BOMAG roller building pressure inside reservoir

[DozerTech78]

Im working on a BOMAG roller, its having issues with blowing fluid out of the cap at times, so the cap/breather was replaced a while ago and it made no difference. There is a substantial amount of pressure that is building up inside of the reservoir. If you put a rubber glove over where the cap goes, it will blow up like a balloon. The fluid is foaming badly and you can watch very small bubbles come to the top over time. This leads me to believe that there is a leak in the suction line, aerating the fluid and causing excess pressure in the reservoir. My question is, would pressurizing the reservoir with shop air be an acceptable way of checking for leaks in the suction side?

 

[Delmer]

Sure, as long as you have a regulator so you're not putting full pressure in it. Are you thinking something like 5 PSI ?

 

[DozerTech78]

Hey thanks for the reply. Yeah, I'm thinking maybe rig up some kind of pressure tester with a gauge and a schrader valve possibly. First run the machine and figure out exactly what the peak pressure is that is being created inside the reservoir is and then charge it with air with the machine off. Slightly above that peak pressure, my idea is, after a little while any sort of air leak in the suction line will start to actually leak oil making it completely visible

 

[Delmer]

Sounds good. If you need to add a tire valve stem to fill with air, use a 3/4" pipe nipple, and a garden hose nut (from a female hose repair end), the rubber on the valve stem is the right size to seal between the pipe threads and the garden hose nut, and the threads are close enough to work.

 

[DozerTech78]

Thanks for the good info, ill give it a shot

 

[Bls repair]

How many hrs on hyd filters,hyd pump making noise,pump may be cavatating causing bubbles

 

[DozerTech78]

How many hrs on hyd filters,hyd pump making noise,pump may be cavatating causing bubbles

Honest, I can't tell you now, I'm not at the shop and I can't remember. So you are saying air can be entering through the seals in the pump? It is not making a whining noise to my knowledge but ill have to check again

 

[Bls repair]

Cavatation is when the pump pumps the oil out faster then it comes in causing air bubbles .An example would be like an outboard engine with boat stopped,give it full throttle,prop pushes water out of way faster then water can fill in void and creates bubbles.

 

[DozerTech78]

Cavatation is when the pump pumps the oil out faster then it comes in causing air bubbles .An example would be like an outboard engine with boat stopped,give it full throttle,prop pushes water out of way faster then water can fill in void and creates bubbles.

alright ill have to see, there was some speculation as to when the filter was actually changed. Ill throw a new one in and see what it does, even if it doesn't fix the issue, it could very well need one anyway

 

[DozerTech78]

Just an update this morning. Went to lowes and rigged up a little pressure tester with a 100psi gauge. I sealed and charged the reservoir with 20psi, watched and waited and could find no leaks. A little disheartening but I did make an interesting discovery, I have a mechanics stethescope with a needle and I Listened to both the left and right pumps on the outputs (pressure side). The right side pump was rather quiet, the left side however had a smasmabut distinctive whine that is typical of a cavitating pump. I was skeptical at first seeing that this pump is the one closest to the engine, but listening around it back up towards the engine I no longer could hear the whine. I may be on to something. My guess now is the fitting for the suction line that is located beneath it. And of course, theres absolutely no room to get a wrench on it where it sits so ill probably endup tearing the pump off of it tonight. Here's a pic of my pressure tester, after I was done testing of course, the plate is unbolted and the cap was reinstalled, I lucked out they even had a 1/8 valve stem there so I didn't have to do the garden hose trick. Just used a reducer

 

[mikebramel]

Pressure test is rarely going to show you a problem with the intake. You need to use a pneumatic A/c evacuation tool or an Airlift coolant bleeder