Unless the factory manual says those powerhead mounting bolts must be 100% dry, I recommend using Permatex's aviation form-a-gasket on both ends. I'm not familiar with what Mercury specifies for the equivalent, would not be suprised if it's the same stuff. The worst thing to use on an outboard is non-marine rated anti-seize because of how corrosion works when steel, aluminum, and other dis-similar metals mix. Aviation form a gasket will dry up and seal well against corrosion if you use the proper amount. If it is a closed hole meaning there is no opening to allow fluid relief, just put enough on the threads to coat them properly so the bolt won't hydro-lock in there.
I got a 2002 Murcury outboard 90. Do you know the torque spec for the main crankshalft? Got all together just missing this number. If you can help would make my dad so so happy.
Can you remove the midsection from the tilt bracket without removing the powerhead? I have a very rusted swivel pin on my Merc 90 4-stroke that needs replacing
Yes. The driveshaft housing is bolted to the exhaust plate assembly which is what the powerhead bolts onto. www.marineengine.com/parts/mercury_marine_parts/sn/0T428176/1090412ZD/3374_160
Howdy Cap'n Fritz.. Thanks for posting these DIY repair vids.. a real life-saver, as I'm repairing my 2003 90hp Merc right now.. all the same part numbers as yours.. Question for ya.. from what I've seen on the bottom of my powerhead, and in the online Mercury parts catalogues, there's a gasket p/n 27-430075 Gasket, Cylinder Block to Exhaust Plate. It didn't see that dealt with in your vids so am wondering if you just left the old one in place, or did you replace it? Would be much obliged if you would reply.. thanks!
Hello! I find your videos very detailed! I have a 1994 Mercury 90 hp 2 stroke where I need to replace the upper shift shaft. I was wondering what steps I need to follow in this series to remove the powerhead from the mid unit. I will not be doing anything besides removing the powerhead and replacing the shift shaft. Also, I am keeping the engine on the boat if possible. The reason I am doing this is because I got a new lower unit that is set up for a 6 jaw clutch while mine is currently a 3 jaw. This requires a conversion for the shift shaft. Thank you for all this information!
Hey, Michael.. seeing you pulled the powerhead off the exhaust plate, same as Fritz did, I'll ask you the question, too.. did you replace the gasket that goes between the powerhead and the exhaust plate? From what I've seen in the online Mercury parts catalogues, It's p/n 27-430075 Gasket, Cylinder Block to Exhaust Plate. I'm in process doing repairs on my 2003 90HP, too.. Please reply.. thanks!
@@lionfishphylum4079 if I saw a gasket during the process I replaced it. The gasket for the powerhead was pretty worn out so it definitely needed it. It's a cheap part though. Good luck!
@@AiPesting Thanks for confirming that Michael.. simply best practice to replace any gaskets found during disassembly, rather than risk more damage from internal corrosion from any further internal gasket leakage one would never see, until it shows up as another costly repair experience! So far, so good on my repairs, just waiting on parts coming in over next couple weeks, including that gasket!!
