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I just had my 2001 OX66 250 Yamaha rebuilt. I have noticed a minor "salt trail" coming from one of the head bolts after I run the motor. Has anyone dealt with this? What is the fix? I've re-torqued the bolts to spec but no change. Replace the bolt? Pull the head and start over with new gaskets? My fear is that it may be leaking into the cylinder as well.
If it bothers you, you could remove the bolt and put some kind of a thread sealant on the underside of the head. Permatex #2, High Tack, or Aviation Form-a-Gasket would be best.
With the relative ease that an OB head can be removed, why wouldn't you do that and clean all services, re-gasket and torque? This is an easy job to do right and the cost of a new gasket is peanuts, why fool around--there is no guarantee that water IS NOT leaking into the cylinder.
No need to pull the head. The threaded portion of the bolt probably goes through to the water jacket. Water is leaking past the threads (machine screw threads are not self-sealing) traveling along the bolt and coming out under the bolt head. The gasket seals around the bolt between the head and cylinder block so there wouldn't be any leakage there. When I built my small block Chevy, all of the bolts got some high temp teflon pipe dope on the threads because they do pass through to the water jacket. Just about any thread sealant will do here. I prefer the ones I listed previously. Silicone is about the only one I wouldn't use. Sealing the threads will help make the bolts easier to remove in the future. Maybe, use some WD40 to wash any salt water out of the bolt holes.
The head bolt holes are "blind". They don't go into any water in the block. There is a coolant passage on the top of the heads and that's where the water is coming from.
ski doc, this motor has a warranty, if yes talk to the builder, yes i said the builder, yes i do build outboard engines, you tinker with one of my builds the warranty is voided
__________________ Beware of A1outboards aka Blackbird ind , = Google
So, assuming water is not slipping past the head gasket it's a non-issue?
just the opposite, if it is true that the head bolts DO NOT go through into a water passage on this engine then the head gasket is leaking pure and simple, cooling water is getting past the gasket and leaking out around the bolt. If it was just rebuilt then get them to fix it. No matter what anyone tells you water seeping from a head bolt needs to be corrected---the right way. The confusion here is that on SOME engines the head bolts go drectly through a casting into a cylinder cooling passage, in those designs you only need to seal the bolt threads.
I have little confidence in my engine assembler. I could take it to them and will likely still be wondering if it is fixed properly.
I am fairly mechanically inclined and plan to fix this myself. Sounds like I might either chat with someone who builds these engines or just pull the head, buy a new gasket, and re-assemble. That way I know it's done right and I will know where exactly the bolt hole goes. I must say, though, reading the Clymer's manual for this engine it seems Grog is right.
Sleeper -The confusion here is that on SOME engines the head bolts go drectly through a casting into a cylinder cooling passage, in those designs you only need to seal the bolt threads.
When torqueing head bolts it specifies in the manual to use no sealant and / or lubricants when applying the head bolt torque.
Follow the manufactures service and repair manual, if you don't own it BUY ONE!!!!!!!!!!!!!!!!!!!!!!!!
__________________ Beware of A1outboards aka Blackbird ind , = Google
So, assuming water is not slipping past the head gasket it's a non-issue?
just the opposite, if it is true that the head bolts DO NOT go through into a water passage on this engine then the head gasket is leaking pure and simple, cooling water is getting past the gasket and leaking out around the bolt. If it was just rebuilt then get them to fix it. No matter what anyone tells you water seeping from a head bolt needs to be corrected---the right way. The confusion here is that on SOME engines the head bolts go drectly through a casting into a cylinder cooling passage, in those designs you only need to seal the bolt threads.
There is a water jacket in the block as well as the heads. I assumed there would be a boss around the bolt that sealed it off from the head which would mean the water had to be coming up the threads from the block. But, if the bolt holes are blind tapped this is not the case. The water jacket in the head may be open to the bolts, however. This doesn't mean the head gasket is leaking. If this is the case a copper gasket under the bolt head or a dab of sealant would be best.
Of course, it is possible that the head gasket is leaking and a cooling system pressure test would be the only way to confirm it either way.
When torqueing head bolts it specifies in the manual to use no sealant and / or lubricants when applying the head bolt torque.
Follow the manufactures service and repair manual, if you don't own it BUY ONE!!!!!!!!!!!!!!!!!!!!!!!! [/quote]
This is a blanket statement used by manufacturers to cover their asses. They are too cheap/don't want to deal with the mess of a lube/sealant during assembly. Therefore, their torque numbers are calculated without lube which is why they specifiy that you don't use one either. This doesn't mean you shouldn't use any lube at all. Simply reduce the torque 15-20% when using anti-seize. 5-10% with a sealant. The 5-10% with sealant is probably within the error of your torque wrench so I usually just ignore it. When using anti-seize I just torque to the lower end of the manufacturers range. I've never had head gasket sealing problems on my engines.
I spent some time working in an assembly plant. We only used lube on fasteners that would gall during assembly. Once the product was assembled, it was out of our hair and didn't matter if the customer would never be able to disassemble it in the future.
The Clymers manual recommends 2-stroke oil to be used to lubricate the head bolt threads.
Do yourself a favor and buy a real shop manual.Aftermarket manuals can get you into trouble.They are not updated nor they don't have all the info one needs to start with.I would put that clymers manual in the outhouse were it might do some good!Check ebay and you can buy a true shop manual for $10 on cd.
If this is the case a copper gasket under the bolt head or a dab of sealant would be best.
Of course, it is possible that the head gasket is leaking and a cooling system pressure test would be the only way to confirm it either way.
Copper is death on aluminum. You can't even using aluminum flashing next to copper treated lumber any more.
Difficult if not impossible to pressure test a block for an outboard motor. How will the bottom of the block be closed off to maintain pressure?
If it were my motor I would bite the bullet and remove the head to find out what is going on. It could be a bad gasket at best or a warped head at worst. Two gaskets at about $75 is cheap insurance if that is all that is needed to fix the problem. Leaks (or seeps) typically don't fix themselves. They usually just get worse with time.
Weeping Head Bolts 
= Google 
