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Pulling the Plunger on a Grease Gun. #4675963
02/23/18 09:41 PM
02/23/18 09:41 PM
Joined: May 2005
Posts: 2,264
Toronto, Canada
George7941 Offline OP
George7941  Offline OP
Joined: May 2005
Posts: 2,264
Toronto, Canada
I like to do it but I wonder if it introduces air pockets into the grease. When the plunger is pulled, air fills up the gap between the grease and the plunger. When the plunger is released, this air has nowhere to go since the plunger acts as a one-way valve. Does this air leak out between the plunger rod and the plunger piston and thus escape?


2006 GMC Sierra 4.3l, NV3500,G80 , Mobil 1 5W30, Dexcool.
1987 BMW R80 - sold
2015 Honda CBR300R

Staying out of the right lane a lot.
Re: Pulling the Plunger on a Grease Gun. [Re: George7941] #4675989
02/23/18 10:15 PM
02/23/18 10:15 PM
Joined: Jun 2014
Posts: 2,039
IL
Vern_in_IL Offline
Vern_in_IL  Offline
Joined: Jun 2014
Posts: 2,039
IL
You only pull the plunger when the cartridge is empty. Pull plunger, lock the shaft and unscrew. Pop out Pop in and shove plunger in, open purge valve, let air out.

Last edited by Vern_in_IL; 02/23/18 10:17 PM.
Re: Pulling the Plunger on a Grease Gun. [Re: Vern_in_IL] #4676031
02/23/18 11:27 PM
02/23/18 11:27 PM
Joined: Dec 2016
Posts: 7,481
Waco, TX
Linctex Offline
Linctex  Offline
Joined: Dec 2016
Posts: 7,481
Waco, TX
Originally Posted By: Vern_in_IL
You only pull the plunger when the cartridge is empty. Pull plunger, lock the shaft and unscrew. Pop out Pop in and shove plunger in, open purge valve, let air out.


Yes..... and invert the grease gun and thump it a few times on the head against a piece of wood.

this gets the grease down towards the business end of the grease gun.


"The evidence demands a verdict".
(Re:VOA)"it's nearly impossible to actually know the particular additives that are in there at what concentrations."
Re: Pulling the Plunger on a Grease Gun. [Re: George7941] #4676059
02/24/18 12:31 AM
02/24/18 12:31 AM
Joined: Jan 2018
Posts: 556
San Antonio, TX
das_peikko Offline
das_peikko  Offline
Joined: Jan 2018
Posts: 556
San Antonio, TX
You pull the plunger and lock it to the side right before pulling the empty cartridge out. Remove the top with trigger assembly, pop in the new cartridge, pull the snack pack lid off, reinstall the trigger assembly, release the plunger, and loosen (not remove) the bleeder to let some grease out to purge the air.

Re: Pulling the Plunger on a Grease Gun. [Re: George7941] #4676293
02/24/18 09:51 AM
02/24/18 09:51 AM
Joined: May 2005
Posts: 2,264
Toronto, Canada
George7941 Offline OP
George7941  Offline OP
Joined: May 2005
Posts: 2,264
Toronto, Canada
NO, NO! Different scenario. This pulling of the plunger is to relieve pressure on the grease inside the gun so there is less oil bleed out.
This article was linked to in another post
http://www.machinerylubrication.com/Read/28761/storing-grease-to-avoid-bleed-separation-
Quote from the article
" If a cartridge tube is left in a grease gun, the grease gun should be depressurized, wiped with a clean cloth to remove any contaminants and stored in a horizontal position inside a clean, cool, dry area to keep the oil from bleeding out of the grease."


2006 GMC Sierra 4.3l, NV3500,G80 , Mobil 1 5W30, Dexcool.
1987 BMW R80 - sold
2015 Honda CBR300R

Staying out of the right lane a lot.
Re: Pulling the Plunger on a Grease Gun. [Re: George7941] #4676414
02/24/18 11:41 AM
02/24/18 11:41 AM
Joined: Dec 2016
Posts: 7,481
Waco, TX
Linctex Offline
Linctex  Offline
Joined: Dec 2016
Posts: 7,481
Waco, TX
Originally Posted By: George7941

This article was linked to in another post
http://www.machinerylubrication.com/Read/28761/storing-grease-to-avoid-bleed-separation-
Quote from the article


"Machinery Lubrication" has been publishing a lot of Bollocks lately... They've lost credibility.


"The evidence demands a verdict".
(Re:VOA)"it's nearly impossible to actually know the particular additives that are in there at what concentrations."
Re: Pulling the Plunger on a Grease Gun. [Re: George7941] #4676635
02/24/18 03:05 PM
02/24/18 03:05 PM
Joined: Jun 2014
Posts: 2,039
IL
Vern_in_IL Offline
Vern_in_IL  Offline
Joined: Jun 2014
Posts: 2,039
IL
Originally Posted By: George7941
NO, NO! Different scenario. This pulling of the plunger is to relieve pressure on the grease inside the gun so there is less oil bleed out.
This article was linked to in another post
http://www.machinerylubrication.com/Read/28761/storing-grease-to-avoid-bleed-separation-
Quote from the article
" If a cartridge tube is left in a grease gun, the grease gun should be depressurized, wiped with a clean cloth to remove any contaminants and stored in a horizontal position inside a clean, cool, dry area to keep the oil from bleeding out of the grease."


The only high pressure area is in the hose, the grease in the tube is pressurized by a SPRING, it's only enough to push up the grease to the piston pump. So just release the pressure in the hose is good enough for me.

If I was worried about oil separation I would store my grease gun in my refrigerator. smile Leaving the shaft pulled will get the shaft dirty and that will get into the grease.

Last edited by Vern_in_IL; 02/24/18 03:08 PM.
Re: Pulling the Plunger on a Grease Gun. [Re: George7941] #4677054
02/24/18 09:58 PM
02/24/18 09:58 PM
Joined: Jan 2009
Posts: 14,046
Illinois
tig1 Offline
tig1  Offline
Joined: Jan 2009
Posts: 14,046
Illinois
George,
I don't know if this will help or not, but I have posted this video in the past on purging air from a grease gun.

https://www.youtube.com/watch?v=eQyd6XrAo4w


2007 Ford Fusion 236,000 miles
M1 0-20 EP
2017 Ford Fusion 62K
M1 0-20 EP
10,000 mile OCIs on both engines
M1 ATF and Valvoline LV
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