engine temperature

[tphil]

I have a 92 nautique with the 351 PCM. Prior to this year, the engine ran at a consistant 155 degrees. This year it runs at 163 degrees and goes to 170 at idle before cooling back down to 163. I replaced the impeller this year. Think I need to replace it again or is 163 degrees OK?

[M3Fan]

You should probably replace the impeller every year anyway. If it is consistently reading a hair hotter I would suspect a bad ground in the dash somewhere that is making the gauge mis-read. Mine will read differently with the blower on or off by about 2 degrees, etc. Did you make any electronics changes this year? The only other thing to check is the T stat, maybe it is slow to adjust. It is 13.00 and takes 20 min to change. But if you are worrying about a 5-10 degree difference, I'd say don't worry and have fun for the rest of the season.

[mrese]

Understanding there is a split school opion on it, but from what I have gathered over the years 160 degrees is becoming a prefered temp. The orginal manuals call for a 143 t stat for me, but folks at PCM, SKI DIM, and other CC dealers tell me that 160 seems to be a better op temp for the engine.
Check the actual temp of the engine (directly at the engine and not at the dash) to get a true reading of the temp. Good chance the guage has developed a bad gad thus more resistance and a higher guage reading. If it is acutually running a true 20 degrees warmer all of a sudden, you need to trouble shoot. SKI DIM has a great procedure in their FAQ sections to trouble shoot the cooling system.
Boil your T stat to see if maybe it is actually a 160 tstat. It could happen.

[efox]

I have the same boat and motor. Mark Q at MD Boats advised that it is porbably a little electrical demon that makes the guage read inaccurately. I think the guages are not "top notch" and the wiring is kinda chintzy. Plus, with the PCM electronic iginition, there is a lot more electronic junk to go wrong!! Anywho, my boat always reads about 150-155 and it appears to run hotter when I run more electrical stuff, like the stereo and lights. AS an example, night cruise with the lights, bilge, and stereo the guage reads like 180. I know this not to be the case as I turn things off it goes down.

For you problem, if you have replaced the impellar, i would just check all the fittings in the cooling hoses to be sure the clamps are tight. Check your strainer basket to be sure you don't have a failing o-ring. Lastly, replace the T-stat with the 143...it's served your boat well so far. I replaced mine with the 160 and now I'm back...no noticable difference. Remember, air is the enemy and will make the boat run hot. You may just be coming up to needing to have the cooling passages cleaned out, but that's a big maybe.

Eric

[skinautique]

One other thing to check is to make sure that you got any of the blades removed from the impeller that you replaced. Otherwise, I would lean towards a bad ground on the gauge.

[SWCC-PART-MAN]

as a correct craft technition.....i would establish that the temperature is a constant. meaning, does the temp climb as you are sitting in idle or under way. if it climbs in idle your old impeller fragments could be restricting flow. impeller fragments usually go DOWN back twards the tranny coller. also i would check the water strainer and look for bubbles entering the cup. if so tighten the plastic hose fittings and hose clamps. also, inspect the o-ring in the strainer. if your temp is off from there i would remove the belts and spin the circulating pump pully and check the "wobble" and the weep hole on the under-side of the pump. if there is a water trail on the pump replace it. call me if you need jason at southwest correct craft 903-882-8593.

[SWCC-PART-MAN]

tphil- also your boat from the factory is lacking ground supply to the dash. in a perfect world you could tap into the battery but yours is all the way in the stern. so with a fish-tape you can run one from the dash to the engine ground on the starbord (drivers) side behind the raw water pump and splice it into the dash ground series. 10 ga. wire is plenty. good luck bro
jason

[M3Fan]

Battery shouldn't be in the stern of a 92 sn...

[SWCC-PART-MAN]

it may be in the floor but i was thinking it was under the stern center cushion. whatever the case i would supply the dash with a ground from the block.

[tphil]

Thank you for all the replies. I had the boat out yesterday and put the navigation lights on and the temp gauge went to 180. I then turned the lights off and the temp went to a steady 155 where it stayed for the rest of the day. I think it must be an electrical problem with the gauge.

[882001]

i would run another ground wire to the daisy chain ground setup. bet that fixes it. very common problem on old nautiques. http://www.inboardtalk.com/cgi-bin/i...num=1069360557