Johnson 9.9 Lower Unit Options

wrmdunker

Petty Officer 2nd Class
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Sep 17, 2010
Messages
170
Hi Guys,

My son has a 1977 Johnson 10EL77A 9.9 long shaft. This is only the second year for this boat/motor and he runs it 2 days a week. He gounded the prop on a gravel bar at low speed today and said it would not shift. I had just installed a new Solas prop I bought him last week since the hub spun on the OMC prop. First time out with the new prop. He is so depressed. Brought it over to my house to diagnose.

I drained the LU oil and found 4 gear chunks, smaller pieces and fine metal particles and a piece of the detent spring. Worked the shifter to so it will shift forward to neutral but not into reverse. In neutral (by the detent on the motor shift rod) the flywheel will not turn more than an inch. The prop turns but is stiff and still feels like pieces grinding.

He says he was at about half throttle, hit the gravel, heard the motor/LU rev up and immediately shut it down.
I have the OEM book and replacing the gears looks like it takes some special tools. The motor is good for a 1977. No fuel, carb, ignition or compression problems. So here are my questions.

I found a gear set on Ebay for $200. Is this a repalcement a DYI job? What else might have to be replaced along the drive shaft?

Should I pull it apart, get the used gears and have a shop put it back together?

Should I go with a used LU for $300 and take my chances with that? I think a ?74 to ?84 will work. Also a 15 hp LU will work.

Invest $1000 for another 9.9 long shart electric start? Need the 9.9 for lake restrictions.

Of course, looking for the best and least cost option. Any advice would be greatly appreciated.
 

sutor623

Rear Admiral
Joined
May 23, 2011
Messages
4,087
Re: Johnson 9.9 Lower Unit Options

If you haven't done a LU rebuild yet then I would buy a used LU from a reputable source. Rebuilding one is not for the novice IMO.
 

emckelvy

Commander
Joined
Jan 16, 2004
Messages
2,506
Re: Johnson 9.9 Lower Unit Options

A good used one is the way to go. It'll get you back on the water faster, and likely there will be lots of expensive parts needed for the damaged unit. You might check your local Craigslist for a donor 9.9 or 15hp, there should be plenty of scrappers kicking around!

HTH............ed
 

wrmdunker

Petty Officer 2nd Class
Joined
Sep 17, 2010
Messages
170
Re: Johnson 9.9 Lower Unit Options

I got on Leroys Ramblings and he has a great step by step for the LU, water pump, drive shaft, gears, etc. A good supplement to the OEM manual. He also has homemade versions of the tools required. I will probably take it apart for practice and if nothing else, sell the parts. Some empty housings are selling for $150. I think a good LU is probably the way to to go if I can find a long shaft. Does anyone have experience with a good boneyard for freshwater motors? Not too much listed right now on ebay.

Thanks
 

gozierdt

Petty Officer 1st Class
Joined
Jun 13, 2010
Messages
364
Re: Johnson 9.9 Lower Unit Options

You don't need to find a complete long shaft lower unit. All of these engines used the same lower unit. The long shaft versions have a 5" spacer bolted between the lower leg and the lower unit. They also have an adapter to lengthen the water tube. The only special part besides these is the drive shaft, which is 5" longer than a regular shaft unit. Take a look at your drive shaft, if it is not damaged, then you can use the spacer, water tube extention, and drive shaft from your current motor with a lower unit you buy.

If you look at the "stickey- Top Secret File" at the head of this forum section, you'll find "salvage yards" listed down towards the bottom. Also, there are always lots of parts for these motors on eBay.
 

wrmdunker

Petty Officer 2nd Class
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Sep 17, 2010
Messages
170
Re: Johnson 9.9 Lower Unit Options

Good point. An option that I had not considered.

Like I said, I will likely disassemble the current unit anyway since I have nothing to loose. Can the driveshaft be pulled out and plugged back in? How does the pinion gear attach to the shaft? From the reading thus far, I can see needing to replace shaft seals. Easier if I can find the 20 inch LU but now may be able to expand my search.

Once I get the old LU out, I hope to be able to turn the flywheel. Any thoughts by ALL to evaluate potential damage to the powerhead?
 

sutor623

Rear Admiral
Joined
May 23, 2011
Messages
4,087
Re: Johnson 9.9 Lower Unit Options

Just check compression. That'll tell ya. Also if you find a short shaft you will have to break it down to get the driveshaft out, so now you will be disassembling two L/Us. Just an FYI.
 

gozierdt

Petty Officer 1st Class
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Jun 13, 2010
Messages
364
Re: Johnson 9.9 Lower Unit Options

sutor623, you do not have to completely disassemble the gearcase to get the driveshaft out, just take off the water pump and pull the shaft out with the pump.

But you are right in that checking compression should tell you pretty much if the powerhead is OK. I'd also take the plugs out and see that the flywheel spins easily to check for crankshaft bearing damage- although that's not a definitive check.
 

Chinewalker

Fleet Admiral
Joined
Aug 19, 2001
Messages
8,902
Re: Johnson 9.9 Lower Unit Options

Since you have to pull the pump apart to replace impeller - you will be installing a new one in a used, .ie unknown service history, unit, right? - it's no problem at all to swap shafts. Yes, shafts. Shift rod swaps, too. It is threaded in, as you'll see when you disassemble the junked one.
 

wrmdunker

Petty Officer 2nd Class
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Sep 17, 2010
Messages
170
Re: Johnson 9.9 Lower Unit Options

When I check the PN for my unit is says 1977 to 1984 for 10's and 15's. Some ebay listings say their LUs will fit 1974 to 2008........I find that a little hard to believe.

Plan to get into the motor next week.

Please check back in on this thread. I appreciate the input. Going to make a LU pressure tester so I can perhaps test all the seals on the one I get. Maybe I'll find one at a shop nearby and have him test it. That might help with the uncertainly of a used unit.
 

wrmdunker

Petty Officer 2nd Class
Joined
Sep 17, 2010
Messages
170
Re: Johnson 9.9 Lower Unit Options

I got it opened up. Not difficult. LU dropped right out. Drive shaft did not hang up in the crank. Only a little persuasion to get the bearing housing out. Did not need a "puller".

Looks like the clutch dog and cradle blew up.





Only a couple pieces of the detent spring came out. Perhaps the rest is still in the shaft.........didn't look for it at the time.

Shaft seems pretty bad as well but perhaps could be repaired but saw them on Ebay for $40.




Also the pinion gear had one chip in it. Using Ebay parts for prop shaft, clutch dog, dog cradle, yoke assembly and pinion gear I'd have about $250 in parts. Getting a bit pricey. Could save by searching more.

The power head turns good with the plugs out. Compression is 90 on both cylinders. No bad karma noises so seems like the head is OK.


OPTION 2
I found a used LU. I understand Ebay is risky but he only sells outboard parts and has a 100 % rating. It is a 1985 short shaft. Got all the PN info off b***s.net and MarineEngine. My long drive shaft and shift shaft are the same. My 5 inch extension is the same (again comparing my '77 to the new '85). The water pumps are the same. My prop is a 9.25x8 and is also the same.

So going to try to convert the SS fit my LS and bolt it up to my powerhead.

Questions: Anything I might be overlooking? Going to have the new LU tested or perhaps just replace seals and not worry about it. Is there anything used to seal the LU housing/extension etc? Is it just a metal/metal fit? Drive shaft may need a little cleaning/polishing around the pump seals. What do you use here?

If I were to go with used parts and rebuild mine (unlikely) what is the process? Add spring amd balls to shaft, Slide on clutch dog, place cradle and yoke. Insert into housing with fwd gear, insert pivot pin. Screw in shift shaft (5 turns is what I took out). Put in rev gear and bearing housing. Etc. etc. Sound right? Any alignment or tolerance issues?

All comments appreciated
 

wrmdunker

Petty Officer 2nd Class
Joined
Sep 17, 2010
Messages
170
Re: Johnson 9.9 Lower Unit Options

BTW....... I emailed a salvage yard from the "sticky" file and they wanted almost $1000 for a LU in a long shaft but they guaranteed it. I'd buy a late 90's motor for that money.
 

raczekp1

Lieutenant
Joined
Mar 30, 2010
Messages
1,327
Re: Johnson 9.9 Lower Unit Options

to convert from Short shaft to long shaft is a 0.5 hour of work if you have long shaft, long shaft gear selector and new impeler
 

wrmdunker

Petty Officer 2nd Class
Joined
Sep 17, 2010
Messages
170
Re: Johnson 9.9 Lower Unit Options

Well I have my Ebay 1985 15 hp short shaft LU and tested it today. Shifts goods as far as I can tell. Made this to pressure test it.

Used parts I had laying around and a few fittings from Napa and Ace Hrdw. Used 1/4 inch. My advice is to use a tire pump. it only took 3 strokes to get to 13#. Using a compressor is way too risky. I also had the gage in my parts drawers. Would have liked 0-30 but the important thing is ....does the needle move.

Used the fitting off my gear lube fill bottle. Did a lot of reading to find out that the OMC units have a 3/8 NC bolt thread (i.e. not pipe). Used teflon tape on the threads after the O ring idea did not work. The fill end is a truck tire valve with male threads from NAPA and plumbed it to a barb fitting. I added hose clamps but for 15# probably did not even need.

Made it long and kept the gage near the fill valve in case I ever want to put a whole lower unit in a tank of water. Have $10 in it not counting hose and gage I already had.

All my seals held for an hour!!! Prop shaft, drive shaft, water pump and shift shaft. Also tested at 4# for an hour.

Pretty sweet hey....................! Now need to swap my long shafts, pump kit and test again.




 

gozierdt

Petty Officer 1st Class
Joined
Jun 13, 2010
Messages
364
Re: Johnson 9.9 Lower Unit Options

Nice progress. It's really nice when you post back about how your project is going.
So many people get a few answers and are never heard from again.
 

wrmdunker

Petty Officer 2nd Class
Joined
Sep 17, 2010
Messages
170
Re: Johnson 9.9 Lower Unit Options

Thanks Gene. I have learned alot with the posts here and like to see the complete project (especially restorations). I also like it when folks share their failures. No shame in them as we are all trying to improve.
 
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