Whaler Central - Boston Whaler Boat Information and Photos

Posted by NB1214 on 06/07/10 - 6:23 PM

I have a 1985 90hp outboard j90mlcos. I hooked it up to the hose today to test it out and at idle it runs 240 plus within 5 minutes of starting it. Any tips or ideas to trouble shoot it? Also where can i find a service manual for this motor?

Posted by Joe Kriz on 06/07/10 - 6:33 PM

Is your water pump streaming water out the telltale hose?
This should be a steady stream.
If not, your water pump may need replacing.

You can get manuals at your local Evinrude/Johsnon dealer or many other places online.

Posted by todd12 on 06/07/10 - 9:01 PM

I had a similar issue with a 1989 90hp johnson, it turned out to be the rubber diverters ( i am not sure of the technical name of the part ) that are in between the 2 pairs of cylinders. I had a mechanic diagnose this problem for me.

Todd

Posted by seahorse on 06/08/10 - 4:02 AM

Most likely you will find thermostats corroded or inoperative and the plastic pressure relief valves stuck and the bleed hole plugged up.

The thermostat housing on the back of the motor can trap water and debris which will cause problems if the motor sits for a while.

When replacing the thermostats - the factory ones are now stainless steel - use a small file to make a tiny notch (1/16) in each white relief valve. That will help drain the housing and provide a place for the air to bleed out so water can reach the thermostats when starting up.

Edited by seahorse on 06/08/10 - 4:04 AM

Posted by NB1214 on 06/08/10 - 7:01 AM

protek9543 wrote:
You can get thermostats at any boating store. I think there are two on yours. Located near the spark plugs.

I found them online for $21 each

http://shop2.evinrude.com/Index.aspx?s1=1a4216017c5d412dd79e1a0084da18cd&catalog_id=0&siteid=1

i guess i will replace them and see if that does the trick.

Posted by NB1214 on 06/08/10 - 7:06 AM

#10

seahorse wrote:
Most likely you will find thermostats corroded or inoperative and the plastic pressure relief valves stuck and the bleed hole plugged up.

The thermostat housing on the back of the motor can trap water and debris which will cause problems if the motor sits for a while.

When replacing the thermostats - the factory ones are now stainless steel - use a small file to make a tiny notch (1/16) in each white relief valve. That will help drain the housing and provide a place for the air to bleed out so water can reach the thermostats when starting up.

The boat has been sitting for a number of years. Just ordered the thermostats and i guess ill start there.

Posted by CES on 06/08/10 - 7:16 AM

#11

Since the engine has been sitting for a number of years, I'd go ahead and replace the impeller (water pump) too. Even though you have a good stream coming out of the motor, the impeller could be dry rotted as they are typically made of rubber and rubber degrades with time.

Posted by John Fyke on 06/08/10 - 7:44 AM

#12

NB1214 wrote:

The boat has been sitting for a number of years. Just ordered the thermostats and i guess ill start there.

You didn't mention the boat had sat for a long period of time in your first post. Definitley replace the whole pump assembly.

Posted by Paul Graham on 06/08/10 - 7:47 PM

#13

iboats.com has a strong Johnson/Evinrude engine forum where mechanics will answer your questions. there is also a link to where you can get a factory service manual

Posted by NB1214 on 06/09/10 - 5:52 AM

#14

Paul Graham wrote:
iboats.com has a strong Johnson/Evinrude engine forum where mechanics will answer your questions. there is also a link to where you can get a factory service manual

Thanks ill check them out.