Lower Unit Question

[gregmsr]

125HP, There is a small hole (approx 1/8 diameter) in the casting in the front leading edge just about half way between the torpedo and cavation plate.
The very front edge and I can shove a piece of wire in about 2 inches +/-.Its not a fill,vent, screw hole....just a hole about the diameter of a stick match.
What is this for?

 

[glenn property of pam]

sounds like a foot drain. Its there to allow the foot to drain when the boat is out of the water.

 

[MickLovin]

Ditto on glenn

 

[Frank Acampora]

NOPE! That hole is an impact tube for a speedometer. Your lower unit may or may not have the rest of the equipment: A rubber plug with a nipple for the top of the lower unit casting and a short length of black hose connected to the nipple that is meant to exit the midleg under the kingpin.

The impact hole enters the front cavity of the lower unit casting which is triangular in cross section and about 2 inches deep. water fills the cavity right to the top where the rubber plug seals it. The black tubing is connected to the speedometer tube with a barbed fitting.

Using this method, the speedometer is more accurate, it won't change reading as the boat turns, and will usually not pick up weeds to clog the impact hole. If you hit a small branch or other floating object, the impact tube will not kick up like the plastic ones and lose pressure, thus the speedometer will continue to read.

 

[gregmsr]

Now for the scary question.....why would I have a small amount of gear oil dripping from this hole? (it IS gear oil)

 

[Frank Acampora]

Now for the scary answer: If gear oil is dripping from this hole it can come from several areas. ASSUMING that you do not have the rubber plug at the top of the lower unit casting---1 There is an O-ring seal at the front of the water pump that seals the water pump to the casting. 2. The shift rod seal can be leaking. 3. There is another O-ring seal at the center of the pump body where it plugs into the casting. 4. Below the water pump there is a seal (actually 2 seals inside the part that plugs into the casting. It can be any of these four areas.

ALL these seals are on the lower half of the water pump. Pull the pump and check all the seals. On mine, it was the two drive shaft seals. You can replace all the seals (except the bellows shift rod seal if your engine is equipped with that.--NLA) for relatively little money and time.

If your lower unit does have the rubber plug, I simply can not imagine any oil, whether it is lower unit or spent lubricating oil, making its way through the barbed fitting in amounts great enough to be noticed.

 

[gregmsr]

Update....
Finally got time off long enough to get the boat home and drop the gear oil and.......yes, about two teaspoons of water came out first, then a small amount of milky oil, then nice blue/green gear oil followed. So I believe I caught things before it got bad.

Questions...
I have not dropped the lower yet but the rubber plug, would that be on the outside of the casting?
I have a 1989 125hp, i assume the lower unit matches the same year, anyone know off top your head the seal kit part number?

I am in the process of gathering parts to make a pressure tester...homemade. Any tips appreciated...never messed with the lower until now.

Thanks, G

 

[gregmsr]

No Title

Update #1...See the shift shaft seal broken/torn. I want to order a new seal kit but don't see one with this type seal included?

 

[gregmsr]

So, after reading up on the shift rod seal, the "boot" is actually a "bellows" that IS the shift rod seal (and I can't find one anywhere).

Anyone know of availability of a bellows, or another gear housing plate that would work on my lower?

Or do I have to find another lower unit....

 

[Frank Acampora]

That bellows is --as far as I know---NLA. No other water pump lower plates will fit that lower unit. However, it would seem a shame to lose a lower unit because of a dollar part. (that is, it is worth a dollar--not what you will actually pay)

Try franzmarine@aol.com. He was a Chrysler dealer and MAY have some newer parts.

I have two lowers that use the bellows and personally, At first I thought "What a GREAT Idea." Then, after learning how they work (shift rod MUST be four turns out from bottomed) and that they are NLA, I thought, "What a crappy design."

If the seal ever breaks on either of mine, I am going to experiment to see if I can't modify the part to accept the press in shift rod seal. That is, make a press-in collar that will accept the press-in seal

 

[gregmsr]

After several hours on-line looking, I have came to the conclusion this $1 part cannot be found on planet earth.
Actually, I just spoke (e-mail) with franz and he has modified several of these to accept the old seal in place of the bellows so i'm going that route.

Unbelievable....and I agree, a crappy design. To lose a lower unit because of a small piece of rubber, unbelievable....
I will pressure test after getting the part and determine if other seals are needed. I suppose a "normal"seal kit will work on the rest of the unit?

I'll post updates..Thanks all...

 

[gregmsr]

Ok, got my re-designed gear case cover back.
I was told that I cannot re-use my existing shift rod and was supplied with another LONGER, one piece threaded on one end rod.
Mine is two piece, smaller section screws down into larger section.

If I must change rods, how does the lower, larger section come out? Screws out? Then screw in the LONGER new rod?

 

[gregmsr]

Disregard the last post.
It screws out, just tight.
Now for pressure test.....