New Guy with bobcat 742. machine wont move anymore :(

Hello everyone, im new to your forum, and this my first post. i have an early 90's bobcat 742 with the ford 4 cyl. It worked ok when i got it last week, i bought a backhoe attachment and i hooked it up to see if it worked, im pretty sure the hydraulic fluid was low to begin with and when hooked it up i think it must have took enough of my fluid to make me run way to low??? anyway, long story long, i unhooked from the backhoe and backed up, then went forward to get my bucket and it started to make a loud whinning sound and didnt wanna go forward. so i shut it down thinking i was low on fluid, and it was! i filled it back up and it took about 2 gallons or so... then started it up and its still loud when i move the sticks, and the machine dont wanna move very good, if at all. it seems when it gets warmed up it still makes noise but wont move the machine at all?? i've heard they self bleed but since it ran low on fluid can air get in the system and cause these simptoms? am i looking at rebuilding the pump? or is there some kinda pressure relief valve that may be stuck open? can anyone think of anything else i should look at? or am i simply up a creek? when i first got the bobcat it would make the same noise, but only when i would turn?? the bucket and attachment hydraulics still seem to work fine... its just the forward, backward, and turning that is acting up also this is my first skid steer and i never even drove one before i got this one. i am a good mechanic and i am familiar with other hydraulic systems so i think i can fix it with help from you all, i just dont wanna take the pump out unless im sure thats where my problem is any and all help is much appreciated... sorry if my post is to long and im rambling on but im trying to give as much info as possible thanks!!!

Ok, first thing
Lift the cab, do you see a square block on your hydraulic pump? it will have about 5 hoses connecting to it? or is there just one big fat black one going to an alloy block on the left side?
If its what i think it is, its just a filter. If its this setup its actually an early 80's model, not 90's. The 74x series was made between 1980 and 1990, the 743b was made for a few years in early 1990.
Let me know whats there, i can then give you details of what you need to do.
You can also send me an e-mail if you wish, taz38sup at yahoo.com.au the at naturally should be ane @

Sounds to me like you're on the right track-hopefully it will come back and you haven't done any permanent damage by running it dry.
Soemtimes, especially older models, the air takes a while to move out. Also, on the 742 your implement pump on the end of the pump stack provides charge pressure for the system. I believe it is a vane pump, and they're not as forgiving to being run dry.
So if that pump is gone, you can have plenty of oil and your drive will whine and sticks will be stiff, and your boom won't work.

thetool said:

Sounds to me like you're on the right track-hopefully it will come back and you haven't done any permanent damage by running it dry.
Soemtimes, especially older models, the air takes a while to move out. Also, on the 742 your implement pump on the end of the pump stack provides charge pressure for the system. I believe it is a vane pump, and they're not as forgiving to being run dry.
So if that pump is gone, you can have plenty of oil and your drive will whine and sticks will be stiff, and your boom won't work.

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1st off, .. thanks for the replys guys I do have that square block on top of the pump that has the 5 hoses going to it like you said... i haven't ran it like this for more than a few seconds at a time just to show some people around here that might be able to help... one of them said it might be a filter also, but he didnt know where its located or how to get to it.. so hopefully i didnt cause any damage runnin it dry. About that implement pump that provides charge presure for the system.. that really makes allot of sence, i see think how it works now... good news is my boom and bucket seem to work great and my sticks dont feel stiff at all, they still feel the same, so i hope its just this filter Tazza was speakin about... i sure would appreciate any details you may have on how to locate and change the filter. Thanks again guys

cadillacderek said:

1st off, .. thanks for the replys guys I do have that square block on top of the pump that has the 5 hoses going to it like you said... i haven't ran it like this for more than a few seconds at a time just to show some people around here that might be able to help... one of them said it might be a filter also, but he didnt know where its located or how to get to it.. so hopefully i didnt cause any damage runnin it dry. About that implement pump that provides charge presure for the system.. that really makes allot of sence, i see think how it works now... good news is my boom and bucket seem to work great and my sticks dont feel stiff at all, they still feel the same, so i hope its just this filter Tazza was speakin about... i sure would appreciate any details you may have on how to locate and change the filter. Thanks again guys

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On the left side, where the 3 hoses enter the block. Remove the middle hose and the fitting from the block. Behind here is a spring and a bronze filter. Not many people know about it, so its hardly ever changed. This is your suction line filter, it will cause the exact problems you are talking about.
Remove the filter and you can clean it with kerosene or de-greaser but they really aren't expensive to buy new.
Clean or replace that filter and let me know how you go. I had this exact same problem on my 731, it refused to turn or drive up hills when warm. Cleaned the filter and it FLEW up the hill and did dough nuts in the dirt with ease.
If you have any questions just let me know. I have probably been there... done that!

Tazza said:

On the left side, where the 3 hoses enter the block. Remove the middle hose and the fitting from the block. Behind here is a spring and a bronze filter. Not many people know about it, so its hardly ever changed. This is your suction line filter, it will cause the exact problems you are talking about.
Remove the filter and you can clean it with kerosene or de-greaser but they really aren't expensive to buy new.
Clean or replace that filter and let me know how you go. I had this exact same problem on my 731, it refused to turn or drive up hills when warm. Cleaned the filter and it FLEW up the hill and did dough nuts in the dirt with ease.
If you have any questions just let me know. I have probably been there... done that!

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One thing i didn't mention.
These machines run 3 separate pumps. They are linked to an extent but if there is a problem in one area they aren't all affected. The problem you have will cause low charge pressure to the hydrostatic pump. It still allows your hydraulics to function normally. It may seem confusing but its just how the system is designed.

Tazza said:

One thing i didn't mention.
These machines run 3 separate pumps. They are linked to an extent but if there is a problem in one area they aren't all affected. The problem you have will cause low charge pressure to the hydrostatic pump. It still allows your hydraulics to function normally. It may seem confusing but its just how the system is designed.

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THANKS A MILLION GUYS it was indeed a cloged filter... i cant belive it was that easy of a fix... pulled the filter and cleaned the heck out of it, and it works great!!! (bobcat was closed and i just couldn't wait till they opened to get a new one).. WOW!! i still cant belive thats all it was now if i can get the engine to run a little better and qiuit knockin ill be good.... the oil light seems to be on all the time but its realy faint.. and sometimes it will get bright and the engine starts to knock at the same time?? but its full of oil?? does the pickup tube ever fall into the oil pan on these? the guy i got it from said he just changed the oil but you know how that can turn out... so im gonna change the oil for myself to be safe and see if that fixes it.... also does anyone know what to set the timing at on this engine? and do you set it in the same manner as a car engine? (unhook vacuum line and set base timing?) thanks again... im a member of this forum for life now!!! the guys at the bobcat store around here couldn't even come close to answering the same questions you did on a key board!!

cadillacderek said:

THANKS A MILLION GUYS it was indeed a cloged filter... i cant belive it was that easy of a fix... pulled the filter and cleaned the heck out of it, and it works great!!! (bobcat was closed and i just couldn't wait till they opened to get a new one).. WOW!! i still cant belive thats all it was now if i can get the engine to run a little better and qiuit knockin ill be good.... the oil light seems to be on all the time but its realy faint.. and sometimes it will get bright and the engine starts to knock at the same time?? but its full of oil?? does the pickup tube ever fall into the oil pan on these? the guy i got it from said he just changed the oil but you know how that can turn out... so im gonna change the oil for myself to be safe and see if that fixes it.... also does anyone know what to set the timing at on this engine? and do you set it in the same manner as a car engine? (unhook vacuum line and set base timing?) thanks again... im a member of this forum for life now!!! the guys at the bobcat store around here couldn't even come close to answering the same questions you did on a key board!!

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oh yeah... one more thing... since mine has that square block with the 5 hoses what year range do you think it is? i was told its an 89? but the bobcat guy thought it was a 91?

cadillacderek said:

oh yeah... one more thing... since mine has that square block with the 5 hoses what year range do you think it is? i was told its an 89? but the bobcat guy thought it was a 91?

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Glad it was a simple fix.
I believe your machine would be between 1980 and 1983. The later machines came with the port block stuck to the side of the chassis on the left side. They did away with a lot of those hoses and the rotten suction line filter!
No way is it a 91 model, they stopped building them in 1990. If you still have your serial number your dealer can look it up for you. Honestly a year won't help you much, these machines are built tough!
As for your engine, the knock could be timing of fuel adjustment but from the oil light you mention, it could be more serious. It sounds like it could be a big end knock. The oil light will be on from wear of the bearings giving you lower oil pressure.
As for timing, that does sound rite, i have never worked on one of those engines.
The oil light, you can try using a heavier weight oil like you use in *older* engines, it may help a bit. Its something you need to look into, low oil pressure is BAD if you run it too long.

Tazza said:

Glad it was a simple fix.
I believe your machine would be between 1980 and 1983. The later machines came with the port block stuck to the side of the chassis on the left side. They did away with a lot of those hoses and the rotten suction line filter!
No way is it a 91 model, they stopped building them in 1990. If you still have your serial number your dealer can look it up for you. Honestly a year won't help you much, these machines are built tough!
As for your engine, the knock could be timing of fuel adjustment but from the oil light you mention, it could be more serious. It sounds like it could be a big end knock. The oil light will be on from wear of the bearings giving you lower oil pressure.
As for timing, that does sound rite, i have never worked on one of those engines.
The oil light, you can try using a heavier weight oil like you use in *older* engines, it may help a bit. Its something you need to look into, low oil pressure is BAD if you run it too long.

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The base timing on the ford 4 cyl in the 632 is 12 btc and I think you have the same engine. It is set the same as a car, disconnect the vacuum advance and plug the hose. set at 600 rpm and then speed up to 2000 to check if the centrifugal advance is working.

jerry said:

The base timing on the ford 4 cyl in the 632 is 12 btc and I think you have the same engine. It is set the same as a car, disconnect the vacuum advance and plug the hose. set at 600 rpm and then speed up to 2000 to check if the centrifugal advance is working.

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Ok guys... i think i got the timing dialed in ... seems to run ok now thanks again.... anyway,... my new problem is that it seems to make a loud whinning sound when i turn? its simmilar to the sound it was making when the filter was plugged?... but only when i turn?.. and it also seems to be weeker when i turn then when i just go forward or backward? like pressure is bleeding off or something? is this normal, or is my pump on its way out? anything i should look at? thanks!!!

cadillacderek said:

Ok guys... i think i got the timing dialed in ... seems to run ok now thanks again.... anyway,... my new problem is that it seems to make a loud whinning sound when i turn? its simmilar to the sound it was making when the filter was plugged?... but only when i turn?.. and it also seems to be weeker when i turn then when i just go forward or backward? like pressure is bleeding off or something? is this normal, or is my pump on its way out? anything i should look at? thanks!!!

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the pump could be weak....the filter that you cleaned should be replaced they don't cost much...they make some noise when turning usually the noise is better(less) with more throttle. check that the radiator and oil cooler are clean and the hydraulic level as well......Jeff

sterlclan said:

the pump could be weak....the filter that you cleaned should be replaced they don't cost much...they make some noise when turning usually the noise is better(less) with more throttle. check that the radiator and oil cooler are clean and the hydraulic level as well......Jeff

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One thing I did with my 642 (which has the same engine in it) was to hook up a Charge Pressure gauge and an engine oil pressure gauge in the cab. If the engine oil pressure gauge reads ok, you may have a bad idiot light sending unit.
Likewise, with the older machines I find it nice to know what the hydrostatic charge pressue is, this is the oil pressure that stuffs the hydrostatic pumps. This is plumbed into the same line as the charge pressure sending unit on the port block.

Bernie

bfingar said:

One thing I did with my 642 (which has the same engine in it) was to hook up a Charge Pressure gauge and an engine oil pressure gauge in the cab. If the engine oil pressure gauge reads ok, you may have a bad idiot light sending unit.
Likewise, with the older machines I find it nice to know what the hydrostatic charge pressue is, this is the oil pressure that stuffs the hydrostatic pumps. This is plumbed into the same line as the charge pressure sending unit on the port block.

Bernie

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Tazza, I think I have the same symptoms described in this post, but mine is the other style with one big fat black hose going to an alloy block. Is there a bronze filter in this setup too? Do I have to drain the fluid before changing this filter? Cheers, Edmund

edo102 said:

Tazza, I think I have the same symptoms described in this post, but mine is the other style with one big fat black hose going to an alloy block. Is there a bronze filter in this setup too? Do I have to drain the fluid before changing this filter? Cheers, Edmund

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Unfortunately the newer style with the big hose doesn't have a filter.
What is the problem with your drive? just lack of power? Hate to say it, but could be the pumps...
Does your oil get foamy?

Tazza said:

Unfortunately the newer style with the big hose doesn't have a filter.
What is the problem with your drive? just lack of power? Hate to say it, but could be the pumps...
Does your oil get foamy?

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When I turn, it is pretty noisy. It is certainly better when full throttle, but I feel it is louder than other 743's I have seen/heard. Also, the last time I was using it for a while to spread gravel, after about 2 hours, the power dropped off, and it was really noisy trying to turn. I turned it off and let it sit for a while, and then it had regained power and wasn't as noisy. I didn't check to see if the oil was foamy, and haven't had a chance to run it for a good stint since. Any ideas? Thanks, Edmund

edo102 said:

When I turn, it is pretty noisy. It is certainly better when full throttle, but I feel it is louder than other 743's I have seen/heard. Also, the last time I was using it for a while to spread gravel, after about 2 hours, the power dropped off, and it was really noisy trying to turn. I turned it off and let it sit for a while, and then it had regained power and wasn't as noisy. I didn't check to see if the oil was foamy, and haven't had a chance to run it for a good stint since. Any ideas? Thanks, Edmund

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I am having about the same problem with my 742. It makes a lot of noise when I try turning it. Gets louder and losses more power the longer I run it. It has the bigger hose on it. Does anyone have any ideas? Thanks?

Deeogee said:

I am having about the same problem with my 742. It makes a lot of noise when I try turning it. Gets louder and losses more power the longer I run it. It has the bigger hose on it. Does anyone have any ideas? Thanks?

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Could it be the Vane pump or maybe the Gear pump. Any help would be Greatly Appreciated!

Deeogee said:

Could it be the Vane pump or maybe the Gear pump. Any help would be Greatly Appreciated!

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My 742 has made that loud whining noise for the 22-years I've owned it. Just turning or partial forward on the sticks. Full forward on both sticks and it is quiet. No leaks, foam or power loss.....just noise. Mine is the later model w/o the suction filter, just the full flow canister.