Johnson VRO 4, 90 HP. overheat problem one side of engine

[B1gM1ke]

sorry Bob, thought I had listed the model number but here it is. J90TLCUR. Pretty sure the thermostat thing is my issue because there was water in the opening leading into the cylinder on the cool side but no water on the hot side in there. I will start by replacing the t-stats and gaskets and cleaning up the housing and clearing the port. If this doesn't solve my issue i will look further into your ideas. thank you one and all. I am heading off for a trip soon not to be back till early June sometime so you may or may not get an update from me till then. Boating season for me won't start until I return sadly.Thanks again everyone, all your input is invaluable to a guy like me.

 

[SparkieBoat]

google v 4 johnson water diverters and click on images.. lots of good pictures. the fact that you cannot find yours tells me that may be part of your problem. here is a great pic

 

[B1gM1ke]

Sorry for the confusion Sparkie, I was not referring to the water diverters when I said I could not find them. I was confused as to what the grommets were but I have that figured out now. Hopefully I will have the issue fixed after I replace the t-stats and gaskets and clear the hole. I haven't had to take my heads off and hope to not have to at least for a little while

 

[SparkieBoat]

no problem man. good luck with it. you may want to invest in a laser temperature gauge. motor getting too hot can cause significant damage. even if it is not hot enough to set off the temp alarm it could still be hot enough to damage your motor over time. proper oil and proper cooling are the keys to a long engine life. these motors will last a long time if taken care of and maintained. could last some people a lifetime, I know of 50 year old motors that have never been rebuild still going strong. I personally own a 1984 110 Evinrude that has never been taken apart. perfect compression and runs like a champ.

 

[B1gM1ke]

Thanks Sparkie, I do have a laser temp gauge , that's how I knew one side was not even at 80 degrees and the other was at 190 when I shut it down after hearing the alarm. I think, or hope that replacing the t-stats will fix it. One definitely was stuck open and the other may not be opening at the 150 or so that it is supposed to open at so since the motor is 30 years old and the t-stats look to be just as old they are getting replaced. Engine has never seen salt so don't think corrosion is the issue.

 

[SparkieBoat]

great.. I wish you the best. check your head temps after running hard for about 10 mins then down to idle and check temps on each head. see if there is a big difference.

 

[B1gM1ke]

Will do and fyi these temps were at idle on ears.

 

[Bosunsmate]

Loose ears suck up a lot of air and is a problem if you havent moved the telltale

 

[Fed]

Pretty sure the thermostat thing is my issue because there was water in the opening leading into the cylinder on the cool side but no water on the hot side in there. I will start by replacing the t-stats and gaskets and cleaning up the housing and clearing the port.

Maybe I'm reading it wrong but that sounds like you're getting no water from the head cover to the thermostat housing.
(Via the rubber hose)

If that's the case then I'd expect you have a blockage up stream or the little hole in the thermostat being blocked is causing problems.
I'd give it a run with the hoses both disconnected to make sure you have water flow out of the motor before the thermostat housing.

 

[B1gM1ke]

I personally have only owned this motor for 1 year but I know the person that owned it the previous 5 years and it has run with no overheating problems. The motor is 30 years old. That being said I do not think the telltale has been moved but i will look and verify that. As for the other comment, there was water inside the t-stat housing just didn't get past that point on the one side. Oh and yes I know the ears are not ideal but it was all I had at the moment to check things out. after I put in the new t-stats I will drop it in the lake and give it a good look at how the engine temps behave. thanks guys