Scary moment on the Bobcat today.

[Dajain]

Hi Guys and gals!
I have a 1999 Bobcat 873 Skidsteer with about 3500 hours on it.

It's been super reliable and we've owned it for 15 years now.

Today, was digging and not pushing it real hard, only about half throttle.
Suddenly, the RPM's spiked and white smoke was coming from the exhaust. HEAVY white smoke.
There was a heavy knocking sound also.
Turned off the key, it did NOT shut down.
Throttled the lever down, engine did NOT throttle down.
Only way I shut it down was snubbing it out with hyd. back pressure.

Once shut down and throttle in the idle position, motor will start and run fine at idle but any throttle more than 1/4, and she does it again.

I'm thinking it's the oil seal in the turbo that is failing.
Engine RPM goes up and so does the oil pressure.
The extra oil in the cylinders causing a run away condition.

I haven't looked into it yet but I'm thinking it's time for a turbo.

What are your thoughts on this? Really need to get this fixed ASAP as I use it every day.

Thanks for any replies and suggestions!
That extra oil pressure going past the seal in the turbo and causing the over run and dieseling

 

[brdgbldr]

I agree with you that it is probably the turbo.

However, a few years ago I came across a guy that actually had the same symptoms but it ended up being a hydraulic hose that was spraying fluid into the air intake. I think this was a once in a lifetime longshot.

If it's the turbo you should notice that the engine oil is getting lower.

 

[Dajain]

I agree with you that it is probably the turbo.

However, a few years ago I came across a guy that actually had the same symptoms but it ended up being a hydraulic hose that was spraying fluid into the air intake. I think this was a once in a lifetime longshot.

If it's the turbo you should notice that the engine oil is getting lower.

Hydraulic spraying into the intake? Did he buy a lottery ticket after that? haha

Due to witnessing a run away once before, I'm not going to press my luck.
I ordered a turbo and when it gets here, I'll swap it out.

I would be almost willing to bet good money that is what it is.
Once I find oil in the intake side of the turbo, it will be a definite.
Crossing fingers.

 

[Tlawdogg]

Where did you order the turbo from and how much was it?
Thank you.

 

[Dajain]

Where did you order the turbo from and how much was it?
Thank you.

There are ebay turbos for $100. didn't go there.
Amazon. $250 plus... No warrantee mentioned
Amazon with a 1 year warrantee? $350 plus...

Bobcat, rebuilt is $2600. New is $3800.

Going with the amazon one year.

 

[Tlawdogg]

Copy that...$2600 & 3800 is nutz..
Keep us posted!

 

[gjinc]

Have a way to block off the air intake. Old Detroit's would run away, only way to stop them was with a peice of wood or heavey blanket over the air intake.

 

[tech.35058]

When I worked in the "old dyno", we would stand by with a rubber "board" to cover the turbo inlet on the first start up after a rebuild. Then we had lines run to dump a big CO2 bottle in the intake if one ran away.
The "new" Dyno simply applied massive load to stall the engine .

Oil smoke should have been black or Dark blue.
White smoke would be unburned fuel, heavy knock might be a fuel knock.
I am not a Bobcat guy, remind me what engine, & what kind of fuel injection pump?

 

[Dajain]

Have a way to block off the air intake. Old Detroit's would run away, only way to stop them was with a peice of wood or heavey blanket over the air intake.

I worked in the underground mining industry for years and an intake shut off is required on all heavy equipment for underground. Wouldn't be a bad standard to adapt to all diesels, but I'm not the engineer designing these things. lol

When I worked in the "old dyno", we would stand by with a rubber "board" to cover the turbo inlet on the first start up after a rebuild. Then we had lines run to dump a big CO2 bottle in the intake if one ran away.
The "new" Dyno simply applied massive load to stall the engine .

Oil smoke should have been black or Dark blue.
White smoke would be unburned fuel, heavy knock might be a fuel knock.
I am not a Bobcat guy, remind me what engine, & what kind of fuel injection pump?

The guy that told me it was white smoke really isn't any kind of diesel person. He said it was white smoke but I could smell that it was burning oil.
And sorry, but I have to correct ya on this one.
Unburnt fuel would be black smoke. In the truck world, they call it rolling coal.
Coolant (Which the bobcat doesn't use) would be white.
A bad injector, or a cylinder lean condition could cause white smoke also.
Burning oil would be light blue and could be considered "white" to the untrained eye.

The other source of black smoke is if the engine is on fire and everything rubber on it is burning.

But, the knock should be a fuel knock, like you said. With the turbo not spooling up, it's dumping the fuel in but not getting the air delivery needed. During restart, it acts "Flooded" but restarts and clears the cylinders out.
The motor is a Deutz BF4M 1011 engine

 

[tech.35058]

Did replacing the turbo cure the problem?

 

[Dajain]

Did replacing the turbo cure the problem?

I replaced the turbo and it did fix the issue. Took right off and was running great.

Then, 2 days later, went to go use it and did all the normal checks.
The oil was about a gallon over full!
Did my checks and found the lift pump was leaking into the crankcase.

New lift pump is now installed. Found them online for less than $30 but didn't skimp on this. Went to Bobcat and got the OEM part.

She is now filled with Royal Purple and running great again.

Can't complain at all. We've owned her for 15 years now and these were the first problems we've ever had.

Thanks for all the help guys.

 

[MalcolmV8]

Turned off the key, it did NOT shut down.
Throttled the lever down, engine did NOT throttle down.
Only way I shut it down was snubbing it out with hyd. back pressure.

That's pretty intense, I hope I never have to deal with that but I have to ask how did you "snub it out with hyd. back pressure" as you put it?
It sounds like some quick thinking there.

 

[Dajain]

That's pretty intense, I hope I never have to deal with that but I have to ask how did you "snub it out with hyd. back pressure" as you put it?
It sounds like some quick thinking there.

I knew that my air filter was about 50% and I think that was a huge factor with being able to stall it out.
Once I realized what it was doing, and the key would not shut it down, trying to stall it was the only thing I thing of.
I pulled the throttle all the way back, turned on the hydraulics and the high flow auxiliary hydraulics and hit all 3 functions at once.
With the bucket tilt up, the boom lift down and the hi-flow activated, it was enough to snub out the engine.

Have the old girl fixed now and she is running great.

 

[MalcolmV8]

I knew that my air filter was about 50% and I think that was a huge factor with being able to stall it out.
Once I realized what it was doing, and the key would not shut it down, trying to stall it was the only thing I thing of.
I pulled the throttle all the way back, turned on the hydraulics and the high flow auxiliary hydraulics and hit all 3 functions at once.
With the bucket tilt up, the boom lift down and the hi-flow activated, it was enough to snub out the engine.

Have the old girl fixed now and she is running great.

Great job and quick thinking there. Thanks for sharing and glad to hear it's back up and running again.

 

[Stumper1624]

I knew that my air filter was about 50% and I think that was a huge factor with being able to stall it out.
Once I realized what it was doing, and the key would not shut it down, trying to stall it was the only thing I thing of.
I pulled the throttle all the way back, turned on the hydraulics and the high flow auxiliary hydraulics and hit all 3 functions at once.
With the bucket tilt up, the boom lift down and the hi-flow activated, it was enough to snub out the engine.

Have the old girl fixed now and she is running great.

flipping lap bar up and full forward would probably work too