Nissan Marine Drain Plug Gasket Distorting

[dwoehrer]

I recently acquired a 2009 15 hp 4 stroke Nissan Marine outboard that had very little hours on it and consequently had absolutely no preventative maintenance done to it. I got a hold of some OEM Tohatsu drain plug gaskets (332-6000060M) and commenced to begin changing out the lower unit lube on it. Upon tightening the drain screws I cranked down on them as per usual and noticed that the washer distorted itself and left a questionable seal. I tried another gasket from the same pack and with the same torque got the same results. I ended up putting the old gasket back on it to preserve the fluid fill.

What is the desired tightening force required on these units? It seemed disconcerting that minimal torque would achieve a positive seal, hence my deferral to the experts.

FYI, The old gasket was bigger and its physical make-up differs from the new one in that the new one appears to be all rubber and the old had some metal backing to it. I ordered the new gaskets using the information from the Nissan Marine Parts List manual. Any help would be greatly appreciated.

 

[pvanv]

Assuming your model is NSF15C. Always specify model (not year) for servicing Tohatsu/Nissan outboards.
No. The Tohatsu/Nissan 332 600060M drain gaskets are tough fiber; they never had any metal insert. They ship in a 10-pack. The surfaces of the LU are machined dead flat. If you use the correct drain plug, it is also dead flat. They are supposed to be tightened with a large slotted screwdriver until firmly seated. They can sometimes be reused. If they were dramatically over-tightened, they could distort, but I have never seen that. Are the correct drain plugs being used?

 

[dwoehrer]

No Title

Yes, the model is NSF15C. Sorry, will remember to include that in the future. I can only guess that the drain plugs are original and of the correct size, I guess I could order 2 more and replace the existing ones. I got distortion from the top plug and not on on the bottom one. While I was waiting for someone to reply to my post I reached out to a Nissan/Tohatsu service center. The tech replied back that after looking in his manual that the proper torque value for the drain screws looks to be 10ft. lbs. I don't know what that kind of torque feels like (I have a history of over-tightening) so in addition to 2 new drain screws I'll be on the hunt for a torque screwdriver.

I've changed out the lower unit lube on a Johnson and on a Force motor. Each had a different type gasket. I've included a pic of the gaskets off the Nissan for a side by side comparison.

 

[Sea Rider]

The older ones are much wider in diameter, having more surface will hold way better between lower leg body and lower bolt body. Buying a torque wrench to screw in oil plugs is throwing money down the drain. Just adjust tight with a wider screwdriver whose tip holds well onto bolt's slot, just don't overtight them. Try to order same ones as seen on second pic.

Happy Boating

 

[pvanv]

Yes. The new gaskets do not look correct. Have never seen anything like that on a Tohatsu LU. Might have gotten the wrong washers somehow.

 

[dwoehrer]

Ok, I don't want to beat this to death, PO anybody, or over complicate the simple process of a lower gear lube change, BUT, what if I added a thin stainless steel washer, the same size as the screw head, onto the head of the lower drain screw? Screw, ss washer, fiber washer. That way if I over tighten, the screw would turn on the ss washer and the fiber washer would then flatten on the surface of the LU and not have a chance to distort.

What about using a ss button head allen wrench screw from the big box store as a replacement for the OEM drain screw? 8mm-1.25 x 9mm or 10mm?
Just throwing an idea out there...

 

[pvanv]

Just use the Factory parts. I have never had an issue in decades of servicing these. In fact, the washers last many seasons if reasonably used.

 

[dwoehrer]

No Title

It took awhile but I think that I've figured it out. I did indeed get the wrong gaskets. The lower gasket looks identical to the one I took off and is the proper one for me to use. The "M" suffix on the upper gasket as best as I can figure is for a 2014 model...?? Thanks Paul for your patience with me as I suggested using non OEM parts and some extra smithing on it to try to make it work.

 

[pvanv]

The issue is that you tried to use aftermarket parts. OEM is always preferable. The M designation is irrelevant.