Runnin' WOT and boiling water...

[Old Charger]

Ok.. Mighty 350 Olds, Jazcuzzi YJ/B...
1. WOT puts me between 4000-4200 rpm. Its it ok to run this speed continously, or should I back out of it now and then?
2. Now that I've got the gate valve on and running at the proper 160 and can actually maintain a steady 4000 rpm, I've noticed a new situation. After shutting the boat off after running WOT for a while, I noticed a popping/crackling sound from the exhaust. Seemed like the water was boiling in the exhaust pipes just past the flappers before the risers. What's up with that? Normal?

[fryzll]

Hey Old Charger, i know this sounds stupid but a friend of mine had the same prob w/ his 460 and it ended up being the pump. Evidently it was so worn it didnt have enough bowl preasure at idle to cool properly. We opened up the gate valve to where it would run at 140 degrees on plane and it only went up to 180 degrees at idle. It might not be your prob but its all i can give you. After my maiden voyage w/ my Challenger this last weekend I know my boat runs at 140 on plane and I idled it for about 10 minutes and it only came up to 185 or so. Im taking it out again this weekend for some dial in time and im going to try to get it to run about 180 to 190 w/ out any funny noises after I shut it down, i will let you Know how it goes.
Chris

[Old Charger]

Any more ideas on this? http://free.***boat.net/ubb/biggrin.gif

[Blown509Liberator]

PSI and Vacuum
Waters boiling point is raised and lowered with pressure and vacuum .Put water under enough vacuum it will boil at room temp. add pressure and it will boil above 211 deg/F. What you hear could be from two things first you getting more heat into the motor so what you hear is normal cool down of the metal. Think about what happens to the cooling water in a jet at shut down. First the pressure is removed, no more water being fed to it from jet to keep block PSI. and the water is escaping back out the way it came... out the jet. what water there is will boil from the heat it is absorbing being stagnate in the motor and not flowing after shut down. So if your temp gauge is right I would not worry about the noise

[Hallett19]

I am having a similar prob with my 460, just recently at idle, the temp is around 180 or so, it never used to go past 140 or so, and it would get cooler at wot!! now it is around 160 at wot and 180 at idle and gets about 210 when I start it up again after sitting, but no funny noises, I THINK and HOPE it is just because the water in castaic is warm now and during the winter it is pretty damn cold, so lets hope I see a change, does that sound realistic, or does someone think there could be something wrong.........? why are boats so confusing !?!??! grrrrrr........

[Old Charger]

Hey Hallett, your water temp theory sounds right to me.
Blown509! You're the man, I think you hit the nail on the head. Thanks for the info..

[LEMON SQUIRT]

I HAVE THE SAME PROBLEM ON MY 454 AT IDLE NO WATER JUST STEAM OUT THE BACK AND WOULD RUN HOT AT IDLE BUT HAS WATER STREAM AT RUNNING SPEED COME TO FIND OUT THE WEAR RING WAS SPINNING AND WORE ABOUT 1\2 INCH OUT OF THE PUMP AND SCREWED THE IMPELLER-WELL 5 BILLS LATER (NEW SUCTION ASSEMBLY-IMPELLER-SEALS AND BEARINGS THE BOAT STAYS DECENT TEMPS PLUS STEADY OUTLET STREAM AT ALL TIMES(AT IDLE NOT ENOUGH PRESSURE TO FORCE WATER THROUGH THE ENTIRE BLOCK WITH A WASTED PUMP. I DONT MEAN TO SCARE YOU BUT CHECK IT OUT.