Jet Pump Grease

[BigTerp]

Have been running my 1994 Johnson 50/35 since last september with zero issues. Have 20+ hours on it now and want to make sure I'm keeping things on the up and up. Never really thought about it before, but when i grease my pump with the reccommended Lubriplate grease, the grease coming out of the other end is no longer grey and almost black. I've yet to see any water droplets in the grease, and have been figuring the darker color is coming from heat/friction generated by the bearing. Am I correct? Or is the darker grease an indication that I've got bad seals and water is getting into my bearing? Other than the grease color, I have no other indications that anything is wrong.

How much of a PITA are the seals to replace if I do have a seal issue?

Thanks!!!

 

[MSRiverdog]

Pump new stuff in until you clean out most of that old stuff, the, put in new grease after every 4 to 8 hours, thet will keep you doing fine.

 

[BigTerp]

MSRiverdog » 48 minutes ago[/url]"]Pump new stuff in until you clean out most of that old stuff, the, put in new grease after every 4 to 8 hours, thet will keep you doing fine.

Thanks!! But I grease my pump after every outing, no matter if we ran the motor for an hour or 6 hours. I've probably greased the pump at least 2 dozen times since we rebuilt the motor, and every time the grease coming out is dark/black. Just wanting to make sure that's not an indication of water getting into the bearing.

 

[Ranchero50]

See what Lubriplate says about their grease. I forget the technical terms but some greases and oils absorb water and some reject it.

The black may just be what happens when water suspends in that grease.

A couple tests will show what's in the excreted grease. You can heat it and see if the water steams out before the oil smokes out. You can also smear some on a sheet of white paper and see if there is a metallic sheen to it. Smell the grease and see if it smells burnt.

 

[dhoganjr]

This is off of Outboard Jets troubleshooting section: ("If you are concerned about the condition of the bearings, watch the texture of the grease coming out of the lube hose during lubrication. The 630-AA Lubriplate grease coming out will normally be light gray. If water is present, the seals need to be replaced. If the grease starts turning dark gray, the bearing should be inspected and replaced if necessary.")

Hope it helps, and I think what MSRiverdog was referring to was pumping grease through the pump until it comes out as clean grease. I do the same thing a couple times a year just to flush out any contaminates. I hold a papertowel or rag under the hose and pump grease till it comes out clean. I also grease after every trip and have only had light gray so far.

I read through your motor build, don't remember if you replaced pump bearings then or how old they are. Might be time to give them a check if not. If nothing else for peace of mind.

 

[dhoganjr]

Forgot to mention about replacing your seal question, I have never done it, but you might post that question on SEMO Jet Boat Enthusiast page on Facebook. I know there are several dealers and others on that page that should be able to point you in the right direction.

 

[BigTerp]

Thanks for all the help.

 

[smackdaddy53]

I totally rebuilt my 45 Merc Jet pump with new bearing kit, seals etc and it was not hard at all. You need a simple hydraulic press to remove the bearing but the seals are easy. Outboard Jets is the place to get a seal kit.

 

[BigTerp]

smackdaddy53 » Yesterday, 11:47 pm[/url]"]I totally rebuilt my 45 Merc Jet pump with new bearing kit, seals etc and it was not hard at all. You need a simple hydraulic press to remove the bearing but the seals are easy. Outboard Jets is the place to get a seal kit.

Thanks. Been doing a bit of reading and it looks like some have changed out the bearings without a press even.

Other than the grease looking dark/black, what else should I look for to indicate bearing wear/failure? Nothing else, that I can tell, seems to be wrong with the motor. Runs great!!

 

[smackdaddy53]

I don't have enough experience with mine yet, I have not even cranked my motor yet. All I know is that it has new bearings, water pump, liner, stainless impeller on the way and 118# compression across all cylinders.

 

[BigTerp]

smackdaddy53 » Today, 9:58 am[/url]"]I don't have enough experience with mine yet, I have not even cranked my motor yet. All I know is that it has new bearings, water pump, liner, stainless impeller on the way and 118# compression across all cylinders.

Gotcha. What motor do you have? Anything else you did to your motor? Mine got a complete rebuild. Freshly bored out cylinders, cylinder head re-surfacing, new pistons, new seals/gaskets, new hardware, new fuel lines, etc. Also replaced the water pump and impeller. Mine only needed 2-3 shims, IIRC, to get the impeller clearance where it needed to be. So hopefully I won't be needing a new liner anytime soon.

My buddy, who is a mechanical engineer and did 99% of the rebuild of this engine, says the bearing was solid when we did the rebuild so hopefully I'm just being paranoid!!

 

[dhoganjr]

I wouldn't be overly concerned about it. I would gently pump the grease through it until all the black comes out and you have clean grease coming out of the hose. Then grease it like you have been doing after every run and see if it is still coming out black. If it does, then think about bearing and seal replacement.

 

[smackdaddy53]

smackdaddy53 » Today, 9:58 am[/url]"]I don't have enough experience with mine yet, I have not even cranked my motor yet. All I know is that it has new bearings, water pump, liner, stainless impeller on the way and 118# compression across all cylinders.

Gotcha. What motor do you have? Anything else you did to your motor? Mine got a complete rebuild. Freshly bored out cylinders, cylinder head re-surfacing, new pistons, new seals/gaskets, new hardware, new fuel lines, etc. Also replaced the water pump and impeller. Mine only needed 2-3 shims, IIRC, to get the impeller clearance where it needed to be. So hopefully I won't be needing a new liner anytime soon.

My buddy, who is a mechanical engineer and did 99% of the rebuild of this engine, says the bearing was solid when we did the rebuild so hopefully I'm just being paranoid!!

1997 Merc 45 Jet (60 powerhead)

 

[BigTerp]

dhoganjr » Today, 12:10 am[/url]"]I wouldn't be overly concerned about it. I would gently pump the grease through it until all the black comes out and you have clean grease coming out of the hose. Then grease it like you have been doing after every run and see if it is still coming out black. If it does, then think about bearing and seal replacement.

I'll give this a try. How much grease should it take to purge all the black out?

I would think that after greasing the pump after every outing, over 20 or so since October, that all of the dark grease would have been out by now?

 

[BigTerp]

smackdaddy53 » Today, 5:35 am[/url]"]
1997 Merc 45 Jet (60 powerhead)

AH, I remember your build now. Coming along nicely, and that 60/45 should push it very well!!

 

[dhoganjr]

It doesn't take a lot, maybe 6-8 pumps. You'll know right away when it comes out clean. It should be thicker and of course whiter. The grease that is in there will come out thinner, darker, and kind of watered down. Hold a papertowel or rag at the end of the hose to catch the grease as it comes out. You can then check the old stuff for metallic shavings, burnt smell, etc.