Conflicting yamaha info

[holmen78]

Its funny how parts diagram and service manual has the lower crank sealing in the opposite direction, see attached picks. I put it like it is in the manual.

Engine is 90TLRA. 005626B9-0E52-45CB-A739-649F27A76D43.jpeg3D448477-51FE-45E1-A89D-96AE12C19AAF.jpeg

[holmen78]

The old lower seal was really bad eaten up but I think it was oriented like it is in the service manual.

[boscoe99]

When it comes to accuracy and consistency of their data, Yamaha is lame. Very lame.

I fail to see how a company can take such great pride in the craftsmanship of their motors while at the same time all but neglecting the data. As if the data is just an afterthought.

They put a caution note in the SM reminding the user to be careful to install the seals in the proper direction, and then don't take caution themselves with respect to the illustration itself.

It is a shame.

[99yam40]

Yamaha service manuals seen to have wrong info from time to time.
maybe look at other manuals to see what they show also.
I would not think Yamaha motors would be different from each other, but you never know what them people will do

the parts breakdown pic in My C40 manual shows the lower shaft seals all pointed in the same direction as this 90 does
and the parts breakdown on this site for my C40 shows the same( matches the SM)

but I was not able to find a step by step of the lower seal with pics in my manual like you show

[holmen78]

Well, ha ha... have to debate which way to install it I guess. If in opposite direction the seals seal from both pressure an vacuum in crankcase? If in the same direction like in the parts diagram sealing is excellent when it’s a vacuum condition in crankcase but less under pressure.

Conclusion could be that it’s better to seal really good under vacuum avoiding lean condition in lower jug.

I have found other things in the service manual that are incorrect also.

PS. I have verified with yamahapubs.com that I have the correct SM.

[boscoe99]

I looked at other 90 HP two stroke SM's and parts catalogs. They vary.

Might be like over at THT. What answer do you want? Any answer desired will be given.

[walleye1]

Put them in the way you took them out.

[99yam40]

having the correct tools to install to proper depth is always a good idea also

[walleye1]

I can tell you those tools aren't cheap either.

[99yam40]

I would think if someone could get their hands on some specs for the tools they could easily be made.


but then a pipe or sockets might work, just have to measure the depths before you take the old ones out and write that info down. as we get older some of those numbers slip right out of our minds

[walleye1]

exactly

[panasonic]

When it comes to accuracy and consistency of their data, Yamaha is lame. Very lame.

I fail to see how a company can take such great pride in the craftsmanship of their motors while at the same time all but neglecting the data. As if the data is just an afterthought.

They put a caution note in the SM reminding the user to be careful to install the seals in the proper direction, and then don't take caution themselves with respect to the illustration itself.

It is a shame.

It's not only Yamaha at that.

I was taught that parts manuals are just that..parts identification. Service Manual is for doing the actual work and that is to be considered right if there is a discrepancy between the two.

In saying that, sometimes it all gets thrown out the window because you find such a obvious mistake in either manual that you cannot trust neither...what a tangled mess.

Boeing now in big time trouble for adding a safety system to their 737 max 8 and seems they didn't tell the operators anything about. They never put it in the operation manual for all to see. How does that happen.????

[holmen78]

Put them in the way you took them out.

The outer one was in very bad condition but I’m pretty sure it was installed in the opposite direction to the inner one, like the SM says.

[holmen78]

having the correct tools to install to proper depth is always a good idea also

In this case they are different sizes and there is a stopper for each one, so I just pressed them in with a socket to the bottom. When installed there is a small space between them I filled with grease.

[99yam40]

In this case they are different sizes and there is a stopper for each one, so I just pressed them in with a socket to the bottom. When installed there is a small space between them I filled with grease.

if that is true, it sounds like a good way to do it.
I like the grease between, I do that also
Just not sure if it is the best thing to do or not