98 SAN overheat

[jeffkukuruda]

So this past weekend i took the boat out, its a 98 SS/SAN with the GT-40 Fuel injected. It usually runs under an indicated 150 degrees on the temp guage, but it got up to almost 200 so i shut it down and got a tow back to the ramp. I checked the raw water strainer and the intake on the bottom of the boat and the belts and found nothing. So i thought that even though i put a new raw water impeller in in the spring, i pulled it today and inspected it and found a perfect impeller unfortunately. So now im stuck, why the high temps? water pump on the motor failure? T-stat? any advice on where to start would be greatly appreciated. Thank you.

Jeff

[Sbt3]

RE: 98 SAN overheat

Were you idling or running full speed when it got hot? It could be the thermostat. It could also be a bad impeller pump. I had my pump go bad a couple of years ago on my 97. The impeller was fine. I couldn't figure out what was wrong with the pump but replaced it and it worked fine again. You could also have an air leak somewhere, possibly the strainer not sealed properly or the rubber o-ring fell off but I would doubt that unless you recently cleaned it and didn't notice it fall off. Also check all of the other hoses before the pump to make sure they are tight and not cracked.

[Joesboatn]

isnt that t-stat on that motor suppose to be a 160? Do you have a 140 in? Like mentioned id go though and check for the airleaks and throw in a new t stat for good measure regardless it may be sticking closed.

[jeffkukuruda]

ok, ill try the new thermostat, any thing special, or just a a normal 351 t stat from autozone? how do i know if the raw water pump isn't any good, i took it off and it spins with a little bit of resistnace from the impeller. And yes, the overheat happened when just putting above idle. thanks again.

Jeff

[jjgag60]

thermostat

You should buy a marine 160 thermostat. They are stainless and a little different from auto zone's. They are less then $20.00.

[WakeSlayer]

You should get a marine T-stat at NAPA. You want the 160*. Car stats are higher temps. Go through the entire motor with a 5/16" nut driver and tighten every hose clamp. And as mentioned above, make sure you have the o-ring gasket in the strainer and that the cup is not cracked or anything.

[Watty]

When does your boat overheat? At idle, under throttle, etc? My thermostat went out and it would take a while for it to overheat because only the block was overheating. The T-Stat is $12 but getting the gasket off is a huge pain so good luck with everything.

[jeffkukuruda]

it overheated when just past idle i was just putting along, how hot does it need to get before i need to worry about internal damage? i saw it around 200, should i be worried about that? I shut it off right away and did not restart the boat. I'll try NAPA tomorrow for the thermostat, thanks alot.

Jeff

[WakeSlayer]

I am guessing you have an air leak. 200 is still pretty safe, most car engines run that hot anyway. You get to the mid 200's and you are in trouble though.