Merc 9.8 hp identification.

[Dutch515]

I just picked this 9.8 hp Merc up yesterday. Can anyone tell me the year just by looking at it? The serial #'s are faded. I also have a problem with the drive mech. The pistons move only a little, the guy who had it before me said he hit a rock or something and the motor wont spin. The propeller does spine fine, could my drive shaft be bent or broke? dutch

 

[Dutch515]

Re: Merc 9.8 hp identification.

Here are some pics.

 

[AMD Rules]

Re: Merc 9.8 hp identification.

Its a '65 or '66 Model 110 9.8hp

Can you read the beginning portion of the serial number on the metal transom tag?

Serial numbers 1742746 thru 1912758 are 1965 models
Serial numbers 1912759 thru 2125963 are 1966 models

I'd suggest removing the lower unit, to determine if it is the powerhead or the gearbox that is the problem. Motor looks to be in great physical condition.

Good luck.

 

[Dutch515]

Re: Merc 9.8 hp identification.

Hey AMD, I found the serial # its 1790368. Also do you know exactly how to remove the powerhead, or do you have any doc. on this motor. I took the six bolts on the underside of the ph but that wouldnt removeit and I dont want to break anything. Just trying to get this going for my grandpa. Dutch

 

[AMD Rules]

Re: Merc 9.8 hp identification.

Nice '65 motor.

Unless you are removing the powerhead to rebuild it, or overhaul it cosmetically...I would leave it alone. Instead, try removeing the lower unit for now.

If you remove the powerhead you need to disconnect and remove a lot of linkages, and pivot arms from the throttle mechanism. Then you need to replace gaskets etc.. best to steer clear unless its a must.

Removing the lower unit is easy... down below you'll see two nuts to remove (see pic). Slide it off and you're set. This will allow you to see if it is the powerhead that is siezed, or the lower unit gearbox. While you have the gearbox off, be sure to inspect/replac the water pump impeller and check/replace the gear oil. Look for signs of water, and metal debris in the oil.

I do not have a manual for that motor. Service manual Merc p/n 90-31945
You can pick them up on eBay occasionally, for a reasonable price.

 

[Dutch515]

Re: Merc 9.8 hp identification.

are those nuts next to where the ph bolts to? I cant see what your saying

 

[AMD Rules]

Re: Merc 9.8 hp identification.

Added a pic to my post as you were replying...hope that helps.

 

[Dutch515]

Re: Merc 9.8 hp identification.

Got it. opened it up and slid the long shaft out and it was bone dry, not a speck of oil in. I can even turn the shaft with my hand or vise grips. If I could Id like to send you some pics but I dont want to keep you up.

 

[Dutch515]

Re: Merc 9.8 hp identification.

Heres what it looks like inside. I would like to know what the shafts do exactly if you dont mind. I think that cut tube goes there but it just fell out when I pulled the lower end off. Thanks again, Dutch

If you look at the third pic the long shaft only rotates clockwise.

 

[AMD Rules]

Re: Merc 9.8 hp identification.

I was hoping you would reply to this thread instead of starting a new one, but you'll see I asked a question in the other new thread about the 'lack of oil'.

You sounded surprised above, that the long shaft (driveshaft) was bone dry. Its meant to be dry, and you will only find oil in the gearcase below. You need to remove the small drain plug to check.

Are you sure the gearcase has no oil in it ?

You stated that the driveshaft woudl turn clockwise, but not counter clockwise?

Now that you have the gearcase removed, can you turn the red flywheel on the powerhead by hand?

Can you turn the prop shaft?