Cat 277C Hydraulic System Question

[Quki22]

I noticed that after running the machine and letting it cool down, next day, the hydraulic oil level seems to drop in the sight glass. When I remove the hydraulic cooler cap to add more oil there is a slight “hiss”. After this the hydraulic oil level returns to the normal level in the sight glass. It seems as if the hydraulic system is in a state of vacuum. Is this normal? I replaced hydraulic tank breather not that long ago.

 

[Nige]

Check the breather again would be my first suggestion.

 

[Quki22]

Ok. Thanks again Nige.

 

[Quki22]

Hey Nige,

Breather seems to be fine. No restrictions at all.

You know I switched to a ultra high efficiency hydraulic filter since I had the hydraulic system open to replace several hoses. Could that be causing the vacuum effect that I am experiencing.

Not seeing any bypass indicator warning.

 

[Nige]

Has it always behaved the way it is behaving now or is this something new.?

 

[Quki22]

Haven’t had the machine that long. Operated may 10 hours since owning. Maybe 2 hrs of operating since getting it all back together. I just noticed it today. I noticed the oil level down in the sight glass, but thought it’s just the air working it’s way out of the system because there are no leaks that I can see. That’s when I noticed the cooler cap was hard as hell to get off and when I did there was a hiss for a millisecond. That’s when I went to watch the sight glass and sure enough the oil level started to rise.

The filter I used cross referenced from the advanced efficiency to the ultra efficiency

 

[Nige]

In that case I’d just keep an eye on it for now. If you are worried about levels then just crack the cap every once in a while and let everything settle.

The filter I used cross referenced from the advanced efficiency to the ultra efficiency

What filter part numbers are you taking about.?

 

[Quki22]

Replaced 1G-8878 with 102-2828

 

[Nige]

Replaced 1G-8878 with 102-2828

102-2828 is a cleanup filter generally to be used only after a system has been contaminated by a failure or something similar. The only reference I can find for your Serial Number is for that specific usage and for no other reason. This from the service manual -

1. Check the hydraulic oil contamination level. Refer to the Testing and Adjusting manual for your machine.
   
   
2. If the levels are not low enough, a 102-2828 Oil Filter (Cleanup) can be installed in order to reduce the levels of contamination. Flush the system up to four times. If the levels are not low enough after the fourth time, drain the hydraulic oil and change the hydraulic oil filter.

1G-8878 is the service filter that should be used in all other circumstances.

 

[Quki22]

Should I switch it back then?

Also 102-2828 was superseded by 465-6502. Sorry about that

 

[Nige]

Also 102-2828 was superseded by 465-6502. Sorry about that

465-5602 is just an updated version of 102-2828 and is still classified as a cleanout element. If you can live with the level/vacuum issue then I would say leave the cleanout element in place no longer than 50 hours or until you get a plugged filter warning, whichever comes first, then switch back to the 1G-8878. See if that changes anything.

Thinking out loud I wonder if your breather is a breaker/relief type that might just retain some level of vacuum without completely relieving it. What Part Number is it.?

 

[Quki22]

It seems like a plain air filter really, with a cover and threads. 258-2829

 

[Nige]

It seems like a plain air filter really, with a cover and threads. 258-2829

I agree. It doesn’t appear to be the type that will retain a certain degree of vacuum.

 

[Quki22]

Think I’ll play it safe and switch it out and see what happens. I don’t want to create a situation when It drops the suction head into the pump to a point that the pump starts to cavitate.

I thought I was doing good by using a filter to clean system out after putting several new hoses in. But no good deed goes unpunished

Thanks again Nige, appreciate you