No Hydraulic Pressure

450c · Post by **450c** » Mon Jan 25, 2010 6:55 pm

About a month ago I used the old girl, not the wife, but a 72 450B crawler loader to plow about 500 feet of snow off my driveway. She worked well with no signs of trouble. Last weekend I went to use her and discovered there was no pressure to lift the loader. She was fine when I put her away last month. No strange noises. No cavitating sound from the pump. I pulled the cover off the hydraulic tank and fired up the machine. I got some flow coming back to the tank, but not very much. Every once in a while it would burp and shoot a stream about two feet high than settle down to very little flow. The pump is definitely turning. Increasing the RPM made no differance in the flow volume. Any ideas ??

cinok · Post by **cinok** » Mon Jan 25, 2010 7:36 pm

I would check the drive coupler on the hyd pump un the front of the machine between the pump and crankshaft.

OneWelder · Post by **OneWelder** » Tue Jan 26, 2010 4:11 pm

could it have some water in it and froze ?

450c · Post by **450c** » Tue Jan 26, 2010 7:47 pm

It didn't appear to be the coupler, as the pump was turning. I am hoping that something may be froze. I was thinking maybe a pressure relief valve was stuck open and dumping to the tank. But the low volume of flow tells me it may be pump problems. Thanks for the reply's.

srs_mn · Post by **srs_mn** » Wed Jan 27, 2010 12:05 pm

I'd still check the front pump drive, as was suggested.... I've run into drive couplings with the splines sheared off on two different machines... the pump will still turn, but the shaft slips when it gets a load on it.

450c · Post by **450c** » Mon Mar 22, 2010 5:21 pm

Well I went back up to check into things a little deeper. Fired up the machine and found that everything worked as it should. I am glad all is well but I do wonder what the problem was. I assume that something was froze and has thawed.

shinnery · Post by **shinnery** » Mon Mar 22, 2010 11:46 pm

Is the fluid milky looking as if it has water in it?
Bryce

450c · Post by **450c** » Tue Mar 23, 2010 3:08 pm

I wouldn't call it milky although it is off colour some.

Tigerhaze · Post by **Tigerhaze** » Tue Mar 23, 2010 4:52 pm

Sometimes the fluid will be much more water-contaminated than it appears from checking the dipstick or even opening the cap on the reservoir tank. It will stratify (layer) and you may not notice how bad it really is. You may want to drain some of it to see.

450c · Post by **450c** » Tue Mar 23, 2010 5:32 pm

It wouldn't hurt to drain and refill the system. I think I will.
Thanks for the replys.

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No Hydraulic Pressure

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