1979 9.8 Merc

[scamel]

Hi I'm new to this site and new to working on outboards. I'd appreciate any help.
I just bought a 1979 9.8 merc. Only thing is that it wasn't peeing like it should when we started it up.
I took off the lower unit and checked the pump assy. The impeller was in excellent condition, but the upper housing seemed melted (like it was put on a flat hot surface). Oh I also "blew" on the telltale tube (after the lower unit was off) through the engine and there was no resistance which tells me that nothings plugged up.
My plan is to replace the entire pump assy on the lower unit. Is this a good first step? Any tips? The parts are 78 bucks so I want to be sure this is the way to go.

 

[Windykid]

Re: 1979 9.8 Merc

If you dont know how old the impellar is, I would change it and go from there.

 

[Windykid]

Re: 1979 9.8 Merc

Also when the lower unit is off, put a water hose to the water tube and see if it pees.

 

[scamel]

Re: 1979 9.8 Merc

I'll try the hose thing tonight, Whats the easiest way to fit the garden hose on the end of that small copper tube. My though was that fitting they make for hoses so kids can fill their water baloons. I dont belive the impeller was the problem, it was contacting the walls of the pump all the way and it was very flexible when removed.
I'm guessing my problem had to do with the housing not being "sealed", but I'm not sure.

 

[scamel]

Re: 1979 9.8 Merc

Alright I installed a water pump assy today on my 9.8. Got it started in the garbage can, it seem to pump good for a little bit then it was sort of off and on pumping. It almost seemed like the exhaust bubbles was causing the pump to loose its prime. Is that common when starting in a trash can filled with water? My intake is right above the exhaust.
thanks

 

[jbjennings]

Re: 1979 9.8 Merc

I'm thinking there may be two possibilities:

1. most likely- the rubber grommet on your copper tube from the water pump to the inlet is leaking exhaust from the midsection into your pump.

#2 less likely--there may be a hole in the gasket under the exhaust cover on your powerhead leaking exhaust into the water jacket.

Just an idea, I've had your same problem with my 9.8 and you can be sure that Laddies or some of the other experts can help you out with this as they did me. You might even search the old posts on this topic and get a little info as this is a common problem.

Good luck,
JBJ

 

[jbjennings]

Re: 1979 9.8 Merc

SCamel,
I've got one more idea for you--
When you installed the impeller, did you lubricate the impeller blades with a little grease and turn the driveshaft in the proper direction when installing it so all the blades were bent in the proper direction? Sometimes, if one or two of the impeller blades aren't right, it will do what you are describing with off and on pumping. But seeing as how it worked good at first, that's probably not it. Just a thought if all else fails.
JBJ

 

[scamel]

Re: 1979 9.8 Merc

Tried 1 more thing before I torn into the lower unit today. My engine was running like crap before becuase of bad gas, so I replaced the gas. I also lowered the engine in the garbage can lower. Get her fired up and it pumped great for 30 minutes until I shut it off.
The only thing I can think of is that the engine running like crap along with the back of the garbage can impeding the exahust was causing the pump to loose prime. I don't know, but it works now, I appreciate all the ideas and help.