how to check u-joints

slredstorm62

Seaman
Joined
Jul 28, 2009
Messages
66
my 87 mercruiser has a knock but i think its in the outdrive. possible u-joint? can i check u joints while in the water or do i have to pull the outdrive off? and would loose u-joints make a constant knocking noise or is the driveshaft only move when boat is put in gear
 

Haut Medoc

Supreme Mariner
Joined
Jun 29, 2004
Messages
10,645
Re: how to check u-joints

my 87 mercruiser has a knock but i think its in the outdrive. possible u-joint? can i check u joints while in the water or do i have to pull the outdrive off? and would loose u-joints make a constant knocking noise or is the driveshaft only move when boat is put in gear
They can make noise either way....
The only way to truly check them is to pull the drive & disassemble them....
Even then, defective/worn ones are not always obvious.....
They are like $25 apiece right here at iboats....
I would just replace them.....;)
 

slredstorm62

Seaman
Joined
Jul 28, 2009
Messages
66
Re: how to check u-joints

can someone tell me what parts i need to order. i will probably replace u joints gimbal bearing and the seal on the outside of gimbal bearing where the gear oil is leaking into my bilge. it is a 1987 mercruiser alpha one 3.0l with an alpha one with powertrim transom number s/n is 0B511930 engine number s/n is B483822 and the drive unit s/n is 0B467167
 

Evinrude Boater

Lieutenant Junior Grade
Joined
Jul 6, 2004
Messages
1,144
Re: how to check u-joints

I'm not sure you've really determined if the noise is going to be eliminated by replacing u-joints etc. The driveshaft is always spinning when the engine is running. Does the sound change when you shift gears or when you raise and lower the outdrive when running? When was the last time you inspected the u-joints and greased them? Are the bellows leaking?
 

slredstorm62

Seaman
Joined
Jul 28, 2009
Messages
66
Re: how to check u-joints

the noise stays the came when shifted into or out of gear and it will go consitant with engine speed but will not get louder. i cant hear it over the engine while running. only at idle. how to i see if my bellows are leaking?
 

hoot

Chief Petty Officer
Joined
Sep 8, 2002
Messages
434
Re: how to check u-joints

start by raising the outdrive and looking at the bottom of the drive bellows. turn the drive to the left and look at the right side of the bellows and vice versa. you need to stretch it out and look for small cracks. and pull the drive. if water is in there, a gooey mess will run out on your shoes!!
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,610
Re: how to check u-joints

Looking at the bellows externally is a waste of time. Pull the drive. You should be pulling the drive annually anyway.
 

tacconelli6

Seaman Apprentice
Joined
Aug 2, 2008
Messages
32
Re: how to check u-joints

Bruce is on. Pull the drive, if water is in the bellows then you know they are shot. It is just six bolts. If you pull the drive you may need to get a gasket set to replace the outdrive gaskets and O-rings.
 

Alpheus

Lieutenant Commander
Joined
Aug 3, 2009
Messages
1,759
Re: how to check u-joints

If you pull the drive you may need to get a gasket set to replace the outdrive gaskets and O-rings.

You ALWAYS replace the gasket and O-rings every time the drive is pulled...
 
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