Plastic grease distribution line

One of the grease distribution lines, on my Tree 750 vmc cracked/ blew out while greasing the machine. I orded some matching size nylon tubing (4MM od x 2.7mm id)to splice in a patch with a staight union. After fixing and trying to pump some grease in, the new tube popped out a bubble. The tube in the machine has no information printed on it. The nylon tube I have has a working pressure of 275psi. Is there a better tube material for grease lines?

Bluejeep,

McMaster-Carr has an extensive selection of tubing, including 'metric'.

My thought would be to investigate the plugged up grease circuit. Many grease guns and probably grease pumps in general can generate up to 10,000PSI which would be beyond the limits of most tubing.

If the circuit is plugged up it needs to be cleaned out somehow. This will allow the free flow of lube without the tube-bursting pressures. That's my simple take on things.

Stuart

I have had a failure of a plastic grease line on my mini excavator.
I found an additional source of metric plastic grease line and Connectors.
US Plastic Corp has nylon tubing with the needed pressure ratings.

I just finished clearing 8 severely plugged grease lines on a 5 axis router. I used a grease gun that I made a new tube and end cap (sealed) to pump cleaning solvent into the lines to liquefy the grease. After that, 5 of the 8 were clear.

The following 3 that were more stubborn needed a lot longer to break down the grease. I took some small air cylinders and plumbed them into the clogged lines. I filled the air cylinder pressure side with solvent and then connected the other side to shop air. It took about 3 days of this constant (low 120 psi) pressure on the solvent to finally loosen things up.

I was very conservative with my pressure, because the last thing I wanted was to rupture a plastic line in a place that was not accessible. I was told to keep pressure below 200psi on the line I was using.

After you get the solvent to go through, be sure to evacuate any remaining solvent with plenty of new grease.

I used solvent tank solvent, as I knew it wouldn't hurt any of the seals that it might come into contact with. Don't use lacquer thinner or the like.

Be patient and you'll get it.

Mike