Thermostat possibly bad

[speterson1011]

I recently changed the impeller in my 90hp V4 2 stroke 2000 Johnson thinking it would fix the two cylinders on the right (when looking at the motor from the behind the boat.) I start the motor from a cold start up and 3 minutes later I cannot even keep my hand on the those two cylinders but the other two are still cool. I was thinking maybe the thermostat has failed and maybe the water deflectors are stuck? Thanks everyone

 

[Joe Reeves]

Re: Thermostat possibly bad

Standing behind the engine, facing the spark plugs, right is starboard, left is port.

The port bank running cold could have a thermostat stuck open or broken..... the starboard bank still running hot..... Sounds like it's time to replace both thermostats. And if that doesn't do it.......

(Water Deflectors)
(J. Reeves)

Water deflectors are actually lengths of 3/8" outside diameter rubber hose, installed between the top cylinder and any cylinder beneath it, and also between the bottom cylinder and the block. The purpose of the deflectors is to have the water follow a definite path around the cylinder walls. Unfortunately the deflectors between the cylinders will at times swell sideways due to either a previous bad overheating problem, or simply due to age and salt corrosion. This causes a water flow restriction which usually allows the water to cool sufficently at low rpms but not at the higher rpms.

This hose material can be purchased reasonably at any automotive parts type store if you care to make your own, or you can purchase individual deflectors at any Evinrude/Johnson dealership at a somewhat higher cost.

Removing and installing them can be a hassle at times, but not always. I use a sharply pointed scribe with about 1/4" of the tip bent at a right angle whereas I can reach in, jab the tip sideways into the rubber, then yank it out. It's necessary to clean the seating surfaces where the ruber contacts the block with a small rat tail file to eliminate salt deposits etc. When installing the new rubber deflector, coat the deflector and the metal surfaces with WD40 which will act as lubrication to allow it to go in as easily as possible.

Make sure that you insert something into that deflector area before cutting and installing the deflectors if you make your own so that you will be certain that they are the right length and also that they will be seated properly. Usually a very small amount will be left extending about the block sealing area..... simply cut the excess off with a single edge razor blade.

 

[speterson1011]

Re: Thermostat possibly bad

I'm not sure why I didn't say that. Way easier. Thank you for the information, I plan on tackling it this week, I didnt think about it being both, so I'll definitely do both while im at it and check it all out

 

[bob johnson]

Re: Thermostat possibly bad

I am not 100% sure, BUT I doubt any of the 2000 motors had water deflectors.. I thought they stopped making the crossflows in 1998.

sounds like the port head is running hot...I also have the same issue..and have jumped through hoops trying to solve it...cant seem to though...only at idle will it over heat though.

many times guys say that the starboard head tends to run hotter than the port...i am not sure why, thought they were saying because the head is higher...

anyway that isnt your case...as you said from inside the boat facing the motor, the right side is running hot...right?

well thats port.

thermostat might be stuck....they are easy to removed and flip from one side to the other to verify.
good luck

bob

 

[Joe Reeves]

Re: Thermostat possibly bad

Bob..... I wasn't thinking about the engine being a 2000 model, just had the 90hp in mind only for some reason. Retiring back in 1991, naturally my knowledge of the design of the 2000 model left something to be desired (deflectors).

 

[metriccrescentwrench]

Re: Thermostat possibly bad

Engines are supposed to run around 150 - 160 deg F (can't remember the exact number off the top of my head - refer to your service manual to be sure) at idle. At that temperature you can only hold your hand on the heads for 3 or 4 seconds before you've had enough.

An IR thermometer is a tremendous tool in tracking down cooling issues. Harbor Freight sells one for $30 or $35 (I don't have any experience with the one they sell, but have heard others say it works just fine).

 

[bob johnson]

Re: Thermostat possibly bad

Bob..... I wasn't thinking about the engine being a 2000 model, just had the 90hp in mind only for some reason. Retiring back in 1991, naturally my knowledge of the design of the 2000 model left something to be desired (deflectors).

actually I am sure many of us are glad you are retired and have time to chime in and help out!! I do !! ha ha

enjoy it, be happy and stop by and help as often as possible!!!!!!!!!!!


bob

 

[speterson1011]

Re: Thermostat possibly bad

Yah I figured out about the deflectors earlier. Thanks for your response though wish I would of read it earlier. Its the starboard side "behind the boat looking at the motor." I'm going to change out the thermostats anyways I got a friend who got them for me fro mthe dealer for only 6bucks each so I will see what that does and let you guys know how it goes soon as they are in. After looking at the service manual it looks like it will be fairly simple to do on my model.

 

[bob johnson]

Re: Thermostat possibly bad

Yah I figured out about the deflectors earlier. Thanks for your response though wish I would of read it earlier. Its the starboard side "behind the boat looking at the motor." I'm going to change out the thermostats anyways I got a friend who got them for me fro mthe dealer for only 6bucks each so I will see what that does and let you guys know how it goes soon as they are in. After looking at the service manual it looks like it will be fairly simple to do on my model.

ok, I must have read it too fast!!..... yeah they say the starboard side usually gets hotter...

good luck


I would have just switched t-stats to verify if it was the head or the t-stat.....no cost in that....


bob

 

[speterson1011]

Re: Thermostat possibly bad

Hey guys I checked it out. Sure enough both thermostats were jammed. Port side stuck open and starboard side stuck closed. I'll have the new thermostats in next week. My model engine they were very easy to get to. They were just above the spark plugs on the top two cylinders.