Bobcat 743B Question

Help Support SkidSteer Forum:

ThomasM

Well-known member
Joined
Aug 29, 2007
Messages
68
I am looking at a bobcat 743b and do not know the year it was made. The owner does not know either. Can you tell by the serial number? It is 509321215 Does anybody know what year this machine is? I am thinking 1993 by it's decals? Thank you.
 

Tazza

Administrator
Staff member
Admin
Joined
Dec 7, 2004
Messages
16,697
Your dealer should be able to tell you from the serial number. Not trying to sound rude, but why is the year so important? it will be early to mid 90's. They are almost identical to the 743, just with a few upgrades. I think they have an electric shut down and 2 piece axles.
 

ThomasM

Well-known member
Joined
Aug 29, 2007
Messages
68
Your dealer should be able to tell you from the serial number. Not trying to sound rude, but why is the year so important? it will be early to mid 90's. They are almost identical to the 743, just with a few upgrades. I think they have an electric shut down and 2 piece axles.
I just wanted to know the year because it makes a difference for the price. Age takes a toll on things. It has 3600 hrs in very good condition, how are these machines in general with this many hrs? Anything to look out for? 8900 dollars. Thank you for the info.
 

sterlclan

Well-known member
Joined
May 1, 2004
Messages
528
I just wanted to know the year because it makes a difference for the price. Age takes a toll on things. It has 3600 hrs in very good condition, how are these machines in general with this many hrs? Anything to look out for? 8900 dollars. Thank you for the info.
Past maintenance matters more than age/hours they are usually good for 5000 or so without too much trouble depending on how it has been cared for Jeff
 

Tazza

Administrator
Staff member
Admin
Joined
Dec 7, 2004
Messages
16,697
Past maintenance matters more than age/hours they are usually good for 5000 or so without too much trouble depending on how it has been cared for Jeff
Exactly, years don't matter much at all. Everyone that is looking for a skid steer knows the 743 machines are very good and reliable. Diesel engines are usually good for around 5,000 hours. After that they usually start getting hard to start and its time to get it re-conditioned. The hydrostatics are basically bulletproof! Keep it serviced and it should out last the machine. The 743 was the best machine they ever built, they made it for 10 years then they made the 743B for a few years with very minor changes. The engine and hydrostats were the same.
Keep in mind that skid steers are nothing like cars, with age they really don't loose value like cars do.
That price sounds a bit high to me, it would want to be in good shape. Over here in Australia they go for around 12-14K. They do come up cheaper when they are not running.
 

ThomasM

Well-known member
Joined
Aug 29, 2007
Messages
68
Exactly, years don't matter much at all. Everyone that is looking for a skid steer knows the 743 machines are very good and reliable. Diesel engines are usually good for around 5,000 hours. After that they usually start getting hard to start and its time to get it re-conditioned. The hydrostatics are basically bulletproof! Keep it serviced and it should out last the machine. The 743 was the best machine they ever built, they made it for 10 years then they made the 743B for a few years with very minor changes. The engine and hydrostats were the same.
Keep in mind that skid steers are nothing like cars, with age they really don't loose value like cars do.
That price sounds a bit high to me, it would want to be in good shape. Over here in Australia they go for around 12-14K. They do come up cheaper when they are not running.
Sound good guys. I will look at it better tommarow. Thanks again.
 

ThomasM

Well-known member
Joined
Aug 29, 2007
Messages
68
Sound good guys. I will look at it better tommarow. Thanks again.
Bought it! The only thing I noticed is that the engine oil was black with 10hrs of use on the new oil is this normal? The tilt cylinder seems to retract slower than extend?? Other than that it is a very tight machine with no leaks or paint damage to speak of. Original tires with 3670 hrs, need new though, 30%. Do you know where I can get an owners manual for it besides a dealer? I may need more of your help in the future. Thanks.
 

jerry

Well-known member
Joined
May 3, 2007
Messages
2,040
Bought it! The only thing I noticed is that the engine oil was black with 10hrs of use on the new oil is this normal? The tilt cylinder seems to retract slower than extend?? Other than that it is a very tight machine with no leaks or paint damage to speak of. Original tires with 3670 hrs, need new though, 30%. Do you know where I can get an owners manual for it besides a dealer? I may need more of your help in the future. Thanks.
my cylinder does the same and I just rebuilt it completely, I think it is because on the retract stroke it has to force all the oil on the back side of the piston out the same size hole as is on the rod side of the piston and the volume of oil is greater because no rod to take up space so it takes longer to do it.
 

ThomasM

Well-known member
Joined
Aug 29, 2007
Messages
68
my cylinder does the same and I just rebuilt it completely, I think it is because on the retract stroke it has to force all the oil on the back side of the piston out the same size hole as is on the rod side of the piston and the volume of oil is greater because no rod to take up space so it takes longer to do it.
It would have to run over relief valve to slow it down on retract. Takes more pressure on the rod end to force the extra oil out the blind end, creating a higher velocity on the blind end. like you said. Does anyone know the issue with the oil color after 10hrs of use? Thanks.
 

Tazza

Administrator
Staff member
Admin
Joined
Dec 7, 2004
Messages
16,697
It would have to run over relief valve to slow it down on retract. Takes more pressure on the rod end to force the extra oil out the blind end, creating a higher velocity on the blind end. like you said. Does anyone know the issue with the oil color after 10hrs of use? Thanks.
Its normal for the oil to go black quickly, especially when the oil was black before it was changed you simply can't get all the old dirty oil out so it will make the oil go black. The older age of the engine will make it go black a little faster as it will have a bit of ring wear but nothing to worry about. All diesel engines turn their oil jet black, just keep it serviced, if it runs well don't worry, just watch the oil and coolant levels and you will be fine. These engines DO NOT like getting hot.
 

ThomasM

Well-known member
Joined
Aug 29, 2007
Messages
68
Its normal for the oil to go black quickly, especially when the oil was black before it was changed you simply can't get all the old dirty oil out so it will make the oil go black. The older age of the engine will make it go black a little faster as it will have a bit of ring wear but nothing to worry about. All diesel engines turn their oil jet black, just keep it serviced, if it runs well don't worry, just watch the oil and coolant levels and you will be fine. These engines DO NOT like getting hot.
Good, that is what I wanted to hear. Mabey I will change the oil and leave the filter if i change it right away. Thanks.
 

mikie

Active member
Joined
Feb 4, 2007
Messages
31
Good, that is what I wanted to hear. Mabey I will change the oil and leave the filter if i change it right away. Thanks.
on the rod extension question, it takes less oil on the rod end than the piston end, different fill rate, thus different speed. dont go cheap on the oil filter and not change it. you are asking for trouble if you take short cuts like this. same goes on the hydraulic filter. the filter(s) go into bypass when plugged or restricted. in other words, you are pumping unfiltered oil continually thru your system. the machine life will be greatly shortened. they all bypass. if they didnt, they would rupture from excess pressure buildup due to the dirty filter. this aint no fairy tale. i see it all the time at work.
 

ThomasM

Well-known member
Joined
Aug 29, 2007
Messages
68
on the rod extension question, it takes less oil on the rod end than the piston end, different fill rate, thus different speed. dont go cheap on the oil filter and not change it. you are asking for trouble if you take short cuts like this. same goes on the hydraulic filter. the filter(s) go into bypass when plugged or restricted. in other words, you are pumping unfiltered oil continually thru your system. the machine life will be greatly shortened. they all bypass. if they didnt, they would rupture from excess pressure buildup due to the dirty filter. this aint no fairy tale. i see it all the time at work.
Yeah, thats what I mean, it should retract faster than extend; but it does the opposite. I just wasnt going to change the filter cus it was just changed, I just wanted to flush the engine oil so it looks cleaner.
 

Tazza

Administrator
Staff member
Admin
Joined
Dec 7, 2004
Messages
16,697
Yeah, thats what I mean, it should retract faster than extend; but it does the opposite. I just wasnt going to change the filter cus it was just changed, I just wanted to flush the engine oil so it looks cleaner.
If you want the oil to look clean you really should change the filter too, it does hold a bit of oil that will make the new oil go black. Filters are cheap, i think i paid like $5 for mine and you can't be sure the previous owner actually changed the filter when he did the oil. Cheap insurance if you ask me, i'd change the filter.
 

mikie

Active member
Joined
Feb 4, 2007
Messages
31
Yeah, thats what I mean, it should retract faster than extend; but it does the opposite. I just wasnt going to change the filter cus it was just changed, I just wanted to flush the engine oil so it looks cleaner.
its going to be hard to keep the oil looking like it does in our cars. theres a lot more going on in a diesel. the oil turns black due to a little blo by going by the rings. this is a natural thing. the standard we use at work is 250 hours on the oil and filter. try oil sampling the oil the firt couple times you change it. you can buy the bottle at your local dealer be it cat or bobcat. it is the best way to see whats going on in your engine without tearing into it. they can even alert you if they feel the oil was in the engine too many hours by the contaminant level. dont overlook your air cleaner also. it doesny take much dirt entry to do serious damage. check your hose clamp connections from the air cleaner to the engine. what i have seen is the customers with the best maintenance level has less overall problems. mikie
 

ThomasM

Well-known member
Joined
Aug 29, 2007
Messages
68
its going to be hard to keep the oil looking like it does in our cars. theres a lot more going on in a diesel. the oil turns black due to a little blo by going by the rings. this is a natural thing. the standard we use at work is 250 hours on the oil and filter. try oil sampling the oil the firt couple times you change it. you can buy the bottle at your local dealer be it cat or bobcat. it is the best way to see whats going on in your engine without tearing into it. they can even alert you if they feel the oil was in the engine too many hours by the contaminant level. dont overlook your air cleaner also. it doesny take much dirt entry to do serious damage. check your hose clamp connections from the air cleaner to the engine. what i have seen is the customers with the best maintenance level has less overall problems. mikie
OK, the only thing I noticed was that the dipstick for the engine does not snap into place. It goes in easily and comes out easy. Thanks for the info guys.
 

jerry

Well-known member
Joined
May 3, 2007
Messages
2,040
OK, the only thing I noticed was that the dipstick for the engine does not snap into place. It goes in easily and comes out easy. Thanks for the info guys.
As far as the tilt cylinder speed this is part of a lengthy answer I got from the fluid power forum. Those guys love questions like this. f you follow all the math you will see that which way a cylinder extends the fastest is all about force. An object will accelerate until the sum of forces acting on it are zero. At that time it will maintain a constant velocity. This will happen at a much higher speed when extending than retracting because the oil on the cap side of the piston has more area to push on than the rod side has less force to oppose the motion. There is less opposing force because the pressure drop across the spool will be less and the piston area is less. by cap side he means the back or nut side of the piston
 
Top