I have a 643 and am having some problems with it. I need some help.... 1. when i am running the bobcat at full throttle, engine dies down to almost stall. I let go of everything and the engine slowly comes back up to full throttle. 2. The bucket and boom are creeping down quickly with the engine off or on. 3. When I start the engine, if the brake isn't on, the bobcat starts moving backwards. The hydrostatic drive appears to be in reverse. 4. The bobcat will not start without ether. (could this be because the hydrostatic drive is engaged in reverse?) Is it possible that a valve that is bypassing could cause these problems. Any help or suggestions would be greatly appreciated. The bobcat is in excellent shape with only 1300 hrs. It is a 91. I have had this problem since i bought the machine 2 years ago. It's now in the heated garage and i am going to change all my filters and put in new glow plugs. I'd like to try to solve the above issues before the snow starts to fly. Thanks
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i will definitely adjust the neutral position. thanks jerry.fuel filters and glow plugs should help and block it up with all 4 wheels off the ground and adjust the neutral position according to the book.
antfarmer2
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I agree with Jerry make sure you do the fuel filter (s) and do not use either you will do damage use wd40 if you need somethingi will definitely adjust the neutral position. thanks jerry.
Antfarmer has a very good point, if you have the glow plugs working don't use ether.I agree with Jerry make sure you do the fuel filter (s) and do not use either you will do damage use wd40 if you need something
antfarmer2
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What is your serial # does it have the hidden brass filter?Antfarmer has a very good point, if you have the glow plugs working don't use ether.
antfarmer2
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If your s# is 13405 or below you have the hidden brass filter and most likely never been changed or cleanedWhat is your serial # does it have the hidden brass filter?
I will look for the serial #... but i know when we bought the machine, it was from germany originally. I will check in the morning. Thanks for all your help. I will keep you posted.If your s# is 13405 or below you have the hidden brass filter and most likely never been changed or cleaned
antfarmer2
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Does not matter but if it does have it I have a brand new one bobcat sold me that I do not need if you need it send me a prepayed box and I will give it to youI will look for the serial #... but i know when we bought the machine, it was from germany originally. I will check in the morning. Thanks for all your help. I will keep you posted.
antfarmer2
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Where are you located might not be worth it lolDoes not matter but if it does have it I have a brand new one bobcat sold me that I do not need if you need it send me a prepayed box and I will give it to you
ok... keeping in mind the bobcat is from germany.... the VIN # is 501524081 there is a filter parts list on the machine door (the machine is MINT so I can read the labels with no problems).... there are 2 hydraulic filters listed but only one number... would there be a number for the brass filter... is it replaceable or do you just clean it? where would it be located? Thank you guys for all your helpI will look for the serial #... but i know when we bought the machine, it was from germany originally. I will check in the morning. Thanks for all your help. I will keep you posted.
thanks antfarmer2 for the offer. I am in Northern Ontario Canada.ok... keeping in mind the bobcat is from germany.... the VIN # is 501524081 there is a filter parts list on the machine door (the machine is MINT so I can read the labels with no problems).... there are 2 hydraulic filters listed but only one number... would there be a number for the brass filter... is it replaceable or do you just clean it? where would it be located? Thank you guys for all your help
antfarmer2
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I was just up at Niagra Falls but in Texas ......what is the # for the filter I will check for you.....,if you have the brass filter when you pick up the cab standing in the bucket you will have a steal block coming of the left side with three hoses going to the left it will be in the center one if it has one big black hose going to the left off the hydro pump you don't have itthanks antfarmer2 for the offer. I am in Northern Ontario Canada.
antfarmer2
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You can clean it but don't think you have itI was just up at Niagra Falls but in Texas ......what is the # for the filter I will check for you.....,if you have the brass filter when you pick up the cab standing in the bucket you will have a steal block coming of the left side with three hoses going to the left it will be in the center one if it has one big black hose going to the left off the hydro pump you don't have it
It may resemble the 632 so the port block is on top of the pumps, square with 3 hoses coming out of the right side, filter is in the block when you remove the center hose.You can clean it but don't think you have it
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Is that when your sitting in it or standing in the bucket?It may resemble the 632 so the port block is on top of the pumps, square with 3 hoses coming out of the right side, filter is in the block when you remove the center hose.
thank you guys... i will let you know how it goes.Is that when your sitting in it or standing in the bucket?
That brass filter will not bog the engine down like that, it reduces drive power but the engine keeps going. Not a bad idea cleaning or replacing it if you have one. Looking at the drive pump, there should be a square block on the hydraulic pump with 3 hoses on the left looking from the bucket. It should be behind the middle one. Remove the hose AND the fitting, it's hiding inside there.thank you guys... i will let you know how it goes.
Replace the fuel and air filters first. Check the primer bulb too, if it is being sucked flat when it looses power, you have a restriction. It could also be sucking in air due to a cracked fuel pickup line, but that generally makes it run poorly all the time and hard starting.
Ensure the fuel bleed screw is all the way in too, i think this model had one on the injector pump too.
I installed and electric lift pump on the bobcat a year ago.... it ran fantastic...i never thought of checking the clamps to make sure they were still tight. Perhaps I have air going in from the clamps. I will keep you guys posted. Thanks for all your helpThat brass filter will not bog the engine down like that, it reduces drive power but the engine keeps going. Not a bad idea cleaning or replacing it if you have one. Looking at the drive pump, there should be a square block on the hydraulic pump with 3 hoses on the left looking from the bucket. It should be behind the middle one. Remove the hose AND the fitting, it's hiding inside there.
Replace the fuel and air filters first. Check the primer bulb too, if it is being sucked flat when it looses power, you have a restriction. It could also be sucking in air due to a cracked fuel pickup line, but that generally makes it run poorly all the time and hard starting.
Ensure the fuel bleed screw is all the way in too, i think this model had one on the injector pump too.
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