How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Derek Neustaeter Your Own Question
Derek Neustaeter
Derek Neustaeter,
Category: Construction and Road Equipment
Satisfied Customers: 4
Experience:  Heavy Equipment Technician at Warner Industries
90335403
Type Your Construction and Road Equipment Question Here...
Derek Neustaeter is online now
A new question is answered every 9 seconds

I am having stalling trouble with a 1994 311 Excavator SN

Customer Question

I am having stalling trouble with a 1994 311 Excavator SN 9LJ00380. It blows black smoke and stalls, or nearly stalls, when putting a load on the machine, or when the cylinders for the boom, stick, or bucket are bottomed out. Also when turning machine. All filters have been changed and I verified machine was not in "limp mode" at the switch behind the seat. Anyone have any ideas how to diagnose and repair this problem?
Submitted: 1 year ago.
Category: Construction and Road Equipment
Expert:  Derek Neustaeter replied 1 year ago.

Hello there! I am a qualified Heavy Equipment Technician here at Just Answer, I will help you diagnose and repair the problem you are having with Excavator. There are a few problems that can cause black smoke with a diesel engine, I will do my best to walk you through a process of elimination to locate and repair the symptom you are having. Does the engine start quickly without any issues? If you perform whats called a "torque stall" you can identify if the problem is related to a powertrain or hydraulic issue, vs an engine issue. If you place the engine in gear and apply the throttle while your foot is on the brake, does the engine power out and smoke? If so, lets start with the following:

Lets start with the simple, least expensive, possible problems. You mentioned that you have changed all the filters, have you check the air filter, housing, and intake piping for any restrictions? One of the most common problems with a black smoke symptom is a lack of air getting into the engine. If the airway is free of restriction there could be a problem with your turbocharger or fuel injection system, and can diagnose this issue further if you are still having problems.

I hope this answer helps you, I am here if you need any further assistance!

Take care,

Derek

Customer: replied 1 year ago.
engine starts very quickly. All filters are good. No leaks. It torque stalls as mentioned in original post. There are no brakes or clutch, everything is hydraulic. Someone suggested the PRV solenoid, but I don't know where it is located, or how to diagnose it. I do not want to just start throwing parts at it to fix it. Caterpillar is very proud of thier parts!!!
Expert:  Derek Neustaeter replied 1 year ago.

It torque stalls with no symptoms such as loss of power, or black smoke?

Customer: replied 1 year ago.
It stalls, or nearly stalls with black smoke when putting it under any load except for the swing.
Expert:  Derek Neustaeter replied 1 year ago.

Throwing parts at a problem is a great way to spend lots of money. Lets see if we can diagnose this problem the first time!

Referring back to my first post, have you check the air filter, as well as the intaking piping, to check for any possible blockages?

Customer: replied 1 year ago.
Yep! All looks good......
Expert:  Derek Neustaeter replied 1 year ago.

Ok, thats great. Is there any chance you would have access to a gauge you could hook into the charge side of the intake? We need to make sure that we have the proper amount of boost reaching the engine while under load.

Customer: replied 1 year ago.
I might have one. What range does it need to read?
Expert:  Derek Neustaeter replied 1 year ago.

The gauge should ready between 0 and 40 psi. At full torque stall this engine should produce more then 15 psi of boost.

Customer: replied 1 year ago.
Nevermind. It is in fact tthe PRV solenoid on the hydraulic system not reducing pump stroke as the engine loads up. Thanks anyway......
Expert:  Derek Neustaeter replied 1 year ago.

I'm happy to hear the problem has been fixed! If there is anything else I can help you with, just let me know. If possible, please leave feedback on the help I provided today. It would be very appreciated!

Take care,

Derek

Customer: replied 1 year ago.
K
Expert:  Derek Neustaeter replied 1 year ago.

I have now enabled the "I am ready to be rated" option.

Thanks for your business, and if there is anything else I can help you with in the future, just let me know.

Take care,
Derek

Related Construction and Road Equipment Questions