OMC gear case question

[Joey31Fjr]

I'm getting ready to put an OMC gear case back together, what should I seal it with?

[ricochet112]

OMC gel seal/Loctite Gasket Eliminator only, same product different name.

[Steve Wilde]

OMC gear case

The clearances inside the OMC gear case are quite close; I have found that any number of the Loctite anaerobic thread lockers work well. Most recently I used Permatex Threadlocker Blue Gel with good results.
My experience with Loctite 518 Gasket Eliminator (for aluminum flanges) has been less than satisfactory; it is quite viscous and started to cure so quickly that I felt that I didn't get the halves fully tightened together before curing started.
Don't forget to secure the water pump impeller first.

[ricochet112]

The Loctite number on my OMC Gel Seal is 515, it will not harden at all with oxygen present, is must have no air at all to cure.

[ram95]

The Loctite stuff has worked good for me. Here are a few part numbers which all end up being the same material:
Yamaha Gasket Maker, by Loctite: 90790-74001-00
Gel Seal Sealant, Evinrude-Johnson (OMC) Bombardier: 327361
Loctite 518 Gasket Eliminator/Gasket Maker (flange sealant): 51831
The Sierra # for the above is: 37394

All of these recommend that the surface to be sealed be completely clean and "primed" with Loctite 7649 (part #21348) or Loctite 7471 (part #22477) or Loctite Klean N Prime: OMC#384884
The Sierra # for the above primer is: 37509

One of the keys is to make sure all the sealant is removed from the surface. It is virtually invisible and you'd think it wasn't there until you spray some gasket remover or paint stripper on there to loosen it up. Laquer thinner, carb cleaners, don't always do the trick (I have found). And the old sealer, thin as it might be, still keeps the case halves from clamping tight around the internals.

Just my 3.5 cents.
Alex

[ricochet112]

Loctite 515 is an anaerobic cure, while 518 is room temperature cure. I wouldn't want any hard cured sealer inside my lower unit, I strongly recomend the Loctite 515.

http://www.loctite.sg/sea/content_data/93791_515EN.pdf

http://tds.loctite.com/tds5/docs/518-EN.pdf

[ram95]

According to the spec sheets, they are both Anaerobic cure.

[ricochet112]

That is odd, but I know for a fact that 515 will not cure with oxygen in contact with it, and if 518 cures in oxygen Steve said...I have never used 518, OMC calls for 515.

[ram95]

This is why I enjoy HR. Do you happen to have the "omc" manual which calls out the 515? These kinds of differences drive me nuts. But, I have to admit, going nuts for the past 66 years has had its fun moments.
Alex

[ricochet112]

The OMC manuals on state Gel Seal II. I did buy some small 1 use tubes from OMC that didn't say OMC on them, just Loctite Gasket Eliminator 515 and those are the ones that I found out it was Loctite 515.

You could ask Ed Runne, he told me to only use Gel Seal II also.

[ram95]

I've done okay with the stuff I mentioned above (and I assume it is all really just 518). That was an expensive experiment I might add.

I'm careful not to load the surface with too much and try to get the case together quickly and torque it. There isn't much surface width on those omc A cases and trying to keep things free of grease (like around the impeller area) is a PITA. Gotta luv it.

[aojesus]

Joe's gearcase

Here is the deal with Joe's gear case....
At speed you could hear a low pitched hum as he went by the pits. Inspection of the gear case showed badly worn teeth where the pinion shaft engages the coupler. All new parts were put in but now you can hear a high pitched scream as he passes the pits.
After taking the case apart I measured the shims on the pinion shaft at .036 (not including the thick one with the tab which measures .060) Total thickness is .096. I was told the case sounded to tight.
Is there a "baseline" measurement of shims that will get us in the ballpark? What is a good starting point?

Thanks for your time,
Russ

[ricochet112]

The last one I did had 2 shims, (excluding the thick thrust/wear washer that has the tab on it) a .005 (or .008) and a .010.

I too would like to know what the pinion gear height should be set at.

[Tomtall]

This works as well

Get it at any NAPA store.Part number on lower right of tube. Same as the OMC gel seal. It only cures AFTER the parts are put together and will not dry when left open to air,even overnight.

Anaerobic is a technical word which literally means without air. Thus meaning it cures witout the presence of air.

Good luck !!

[Steve Wilde]

Gear case noises

The shims under the pinion gear and in front of the propeller shaft gear are used to compensate for gear case tolerances; installing a new pinion or prop shaft gear should not alter the shim pack much, if at all. (Assuming the original shim selection was correct). Ideally the initial set up of the shims should be made without the pump installed, so you can 'feel' how the gears are meshing. The pinion should have some vertical movement, and should be pulled away from the prop shaft when checking back lash and 'feel'. When turning the shafts by hand it should feel smooth with only a hint of gear meshing. If properly maintained these gear cases will last almost forever, except for the impeller.