150GT just a different color.
The concept is the same for many different outboard makes and models. A stuck or bad thermostat can cause your outboard to idle
poorly or overheat and cause serious damage to the motor.
**NOTE** There are may different types of individual thermostats and complete kits. Make sure you double check that you have the EXACT one you need by verifying the part numbers.
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Evinrude/Johnson Thermostat Kits:
Crossflow V4 65HP-140HP Kit: amzn.to/2w4jj0s
Crossflow V4 65HP-140HP Kit (Alternative Kit): amzn.to/2uU0fU6
V6 Thermostat Kit: amzn.to/2hmoF3A
V6 Thermostat Kit (Alternative Kit): amzn.to/2uXhCBy
V6 90 Degree Kit: amzn.to/2hls2rE
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Mercury/Mariner Thermostat Kits:
Complete Kit: amzn.to/2vgXM7j
135HP-200HP Kit: amzn.to/2u2iw2v
Poppet Valve Kit: amzn.to/2uTfBYO
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Chrysler/ Force Thermostats:
Thermostat 1: amzn.to/2u2lBzS
Thermostat 2: amzn.to/2w3UsK5
Thermostat Oring/Gasket: amzn.to/2uTnLR2
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Yamaha Thermostats:
2 Stroke Outboard: amzn.to/2uWT4c9
9.9HP-55HP: amzn.to/2uTR7ip
60HP-70HP: amzn.to/2uTDAad
25HP-90HP: amzn.to/2vhdW0m
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[@MattsShop]

Hey, links to boat parts in description (Amazon Affiliate)

[@flipper2473]

Hello, do you know if the control valve assembly on a 1989 120 hp johnson can be disassembled to replace a leaky seal? I have water coming out of the assembly. There's 3 water lines that meet in assembly. Thanks

[@MattsShop]

Maybe. I am not familiar with a "control valve" on outboards. Can you be more specific please?

[@jchip777]

What’s up dude, got my 1984 GT 150 running. Idles just fine and throttles up. I feel like it’s running a bit hot though. Got a temp gun in the mail to check the power heads temp. One side is pretty hot to touch while on muffs. When I did my T stats I did notice a bunch of corrosion build up. Could there be a layer or corrosion inside that’s preventing it from cooling properly? Do the T Stats have to be rolled a certain way when installed or just slap them in? Same with that little valve below T Stat, certain way or just inserted?

[@MattsShop]

Hey, what's up. The t-stats just slip in. I don't think there's any blockages with corrosion. Have you changed your water pump impellor? Check out my video on that. I'd change that first. How's the pressure out the tell tale?

[@jchip777]

@@MattsShop I did rebuild the water pump. It’s pissing really good. I’ve ran it submerged and on muffs. Pumps better submerged. Pisses really hard to.

[@MattsShop]

Is this a saltwater engine? The water jacket can get corrosion and shells built up in them, but you dont want to try to take the waterjacket covers off. You'll snap bolts left and right.

[@jchip777]

@@MattsShop yes sir it the previous owner ran it in saltwater for the 25 years he had it. Said they always flushed it. We know how that goes. I had a lot of build up when I pulled the T Stats. Did fail to look at that black grommet/rubber washer inside. Temp gun should be here tomorrow. Going to see what the external reads.

[@MattsShop]

Yea, see what the temp says and post back. You know something's wrong if there is a huge difference.

[@mando0503]

Do you know if that inside seal has a metal cup behind it or in front of it

[@MattsShop]

Yes there is a metal cup behind that seal. You can see it at 1:30.

[@mando0503]

Matt's Shop but does it go in like that on the engine ?? I’m asking because mine doesn’t have it at all like they forgot to put it in or were to lazy to do it

[@MattsShop]

It's behind the water jacket. You have to take the water jacket off to replace it along with that seal. I showed it at the very beginning of the vid. I'd leave it alone unless that seal is destroyed.

[@mando0503]

Matt's Shop it’s completely gone on both sides so I have to replace it

[@davelai6373]

What is the torque specs on the thermostat?

[@MattsShop]

The service manual says for 90HP-110HP and 150HP-175HP thermostat cover bolts it is 60-84 INCH pounds.

[@Shokenryu]

I cannot find a complete thermostat set besides buying them peice by piece. 1993 9.9 outboard J10RETM.

[@MattsShop]

They don't sell them as a set. You have to buy them individually.

[@Shokenryu]

@@MattsShop Ahhh booger. Thank you. Looks like I only need a few things for a set. The springs and the caps are good but the diaphragm is questionable. They don't have those in stock anywhere. Maybe I can reuse them.

[@totowolf9716]

Nate Diaz