Rebuilding gearcase on 97 70hp Johnson

So my bad luck with this engine continues. After about 25 hours of operation with the boat since I bought it the engine begun to make a lot of noise, I immediately shut it down and paddled to the nearest ramp (which luckily was only 15 min of paddling away). When spinning the prop i could feel that someting was wrong with the gearcase so I dropped it and took it apart. The inside was a complete mess, the forward gear and the gear on the shaft was completely worn down on some tooths (my guess is that a tooth broke of and chewed away on the gears).

So my options now are to try to find a used gearcase or rebuilding the one I have. I have a few things which i need expert advice on before considering to rebuild:

Question 1: The hole in the lower unit where the vertical shaft is rotating have been scratched by the metal parts which was pumped up together with the oil by the shaft (the shaft itself does not seem to be damaged). Also in the area where the top bearing on the shaft is located there are rotation-marks in the cast-aluminum. Would it be alright to hone these areas, or does this mean that the gearcase itself is destroyed? Will attach photos as soon as I get back from the cabin...

Question 2: How hard is it to get the shimming correct? I don?t want to spend money on rebuilding it myself if I screw up with getting the tolerances correct...

Question 3: Do you think I?m getting on over my head with doing this myself, I (of course) have the Clymer manual, and will follow the instructions carefully if I decide to do the work myself. I am rather experienced with working on motorcycles, but have not really done any advanced things on outboards.

Thanks!

//Jimbo

Re: Rebuilding gearcase on 97 70hp Johnson

Get a rebuilt lower unit.

Re: Rebuilding gearcase on 97 70hp Johnson

Well, that is of course an alternative... Any recommendations to online sites which sell good quality rebuilt lower units?

Anohter thing, does anybody know where to find out exactly what is included in the BRP-5005458 GEARCASE & BEARING ASSY. kit?

Thanks,
Jimbo

Re: Rebuilding gearcase on 97 70hp Johnson

jimbo,the shimming is not hard,BUT you need the expensive tool,without seeing what your talking about as for scratches etc.I cant say for sure you are out of woods for damage.That said,Ive seen some horrible cases blow and as lond as you replace the bearings and gears,your probably ok.Now,your options of course,get a rebuild,but,look on ebay,lots of good inexpensive stuff there .Besure to ask questions,like why its for sale,corrosion probs.oil condition(which needs removal for shipment)you might find a salvage yard,lake used stuff is best.I know there are a few in Ga.The berings and gears plus seal kits can be erxpensive big time.When your done,with all respect,you rebuilt it.Will you be confident AND do it right.You could end up same problem or worse a few hundred bucks down the road,

Re: Rebuilding gearcase on 97 70hp Johnson

Thanks Mikesea, I have continued looking for the cause and found out that the propeller-shaft is bent (somebody must have hit something and just changed the prop). I have contacted an experienced mech who have the shimming-tools and he will put the lower unit together for me. The prolem is that I need $1100 worth of parts (plus shipping and taxes for another $500 to get the parts from US to Sweden where I live), buying the parts here is not an option since BRP wants about $4000 for them...

So I?m looking for another lower unit (which is hard to find here since there are not that many motors around). The other option is to sell the rest of the motor and buy a new 4-stroke. But I was satisfied with the wholeshot before so it feels as wasted money to get a new engine, on the other hand next time something else might break and a new engine I will know the history of.

When it comes to scratches, the mech looked at it and said it was no problem as long as they are polished a bit and that all metal-residue is carefully cleaned out.

As for bearings, it is not possible to remove and change the bearing in the bearing-housing of the shifting mechanism right?

Thanks,
Jimbo

Re: Rebuilding gearcase on 97 70hp Johnson

Look here:
http://www.boatmotors.com/motorpart...anufacturer=5&hp=70&submit=Search&disp2=&cyl=

Re: Rebuilding gearcase on 97 70hp Johnson

I don't believe the bearing in the shift housing is sold seperately, but with all the broken metal, you will want to change all bearings. As you have found, a gearcase can add up to a lot of money in a hurry. It would be great if you could find a good used one.

Re: Rebuilding gearcase on 97 70hp Johnson

Thanks guys!

Anybody who know any good dealer in NYC who sells rebuilt gearcases? I go to NYC from time to time and if I can fin a good one there I can bring it back myself.

BR Jimbo

Re: Rebuilding gearcase on 97 70hp Johnson

Lived in that area for years and know of none in the NYC area. I would see if any of the rebuilders I flagged above will ship to Sweden.

Re: Rebuilding gearcase on 97 70hp Johnson

So I seem to have found a used gearcase in my area, unfortunately is?s from an Evinrude so I will have some painting to do this winter. Or just bee confortable with another Johnnyrude...

Anyway, the gearcase is from a -93 20-inch shaft, but as far as I have understood they are identicall between a -93 Evinrude and a -97 Johnson 70hp. Any tips on what to check before buying the used gearcase? Apart from water in oil, metal-residue on the magnet and overall shape. I will of-course get a new impeller before assembly.

BR Jimbo

Re: Rebuilding gearcase on 97 70hp Johnson

Jimbo,I will assume when you go to NYC you fly into Kennedy airport.If so,there are outboard businesses in the areas.Known as Rockaway,Broad Channel ,Woodmere.All whithin a 30 min.cab ride.If you are thinking of going to NYC in near future.I will make a few tel.calls for you,I know the area well and perhaps can get you some contacts.Contact me by private message on this site.They dont allow advertising on the message boards

Re: Rebuilding gearcase on 97 70hp Johnson

Thanks Mikesea,

I will check the condition of the unit I located here, if it?s ok I can get the boat in the lake before the season is over. Otherwise I will contact you before I go to NYC, which probably will be sometime in October. Thanks again for helping me, as always boating-people are helpfull all around the world!

//Jimbo

Re: Rebuilding gearcase on 97 70hp Johnson

So I finally found a used lower unit! Its an Evinrude so I?ll paint it white this winter, but for now I will run it as is. In addition to impeller and oil change, is there anything else I should replace or adjust before assembly? Do you think any adjustment is necessary to get the shifting to work properly?

Thanks!

//Jimbo

Re: Rebuilding gearcase on 97 70hp Johnson

Shift rod length has to be set.

Re: Rebuilding gearcase on 97 70hp Johnson

Hello,

So I bought the Evinrude gearcase, got it mounted with some help from my buddy. The mounting was smooth after I found out how to connect the shift-rod...

However, since I am a bit paranoid after the problems I had with this motor I have a few questions before starting it up:

1: Spinning the prop in neutral I have a slight sound every turn or so, I figure it has something to do with the clutch-dog touching one of the gears... Is this normal, it is not a banging sound.

2: How much should the prop-shaft be able to move in-out? I have a mm or so of play (very little play up-down) is that ok?

Thanks!

/Jimbo