Thread subject: Whaler Central - Boston Whaler Boat Information and Photos :: Where is the thermostate located

Posted by Bilito on 06/01/11 - 8:25 AM
#1

1991 Merc 40 hp, 4 cylinder, two stroke, I cannot find the location of the thermostat housing anywhere, and in the manual under cooling systems it only shows me how to repair the water pump.
Anyone know where it is? The water coming out of the pee hole is pretty hot. I can barely hold my hand under it.

Posted by whalerman on 06/01/11 - 9:44 AM
#2

Go to the library and ask if they have a section with repair manuals for boat engines. You can either stay and research it there or check the book out for a couple weeks and do your repairs. Next best thing is to GOOGLE it.

Posted by Michael A on 06/01/11 - 11:25 AM
#3

Why not just look at one of the online parts diagrams for your motor?

http://boats.net
or
www.mercruiserparts.com

Posted by Finnegan on 06/01/11 - 12:26 PM
#4

Those old classic 40-50's may not have a thermostat.

I know that the classic in-line sixes 90-150HP don't have one.

Posted by Bilito on 06/01/11 - 4:01 PM
#5

1991 is already called a classic????

Posted by Finnegan on 06/01/11 - 10:18 PM
#6

I believe that the design of the 4 cylinder 50 HP engine, later changed to 45HP and then 40 HP, dates to 1963. As you can tell by the length of it's run, it was one of Mercury's great 2-strokes.

Posted by Bilito on 06/02/11 - 6:57 AM
#7

I just got it with the 91 whaler 13, and it is a smooth running quiet engine especially at idle or slow speeds.

Posted by Tom W Clark on 06/02/11 - 7:06 AM
#8

The 1991 Mercury 40 does not have a thermostat.

Posted by Bilito on 06/02/11 - 9:43 AM
#9

Thanks for that info Tom, the guys at iBoats just told me that too