150 Johnson, Too Much Water Pressure

[Mr.Ladyfish]

2002 Johnson 150, 270 hours, Had the impellar changed last month. Water pressure guage used to read 5-10 at idle and 20 - 30 when running. Now it reads 10 -15 at idle and on the peg, 30+, when running, strong pee stream. Ran around fishing all day with no other obvious problems. After running for 3 min. at WOT the overheat alarm sounded. I immediately shut down. Pulled motor cover off. The engine was barely warm to the touch. Fired it back up and no alarm. Ran the boat another 2 hours at 4500 RPM with no alarm or other signs of problem. <br /><br />Did I damage or am I damaging the engine by running it? What could be causing the water pressure to be so high? I'd like to have a little info before I call the mechanic who changed the impellar.<br /><br />Thanks in advance for your help.

 

[ob]

Re: 150 Johnson, Too Much Water Pressure

I'd have your mechanic inspect and /or replace the T/stat assys.

 

[Dhadley]

Re: 150 Johnson, Too Much Water Pressure

If it overheated it should have went into SLOW. If it didnt go into slow the alarm was probably for something else like fuel pressure.

 

[ob]

Re: 150 Johnson, Too Much Water Pressure

Very good point Dhadley.That one escaped me.

 

[clanton]

Re: 150 Johnson, Too Much Water Pressure

It is very easy to install the wrong waterpump kit in this engine. The pn of the waterpump kit should be checked against the model number of the engine. There are two pump kits that look amost the same except for a relief hole in the pump housing.