Tech Tip: High Speed Overheat?...

[cigdaze]

Check your drive water passages.

This is from a friend's 36 Baja. The engine would run fine on the hose, would idle cool, cruise fine, but it would overhear at higher speeds. He flushed the cooling system, changed the impeller, the pump, etc. all to no avail.
He finally pulled the drive and found this.

The pics aren't the best, but you get the point.

[old377guy]

Mama mia!

[cigdaze]

Apparently, he has a special kind of in-line flush system where he can block off the flow to/from the drives so you can flush the motors while sitting in the water.
Well, naturally when the drives never get flushed, this is what happens.

The passage was no more than 3/8" around after the corrosion swelling choked it off.

[MOBILEMERCMAN]

That is not uncommon. Flushing really has no effect. The salt builds up in the transom assembly around the outside of the hose. It is difficult to soap and spray in there. I rinse and douche with CRC around the gimble and in around the hose passage area. Not sure if it helps but, I feel better doing it.

[Geronimo36]

I agree with Jimmy, common problem on all saltwater boats! On a list of 5 it's probably the 3rd thing I check.

Back in the late 90's we had one of the mechanics working on a 38' Chris Craft Stinger for 2 days and couldn't figure it out... He even started replacing wirebound hoses thinking they were collapsing... On the third day he threw in the towel and the service manager asked me to check it out. I was in there for all of about 15-20 minutes when I found the problem... The other mechanic felt like a douchebag.. lol

[MERPerformance]

That is a common problem, you can flush the engine 24/7. Take it apart clean the housings prime and paint them, buy a new hose and inserts and put it back together.