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1984 Mariner 99 questions

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mark55

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I recently purchased a 1984 Ma

I recently purchased a 1984 Mariner 9.9 for my small boat. I am wanting to do some pm on it and have a couple of questions. I drained the lower unit. The lube that drained was a green color. I bought some "Super Tech Marine SAE 80W-90 Lower Unit Gear Lube" to replace it with. I noticed that what I bought was not green. Is this the right stuff to replace it with? Also I am wanting to replace the spark plugs. I pulled the old ones and they are NGK B9HS. The guy at advance auto gave me some Autolite 4092 as replacements. Are the orginal NGK B9HS the correct plugs? (Being an older engine I thought perhaps someone may have incorrectly replaced them.) Also what is the correct gap to set the plugs at. Thank you for your help.
 
"Mark, the gear oil you got is

"Mark, the gear oil you got is fine. Depending on the brand etc it may be a different colour. The stuff I use is sort of a (honey) colour.

As to the plugs - get NGK's, your motor was engineered to use them. Plugs are all about resistance. The correct plugs for that model (and I have 2 of them) are BP8H-N-10.

Someone had the incorrect plugs in there (B9's) - take the autolite's back. They may cross ref (like some of the Champions) but the motor will run better with the NGK's (and that's what Merc calls for).

There is also a BPZ8H-N-10 which will work. Designed to cut ignition noise (to electronics) but cost about 3 times as much.

Plugs (NGK's) should be gapped at .060""
 
That is a Japaneese Mariner.

That is a Japaneese Mariner.
The suppressor resistor is inside the plug boot/cap on some in those years. NGK B7HS is the correct plug for the 9.9C with the Yahama CDI magneto ign.

Green gear oil is Hi-Performance blend. That is overkill for a 9.9. Brown premium is fine. The two don't like to mix. Drain it out overnight real well.
 
"Sorry, wasn't even thinki

"Sorry, wasn't even thinking of the Yami built Mariner model - I have a pair of 9.9 Mercs - oops.."
 
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