90 nautique running hot?

[R-mallis]

Me and my friend are the new owners of a 90 sport nautique with a pcm 302 in it. The the boat was completly restored and the engine was rebuilt
when we purchased it. It looks to me like the engine was a crate motor by the way its all freshly painted one color. Anyways the engine runs great and seems to run cool all the time except after you run it for an hour or so and then shut it off, then restart it say 10 minutes later or so. After restarting it the temp jumps to 200 sometimes 220 for about 10 to 20 seconds then slowly falls to 160. If i put it in neutral and rev the motor a little it falls much quicker. I myself work for a ford dealer as a mechanic and i know from experience especially with older cars that this is a normal condition, its just the stagnant water in the block heating up and causing the temp guage to rise. On the other hand this is my first boat and i know nothing about how the cooling should work. I've been reading some of the other topics and i'm thinking maybe i could have a loose intake line sucking in air. Please write back if anyone knows if this is a normal condition or if i have a problem....thanks
just to add...while running at full throttle i'm at about140 to 150, and when at idle i'm at 160 to 180.

[Hollywood]

engine temp

It sounds like your engine is fine. after you've been driving around hard let it idle so the impeller can do it's job and get fresh cool water in the block. Even those high temps you experience at start up aren't out of the ordinary as long as the temp comes down as water circulates through the block. Of course go ahead and check for loose hoses and lines, but it all in all sounds ok.

edit. those temps are higher than normal. i'd be especially alarmed if they went any higher than 220 though.

[M3Fan]

First off, it's interesting to hear you have a 302 in there- I didn't think CC used 302's since the Ski Tiques dropped off in the early 80's. Maybe it has the same mounts as a 351, which should be the engine in there, so they dropped it in.

Now, for the heat question. The temp you describe seems high- mine will pop up to 180 after sitting for a few minutes, then come down immediately when started. Here are some things to check in case you don't think your engine is getting enough water:

- Water strainer, if you have one- it should have a rubber gasket on the clear portion to make a nice tight seal. Make sure the gasket is there. The strainer will be located before the trans cooler on the water intake hose.

- Swap out the raw water pump impeller no matter what. It's cheap and can work wonders with a new one.

- Same goes for the Thermostat. It's cheap insurance.

Other than that, I don't know what to tell you. The temp jumping up is normal, but that is pretty high.

[R-mallis]

90 nautique

Thanks for the info m3fan and holleywood. As for the engine size, it probably is a 351 i just didnt look at the engine close enough, they are pretty similar engines, ill check that out tommarow when we take it out. Anyways, as for my overheating concern, i had my friend check out the water strainer because we keep it at his house and he told me there was no strainer or cooler. that something we should look into getting? So what i figure we'll try doing is tightening all the clamps on the intake hose to make sure we're not sucking any air and we've already replaced the impellar when we firstgot the boat so i know thats good. Im also thinking about hooking up a manual temp guage that i had on my old mustang just to make sure the guage isnt innacurate. Im going to try all this tommarow so i'll let you guys know what happens. Thanks again

[Daryl]

re - 90-nautique (LONG)

wow - R-Mallis - your experiance sounds EXACTLY like mine.

have a 1990 Ski Nautique, PCM351

had/have what seemed to me to be a heating problem.

here are some details of mine.

at beginning of season (i just bought this boat this year), seemed to run ok temp, i changed the impeller (the old one wasn't 100%), a few weeks later, had some temperature issues. would run up to 190 and seemed to be all over the board with temp. so i thought it was an air leak... checked and tested all connections, strainer (had a crack), trans cooler, put in a new automotive t-stat (160Deg because i have a heater). Thought the cracked strainer might have been the problem.

what i learned is not to use an automotive t-stat - they appear to be a lower water volume and the boat doesn't cool right. (can someone comment on this?)

i ran all kinds of tests with this 160 automotive tstat - raw water pump volume seemed good, water would shoot out of the drain plug (so i assume the circulating pump is good), checked temperature sending unit, seems ok (might read a little high on the guage but there are voltage drop issues with that)

right now the original 142 t-stat is back in the boat, there are NO air leaks. So maybe all i had was a cracked strainer all along.

temp is 160-170 at idle (and that varies), will pop up to 180 (or mabye a little more) after you turn it off.

145 at speed. - I haven't had it like this all that long and I still don't like the temperatures at idle - so i'm a bit aprehensive to declare the problems solved.

maybe a little winded - I've spent alot of time playing with this temperature thing and I can't possibly put it all in an email.

maybe someone can answer these questions:

what is normal operating temperatures for the PCM351 carb engine with a 142 degree thermostat? what is it with a 160 degree tstat? at idle? after you turn it off? (i think we can all agree on the temp when running speed or higher than idle)

what about the automotive t-stats? (i have no access to PCM parts where i live - small town - canada - so SKIDIM is very expensive)

I also found an issue in my dash with a bad connection - the voltage was low in the dash and this added 10-20 degrees to the temperature guage.... the more load on the accessories, the higher the temperature. I have fixed many connections and improved this alot.

[Hollywood]

cooling

You should definitely put a strainer in. A clogged cooling system is the last thing you want to deal with.

[NCH2oSki]

I dont know if this will help, but my 99' with the GT-40 never runs over 160. Even when the lake temp was 95, it still held at 160.

I havent replaced the t-stat, but its probably due this winter when I change the impellor. I think there is a difference in the auto and marine t-stats. My MC 190 had the gt-40 with carb and ski-dim suggested I run a 180 t-stat since it had a heater. It never got over 180ish.

Good luck.
Jeff