I have a minty clean 1990 9.9hp Yamaha four stroke motor, in a long shaft model, recoil start. That someone destroyed the cylinder head on. The guy broke off the sparke plugs, then proceeded to drill out the heads and install two 18mm Motorcraft spark plugs so his outboard and truck could share spark plugs. To make it short, he drilled into the back of both valves doing so and it never ran again. It sat in his basement like that since April of 1990, two weeks after he bought it new.
FF to 2026, I got the motor off his widow for $20. Its still got the hang tags on it from the dealer.
The dealer tells me no parts are available for it. I have the owners manual and it calls for the following,
FT9.9ELD 1990
6G8-11181-A0-00 head gskt
6G8-11111-02-94 head
Now, I also have a 1996 Yamaha/Mariner that was hit by a car. Its cylinder head is perfect, it was hit when it was new. It severed the mid above the lower mounts. It was given to me by a local dealer who closed down about 10 years ago, it was hit while on the lot when new.
I pulled the power head figuring one cay I'd find a good lower for it.
I see no way to cross over the part numbers from Mercury to Yamaha, but the aftermarket listings show confilicting information. Apparently the power head won't swap but the head may?
Again I'm being told that the head on the 1990 Yamaha is a 1988-1994 year span,
I have a 2001 here, and that head is very different, but is the 1996 mariner and the 1990 Yamaha the same head? The dealer says no, aftermarket listings show two different gaskets. I have both in hand,
6G8-11181-A0-00
6G8-11181-A1-00
Both gaskets in hand look identical, they're the same thickness and have the same size holes.
Five dealers told me that the two motors are not at all compatible but they look identical other than color. One dealer swore up and down that the power head was Mercury built.
What years were the same when it came to the power heads with Yamaha?
The Mariner head will bolt up, the head gaskets look identical. The pistons look identical, as does the entire rest of the motor. (Even the hoods will swap, they appear to use the same pan) but the lower units are obviously different.
FF to 2026, I got the motor off his widow for $20. Its still got the hang tags on it from the dealer.
The dealer tells me no parts are available for it. I have the owners manual and it calls for the following,
FT9.9ELD 1990
6G8-11181-A0-00 head gskt
6G8-11111-02-94 head
Now, I also have a 1996 Yamaha/Mariner that was hit by a car. Its cylinder head is perfect, it was hit when it was new. It severed the mid above the lower mounts. It was given to me by a local dealer who closed down about 10 years ago, it was hit while on the lot when new.
I pulled the power head figuring one cay I'd find a good lower for it.
I see no way to cross over the part numbers from Mercury to Yamaha, but the aftermarket listings show confilicting information. Apparently the power head won't swap but the head may?
Again I'm being told that the head on the 1990 Yamaha is a 1988-1994 year span,
I have a 2001 here, and that head is very different, but is the 1996 mariner and the 1990 Yamaha the same head? The dealer says no, aftermarket listings show two different gaskets. I have both in hand,
6G8-11181-A0-00
6G8-11181-A1-00
Both gaskets in hand look identical, they're the same thickness and have the same size holes.
Five dealers told me that the two motors are not at all compatible but they look identical other than color. One dealer swore up and down that the power head was Mercury built.
What years were the same when it came to the power heads with Yamaha?
The Mariner head will bolt up, the head gaskets look identical. The pistons look identical, as does the entire rest of the motor. (Even the hoods will swap, they appear to use the same pan) but the lower units are obviously different.
