1976 115 Johnson Lower unit

I have a 76 Johnson 115 Longshaft, hasn't been used for a couple of years and I am going over it getting it ready for use. There were small bits of metal in gear oil, so I took it apart. I found found pitting in many of the teeth of the driveshaft pinion gear and several of the teeth of forward gear are showing what looks like some surface fatigue, looks like it is on the way out. Reverse gear looks ok. <br />The bearing surfaces seem OK. What I'm wondering is how much to replace and if OEM or alternative manufacturers are better value for money. Should the gears and associated bearings be replaced as a set, or just the ones showing wear?<br /><br />Another thing that concerned me is the bearing carrier (on prop shaft) and the oil pump were eary to remove, needed hardly any mechanical assistance. This didn't seem right according to the manual which said they'd be very tight and hard to extract. I don't know the history of the motor, but could this looseness be caused by previous work and is it a problem?

Re: 1976 115 Johnson Lower unit

The problem is, when those gear's start to break up, those metal chip's are glass hard, and get run through all of the moving surface's. It is generally a good idea to replace all bearing's, and gear's in this case, as you don't want another failure on the new parts. I don't know what to say about that bearing carrier, as I have no experience with salt water engine's. I'm sure someone else will comment on that.

Re: 1976 115 Johnson Lower unit

It will probably be cheaper to buy a serviceable used lower unit than to rebuild yours.

Re: 1976 115 Johnson Lower unit

I repaired/resealed my LU on my '76 V4 last year. The carrier was hard to remove, but that was mainly due to deposits within the case that kept it from sliding out. I would think if your's came out easy, it just means you have a clean motor. The screws keep it in place anyway. So, it was not designed as a press fit. I suppose if the bore that the carrier fits into was excessivly oversize, it would be a problem. But I can't imagine a condition that what would enlarge the bore other than a crack, which you'd know about if you had one. I'd say don't worry about the carrier. Just make sure you seal it up good with new orings and seals.<br /><br />I also had to remove my pump for repair. I seem to recall that it slipped right off the end of the prop shaft. It's not like there is any press fit or anything like that between the pump and the prop shaft.<br /><br />I'm not sure how bad your gears are without seeing them. My reverse gear had one little ding on it. I just let it ride. Seems to be doing fine. But, if in doubt, replace them. As for the bearings, all seemed to be in good shape. So, I just cleaned, lubed and reused them.<br /> <br />I put quite a few hours on the motor this seson without problems. I hope this helps...

Re: 1976 115 Johnson Lower unit

Thanks for all the advice, its very helpful. If I can find a secondhand unit in good condition I suppose it would be a quick way out. Replacing everything would be ideal, but apart from the parts, there seem to be quite a few special tools needed and I haven't priced it all yet. Any suggestions about kits available?<br /><br />Wouldn't the screen on the oil pump stop the metal fragments being circulated and damaging other parts? There was quite a bit of grit on the screen side of the oil pump, so I suppose it was doing its job. Is it generally acknowledged that repaired lower units fail after this sort of repair?<br />As an aside,the oil pump only had one of its screws still intact. One was finger tight and two were out.<br />I don't know if I can post attachments to this list, but if it is possible I can send in photos of the damaged gears.

Re: 1976 115 Johnson Lower unit

A properly repaired gearcase is not prone to failure. The screw's that were missing in the oil pump, where did they go? The screen on the pump will protect the pump itself, but those metal fragment's will go through the moving part's. A damaged bearing can sometime's be very hard to see. It take's a good cleaning, plus magnification, and a rolling test to find this. As I said, the bad part about a bearing failure, It will tend to take everything with it. A complete gearcase rebuild can get very exspensive, but a used replacement can be a coin toss, unless you know it's history. I have seen gearcase's advertized as excellent condition with a chunk of the skeg missing, It take's a pretty good blow to do damage like that. I have also seen gearcase's run into a log. The inside is junk, and the outside won't even have the paint scratched.

Re: 1976 115 Johnson Lower unit

The two loose screws were in the void between the front of the gearcase and the oil pump. Nowhere elce for them to go I suppose and too big to go through the screen. Would there be much force on those screws, ie would them being off be expected to damage oil pump, or would there not be much force in that diretion anyway and the pump function ok with just one screw holding it together?

Re: 1976 115 Johnson Lower unit

Those screw hold on the front cover of the pump, which hold the pump impellor's in place. This cover is also recessed so there is'nt much force on. I was concerned that the screw's may have went through the gear's.

Re: 1976 115 Johnson Lower unit

I your motor had ever seen saltwater, the bearing carrier shouls have come out hard. I have had to heat many LU's with a torch to get the carrier out on V4 and V6's. If the rest of your motor is OK, I would look for a used or rebuilt LU. I would expect ~ $900 to 1200 US for a rebuilt, a used one a lot less, but more risk. Good luck.

Re: 1976 115 Johnson Lower unit

Its been a while, but I haven't decided whether to go the second hand or repair route. Secondhand units are around and that option is there. The only other viable option I can see is to get new non genuine pinion & forward gears.Their price to me is a lot cheaper than what I've been quoted for genuine parts which seem over the top price-wise. The fitting of a new pinion gear bothers me as the manual talks about shimming the gear using a special tool. Is this the only way to set up new gears or is there a way to set up new gears without special tools?

Re: 1976 115 Johnson Lower unit

I have a 71/72 115 johnson with brand new water pump fitted for sale. the gear box was checked at the time the pump was installed, the nechanic told me it was fine. But the motor was running when i took it to him , now it doesnt go. It is has no vacumme at the top carb and negative vacumme at bottom carb (blowing backwards) I dont know if this motor is any good to anyone. I just spent $700 on it (have receipt for work done). If any body is interested let me know or if anyone has a idea whats wrong with it please let me know.

Re: 1976 115 Johnson Lower unit

I am really at a loss as to what he may have done to cause that!

Re: 1976 115 Johnson Lower unit

What does it say on the service ticket?

Re: 1976 115 Johnson Lower unit

thanks for the reply's. the service ticket only mentions the water pump and gear box.i was told that it might be the reed valves so i pulled them out and they are all closed. I dont have a manual so I dont know if they are as strong as they should be but they look fine. I have also uncovred the exhaust ports and the pistons are not scored and the exhaust is not blocked.thanks