White Smoke/Overheat - 2001 Nautique GT40

[EchoPuller]

Good afternoon,

Yesterday evening I was towing, when my boat started to white smoke. As soon as I noticed I check my gauges and my temp was steadily climbing. Luckily, I was able to get it on my trailer at ~220 degrees.
I've checked all my hoses and connections; all seems to be fine.
I've checked my prop; all seems to be fine. Although, I did run it in the sand earlier that day.

I'm mechanically inclined and a "shade tree" mechanic, so I figured I would ask some professionals before taking it to my local dealer.

Thanks for any advice!!

[Tom_H]

Most likely cause is an air leak on the inlet side of the raw water pump or a failed impeller. Impeller's for those have been known to have a failure where the hub separates from the outer rubber and can look fine but now pump any water. Could have also filled your inlet water strainer if you pulled a bunch of crap in from the sand.

[peteb]

My advice. Start with disconnecting the fresh water hose or add a temp hose on the supply side of the fresh water strainer and use a 5 gallon bucket of water in the boat to make sure your sucking water at idle. If your not sucking water then go to the water pump and inspect your impeller. If you dont have a fresh water strainer then you should look at adding one since it keeps debris out of the system. If you dont have the PCM parts manual for your boat download it to understand the raw water cooling system and start working from the fresh water side. If you havent change the impeller or Tstat in a while definately replace those.

[jpwhit]

White smoke from exhaust or from Engine Compartment? From exhaust would suggest water getting into the combustion chamber. That could be a blown head gasket or less likely a cracked block or heads. Doing a compression and leak down test on each cylinder would be a good place to start.

[Scooter G]

I might throw in a couple of cents with jpwhit. Let's hope it's not a head gasket, but water in a cylinder will cause white smoke along with potential air pockets in the cooling system causing over heating...
Pull your spark plugs and check their condition, that in itself may show you what you need to know. If you don't have access to a compression tester (a screw in is the best), start down your Buddy list, or time to add one to the tool box. You will use it sooner or later.
2001, time for a baseline compression test anyway, good to have numbers going forward if you plan on keeping the boat.