2006 15hp Merc lower unit leak

[Guest]

This is from a previous thread that i had water come out the lu when i was changing oil. was just waiting on the pump and seal kit to come
So i purchaed a pump from D.i.cks sporting goods and used the lu kit for filling in LU oil found in all auto parts stores. Since the tip is plastic the thread gets destroyed quick so i put some thread tape over it (used for pipes to stock leaks) and it held pressure nicely (checked with soapy water). Pumped to 20-30 psi and used soapy water to check all outer seals and they looked all tightly sealed. I did hear hear a noise that from the lower unit like the leak is coming from the inside. (i still did not remove the LU). I will now have to remove the LU and change all the seals and try again.

 

[oldman570]

Re: 2006 15hp Merc lower unit leak

All that is needed to pressure test a LU is less than 10 Lbs. as above that the O ring seals will leak by and give a faults test. It will blow by the shift shaft seal and the water pump/drive shaft upper seal also. This is probably why your hearing air leak inside the LU case. JMO
Oldman570

 

[Guest]

Re: 2006 15hp Merc lower unit leak

So I need to remove the Lu and test again? How do I get accurate results

 

[oldman570]

Re: 2006 15hp Merc lower unit leak

The best test is to remove the LU, drain the oil, using a spray bottle with soapy water and 7 Lbs. of air pressure. Pressurize the LU and spray the soapy water on all areas of it that the seals are near, do not forget to spray the drain and fill screw area. If it passes this test then remove the tools and replace the drain/fill screw tightly and place the LU in a barrel full of water so that the LU is near 6In. below the water level overnight. Remove the LU in the morning and check for any water in the LU. This way you pressure test the complete LU for any leaks from both inside and outside pressure that can cause any leaks. JMO
Oldman570

 

[Guest]

Re: 2006 15hp Merc lower unit leak

The best test is to remove the LU, drain the oil, using a spray bottle with soapy water and 7 Lbs. of air pressure. Pressurize the LU and spray the soapy water on all areas of it that the seals are near, do not forget to spray the drain and fill screw area. If it passes this test then remove the tools and replace the drain/fill screw tightly and place the LU in a barrel full of water so that the LU is near 6In. below the water level overnight. Remove the LU in the morning and check for any water in the LU. This way you pressure test the complete LU for any leaks from both inside and outside pressure that can cause any leaks. JMO
Oldman570

OK this was weird. All the bolts were loose on the water pump! tightened them and now it looks like its holding pressure. Soapy water check shows no bubbles (white stuff in pic is soapy water). Going to perform the submerge over night test tonight wish me luck. I do not understand why the bolts were loose.

 

[Guest]

Re: 2006 15hp Merc lower unit leak

Ok overnight test complete no water in LU. Tonight i will open up the water pump to take a look at the impeller. I have a seal kit i ordered, shoul i just change the seals anyway?

 

[carholme]

Re: 2006 15hp Merc lower unit leak

If the pressure test indicates no leaks, why risk more leaks by changing the seals? Did you gently rotate the prop during the test to ensure it didn't leak throughout a complete revolution of the sealing areas?
If you did and it was good, I would be saving the seals for a time when you may need them.

Gerry

 

[Guest]

Re: 2006 15hp Merc lower unit leak

If the pressure test indicates no leaks, why risk more leaks by changing the seals? Did you gently rotate the prop during the test to ensure it didn't leak throughout a complete revolution of the sealing areas?
If you did and it was good, I would be saving the seals for a time when you may need them.

Gerry

Good point Gerry, I plan on changing the impeller because I have not changed it since ob purchase 2 months ago. I figured if I am opening it up might as well change the seals. I did twist the shaft and there was no leak

 

[carholme]

Re: 2006 15hp Merc lower unit leak

If it was mine and turning the shaft produced no leaks, I would definitely leave it alone.

Gerry

 

[oldman570]

Re: 2006 15hp Merc lower unit leak

As Gerry has stated, If both test were good after tightening the pump housing bolts then save all the parts for future need. The bolts being lose happens at times when one gets distracted, or mind starts wondering. Happens often when the phone rings or the wife wants something done, or its time to eat. Replacement of the impeller will give you piece of mind, and should not have to be looked into for a few years.
JMO
Oldman570

 

[Guest]

Re: 2006 15hp Merc lower unit leak

As Gerry has stated, If both test were good after tightening the pump housing bolts then save all the parts for future need. The bolts being lose happens at times when one gets distracted, or mind starts wondering. Happens often when the phone rings or the wife wants something done, or its time to eat. Replacement of the impeller will give you piece of mind, and should not have to be looked into for a few years.
JMO
Oldman570

The bolts do get loose after about 5-10 minutes of tightening them. Is there something i can put over the thread so that doesnt happen? i noticed on my old LU bolts the thread had a blue lining that looks like it keeps them tight

 

[carholme]

Re: 2006 15hp Merc lower unit leak

From Section 6-30 of the service manual:

7. Apply Loctite 271 to threads of bolts. Secure cover with bolts and torque to 50 lb. in.

Loctite is a thread locking fluid and if you haven't used it, is probably the reason you keep losing toque on the bolts.

Gerry

 

[Guest]

Re: 2006 15hp Merc lower unit leak

From Section 6-30 of the service manual:

7. Apply Loctite 271 to threads of bolts. Secure cover with bolts and torque to 50 lb. in.

Loctite is a thread locking fluid and if you haven't used it, is probably the reason you keep losing toque on the bolts.

Gerry

its funny i looked at the manual and then came on here to say i found what i need lol then seen your post. Thank You to everyone helping me. I am new to working on my LU but learning fast

 

[Guest]

Re: 2006 15hp Merc lower unit leak

looks like i did everything possible to keep the lower unit sealed but it keeps leaking air somewhere. If there is no seal on the intake pipe will this cause a leak?? the seal fell into the cavity hole and i cant get the screw off the cavity screw. (work in progress with pb blaster to get it off and pull original seal) will this cavity seal cause a leak??

out)

 

[carholme]

Re: 2006 15hp Merc lower unit leak

Have you put the LU under water while pressurized to see where the leak is?

As well, did you replace the seals under the Drain/Fill and Vent screws?

Gerry

 

[Guest]

Re: 2006 15hp Merc lower unit leak

Have you put the LU under water while pressurized to see where the leak is?

As well, did you replace the seals under the Drain/Fill and Vent screws?

Gerry

When push the pump in the air goes in an out of the lu like its not sealed at all i dont get what i am doing wrong.

 

[Guest]

Re: 2006 15hp Merc lower unit leak

after installing new seals it would not hold pressure. I put in the old base gasket, old bottom housing and it is now holding pressure. Can this quicksilver kit be damaged or these gaskets be thinner then original? Also i was mostly not using loctite and this time i drenched everything in it lol. What do you guys think caused it not to hold pressure with the new seal kit?

 

[oldman570]

Re: 2006 15hp Merc lower unit leak

The seal in the new housing is probably not sealing on the drive shaft because of the wear that the old seal has done in that area or the drive shaft is dirty or corroded where the new seal sets on the shaft. It could also be that when you installed the new seal damage to it was done when it was slid over the splines of the drive shaft if LU oil or other lube was not put on the seal before installed. Depending on the manufacture of the kit some after market kits are not as good as manufactures kits are. If the LU is sealed using the old housing and base plate, then it should be fine and the water leak gone. You can look at the new seal in the housing and see if it has the round spring around the inner part of the seal. It might not have it where the old one probably dose. This can be a newer type of seal that will expand when the rubber is exposed to oil/water for a period of time, if it dose not have the spring around the seal. JMO
Oldman570

 

[Guest]

Re: 2006 15hp Merc lower unit leak

still had the rubber spring this kit was by quicksilver. It was weird but leak is gone. I do not remember: when in fwd gear and i spin the prop backwards it clicks. That's normal right?

 

[carholme]

Re: 2006 15hp Merc lower unit leak

From 6-36, para 13 of the service manual:

13. Check shift operation as follows:
a. Place shift lever in FORWARD. Gear housing should ratchet when propeller shaft
is turned clockwise and resistance should be felt when propeller is turned counterclockwise.
b. Place shift lever in NEUTRAL. Resistance should NOT be felt when propeller shaft
is rotated in either direction.
c. Place shift lever in REVERSE. Resistance should be felt when propeller shaft is rotated
in either direction.

Gerry