1996 150 Mariner Operating Temperature

[JR333]

I'm trying to determine what the normal operating temperature is for my 96 150 Mariner Outboard. It seems to run between 185 and 200 when at about half throttle then cools down to around 165-170 at full throttle. Idle speed is about 170.<br /><br />The power head was completly rebuilt a little over a year ago. No lower end work has been done to my knowledge as I've owned the boat just under a year.<br /><br />Is this the normal operating temperature at these speeds for this engine? Or, do I have a cooling problem?<br /><br />This is an Ocean Series engine I run in saltwater.<br /><br />Thanks

 

[gss036]

Re: 1996 150 Mariner Operating Temperature

The thermostats are 143 degrees, so in my humble opinion, you are a little on the high side. Are you getting good water flow out of the pee hole?Check the t-stats, if they are ok, maybe the poppet is stuck open and letting most of the water run out the lower end instead of cooling the engine. Do a search and read the articles, lot of good info gained by doing that. Tere are links in the threads for online manual, etc.

 

[KCLOST]

Re: 1996 150 Mariner Operating Temperature

The key here is to determine what the temperatures are coming from!!!!<br /><br />Are they water temps or metal temps from the head of the engine.<br /><br />If they are "metal temp" readings, you are ok!<br /><br />If they are temps from water inside the water jacket you are too hot IMO.<br /><br />This can be easily determined if you find the temp sensor, remove it and see if it actually enters the water jacket and gets wet, or goes through a sealed off portion of the jacket and touches the cylinder head. The later would be a case of measuring metal which is always going to be much higher temps than water...<br /><br />gss is correct about the t-stats at 143 degrees, but that's water temps as doesn't mean that your readings are too high if they refer to metal temps.<br />Yours are just about like mine on my 86' Merc. 175, actually a little lower, but we need to make sure what the sensor is measuring.<br /><br />Let us know...

 

[KCLOST]

Re: 1996 150 Mariner Operating Temperature

I would check that poppet though, very easy to do.<br /><br />And your overheat switch should set off the alarm at I think around 245F-265F...Depending on which one you have, again based on metal temps from the head.

 

[JR333]

Re: 1996 150 Mariner Operating Temperature

Thanks,<br /><br />I'm not sure what its actually measuring (water vs. metal) so I'll definately have that checked.<br /><br />It's never maxed out on my temp sensor at 220, of course I tend to keep an eye on it to prevent that. <br /><br />Good consistent flow coming from the peehole.<br /><br />Thanks