Oil blowing out - Hyd. resv. & engine -742

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M700man

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Hi guys, Been off the board for awhile. Have been running the 742 pretty hard this week. Checking engine/hydro oil twice daily. No problems, until this afternoon. Checked both and they were right on the full marks. After about 3 hours of running, I noticed that a good bit of oil had come out of the hydro tank, around the dipstick. Further investigation revealed oil covering the left hand side of the engine compartment floor. Dip stick showed engine to be about a pint low. What gives ??? I am on a job with quite a bit more to do, so any help would be greatly appreciated. Thanks, John
 

skidsteer.ca

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Must has a bad seal or gasket.
Top up engine oil and start engine let it idle.
Put your finginer over the blowby tube until a small amount of pressure is felt and look for the leak(s)
Ken
 

Tazza

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Must has a bad seal or gasket.
Top up engine oil and start engine let it idle.
Put your finginer over the blowby tube until a small amount of pressure is felt and look for the leak(s)
Ken
What colour is the oil in the engine bay? If its nice and golden (or whatever colour oil you run) it will be hydraulic oil. It its brown it will be engine oil. If its engine oil and you can't see the leak from the front it may be your rear main seal.
As for the hydraulic oil leaking out the dip stick, this is quite odd, have you checked your cap is vented? if not, when the system warms up it expands and can only escape out the dip stick. Even then, it would have to be on a slope for it to come out.
I do suspect you checked your engine oil level on flat ground?
 

M700man

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What colour is the oil in the engine bay? If its nice and golden (or whatever colour oil you run) it will be hydraulic oil. It its brown it will be engine oil. If its engine oil and you can't see the leak from the front it may be your rear main seal.
As for the hydraulic oil leaking out the dip stick, this is quite odd, have you checked your cap is vented? if not, when the system warms up it expands and can only escape out the dip stick. Even then, it would have to be on a slope for it to come out.
I do suspect you checked your engine oil level on flat ground?
Thanks for the replies, guys. No, we're definitely dealing with two seperate problems. The engine has not lost a drop since it's last oil/filter change (Delo10w30) and as I indicated, I had just checked the oil before startup, yesterday AM, and then again after lunch. Dead on the full mark. After seeing the oil leaking from the engine compartment, my first thought that it was hydro oil. But, the dipstick shows it to be a little below the full mark, at least a pint, maybe a little more. It does have the Bobcat vented cap on the hydro tank, and I should correct my previous statement to say this: I have always noticed a slight leakage around the dipstick tube itself, but nothing that a shop cloth would not clean up. But, this is closer to the "Exxon Valdez" !! (lol). It's a pretty good loss. However, come to think about it, I have been working on some pretty unlevel terrain as well as doing some tight turning between the rolloff container and a bank of earth on one side. It seemed to be "hopping" more than usual yesterday so perhaps it really got the oil to sloshing in the tank. Good question - but yes, both dipstick checks were made on flat ground and after the machine had been cut off for about 20 minutes. I suppose I might refill back up to full on both and run it for an half hour or so (on level terrain) then recheck for leaks. I hope this is all it is. Does this machine have a charge filter ? Additionally, is there a service manual I can view online, for this 742 ?? Thanks for your time and attention. John
 

skidsteer.ca

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Thanks for the replies, guys. No, we're definitely dealing with two seperate problems. The engine has not lost a drop since it's last oil/filter change (Delo10w30) and as I indicated, I had just checked the oil before startup, yesterday AM, and then again after lunch. Dead on the full mark. After seeing the oil leaking from the engine compartment, my first thought that it was hydro oil. But, the dipstick shows it to be a little below the full mark, at least a pint, maybe a little more. It does have the Bobcat vented cap on the hydro tank, and I should correct my previous statement to say this: I have always noticed a slight leakage around the dipstick tube itself, but nothing that a shop cloth would not clean up. But, this is closer to the "Exxon Valdez" !! (lol). It's a pretty good loss. However, come to think about it, I have been working on some pretty unlevel terrain as well as doing some tight turning between the rolloff container and a bank of earth on one side. It seemed to be "hopping" more than usual yesterday so perhaps it really got the oil to sloshing in the tank. Good question - but yes, both dipstick checks were made on flat ground and after the machine had been cut off for about 20 minutes. I suppose I might refill back up to full on both and run it for an half hour or so (on level terrain) then recheck for leaks. I hope this is all it is. Does this machine have a charge filter ? Additionally, is there a service manual I can view online, for this 742 ?? Thanks for your time and attention. John
As Tazza keep a eye on the color of the oil to help determine if its engine or hyd. I'm not sure how extreme the slope was, but you problem may have just been duo to the angle and the hopping. Neither level was critically low so just try it under more normal circumstances.
Ken
 

Tazza

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As Tazza keep a eye on the color of the oil to help determine if its engine or hyd. I'm not sure how extreme the slope was, but you problem may have just been duo to the angle and the hopping. Neither level was critically low so just try it under more normal circumstances.
Ken
There is a suction line filter on the earlier machines. If there is a square block on the hydraulic pump you have a suction line filter. If there is no block you do not have a hidden suction line filter.
If you have the block, its on the left side where 3 hoses join, its behind the fitting for the center hose.
I would suspect it was just the angle you were working on causing the hydro oil leak, but the engine oil leak will not be angle related. Keep an eye on it.
 

M700man

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Mar 26, 2006
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There is a suction line filter on the earlier machines. If there is a square block on the hydraulic pump you have a suction line filter. If there is no block you do not have a hidden suction line filter.
If you have the block, its on the left side where 3 hoses join, its behind the fitting for the center hose.
I would suspect it was just the angle you were working on causing the hydro oil leak, but the engine oil leak will not be angle related. Keep an eye on it.
Just a brief update to let everyone know my findings. The hydro oil leak was a result of a broke dipstick tube - poor system, if you ask me, to solder a dipstick tube into the side of the hydro tank. Apparently a limb had hit it and broke it loose. Not wanting to drain and remove tank for repair, I took a chance on JB Weld and so far it has worked. As to the engine oil leak, it was coming from the cover plate on the oil pump. Replaced O ring behind same, and stopped leak. It still stands to reason, that some of the hydro oil may have sloshed out due to extreme grade operations. Thanks to all who replied. John
 
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