thermostat question (boat overheating)

alanp 08-27-2007, 9:25 PM

my boat is overheating (1995 supersport nautique 5.8 ltr 351 pcm). ive checked everything. impeller, tranny cooler, strainer, hoses for blockage. i pulled the thermostat and boiled it in hot water to see if it was working. its a 160 thermo and it only seemed to open when the water was boiling. so i thought it was bad and i replaced it with an automotive thermostat. i called california correct craft and they said i shouldnt need an oem (pcm) thermo. i put the new thermo in and the boat got to about 190 and i turned it off. soo i pulled the thermo out all together and ran the boat one and it ran cool. 1) could i have gotten a bad termostat from the auto parts store 2)should i get an oem thermostat because an auto thermostat wont work for this application 3) could there be a sensor problem.

(bjeremi) · (bjeremi) **Join Date: Mar 2006** 08-27-2007, 9:31 PM

I had a grounding problem. Try running a ground directly from the gauge to the negative battery post.

alanp 08-27-2007, 11:57 PM

i dont think that is my problem because when i removed the thermostat altogether the boat ran fine albeit cool.

(95sn) · (95sn) **Join Date: Sep 2005** 08-28-2007, 12:16 PM

You can check #1 by putting the tstats in a pan of hot water on the stove w/ temp guage to know when it pops. I believe its fairly common to get a bad one.

(wake_upppp) · (wake_upppp) **Join Date: Nov 2003** 08-28-2007, 6:36 PM

190 is fine. that is a common running temp. the marine thermostat is a 160 however. that is the difference between the automotive and marine is the opening temp. i don't think you would find a 160 in an automotive parts store. again, 190 is fine if the temp stays there.

(sidekicknicholas)

Do you still have the stupid nautique strainer, if that has any crack, an airleak in the o-ring, anything at all the boat will over heat like crazy, just rip the strainer out and run the water straight from intake to impeller housing... the strainer screws everything up

alanp 08-28-2007, 10:27 PM

hey sparky i did find a 160 at an auto parts store(checker). if the boat stayed at 190 at idle i wouldnt have a problem with that however it gets over 220. in az i run the boat in water temps over 90 degrees.

i drilled 1, 1/8" hole on each side of the flange and that seemed to help alot.

nick i have tons of hydrilla in lake i cant afford to not run the strainer