Mercury 402 40hp 1970s prop unit removal

[Cjames2118]

Hi I'm trying to remove the prop shaft and I can get it out I've tryed submerged in diesel fuel for 2 weeks and and I've heated it up with blow torch and even broken at sliding hammer trying to remove it any got any other information about removing the prop.

Attachments​

• 
  
  IMG_20210913_113139_571.jpg
  1.8 MB · Views: 2
  
  
  

 

[mick087]

not experienced with rebuilding mercury 40 lower units but I changed the seals on a mercury 25 and the carrier holding the prop shaft is a right hand thread

 

[racerone]

????----That carrier is NOT THREADED !!!

 

[The Force power]

Soaking in diesel fuel is going to do nothing!
Lots of heat and a sliding hammer will!
However.... damage may occur to the LU and bearing-carrier!?!?
(may have to replace the carrier & clean/deburr the housing for the O-ring to seal)
IF you're trying to remove it only to replace the prop shaft-seal ten I suggest to leave it together and just pry the seal out and drive a new seal in with the right seize/diameter pipe

 

[merc850]

I'm afraid you are going to have to replace that LU because you have taken a piece out of the area where the exhaust goes into the prop. It will leak and cause cavitation and loss of speed.

 

[The Force power]

I'm afraid you are going to have to replace that LU because you have taken a piece out of the area where the exhaust goes into the prop. It will leak and cause cavitation and loss of speed.

very good point!!

 

[merc850]

Here's a still from a video I shot of my 850 running in forward.

 

[Cjames2118]

Hi thanks for your replys im not sure if its all the seals or just the prop berring seal attached is picks of the water surface after running the motor.
is it the hole prop shaft that comes out or is it the prop and the berring carrie as one unit including the cercle peice with the 3 legs witch link to the berring carrie, when i look right down inside the unit i can see what looks like a key way does this need to be removed.

what is the LU

thanks

 

[racerone]

The wee key just keeps the bearing housing from turning.----That key will fall out if and when you get the bearing housing moving.-----Corrosion product / nature have jammed it up !!!

 

[The Force power]

Hi thanks for your replys im not sure if its all the seals or just the prop berring seal attached is picks of the water surface after running the motor.
is it the hole prop shaft that comes out or is it the prop and the berring carrie as one unit including the cercle peice with the 3 legs witch link to the berring carrie, when i look right down inside the unit i can see what looks like a key way does this need to be removed.

what is the LU

thanks

As Merc850 already said; you are better of at this point to shop for another LU (lower-unit) because of the chunk missing
there's a lot of corrosion built-up and I have my doubts if the surface still can be re-finish/polished smooth for the O-ring to seal
Normally after the retaining-ring (aluminum or plastic) is removed the entire Bearing-carrier incl. the prop-shaft can be pulled out.
as Racerone said, the key will just slide out with it (don't loose it)

Did you pressurize the LU to see where it is leaking?

 

[merc850]

I had the same problem with my 850, the carrier would not come out and the housing was damaged trying to remove the internals; I used a cutoff wheel to cut it in half and saved the gears and propshaft to use in another case. Another way is to buy a complete dead motor with a good LU.

 

[racerone]

Sir James -----Your location ?

 

[Cjames2118]

As Merc850 already said; you are better of at this point to shop for another LU (lower-unit) because of the chunk missing
there's a lot of corrosion built-up and I have my doubts if the surface still can be re-finish/polished smooth for the O-ring to seal
Normally after the retaining-ring (aluminum or plastic) is removed the entire Bearing-carrier incl. the prop-shaft can be pulled out.
as Racerone said, the key will just slide out with it (don't loose it)

Did you pressurize the LU to see where it is leaking?

No I have not tried that please how do I do that.

Sir James -----Your location ?

Gloucester UK