L/U seals

[pstephens46]

I generally buy from Boats.net (it may be how I found this forum)

What I particularly like is that they have Mercury parts as well -

so for the F90 and F225 I can easily "comparison shop".

When I did my LU seals last month, I went with "Quicksilver" label -

IIRC they were about 1/2 the price of "Yamaha"

Regarding L/U seals. How much of a pain in the ass is this repair?

It is commonly considered that lower units fail in time. I hear many people talk of full replacement, no big deal, just part of owning a boat.

IF, someone replaced seals at a regular interval, couldn't a lower unit last the life of the motor?

Also, what is the purpose of those little circular springs? They can't provide much compression. Are they there to aid in installation?

[fairdeal]

Also, what is the purpose of those little circular springs? They can't provide much compression. Are they there to aid in installation?

the "garter spring"



everything you want to know about radial shaft seals - "and more":

Oil Seals - Radial Shaft Seals at All Seals

[rodbolt17]

they are called garter springs,
they provide just enough tension to keep the seal following the shaft.
without them the seal leaks.
for some reason the springs on the v4 and v6 motors tend to fail.

[boscoe99]

Regarding L/U seals. How much of a pain in the ass is this repair?

It is commonly considered that lower units fail in time. I hear many people talk of full replacement, no big deal, just part of owning a boat.

IF, someone replaced seals at a regular interval, couldn't a lower unit last the life of the motor?

Also, what is the purpose of those little circular springs? They can't provide much compression. Are they there to aid in installation?

With regular maintenance, and without operational abuse of the lower unit, I think a lower unit could last the life of the motor. Certainly the better the maintenance, the better the likelihood of any part lasting longer than it would otherwise last. But too much maintenance sometimes is also not good for a device.

Now does a lower unit have the same expectation of life as does a four stroke power plant for instance? I don't think so. Think of all of the power of the motor being concentrated within and transmitted through the gear case. Think of 99% of all of the exhaust heat flowing through and out of the lower unit. Think of the lower unit environment vis a vis the power plant.

[fairdeal]

Regarding L/U seals. How much of a pain in the ass is this repair?

As a "backyardigan" I found the driveshaft seals to be a piece o' cake -

the carrier came out easily.





The propshaft - not so much.

Rodbolt would probably chase me out of the shop with hammer in hand if he saw it attempted -


but after two days of futile battling to extract the bearing carrier,

I pulled and replaced the lower seals "in situ"

[99yam40]

something that is expensive enough has to fail to end the life of a outboard.
Owner gets to decide what that part and expense is.

very few end life because they cannot be fixed, just costs too much to do it for the owner

[rodbolt17]

I cannot tell you how many shafts and carriers I have replaced by someone destroying them using that screw method or by not being able to reset the seals to the pre measured depth.
it is better to remove the carrier do it right clean the corrosion from the carrier oring surfaces replace the seals and reassemble.
the drive shaft seals also set to a certain depth.

[pstephens46]

Fairdeal: maybe I am not looking at the right parts, BUT it seems the Yamaha seals for your lower unit are $7.25 apiece Boats.net? Is that expensive?

[rodbolt17]

7 bucks or so is about correct.
I do a lot of them.
I do like the shim stock protecting the shaft.
however to ensure it was a fresh shim I would have to test several cans.

[fairdeal]

it seems the Yamaha seals for your lower unit are $7.25 apiece Boats.net?
Is that expensive?

The wrong question. Ask "is Fairdeal pathologically frugal".
Answer: Yes.

[pstephens46]

How about contemplating $350 for a set of stainless Brake calipers?

It sucks....

Why? No way to rinse the gd salt off from behind the piston seals. Corrodes no matter what. Then piston seizes. 3rd time in 5 years. Spent way more on trailer than the rest of boat/motor combined. Need a 40ft boat, then will not need the trailer......

[fairdeal]

it is better to remove the carrier do it right clean the corrosion from the carrier oring surfaces replace the seals and reassemble.
the drive shaft seals also set to a certain depth.

The detail in the SM on the "depth" of the seals puzzled me.

measured before I pulled the originals
measured when I put the new ones in.
Both seemed "right" per the SM

But it also didn't seem like there was much opportunity to "go wrong" ?

[pstephens46]

The wrong question. Ask "is Fairdeal pathologically frugal".
Answer: Yes.

Is there a compatibility chart somewhere that shows these Quicksilver parts as matches for the Yamaha version? Part numbers are obviously different.

[fairdeal]

Is there a compatibility chart somewhere that shows these Quicksilver parts as matches for the Yamaha version? Part numbers are obviously different.

While there may well be parts on many motors that are shared by both Merc & Yamaha,

the only "cross-reference" I am aware of comes from the fact that an early 2000s Mercury "EFI 4-stroke" IS a Yamaha - or largely so.

The F225 seems to have been supplied in its entirety - don't know how the black paint went on.

The 90 hp was a Yamaha powerhead, but everything below apparently "real" Mercury.

It is interesting to see how the same part ends of being "valued" differently by the two companies.


The selling prices of Factory/Dealer supplied "spares" results from some decision-making process in which the acquisition cost plays only a part.

And I imagine that overall, "spares" support can be, or perhaps always is,
a "cost of doing business" rather than a "profit center"

[99yam40]

The detail in the SM on the "depth" of the seals puzzled me.

measured before I pulled the originals
measured when I put the new ones in.
Both seemed "right" per the SM

But it also didn't seem like there was much opportunity to "go wrong" ?

I thought SM did not give specs on depth.
Yamaha has special tools to set proper depth.
I could be way off/wrong though