I have an 520 Bobcat with an engine that dies in a few seconds after starting. When first started it will run about 45 seconds and dies. Each subsequent start it runs for a shorter time eventually won't turn over, battery still OK. I went through all the fuel checks and find no problems. Engine appears to run fine. After a couple of days messing, it appears to me it is the Hydro system loading up and stalling the engine. If it sets for a few hours it will repeat the above sequence. Any help would be greatly appreciated.
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OldMachinist
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The only thing I can think of is if it has auxillary hydraulics they may be engaged causing it to load up. I seem to remember somebody posting a simular problem and that was the cause.
It doesn't have any auxillary attachments. It has a Kubota Diesel engine that someone put into it. It seems the engine is working hard and then dies. Sounds very similar to when I am using it and overload what the machine can do and it dies, this is why I think it is the hydrostatic is loading the engine down ???
OldMachinist
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I don't know much about the 520 does it have a belt you can take off so the engine doesn't have any load on it to verify the problem is the hydraulics not something with the engine.
No belt, It is a direct drive. It would be nice if there was some way to do this with a valve or something someone out there would know about. Otherwise I guess I will need to pull the engine out to verify where the problem is. Thanks for your time, it is appreciated!
mrfixitpaul
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Even if it doesn't have have auxiliaries, the valve is probably set up for it and may have been engaged. Try and move the right steering lever from left to right to disengage them. Does the machine try to drive when it is running? May need to jack up the machine and leave the brake off to reduce load on engine until it can be adjusted.
Pulled the engine out and the engine runs fine. As far as moving the lever left to right this machine has none of these newer features. I believe this is the first year for hydrostatic drive and everything is very basic. There is no interlocks, parking brake etc. My thoughts are still that some type of pressure relief valve is not operating and the hydro preasure just builds up and kills the engine. I believe this as each successive time I start the engine it runs for a shorter time and is harder to restart, finally ending in not turning over at all. If it sets for a few hours it will again start and go through the same cycle again until it won't turn over. It starts and runs the longest when it sets overnight. My hope is that someone has some knowledge of these older machines and would know which valve etc may be the usual culprit. Thanks to all for your help.
Check your hydraulic control valve for the boom and bucket, if there is a third spool you may have auxillary hydraulic plumbing and that system is open center so fluid can flow to the tank in the neutral position but has no escape route if engaged, that would be in the control of the attachment. If accidentally engaged it will reduce engine power by a lot if it even will run at all. The guy who sold me my 825 said the center pedal was the park brake, I quickly learned that just was not true. It would nearly stall my larger perkins diesel. It sounds like you will find either the auxillary or a relief valve stuck in the closed position . In any event, proceed with caution because old hydraulic hoses can burst under high pressure and that can be very hazardous to your health and/or eye sight. Hope some of this makes sense, jeffco
