1999 250 OX66 Water in cylinders - The Hull Truth

JF123 · 10-26-2009, 05:48 AM

I am convinced my engine is taking water into cylinders 3 and 4. It originally started with #4 last year and has since gone to #3. Both spark plugs get coated with a tan substance every 10 hours or so. Compression is equal on all cylinders. I replaced the head gaskets and did not see any signes of failure in the gasket or heads. Is there something in the block design that can cause this? I'm running out of ideas.

BigPumper · 10-29-2009, 08:36 PM

That's definitely a mix of water, oil, and gas on the end of those there plugs.

JF123 · 10-30-2009, 05:59 AM

The big question is where is it coming from. I'm convinced I will be replacing the powerhead just for my peice of mind I would like to know what is causing it and where it is coming from. I can't be the first person that had this type of failure.

A1 Outboard · 10-31-2009, 02:48 AM

From what we have seen of that block it leaks in the exhaust cavity...With that said I have some like brand new 2003 powerheads just in from Yamaha that need minor repairs. Give us a call on options and pricing..Mike Sr 1 877 9832537