Cold hydraulics

[SteveNY]

I own a IH3414 backhoe and was digging last week-end while it was snowing, about 30 deg. F. Before the machine warmed up the pump was cavatating fairly bad. I think that was what it was doing anyway. I have the recommended oil "Hytran" in the reservoir. Is there a trick to solving this problem? Heater maybe? The oil is new that I put in, cost $90 so I don't want to change it. Does this cavatation hurt the pump? I know you guys have all the good answers so thank you in advance.

 

[DarinRay]

Well first how do you know it was cavitating? What was the unit doing that makes you think that? I am not sure if I can give you any info but will try after hearing what you have to say. Just basically give us the details of what was going on? Well talk later

Darin

 

[JohnMiller3]

<font color=blue>...Does this cavatation hurt the pump?...</font color=blue>

1st... Cavitation is NOT Good... /w3tcompact/icons/frown.gif

Depending on the circumstances and type of pump, some hydraulic pumps can "self destruct" very quickly without addressing the cavitation issue... then you have a major expense... (worse case scenario is running a hydraulic pump without any fluid (or bone dry) /w3tcompact/icons/shocked.gif)

Check with your Case/IH dealer to verify if a "heater" is available for your unit...

By the way, how many gallons did you change to cost over $90...? /w3tcompact/icons/eyes.gif

 

[WVBill]

My Kubota B6100 loader hydraulic pump does that when it's cold out. (Pump makes a noise that is clearly cavitation whenever the loader controls are operated).

It's not nearly as sophisticated a system as your IH3414 backhoe (or anyone else's equipment for that matter).

The service manager at the Kubota dealer told me to "cut" the hydraulic oil 50/50 with diesel fuel in the winter time to thin it out. Well, I know it's an old tractor but I just couldn't bring myself to trust that advice. I just try to do minimal operating of the loader until the hydraulics warm up. I suppose some kind of a heater on the hydraulic reservoir might work, though.

 

[DarinRay]

Re: Cold hydraulics & pump cavitation

I guess maybe I'm missing it but what are you guys meaning about the "cavitation" symptoms? And how does a full system cavitate if maintained with the proper fluids and filters? I am not questioning that it's cavatating or not but I would like to know how and why now.

I don't blame you for not wanting to put diesel fuel 50/50 mixture in your hydraulic system either. I mean if anything go with a thinner or synthetic blend.

Darin

 

[DarinRay]

Re: Cold hydraulics & pump cavitation

ANother thing is that they (most brands o.k maybe some /w3tcompact/icons/wink.gif) do tell you to warm up the hyd oil by fully extending or curling cylinders to pass oil through system and raising pressures. Is the cavitation caused by the suction pressure being lower? But how much lower can this be to create such havoc in our systems with hydraulic oil? Basically just thinking out loud. /w3tcompact/icons/smile.gif

Darin

 

[MossRoad]

I have an IH2500B and use the same fluid. When I was operating it often and the temps start dropping, my warm up times started rising. Especially in the 30s and 20s. I usually started it up and let it run for 20 minutes at about 1/3 throttle. After that, there was no sluggishness to the hydraulics and no "noises". I have never operated it below 20 degrees. There are some instructions in the operators manuals dealing with cold weather. Don't have the manuals? for IH parts and manuals at <A target="_blank" HREF=http://www.batescorp.com>http://www.batescorp.com

My PT425 uses motor oil for hydraulic fluid. I warm it up for 10-15 minutes when it is under 32 degrees as well.

 

[GSS]

I had to change 20 gallons in my old IH656 Hydro and HyTran was about $30+ per 5 glns... Ouch.

 

[Mike_Dumond]

I can empathize with that Bill. On my 6100, I usually put a space heater to it for a while, then I run it with the PTO engaged for a few more minutes. Then I cycle everything a few times just to stir it up abit. Sounds like a long process, but easier on these old tractors than just heading out to the first snow bank.

Went out to start the 6100 this afternoon, (got 12 inches of the white stuff), and it started right up. Ran for 2 minutes then stopped. Summer fuel gels pretty good in this weather. Put the heater on it, warmed it up real good, then ran the battery down starting it. Got that charged up and the hydraulics froze. Back came the heater. (Did I mention that the tractor was not anywhere near the house? Teach me to leave it out for a few days.)

Anyway, got the hydraulics working and noticed the bucket wouldn't lift. Curls OK, great down pressure, but no lift. Did alot of what my father called backwoods praying. (My mother washed out our mouths when she caught us praying in this manner. Finally found a frozed section of pressure line. Seems my fluid has more than a little moisture in it. Guess I'm gonna be changing fluid between blizzards this winter.

 

[s1120]

Re: Cold hydraulics & pump cavitation

<font color=red>And how does a full system cavitate if maintained with the proper fluids and filters? I am not questioning that it's cavatating or not but I would like to know how and why now.
</font color=red>

I could be wrong, but here is why I think it happans. When the oil in the system is cold it gets a lot thicker. The pump trys to suck the oil from the tank, but the oil is so thick, it does not flow to the pump. Think of sucking Jello through a straw. It is not going to come up the straw like water, it will come up in blobs of Jello. Thats what the oil does, and inbetween each blob is a little pocket of air.

My Ingersoll is fully hydro powerd, and also uses motor oil for the fluid. In the cold she does make a racket. I start it up, let the motor warm up, then put the trans in nutrul.[hydro driven two speed trans] then send psi to it. That spins the drive motor, with very little load on it, and lets it warm up. When its REAL cold, it will almost stall the motor. After a few min, its fine.

 

[WVBill]

Mike:
Is the hydraulic reservoir for your loader in the right-hand FEL upright member like mine? I was thinking of just wrapping that upright with heat tape (like they make for keeping pipes from freezing) and leaving it plugged in all the time. There's probably almost as much fluid out in the lines and cylinders as there is in that "reservoir" but I'm thinking that having that fluid "pre-warmed" would be a big help.

I don't know how hot those heat tapes get. Any idea?

Paul got the description right as to why I think the pump is cavitating.

 

[SteveNY]

Thanks all for the info. My tbl had transmittion fluid in the reservoir when I boutht it. For great fear of the 0-rings and seals not being compatiable and having to replace them, I changed to the recommended Hytran (thats right $30/5gal.) oil. When first started at cold temps. the pump makes louder than normal noises when operating the levers and the arms make jerking movements. I think the jello explanination sounds like what is happening. There are magnet type oil pan heaters but I'm afraid that they might be too hot and hurt the oil. I just built a garage with 11 foot high overhead door but it is with out heat. Maybe I can talk my wife into letting me bring my tractor in the house?????

 

[Soundguy]

Re: Cold hydraulics & pump cavitation

In hydraulic systems, cavitation can occur when there is an obstruction in the suction line. The suction on the low pressure side lowers the vapor pressure and any moisture and disolved gasses in the oil can boil out. I soppose depending on the fluid, you might even reach the vapor point of the pumped fluid as well. In any case.. cavitation is bad for the system.. it will start to erode all contact surfaces... that is a real basic explanation
In more specific terms for the other engineering types out there, fluid is not really sucked into the pump, it is pushed in under pressure.. generally atmospheric pressure.. this fluid pressure floods the pump. A pump will have a NPSHR number as determined by the manufacturer ( net positive suction head required )( minim fluid energy needed at the pump inlet for correct opperation ). The NPSHA ( net positive suction head available ) is the force pushing the fluid into the pump. NPSHA must exceede NPSHR or cavitation will occur. Again, cavitation is vaporization of the liquid in the suction line. If the fluid pressure is less than the vapor pressure of the fluid in question, pockets of vapor will form. Once these pockets reach the impellor or piston surface, they will again be acted on by the high local pressure of the pump, and will collaps.. this will cause vibration.
Per the Civil eng/ ref. manual, the following situations can cause cavitation:
"discharge heads far below the pump's calibrated head at peak efficiency.
suction lift higher or suction head lower than the manufacturer's specifications.
Operating the pump at speeds higher than the manufacturers recomendations.
pumping liquids at higher temperaturers than manufactureres spec's ( higher temps will have different vapor pressures..etc )

Soundguy

<font color=green>And how does a full system cavitate if maintained with the proper fluids and filters? I am not questioning that it's cavatating or not but I would like to know how and why now.


I could be wrong, but here is why I think it happans. When the oil in the system is cold it gets a lot thicker. The pump trys to suck the oil from the tank, but the oil is so thick, it does not flow to the pump. Think of