240D bravo 3 instant overheat intermittant

[389560]

On launch this spring, the engine immediately overheated (within 5 minutes) temp to 200+. While nursing back to dock, dropped back to normal and stayed. Ran perfectly for a couple days, then yesterday overheated again on launch but would not return to normal. 2004 240D 350 bravo 3, 120 hrs. What has me confused is that it runs perfectly one day, than instantly overheats the next. Another fact, boat is kept out of water on lift (Lake Champlain, Vermont). I can't trust it take it out.... HELP please from any of you experienced guys or gals!!

 

[JediJD]

Are you relatively certain of the information you are getting from your gauge? For example, is the engine smelling differently or running differently...or is it only the gauge reading? An infrared temp gauge can be a pretty valuable tool to test true temperatures. Also, did it go hot during use, or only during warmup? What were the conditions?

Assuming this is a closed cooling system, if you know its intermittantly running hot...the first thing I would be checking is the thermostat. If, for example, it sticks closed, then there is no circulation of coolant in the engine. (cheap fix) or compression testing/leak down testing (expensive fixes)

(I think you have a traditional waterpump system...I don't think the '04 240 is impeller based, but one of the experts will chime in.)

 

[mwph]

Don't take my word for it but I thought all B3 outdrives used an engine mounted water pump. That being said, the thermostat could still be the issue, its just not a closed cooling system.

 

[Dave S]

A couple of questions for you.

Is this engine closed cooling (with antifreeze) or is it sea water cooled?

When was the last time you changed the seawater impeller?

Do you get an overheating alarm when this happens?

Dave

 

[389560]

Frankly, the impeller has not been changed.

By the fact that it sometimes works perfectly I assumed that the impeller was ok. I didn't think it was a closed system, but frankly I don't know for sure (how would I find out?) Is there a thermostat regardles of whether it is a closed system or not?

Yes, I get the overtemperature alarm (and LCD display) when it overheats, and the risers, which are normally cold with cooling water are too hot to touch. Slight smell also.. It is definitely not a false alarm.

Other co-incidence: First time it happened was on launch, once boat was in water, no problem. Just got lift out and now it happens again once boat was out of the water for awhile... wonder if any relevance....

Thank you all for you continued help. If successful it will salvage my fathers day weekend!!

 

[389560]

Oops, missed a detail of your reply: If closed system uses antifreeze than it is NOT closed.

 

[Dave S]

Your sea water impeller is likely shot if it never has been changed in six years. These things ought to be changed every two to three years at a minimum. Some folks change them out annually. The intermitent nature of the problem may not be as easy to explain but I'll take a shot at it. Once an impeller begins to fail, pieces of it will break off and become lodged in various areas of the cooling passages. Possibly a blockage caused your first overheating incident and maybe the pieces cleared themselves well enough that you didn't overheat on your other outings. This is just a guess on my part but you need a new impeller regardless. You may also have the plastic housing water pump which in all likelihood means it is best to replace the whole pump assembly rather than just the impeller because these housings tend to wear out. If you have a brass pump then only the impeller needs changing.

Make sure whomever changes the impeller also gets all the old impeller pieces out of the cooling passages all the way up to the thermostat. Since the thermostat housing will also have to be opened up, I would also throw in a new thermostat while you are at it.

If you are thinking of doing the work yourself, be aware that changing the impeller on a 240SD is a big pain in the butt. I never did mine myself on my 240SD after watching the gyrations that a Technician went thru to get a pump off and back on a 240SD. The 240SD has to be one of the worse boats in the Sea Ray line up to work on when it comes to things like this.

Dave

 

[389560]

Thanks to you all. Dave was right on about changing water pump (at least the impeller)..... live and learn. Not sure why my "professional" winterizers (one a local Searay dealer) didn't do it, or even mention it.

Had 2 broken vanes on impeller. Kindof strange how it would sometimes work perfectly and other times not... I guess it just depended on whether a broken-off vane was in the right/wrong place when the engine started:smt038!

Weekend salvaged!