Identification of old Mercury 9.8 + water problem

[jtogle]

I'm a newbie to both this forum and boat ownership. I recently picked up an old Sears jon boat with a mercury on it. My first problem is that I can't get it to pee. I've blown air from the outlet under the cowl through the pickup below the skeg. I'm thinking maybe I've got a gasket problem in the exhaust? The other problem is that I can't identify this thing. I've attached pictures. The cowl decals are the brown theme. The serial number is A113145. I can't find that series on any of the common Mercury identification sites. Without this I don't know how to work on it or what parts to get. Oh yeah, I also can't get the electric start to spin, but am guessing I need to clean the contacts on the button before I move on to the deep regret phase of this purchase. Is it an anchor?

 

[carholme]

Re: Identification of old Mercury 9.8 + water problem

That s/n comes up as:

MERCURY - ( 9.8 H.P. (1985 ))
Serial No: 0A113145 Model No: 1010525

Parts and Service Bulletin list for s/n 0A113145:

Search Results - Crowley Marine


From the pictures the engine does not seem to be deep enough in the bucket. The water level should be well higher than the cavitation plate. Also, locate the pee tube and shove a length or plastic lawn trimmer wire up the tube to make sure that it is clear. Mud daubers love to nest up in the tube and you wouldn't believe the pressure their nests can withstand.

Have you had it running and can you rope start it?

Gerry

 

[racerone]

Re: Identification of old Mercury 9.8 + water problem

Way more water is needed in the bucket.----A new to you motor must have a new impeller installed.---On severe overheat there is a plastic washer at the top of the water tube and it melts blocking the water flow.

 

[jtogle]

Re: Identification of old Mercury 9.8 + water problem

Thank you for the identification. I must have been looking in the wrong places. I was running it with water to the rim of the barrel, this picture was taken this morning after it sat all night. I don't know if that would have been enough water still. It was a few inches above the cav plate. I'll try the trimmer line tip.

That s/n comes up as:

MERCURY - ( 9.8 H.P. (1985 ))
Serial No: 0A113145 Model No: 1010525

Parts and Service Bulletin list for s/n 0A113145:

Search Results - Crowley Marine


From the pictures the engine does not seem to be deep enough in the bucket. The water level should be well higher than the cavitation plate. Also, locate the pee tube and shove a length or plastic lawn trimmer wire up the tube to make sure that it is clear. Mud daubers love to nest up in the tube and you wouldn't believe the pressure their nests can withstand.

Have you had it running and can you rope start it?

Gerry

 

[Mi duckdown]

Re: Identification of old Mercury 9.8 + water problem

If I were you. I would drop the lower end and replace the water pump impellar, since you don't know when it was last replaced. It could be bad.

 

[jtogle]

Re: Identification of old Mercury 9.8 + water problem

I dropped the lower unit last night to find that indeed the impeller was shot. More like non-existent. Photos are attached for entertainment purposes. If you squint you'll notice the remains of the vanes packed into the upper and lower halves of the pump. I think I'm going to order a new pump kit in its entirety rather than just the impeller. In one picture you'll see I've slid the impeller up on the shaft and there are ZERO vanes left. I can blow air through from the output hose, but am concerned about possible debris in the water jackets. Can I backflush this critter with water or do I risk pushing the head gasket? Also, the water tube came out with the lower end, so I can see the orifice on the block and it looks clear. I'll look for a new seal or grommet or whatever goes on that end as well.

 

[racerone]

Re: Identification of old Mercury 9.8 + water problem

No cylinder head gasket on this motor.---Just a water jacket cover gasket.-------------See impellers like that all the time.--------Need to do a compression test first.----Then inspect pistons and rings through bypass cover on starboard side.----Narrow cover withh 3 screws.------Spend no money untill you examine this motor more.

 

[jtogle]

Re: Identification of old Mercury 9.8 + water problem

Thanks. I have a compression tester. I don't know how many PSI I should look for but I will look at the result for each cylinder and see how close they are to one another. I would hope for at least 120 lbs I think. I used to wrench on my two stroke motorcycles so I know the sadness I'm looking for. In fact I still have the last seized piston out of my '87 CR125 as a memento of simpler times. And a paperweight. Will I be looking down the exhaust port if I take off the cover you suggest?

 

[racerone]

Re: Identification of old Mercury 9.8 + water problem

The intake bypass cover ( 3 screws ) allows you to look at pistons and rings.---You should do that and might have to make a simple gasket !

 

[Oldcraneguy]

Re: Identification of old Mercury 9.8 + water problem

I wouldnt get my heart set on 120+ Ive had 2 of these motors and neither one had more than 105 but they were both strong little motors, good luck.....OCG

 

[jtogle]

Re: Identification of old Mercury 9.8 + water problem

OK, folks. I managed to order the proper impeller from our friends at iboats.com. I backflushed the powerhead and cleared the pieces of the old impeller from the pump. Seems that the fragments were contained within the pump. Buttoned it up and it pumps beautifully! I need to change the fluid in the lower unit next and work out why the electric start isn't working. I've got continuity in the starter button, and 12+ volts when probing both the ground and the downstream side of the starter button, which goes to zero volts when depressed. I don't get the slightest hint of interest from the starter, so I have to assume it has taken a crap. Not sure what else it could be at this point. Ideas are welcome!