1976 Merc 110 (9.8) Running Hot

[Squawfish]

I've read some of the posts on this issue and I think I need to replace the impeller on the 9.8 Merc I just bought. I ran it for the 1st time today and it got hot very fast so I shut it down and paddled back to shore. No water is coming out of the engine and there appears to be sooty charred material in the exit hole.
The big question is, how can I get at this assemby to see and/or repair it?

 

[Squawfish]

Re: 1976 Merc 110 (9.8) Running Hot

I just spoke with the previous owner of this outboard and he told me that he recently had the impeller replaced. I mentioned that there was no water coming out in my original post but there were air bubbles coming from the lower unit. Could it be that the repair tech put the impeller in backwards? Instead of sucking water up it is pushing air down???
I still need to know how to get at the impeller.

 

[Laddies]

Re: 1976 Merc 110 (9.8) Running Hot

No, the mechanic did not install the imp backwards but he also did not test the engine so take it back and talk to him. It is a good idea if you plan on working on this engine to buy a OEM manual

 

[Squawfish]

Re: 1976 Merc 110 (9.8) Running Hot

No, the mechanic did not install the imp backwards but he also did not test the engine so take it back and talk to him. It is a good idea if you plan on working on this engine to buy a OEM manual

Thanks for your reply Laddies but it was the previous owner who said he had this work done. It was over a year ago from what he told me, and I am now in the middle of nowhere and over 200 miles away. He may or may not have tested the engine but if he didn't, why would I have the guy do work for me?
I do plan on doing any maintenance on this engine that I can do and am looking for a manual, but in the meantime, can anyone tell me how to inspect the impeller?

 

[Laddies]

Re: 1976 Merc 110 (9.8) Running Hot

If your doing your own repair you need to stsrt with a manual. To ck. the impeller you need to drop the lower unit 2 nuts one under the cavitation plate facing down and one at the front of the unit facing up remove them and the unit comes down then there are 2 nuts holding the top on the pump, remove them and lift the plate and there is the impeller.

 

[Squawfish]

Re: 1976 Merc 110 (9.8) Running Hot

Thank you sir!

 

[Squawfish]

Re: 1976 Merc 110 (9.8) Running Hot

Well, I dropped the lower unit and opened the pump assembly. Sure enough, the impeller is shot. There were pieces if it stuck in the screen over the water intake hole.
While I'm in there, should I replace anything else?

 

[Laddies]

Re: 1976 Merc 110 (9.8) Running Hot

Just try to get all the impeller pieces so they don't get up the water tube and plug it up there, hope it's not already done.

 

[emckelvy]

Re: 1976 Merc 110 (9.8) Running Hot

While you have it apart, blow air (or connect a supply of water) into the copper water supply tube and check to see that you have free flow thru the powerhead. If not, you have issues other than your impeller that need to be addressed.

You should get indication of flow out the telltale (unless it's blocked) and the majority of outflow will be down the center section (aka exhaust tower).

HTH.........ed

 

[AzAngler]

Re: 1976 Merc 110 (9.8) Running Hot

Good stuff! I have a 66' 110 with a lot of the same stuff, waiting on parts to rebuild. Same issue on the water flow, lots of small debris from the old impeller. Probably would have just put it back together and ran it without checking. Thanks for the posting. Also doing the fuel pump and carb, I guess I'll grab a bunch of pics for future reference if anyone has questions. On a side note I use an online manual, Seloc Online Repair Manual Hope this helps and thanks again!

 

[Squawfish]

Re: 1976 Merc 110 (9.8) Running Hot

I was able to buy and download the manual for $9.95 from a guy on ebay. I also ordered a couple impellers for under $10 each on ebay AND I got a good looking used prop for $26.
I was able to blow the impeller pieces out of the lower water pipe and the lower part of the pump assembly with a compressor. The upper tube is unrestricted so I should be good to go with a new impeller. I'm going to drive 50 miles to get one today so I can get on the water. When the others come in I'll have a couple spares.

 

[Squawfish]

Re: 1976 Merc 110 (9.8) Running Hot

Oh oh. I said air went unrestricted through the upper tube but nothing is coming out of the exhaust tower. I took out the flush screw and air comes freely out of that. I ran a wire up the exhaust tower and was able to break loose a bunch of black sooty material but there is still no air coming out of it.
What's next?

 

[hunterope]

Re: 1976 Merc 110 (9.8) Running Hot

Keep Cleaning!! lol.. The black sooty stuff is probably your melted pieces of your old impeller. There can be a lot of gunk that builds up in there so keep cleaning. You should be able to get most of it out. Once you get the water flowing again, the rest should come out, but keep a really close eye on it or your going to go back to square one. Good luck with it..

 

[jbjennings]

Re: 1976 Merc 110 (9.8) Running Hot

Hey Squawfish,
WHen you get it running perfect, I just thought I'd mention that vintageoutboards.com has some AWESOME decals that will make it look like new. That's a good year, the first with stainless driveshaft.
Just a thought,
JBJ

 

[Squawfish]

Re: 1976 Merc 110 (9.8) Running Hot

Well, I got the water vent cleaned out and air now blows freely from the water intake to the exit port but I think I got the gears mixed up when I put the lower unit back on. I haven't tried starting it yet but the prop spins freely with the shift lever in reverse but not in neutral or in forward.
I read that the shift lever should be in forward before pulling the lower unit but that was after I had already pulled it. I'm pretty sure I had it in neutral. How can I get this corrected?

 

[Harker]

Re: 1976 Merc 110 (9.8) Running Hot

You have to drop the lower unit again. Spin the prop while turning the shift rod and it should go into gear....then, shift the handle into whatever gear you are in...turn the motor up on it's head so you are looking down into the exaust housing. Where the shift shaft goes, you will see the upper part of it through a hole...twiddle the shift handle slightly to center that socket in the hole and slide your lower down and onto the exaust housing. That is the easiest way of putting a lower back on that I have found.

 

[Squawfish]

Re: 1976 Merc 110 (9.8) Running Hot

OK, I got the gears right and put it in the water. It still won't pump water and I just figured out why. There is no KEY and I seriously doubt there was in there when I disassembled it.

 

[Harker]

Re: 1976 Merc 110 (9.8) Running Hot

The impeller key? That's pretty important. I always wondered why the made them that way, seems it would have been as easy to make a fixed key as it would to mill the slot. When you get the key, put a dab of thick grease on the back to help hold it in place against the shaft.

 

[emckelvy]

Re: 1976 Merc 110 (9.8) Running Hot

These can be a real bugger to get installed and have the key properly in place. The grease does help a lot.

Also you can make a mark, higher on the driveshaft, which coincides with the center of the flat where the key will sit.

Take note of the keyway in the impeller and line up with the mark you just made on the driveshaft.

Then, while simultaneously turning the driveshaft and impeller clockwise, push the impeller into the pump housing. If you're very very lucky, the key will be in place!

The rotation allows the impeller blades to "peel" into the pump housing, and moving both impeller and driveshaft at the same time keeps the keyway and key aligned on the way down.

You can verify this by rotating the driveshaft and making sure the impeller is being positively driven by the key, before you reassemble the upper housing.

Some aftermarket impellers have a very visible keyway, while the Merc replacements tend to have the rubber center obscuring the keyway. You could even make a match mark on the impeller for keway location,if you wish.

Well, HTH and sounds like you'll be back on the water soon!........ed

 

[Squawfish]

Re: 1976 Merc 110 (9.8) Running Hot

Oddly enough, I found the old key in the bottom of the boat before driving 100 miles to get a new one. It must have fallen out and I didn't notice it. It wasn't easy but I was able to get it in place and push the impeller over it without grease. Next time I'll use grease to help hold it in place.
I now have another problem. Apparently I didn't get the copper water tube into the guide on top of the pump last time I installed the lower unit and I pushed the guide up over the bend in the copper tube. When I tried to pull the guide down off the copper tube, the whole tube came out.
I turned the powerhead upside down and tried to get the copper tube back into the right hole. I missed and now the copper tube is stuck up there and I can't get it out.
The wind was blowing about 20 mph yesterday and it's gotta be 35 mph today so I'm taking a much needed break. I presume this has happened to someone else along the line. Were you able to reinsert the copper tube without disassembling the powerhead?