90 HP Cylinder head installation tips needed

[Bob]

I am replacing the cylinder head on my 1998 C90TLRW with a new head from Yamaha Outboard parts. I have all new gaskets, T-Stat, and Pressure control valve. Do I need any sealant on the head gasket or water jacket to cylinder head gasket? Also I would like to use an anti-seize compound on all of the bolts and need a recommendation for a product. I just received my parts and would like to complete this tomorrow so any help is greatly appreciated. Thanks Bob T

[Sheff 69]

I just did this on a 2002 motor.
I was told by a marine engine rebuild shop to not use any sealant on the head gasket, it already comes with an adhesive on it. I didn't use anything on the head cover gasket or the Tstat gaskets, I figured they were small enough not to have to worry about them. If they leaked, I'd just replace them, this time with a gasket sealer.
Even though Yamaha advises to install the head bolts dry, the engine re-builder advised to use a thread sealer on all the bolts. I used Permatex thread sealant.
However, instead of using it on the first thread as advised, I used it on what I estimated to be the last couple of threads of engagement at the surface of the block. That way it should protect the threads from salt water ingress. I have about 2 hours of running so far and have no leaks.

[99yam40]

I would think protecting all of the threads from corrosion and dissimilar metal problems would be better, which putting on the 1st threads would have done

[Bob]

Permatex has an Anti-Seize Lubricant that claims to be ideal in marine applications and protects against dissimilar metals (alum head an steel bolts) Any experience with this? I would be inclined to put on all threads on the bolts as on previous head 4 bolts from water jacket to head could not be removed and snapped off.

[zenoahphobic]

I always add some gasket sealant to gaskets and have never found a negative in doing so. I do this because the surfaces are not new and have already been used (obviously), so not pristine. Yes gaskets have added sealants on them, but they are plastic required to be squeezed to fill the gap sufficiently. Using liquid sealant means you already have coated the metal (not new) mating surfaces, filling some of the imperfections from micro corrosion that has occurred whilst in service.

Similarly I use an antiseize appropriate for stainless steel bolts to aluminium threads. As Yam99 implies placing some on the first threads spreads it to the upper threads anyway.
It is standard procedure for manufacturers to specify dry installation. This is because proper torquing of bolts requires friction in the threads to be properly duplicated to assure they do not undo. It is worth noting manuals are written and released when a model is released, and therefore the manufacturer is in total ignorance of how their product will perform years done the track. Nor would they care anyway if bolts break then!!

[zenoahphobic]

That begs the question why not on head gaskets?
I was talking about small amount on used surfaces.
And it is assumed the sealant does not react with the gasket and is of adequate heat rating.

[walleye1]

I have never used anything on a head or gasket, make sure surfaces are clean, never a problem. Head bolts were always coated with 2st oil when installed and torqued.

[Bob]

Has anyone used permatex anti-seize lubricant on the head and water jacket/ t-cover bolts?

[99yam40]

do not use any that contain copper when installing in aluminum

I would follow the service manual procedures
they will have what to use on things

[DennisG01]

Has anyone used permatex anti-seize lubricant on the head and water jacket/ t-cover bolts?

It was mentioned above, but you need to make sure that whatever antiseize you are using does not contain any metals. The "most common" Permatex that most of us are familiar with DOES contain metals. I believe that Yamaha makes their own? But, in any case, Merc makes a product called Perfect Seal that is fantastic. It's not cheap, but it works great. Probably less expensive than the Yamaha stuff, though... it seems Yamaha is even MORE proud of their products than Merc

[Sheff 69]

I would think protecting all of the threads from corrosion and dissimilar metal problems would be better, which putting on the 1st threads would have done

I had conflicting instructions.
My local Yamaha Master Tech said do not lubricate the threads, install the bolts dry. The marine engine re-builder (Flagship Marine in Punta Gorda, FL, supposedly with a very good reputation) said use Permatex. So I used Permatex on the top few threads as a compromise.
Who do you believe?