Help -fuel sending unit issue, hydo oil in engine

[Work Horse]

Hello everyone,

My b7200 has a couple issues I'm looking to sort out and would appreciate the help.

I recently discovered hydraulic oil is getting into the engine. I've read the pump is usually the culprit. It looks like (per diagrams) all I need is a gasket for the pump assy, and an oil seal. Is that all? From what I've been able to find this is a very straight forward job. Sound right?

2nd issue is I recently ran into a lot of electrical issues. I have since fixed all but my fuel gauge. I have 7v (if I recall) from the regulator at one wire, and 12v at the power wire and the fuel sending unit. I bought a new fuel gauge and still have the issue. Is there a way to test the fuel sending unit before purchasing a new one for $100. Thank you guys, appreciate it!

 

[Roadworthy]

The hydraulic oil could be as simple as a bad seal on the pump. Externally the pump WOULD appear normal if only the seal was leaking. Generally a sending unit is simply a variable resistor changed by the float in the tank. Try moving the float up and down. The gauge should follow. You don't indicate if you think your gauge is reading high, low, or somewhere in between.

 

[Work Horse]

The hydraulic oil could be as simple as a bad seal on the pump. Externally the pump WOULD appear normal if only the seal was leaking. Generally a sending unit is simply a variable resistor changed by the float in the tank. Try moving the float up and down. The gauge should follow. You don't indicate if you think your gauge is reading high, low, or somewhere in between.

The pump "appears" normal. I'm gonna go ahead and order the seal/gasket after I confirm if I need a sending unit as well.

The fuel gauge is stuck on empty. I replaced the gauge with a new one and same result. I tried reversing the wires in case I mixed them up and no difference was made. When I had the old gauge in I was accidentally a big dummy and tapped the power to ground and blew a fuse. Did I blow the resistor too? Moving the float doesn't change the gauge. Thanks!

 

[Roadworthy]

If you have an ohmmeter disconnect the sending unit wires. Replace them with the ohmmeter wires. Moving the arm on the sending unit should have a corresponding effect on the ohmmeter. At one end of the travel you should read zero. At the other end you will see what the full scale resistance is. As you move the float you should get varying resistances in between.

 

[Work Horse]

If you have an ohmmeter disconnect the sending unit wires. Replace them with the ohmmeter wires. Moving the arm on the sending unit should have a corresponding effect on the ohmmeter. At one end of the travel you should read zero. At the other end you will see what the full scale resistance is. As you move the float you should get varying resistances in between.

Yup, I got nothing. Placed the meter's ground on the original position as well as the battery terminal, and no change. I wasn't sure how many omhs it might draw but there was no difference switching from each Ohm setting. Looking like that's my culprit, although it doesn't seem very common.

 

[Roadworthy]

Nothing "draws" ohms. It's a measure of electrical resistance between two points. With your meter leads apart the meter should read infinite. Shorting the leads will get near zero. With your two leads on the two terminals of the sending unit you will be measuring its resistance. That will vary from near zero at one end of its travel to the resistance of the unit as you move the float to the other end of its travel. In actual use a small current passes through the sending unit and as the float moves up or down this current is read on the meter as the fuel level in the tank.

 

[Work Horse]

Nothing "draws" ohms. It's a measure of electrical resistance between two points. With your meter leads apart the meter should read infinite. Shorting the leads will get near zero. With your two leads on the two terminals of the sending unit you will be measuring its resistance. That will vary from near zero at one end of its travel to the resistance of the unit as you move the float to the other end of its travel. In actual use a small current passes through the sending unit and as the float moves up or down this current is read on the meter as the fuel level in the tank.

I wish I learned a lot of this stuff in school, or from somebody knowledgeable. I'm 28 now and I've been figuring this kind of stuff out "on my own" for a long time now. Back to my first oil change at 16, which I learned how to do on-line.

Anyways. The sending unit only has one lead. A positive (+) that connects to the fuel gauge. The other is grounded to the plate that holds the sending unit it place. Is there something I'm missing? Can the same terminal be used for both leads to measure Resistance? TIA

 

[Dave_eng]

I wish I learned a lot of this stuff in school, or from somebody knowledgeable. I'm 28 now and I've been figuring this kind of stuff out "on my own" for a long time now. Back to my first oil change at 16, which I learned how to do on-line.

Anyways. The sending unit only has one lead. A positive (+) that connects to the fuel gauge. The other is grounded to the plate that holds the sending unit it place. Is there something I'm missing? Can the same terminal be used for both leads to measure Resistance? TIA

To measure the sending unit resistance use the body of the sender as one terminal and the actual wire terminal as the other.

Dave

 

[Roadworthy]

I've got over forty years in the electrical construction trades and it's not all intuitive. I've got schooling beyond that. There are ALWAYS two terminals minimum. One of these may be ground. Hook one ohmmeter terminal up to ground and the other to your lonely terminal. The meter has power in it so it will essentially act as your fuel gauge. Move the float and watch to see if the reading changes. That will tell if the sending unit is working.

 

[Work Horse]

I've got over forty years in the electrical construction trades and it's not all intuitive. I've got schooling beyond that. There are ALWAYS two terminals minimum. One of these may be ground. Hook one ohmmeter terminal up to ground and the other to your lonely terminal. The meter has power in it so it will essentially act as your fuel gauge. Move the float and watch to see if the reading changes. That will tell if the sending unit is working.

That's what I tried before. One on the ground of the sending unit and one on the lead. No resistance at any position of the float. I re-tested and same result.

Ordered a new sending unit, will send back the new gauge if old gauge is still good. Thanks for the help guys! Definitely basic electrical, but I've never messed with resistors so I appreciate it.

I need to use the tractor this weekend. While I'm waiting for the pump seal to arrive, do you think I will be ok if I do an oil change and continue to run it? IDK how similar hydro fluid is to engine oil but certainly don't wanna ruin the engine.

 

[D2Cat]

Since you are getting hydraulic oil in the engine, I would not use the tractor until that is cured. You're asking for a possibly larger repair bill if you do.

 

[Roadworthy]

In my old Mitsubishi it was normally a failure of the shaft seal on the oil pump. Oil leakage could be slow or fast depending on how badly it failed. If leaking too fast it can overfill your crankcase in the course of a days work possibly causing hydro lock (or whatever it's called) in the engine resulting in fantastically high repair bills. In any case it will degrade the lubrication properties of the oil. Use the tractor at your own risk. If you MUST use it keep a close watch on the dipstick oil level.

 

[Work Horse]

In my old Mitsubishi it was normally a failure of the shaft seal on the oil pump. Oil leakage could be slow or fast depending on how badly it failed. If leaking too fast it can overfill your crankcase in the course of a days work possibly causing hydro lock (or whatever it's called) in the engine resulting in fantastically high repair bills. In any case it will degrade the lubrication properties of the oil. Use the tractor at your own risk. If you MUST use it keep a close watch on the dipstick oil level.

I've done some more research online, and I'm hoping someone will confirm this. I've read hydraulic fluid is essentially engine oil without the detergents.

What happens when you run an engine with hydraulic oil in the engine oil? - Quora

.

My plan was to do an oil change and check the levels periodically during use. "Luckily" the crankcase hasn't overfilled because of the crank leak - only reason I knew something was off was I had been leaking oil for days and somehow the dipstick always read "full." That's when I checked the trans fluid level...

 

[Pau7220]

Since you are getting hydraulic oil in the engine, I would not use the tractor until that is cured. You're asking for a possibly larger repair bill if you do.

You're getting good advice here...

 

[Work Horse]

Changed the oil and ran the machine for a few hours yesterday and all is good.

Super pumped, got the parts I ordered today - only 3 days. Go Messics and FedEx! Tested the new sending unit before installing and all is good! Hoping to get to the oil seals withing the next couple days. Thanks everyone!