OMAX 55100 extremely hot water from one cylinder

I've been fighting an issue with my OMAX 55100 2040 for a while (almost a year) and can't seem to find the root cause.
I keep blowing the dynamic seal on cylinder one.
I'm pretty confident the failure is from extreme heat. The water coming from cylinder one is very hot and gets to a scalding temp within a minute.
I've checked the water flow through the coolant housing assembly and it seems to be as good as the other two. I've replaced the cylinder, displacer, plunger and check valve assembly in addition to the standard consumables and still not getting anywhere. After replacing the dynamic seal I'll get anywhere from 25-75hrs before it fails again and sometimes even shorter when I used to go a year or more. It's so consistent that it's just factored in to my work flow expectations that I'll be replacing it within that time frame. It's so hot the tank water is getting over 110F after 8hrs of cutting.

Hoping someone has seen something similar and can point me in the right direction.

If you have a gauge on the pressure you can see the pressure rise on each stroke, it will be very high so not any ordinary old gauge. you can compare one stroke to the other.
If water is getting hot to me it appears there is a check valve issue it could have a bad seal. Obviously if its bad it won't last long under the pressures it runs before it craters, so that will be telltale. There will be a inlet and outlet seal obviously per side.

It could also have a bit of gunk in the line somewhere like a bit of broken seal( old failed seal) and giving back pressure due to flow restriction, on Techni waterjets there is a sintered metal filter and if that blocks the pressure rise is so large it will blow a metal fitting and it sure goes off with a bang. Usually this is on the main line so effects both cylinders but yours may be different ie have one on each line.
Forcing water through a restriction gives a heat rise.

Only other thing i have had heat rise is when i forgot to turn the AC cooler on>>> then it maxes out temp and shuts off ( oil temp ) things happen.

Not so sure if the main inlet filter if its blocked ( cartridge ) will give this i think it will just cavitate but look at that also as the seal my run dry due to this. Both cylinders would have the problem as well not just one.


Have a poke around, gunk issue would be my first place to look at.

Unfortunately this unit doesn't have a high pressure gauge so I have to watch the input water pressure for indications of trouble. The flow appears very even however.

Debris was my initial thought. Are you thinking something in the coolant housing? I've taken it apart and inspected it but didn't see anything. The check valve assembly was replaced after a four or five failures. I was still trying to find root cause and not having found any obvious issue it was mentioned it might have an internal crack affecting water flow.

Kind of was worried about part of the seal getting stuck somewhere but couldn't find any evidence of it. Rebuilt this a dozen times but ever since the rebuild a year ago this first cylinder just never came back.

Its hard to tell pressures from the flow, If you can fit a very high pressure gauge it would help ( check operating pressure beforehand for sizing and be carefull with fitting and lines for rating) i cannot see any flow drop so may be of no use.
It will bounce up and down a bit as the accumulator if you have one fitted should even it out a bit but not completely. You can tell a lot of faults from the main pressure gauge before you see actual total failures, like a warning sign.
When the hydraulics cycle it should have a telltale light to say the solenoid is engaged this is used with the pressure gauge to see which side is affected and in your case confirmation as you know which side.

Failure of check valves if they are not good will bet very short time period. Normal for them to go several months of varying times for no particular reason, they are two part with lapped seats if yours are single part you need to grind then lapp the seat.
if it lasts only a month or less its got problems. WSI if thats where your getting your parts from? have some good parts and some not so good, you sometimes have to use oem parts for certain things.

i would force water with simple mains pressure through all fittings and lines including any drilling holes in housings ( especially cross drilled holes could be a problem) and get a visual on flow if one side looks less than the other investigate. You should also spot if you have a metal sintered filter in line by doing this as well sometimes they look like a extended hex so hard to tell unless you take them apart.

The water side on the machine i have worked on has no cooling system only the oil side has it.

Other than what i have said you may be best to get the dealer to look at it, but expect to pay for the fault finding exercise.

Find the flow restriction, restriction causes excessive heat.

A restriction was my second thought after thinking I had made a mistake in the rebuild. Took it apart from the pump all the way to tip and didn't find anything. I ahve noticed a chirping sound during operation. Guessing this is the plunger rubbing? Everything from the pump drive to the tip has been replaced since this problem raised it's ugly head with a recent rebuild.

If the bearings in the Meyers drive pump were getting worn would it cause enough vibration in the plungers to cause the excessive heat/wear?

I'm also seeing a lot of vibration in the supply line to cylinder one and some in the line to cylinder two and minimal in the supply line to cylinder three. Guessing this is back pressure on the lines or could it be from the charging pump?