HOW TO Replace Thermostats Johnson Outboard the EASY WAY!

Port Canaveral Florida. A quick video on how to replace the thermostat on an Johnson outboard the easy way! (90HP V4 1998)
Check your model number here www.boats.net/catalog/johnson...
A faulty water pump is a major cause of overheating-related outboard engine failures. An incredible number of pumps are damaged by starting the engine with the gearcase out of the water. Running the engine - even for a few seconds -- without water can destroy the rubber vanes (blades) on the water pump.
Debris - plastic bags, weeds, mud, or a combination thereof - clogging the water intakes on the gearcase won't let sufficient cooling water into the engine. Trimming the outboard up too much while underway or in turns can cause the water pickups to ingest air - this causes a sudden loss of water pressure - not a good thing.
Most late-model outboards have integrated warning/self-preservation systems that sound a buzzer or horn, as well as automatically reducing engine RPMs if the on-board computer detects that the engine temperature is higher than it should be.
The temperature gauge (if equipped) will indicate a higher than normal reading. The water pressure gauge (if equipped) reading can be significantly lower than usual. Gradual loss of power, often accompanied by scary and unusual noises (even sometimes there won't be any noise!) from under the cowling. Smaller outboards may not have sophisticated warning systems, so pay particular attention to the engine's power output and flow of water from the tell-tale tube; if either decreases abnormally, the outboard could be running hot (overheating). Refer to the owner's manual for overheating information specific to your outboard.

[@susantapia8335]

This is one of the most helpful videos I've ever seen. I tried to change my therms and was unsuccessful so I need to do what you did. Did you use a specific dremel blade for that and what rpm etc is the dremel you used? Mine might be too cheesy so I may need to get a newer, better one.

[@PortCanaveralFlorida]

Susan Tapia , nothing special, I used what was in my 4200 kit.

[@PortCanaveralFlorida]

Zero, works like a champ!

[@timhardegree1795]

Thank you Thank you Thank you! Saved me countless hours of removing lower units, upper cowlings, power head, etc.....10 minutes of cutting, loosening bolts, cleaning, installing new thermostats, and tightening. GREAT VIDEO!

[@BrianSOLDit]

Thank you!! After watching I'm taking mine back. They charged me $50 each thermostat plus gasket kit! Great video someone already cut the holes for the socket wrench in mine covered with metal tape works perfect...

[@keithandrew231]

Dude, THANK YOU for this brilliant idea!!!! you probably saved me a couple days of work or hundreds of dollars if I had taken this to a mechanic to have them do it. Thank you thank you thank you!

[@PortCanaveralFlorida]

Your welcome Keith!

[@ronofnc]

Tomorrow morning I am going to do the job just as you did. I really appreciate you placing this problem on you tube. I have a 115 hp Johnson and looking forward to the job, thanks a lot! By the way Florida's great isn't it!

[@PortCanaveralFlorida]

Sure is!

[@davidclements3252]

this video was a big help for me on my 1979 100 HP Johnson Javelin, thanks for the video!!

[@californiahomeinspector]

I have a 1997 Johnson 115 SPL non-vro motor and I just drilled 3 one inch holes at the location of the bolt heads of where your cutout is instead, and it worked beautifully. I put off white plastic bushings with plugs in the holes afterwards and it looks like it came from the factory with them. Tip: use electrical tape to hold everything together while installing then pull it off when you get a bolt in before tightening.

[@PortCanaveralFlorida]

Derek Porter . That also would do the trick, sq vs round. The curve would get me though, but it worked for you!

[@jacobrusso9522]

Great idea!

[@osbornebay944]

Great to be able to do the same on my 94/Ev 90, as your smart way, thanks a million.

[@theonlinebusinessadvisor96]

Just did this way too. I used two zip ties to hold the springs to the thermostat housing while installing and cut them over secured with the bolts; worked great. I struggled with where to put the cork gaskets but decided to install under the thermostat which seems to be fine.

[@aspenrebel]

Oh yeah you have to be a little careful there when you put the new one in that everything stays together you don't drop it down into the engine. But why 3 holes you only need to do the 2 end holes. I commented above. I use black round the grommets because my engine is black. I guess your engine is white. Use A lot of clear marine waterproof cement

[@scottallways7998]

Thank you so much, i have the same engine just 115 , Great idea glad i found you . cool have a great day

[@AgTires4295]

Thanks for the vid! Was able to get a great idea of what I was getting into by watching you first. I didn't cut anything but it was a PITA. If I do it again, there will be surgery.

[@AgTires4295]

@pencil whip The rubber plugs are a winning idea!

[@timziegler8848]

Dude you rock the Casbah!

[@axed1929]

I drilled three 5mm pilot holes, eventually taking them out to 12mm to get a socket on the bolts them once finished i siliconed in rubber grommets. Worked well, looks good.

[@Blackford86]

I too am a J-B weld believer thanks for showing this 👍

[@scottallways7998]

Saved allot of time and money and unnecessary disassembly, easy job. thanks again

[@PortCanaveralFlorida]

You're very welcome Scott!

[@sashadeas8113]

Just did this to my 1987 Johnson 90hp.. it has been in one family since it’s make and I bought it from that family, so I’m the second owner..they had been using one mechanic shop throughout the boats life. June of 2020, the owner said that he was having over heating problems at idle only. Mechanic shop said they changed the impeller, thermostat hoses, and spark plugs. All was good. Then the guy sold the boat to me a few months later. I get the boat and after about 10minutes idling, the overheat alarm goes off. I replace the water pump AGAIN (being less than 1 year), and it had not been replaced in at least two years. It was dry rotted. I test it, still over heats. So naturally the thermostats are next to replace. I found your video and did what you did-but the sad part is, that I did not even need to replace them! The brand new thermostat hoses that were replaced in June-the left one had silicone blocking both ends of the hose!!! Intentionally!!! As if they were trying to create an overheating issue. There are SO MANY sketchy mechanics out there. I went ahead and replaced the thermos and all since I already cut out my hole LOL but lesson learned. Always do your own work unless it’s out of your scope of knowledge 🤦🏻‍♀️ Sorry for the rambling! Lol but also glad I found your video!

[@ct1762]

sorry to say, but they didn't replace the impeller either! those impellers are tough, and you only start seeing little cracks after atleast 4-5 years.

[@dannykretzer7466]

Fantastic man, I've got a 115 Johnson I need to do the same thing to thank you very much.

[@PortCanaveralFlorida]

You got this Danny!

[@karlmroch3394]

Amazing thank you brother, enjoy the water !!

[@chucklz757]

that was awesome man!

[@ziggyr9746]

That’s a great video I have a 115 special and I am Definitelygoing to do that looks great

[@jacobrusso9522]

Awesome thanks for the video! Exactly what I was looking for

[@PortCanaveralFlorida]

Glad it helped Jacob - now get back out on the water!

[@HoustonR6ryda]

awesome man... you did that

[@tonyt861]

Awesome thanks for sharing this great idea

[@dossary91]

I like the way you did it thank you for very nice video it help me .

[@Oheyjude]

Thanks saved me time and work

[@PortCanaveralFlorida]

Judy? (See guys even a woman can twist a wrench!) Glad it helped Judy!

[@osbornebay944]

Man you did a super job, I ll do the same to my 94 Ev 90 hp therms.

[@PortCanaveralFlorida]

Thanks

[@magosteamj1243]

mon/ jan /6 . thanks . you make so easy !! THANKS .!!

[@holderhouse3371]

With stubborn bolts like that, hit them with PB blaster a few times a day for a few days while tapping it with a brass blow to break it loose. Time consuming, but better than a snapped bolt!

[@BillyBob-fq2sr]

Thank you for putting this video out. After watching the video 10 times, I did it today. Little different then your video OR? I just missed that there's 2 bolts on the inside of the lower Cowl. But got to them OK. Also I did not know the Cowl was Aluminum. Thought it was Plastic. Took a lot longer then I thought with the Dramel . BUT I got it cut out and the whole thermostat housing popped out pretty easy. MY Thermostats were very clean and no Salt build up at all? Last replaced 3-4 yrs?? ago?? Guess Salt Away works. Again thanks for the info..

[@PortCanaveralFlorida]

Very welcome Dan

[@mangas32]

Thanks for video Great!!!

[@RetroVertig0]

greatest pro tip ever

[@PortCanaveralFlorida]

Thank you for the kind words Marc. Hope this video helped!

[@jameshenderson4932]

I did this and it’s great. I’m just wondering where the cork Haley rings go. Is it under the lip of thermostat or on top of the lip. They are going to have to get really swished either way on reassembly. That’s where I’m at now. Trying to find out exactly where these go before I reassemble. Nothing in both manuals I have shows me. I have same engine you have in the video. Any help would be appreciated. Thanks.

[@jameshenderson4932]

Not Haley rings. Cork rings.

[@JimTMcDaniels1]

Thank you sharing how you have found to make this job doable. Let me add: ONCE AGAIN, a Video involving the possibility of BREAKING Bolts that when you are dealing with such bolts that you must remove: If the bolt feels like it may break at all, they are full of corrosion crud. So don't break it, do this instead: you must give it patience and slight back and forth movement to work it out, the corrosion will fall out: So try to tighten it just something of a move, then try to looses in just something. Then repeat and repeat and repeat. So a rocking motion of back and forth without putting too much force in either direction where it may over stress the bolt and break it off. As you continue, if your observant enough, you may even see little sands of corrosion dropping out of bottom of the bolt as you do this. And that the bolt is able to move more than it did. Now you can't loose once you have some movement. Because if you are patient and keep only rocking the bolt back and forth back and forth, more corrosion will come out and the bolt will move even more from tight to loose. Of course also spray penetrating oil into the threads as you can and walk away and come back after soaking. Take care

[@lewkono1714]

Nice. Love it

[@hkm_865]

Wow! Huge help dude. Thank you so much!

[@PortCanaveralFlorida]

Beats taking everything apart! Seal it up, paint it and your done!

[@tsugacanadensis8663]

I thought you were taking the piss for a second. I have an older johnson and my thermostats on top. Woulda been a good troll video if that were the case.. "Yeah so today we're gonna change out our coils. First, let's drop the lower unit. Then get your handy grinder and cut an access hole through the base of the motor mount" lmao!

[@MattsShop]

A design flaw really, but this is a good tip to get them out. It'd kill me to have to cut up a beautiful outboard though. Great Vid!

[@PortCanaveralFlorida]

Cut and paint it, or, super pain in the buttocks (you chose) Thanks!

[@darrinwright1655]

I was able to do this without cutting case. The top bolt will come out the bottom 2 bolts will stay in the housing but all you have to do is remove the housing with them in it and reverse this when installing. The bolts come far enough out of the block to clear.

[@darrinwright1655]

Maybe it's different on other sizes but mine is an 88SPL JOHNSON.

[@PortCanaveralFlorida]

Yep, you have a different motor. You can't leave the outer bolts in with this motor.

[@samelson2748]

I just found out I can do the same with my 85 90 V4 Evinrude. Glad I tried that first. Also I want to comment that the shop manual calls for btwn 5 to 6.5 ft lbs (60-80 in lbs) of torque on the bolts. Looked to me like you went a bit 'much' with the ratchet. Mine came out easily with a 5'' box end wrench.

[@peterwickham3615]

I am doing the job now and I drilled holes to access the bolts but after seeing your video I am going to cut the section out and as I have a spare motor for parts I will cut the same section out but larger and cover the hole, attaching it with ss screws so that it can be easily accessed. Update.....Job done all ok, cover plate fitted over the hole ok but needed or a gasket to seal it properly.

[@jaimeregatieri2144]

Hello. Your video is very practical and enlightening. It could help by arranging a cut mold with measurements. It would be very useful to dictate this information.

[@dneuman7455]

Thought I had a blocked or broken impeller because of low pressure on the exhaust water port . Pulled thermostat water shot out the thermostat hole plus it started pumping out the exhaust water ports up top. Carb sounds clean at not in gear throttling it with cleaner. But bogs in gear. Carb issues and needs thermostat and maybe an water pump kit.

[@samelson2748]

Great video and great idea! My only question is have you experienced any operational problems, engine performance wise since you made this repair? Has the plate come loose or have you since lost it?

[@PortCanaveralFlorida]

Zero issues. I use hot glue from the back, works like a champ!

[@aspenrebel]

It won't affect performance of the engine

[@darrellladnier1139]

I use bored holes in front of 2 end bolts for socket removed bolts .put rubber plugs in holes easy to do.

[@dsciarrino3663]

The Best money can buy.

[@jaimeregatieri2144]

Great tip. Great video! Hello. I have an 85 hp 78 year engine and it is not as easy to trim as on your engine. What do you suggest for my engine?

[@PortCanaveralFlorida]

Jaime, This video had nothing to do with "Trim"

[@jaimeregatieri2144]

@@PortCanaveralFlorida Thanks for your answer. It happens that I did not ask about trim. I said that the model is 78 with power of 85 HP and that the cut plate in your Jhonson is not equal in mine. Anyway your video is very good.

[@caverunbassmaster7659]

I have a 1989 110 Evinrude Tracker Pro Series with low hours are my thermostats in the same location?

[@PortCanaveralFlorida]

I don't have a manual for that 110, someone might chime in.

[@cnn94001]

for most johnson outboard, thermostat are in the back? I have a 50hp Johnson, just wondering the thermostats are around that area

[@PortCanaveralFlorida]

No idea on the 50s

[@eugeneanderson6316]

can someone help me,i have taken the thermostat out of my 1977 /85hp Evinrude and can't figure which way it goes back in.there are two springs.one heavier than the other.

[@PortCanaveralFlorida]

View the vid again an you'll see the difference

[@TheJoejoe7716]

Good idea but you really don’t need to make cuts. Even on the bubble back exhaust models. Just an 11mm wrench and some patience.

[@aspenrebel]

What are you talking about you can't get the 2 end screws out because the metal of the motor in the way. otherwise you have to unbolt the whole friggin motor and lift it out of the casing. Those 2 end bolts on the thermostat are very long but middle one is shorter.

[@TheJoejoe7716]

@@aspenrebel next time one comes in for a thermostat job, I will video it. Trust me. I have done several, you certainly don't need to remove the power head.

[@aspenrebel]

@@TheJoejoe7716 nope! The last thing you want to do is to remove the power head or to try to remove the power head. Only about 100 things can go terribly wrong. I have to look if I have a picture of my phone here what I did.

[@aspenrebel]

@@TheJoejoe7716 ok here's how I did. 1 inch cylinder drill bit and 1 inch black rubber plugs cemented in place to plug the holes. Hkpefully I can post the pics I took today.

[@aspenrebel]

@@TheJoejoe7716 well, I took photos of what I did, to show, but I cant get them on here. I dont know how. It not working. ?????

[@rocketroy469]

Thanks a bunch..really thanks..I owe you a beer.

[@PortCanaveralFlorida]

Glad this tip helped Roy!

[@rocketroy469]

I did exactly what you said only I didn't have a dremel so I used the skinniest smallest cutting disc for my angle grinder and it worked really well... At some point I'm going to have to lift the power head though to change the corroded sterling tiller on the front..

[@PortCanaveralFlorida]

The new steering arm is made from better materials now days, mine still looks new.

[@PortCanaveralFlorida]

P.S. I've been hitting the 2xIPA from Southern Tire Brewing Co, send one when you can lol.

[@rocketroy469]

I have an uncle in St Pete. .IL throw a couple in my case if i can remember in the fall

[@juantabullo3126]

I was under the impression that the plastic part also takes gasket sealant...? Or only the metal parts boat at thermostat cover?

[@PortCanaveralFlorida]

Only the metal side.

[@eddymartinez1574]

Very good video. Do you have the part #?

[@PortCanaveralFlorida]

Not on hand, just call up a local repair shop, I'm sure you can obtain the number for your motor.

[@fking3635]

Yes in deed that helped THANK U.........

[@robboat3864]

My 1980 85 you do not need to cut or remove powerhead or lower unit . Just remove the trim cover he said 4 bolts but there is 6 on mine 2 under bonnet at rear corners of the trim cover. Then take your wrench from under neath for the 2 out side bolts for the thermostat cover. About 3 turns with boxed end then switch to the open side of the wrench. The top middle was a bitch for me tight in the thermostat cover 1/4 inch ratchet and socket to break it free then wrench. 6 point wrenches and sockets can save a headache. Why make your outboard look like a hack job for nothing. The only time to make a hole in your outboard is if the drive shaft is seized in the crank. The hole would be to cut the driveshaft.

[@donaldbaylor7744]

I have a mercury 90 horse outboard motor and I want to change the thermostat how do I change the thermostat

[@PortCanaveralFlorida]

Look for tutorials for Mercury 90hp.

[@aspenrebel]

I came up with an easier way than that. I got a 1" cylinder type drill bit. drilled (2) 1" holes in line with the 2 end bolts of the thermostat, so I could easily take the screws in-and-out. then I filled in the holes by cementing in 1" dia black rubber grommets, which had a groove around edge. The only problem was the metal was thicker than the groove opening. But still made it work with a lot of waterproof marine cement. Bought an extra pair of grommets just in case, to keep on hand.

[@rubengonzalez8399]

What about the middle bolt?

[@aspenrebel]

@@rubengonzalez8399 the middle bolt I could get out no problem. It was just the two end bolts.

[@davidedwards2773]

Remove the six lower cowling bolts. Takes a little time, but it doesn’t looks like crap when you cut it up.

[@ashbucharon8263]

Your use of a Dremel type tool is an improvement on the method I used ( forums.iboats.com/forum/engine-repair-and-maintenance/johnson-evinrude-outboards/632862-thermostat-replacement-on-1990-115-v4-crossflow ). On the other hand, I've had bad experience with using JB Weld type products on Aluminum, so I would not rely on it to hold that plate you cutout. That plate could pop out in the water and you lost it. I used screws. My engine was the cross-flow bubble back which has even less room than yours I think.

[@PortCanaveralFlorida]

Hey Ash, I used a glue gun, worked perfectly and sealed the cracks too!

[@Johnfor3]

What engineer thought this design would be ok! Why on earth wouldn't they have added some kind of assess panel at the very least!

[@hotrod539]

Might be a stupid question but how do you know if your overheating???

[@PortCanaveralFlorida]

Your alarm will sound on the motor

[@lakeratatouille]

Yeah it will also start running rough

[@Mudflap496833]

an obvious backyard mokanic,,,its so easy doing it the right way

[@jonathanmercadosd473]

What if I accidentally threw away the part I cut away?

[@PortCanaveralFlorida]

Try not to slap yourself.

[@gr8dfender742]

Can you please share the Iboats item number for the kit?

[@PortCanaveralFlorida]

Take a still off the vid

[@gr8dfender742]

@@PortCanaveralFlorida the video isn't clear enough. Paper is blurry in video

[@PortCanaveralFlorida]

@@gr8dfender742 you need to check your model number here> www.boats.net/catalog/johnson/outboard-by-hp/90hp

[@peterwickham3615]

I drilled half inch holes.

[@osbornebay944]

did your way work well?

[@joyned1]

No criticism from me but I should point out that the cork gaskets should sit on top of the thermostats. They are the last piece of the puzzle before the final body gasket which in the video is already attached to the engine body. It probably doesn’t make a difference but that is how it is installed on my original untouched 1979 85 hp v4 evinrude, basically it is still the same engine and I am using the same thermostat kit.

[@PortCanaveralFlorida]

Looking at the diagram now that you drought it up, they sit under the stat.

[@joyned1]

It looks that way in the diagram but the original body gaskets covering the cork washers were made of a thin metal (not like today’s paper gaskets). They were stamped with an indentation that only allowed the cork washers to be assembled on top.

[@PortCanaveralFlorida]

@@joyned1 what can I say, its still running just fine. It's, do you like your cheese on top of the burger or at the bottom.

[@samtate1260]

Why not just drill two holes were the bolts are

[@ct1762]

just so everyone that does this is aware: he use the wrong sealant and didn't apply it to BOTH sides of the gasket. do it this way, and it will leak at some point down the road. the factory service manual says OMC gasket sealing compound on BOTH gaskets, front and back. the sealer doesn't effect the pressure relief valves because there is a huge hole in the gasket, and if you get a tiny bit on the t stats... so what? they just need to open to bring water in.they don't get unseated like other models at higher pressure. OMC gasket sealer doesn't harden either, so completely harmless.

[@PortCanaveralFlorida]

It's 2021, I posted that in 2015 and it's still holding. Thanks for your input.

[@davidtimmins8701]

I Jane the exact motor. What part number did you used to order the proper parts? Thanks

[@samtate1260]

You might want to screw that plate so it doesn’t vibrate off the engine stainless steel screws maybe

[@PortCanaveralFlorida]

No crews needed. Touch of JB Weld does wonders thanks.

[@CRAKAJAK2324]

could you do the cut out for me I'll take my boat to you?

[@PortCanaveralFlorida]

jose ocasio. Really?

[@Z-Ack]

I didnt see you put in the 2 cork circle gaskets around the individual thermostats.. thats whats confoozn me. Plastic, cork, thermo, gasket sandwich or plastic thermo cork gasket sammich? Dunno whether it makes a big difference to put the maters under the burger or on top.. On a side note, you ever think how long it took some engineer to sit there with different alloys, heat em up and watch how much they bend per degree..? Crazy sauces.. and then mr guiness had a stroke of genius and stuck a mercury switch on it and boom central air. Boggles the nugget thinking about that kinda shtuff.. that And compressing a toxic gas with handbuilt stuff that you had no ideas if your idea would work..

[@PortCanaveralFlorida]

I reviewed the vid and the cork gasket was there in the kit, I did place them in, you just didn't see it in the edit.

[@theonlinebusinessadvisor96]

I had the same issue. Wasn't in the video unfortunately and I tried to look very closely. Guessed they go under the thermostat. Seems to be ok.

[@centralparkfitness]

What were the symptoms that led to you changing the thermostats? You may have said it in the video but I'm watching in bed with low volume trying not to wake the wife

[@PortCanaveralFlorida]

Over heating Dave

[@theonlinebusinessadvisor96]

Me too and wanted to know they were not full of muck. Found mine were completely dissolved and I just had a hole so they never shut off the flow.

[@tracyreed1522]

I have an 89 same motor, used the service manual that those engineers make, no holes, no problems, much easier than this nonsense

[@PortCanaveralFlorida]

Then why did you come here looking for answers? Just to comment?

[@Little.Bow.Big.Crybaby]

DO NOT DO THIS!!! YOU CAN REPLACE THE THERMOSTAT WITHOUT CUTTING YOUR FRAME OR REMOVING POWER HEAD. I JUST DID MINE WITHOUT CUTTING OR DRILLING HOLES.

[@PortCanaveralFlorida]

Thanks for the comment. The chance of broken bolts is SUPER common. This is very easy to do and get back on the water, hurts nothing, a little JB weld, paint if you choose and your done.

[@robertpapp96]

Geez... poor motor.. Perfectly unnessesery that cut... just need right tools, and some knowledge.. I can imagine how these people do other "fixing"..