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Low oil pressure at idle 953C BBX Cat won’t idle engine

Customer Question
Low oil pressure at...

Low oil pressure at idle 953C BBX Cat won’t idle engine stops

Mechanic's Assistant: What is the complete model and serial number of your machine?

953C BBX01022

Mechanic's Assistant: Are you fixing this yourself? What have you tried so far?

Installed new hi pressure pump assy new transfer pump and icp sensor changed oil and all fillters

Mechanic's Assistant: Anything else you want the Construction Mechanic to know before I connect you?

Starts with ether won’t start on its own runs at full throttle ok

Submitted: 1 year ago.Category: Construction and Road Equipment
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Answered in 43 minutes by:
12/31/2020
Mechanic: catmastertech, Technician replied 1 year ago
catmastertech
catmastertech, Technician
Category: Construction and Road Equipment
Satisfied Customers: 4,040
Experience: Field service technician for CAT 19 years.
Verified

Hey, sorry to hear you are having these problems. I know that can be frustrating. Hopefully, we can get you back to work quickly. I see no one could help you earlier, and I hope this is not too late to be helpful. Please note that I am not set up for phone calls, you can ignore the site pop-ups. We can post to this chat as much as you like to work through this issue. All experts are not employees, and we work from home in our spare time to answer questions.

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Hard to start and poor idling are normally due to worn out injectors. The HEUI pump can also be an issue but, dirty fuel and frequent plugging of fuel filters is a clue that the injectors are the problem.

However, if the engine oil pressure is too low, internal wear of the pump or the engine may be an issue as the engine oil pump supplies the HEUI pump its oil.

Engine Stalls at Low RPM

Probable Causes

  • Unit injectors

     

  • Fuel supply

     

  • Air supply

     

  • Engine idle

     

  • Accessory equipment
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Customer reply replied 1 year ago
Installed new HEUI pump engine runs fine under throttle won't start or idle when started oil pressure lights starts flashing engine shuts off seems to be low oil pressureNot injector issue
Mechanic: catmastertech, Technician replied 1 year ago

I assume you have tested the actual oil pressure? Was it far from spec?

What is the actuation pressure at idle? And full speed?

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Customer reply replied 1 year ago
Spinning the engine over it will only build 10 psiChecking with direct guage
Mechanic: catmastertech, Technician replied 1 year ago

Low Engine Oil Pressure

Probable Causes

  • Engine oil level

     

  • Engine oil filters and oil filter bypass valve

     

  • Engine oil pump

     

  • Engine oil cooler

     

  • Fuel dilution

     

  • Engine wear

The minimum engine oil pressure at 1200 rpm should be approximately 275 kPa (40 psi). Minimum engine oil pressure at low idle rpm (400 to 600 rpm) should be approximately 100 kPa (15 psi).

The maximum oil pressure should be no higher than 600 kPa (88 psi) for all rpm ranges.

I can't say what the pressure would be at cranking speed.

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Customer reply replied 1 year ago
75 lbs at full throttle leaning towards oil pump issue
Mechanic: catmastertech, Technician replied 1 year ago

Reasons for Low Engine Oil Pressure

  • Engine oil level is low. Refer to Step 1.

     

  • Engine oil is contaminated. Refer to Step 2.

     

  • The engine oil bypass valves are open. Refer to Step 3.

     

  • The engine lubrication system is open. Refer to Step 4.

     

  • The oil suction tube has a leak or a restricted inlet screen. Refer to Step 5.

     

  • The engine oil pump is faulty. Refer to Step 6.

     

  • Engine bearings have excessive clearance. Refer to Step 7.

 

  1. Check the engine oil level in the crankcase. The oil level can possibly be too far below the oil pump supply tube. This will cause the oil pump not to have the ability to supply enough lubrication to the engine components. If the engine oil level is low add engine oil in order to obtain the correct engine oil level. Refer to Operation and Maintenance Manual for the recommendations of engine oil.

     

  2. Engine oil that is contaminated with fuel or coolant will cause low engine oil pressure. High engine oil level in the crankcase can be an indication of contamination. Determine the reason for contamination of the engine oil and make the necessary repairs. Replace the engine oil with the approved grade of engine oil. Also replace the engine oil filter. Refer to Operation and Maintenance Manual for the recommendations of engine oil.

    NOTICE

    Caterpillar oil filters are built to Caterpillar specifications. Use of an oil filter not recommended by Caterpillar could result in severe engine damage to the engine bearings, crankshaft, etc., as a result of the larger waste particles from unfiltered oil entering the engine lubricating system. Only use oil filters recommended by Caterpillar.

  3. If the engine oil bypass valves are held in the open position, a reduction in the oil pressure can be the result. This may be due to debris in the engine oil. If the engine oil bypass valves are stuck in the open position, remove each engine oil bypass valve and clean each bypass valve in order to correct this problem. You must also clean each bypass valve bore. Install new engine oil filters. For information on the repair of the engine oil bypass valves, refer to Disassembly and Assembly, "Engine Oil Filter Base - Disassemble".

     

  4. An oil line or an oil passage that is open, broken, or disconnected will cause low engine oil pressure. An open lubrication system could be caused by a piston cooling jet that is missing or damaged.

    Note: The piston cooling jets direct engine oil toward the bottom of the piston in order to cool the piston. This also provides lubrication for the piston pin. Breakage, a restriction, or incorrect installation of the piston cooling jets will cause seizure of the piston.

  5. The inlet screen of the oil suction tube for the engine oil pump can have a restriction. This restriction will cause cavitation and a loss of engine oil pressure. Check the inlet screen on the oil pickup tube and remove any material that may be restricting engine oil flow. Low engine oil pressure may also be the result of the oil pickup tube that is drawing in air. Check the joints of the oil pickup tube for cracks or a damaged O-ring seal. Remove the engine oil pan in order to gain access to the oil pickup tube and the oil screen. Refer to Disassembly and Assembly, "Engine Oil Pan - Remove and Install" for more information.

     

  6. Check the following problems that may occur to the engine oil pump.

     

    1. Air leakage in the supply side of the oil pump will also cause cavitation and loss of oil pressure. Check the supply side of the oil pump and make necessary repairs. For information on the repair of the engine oil pump, refer to Disassembly and Assembly, "Engine Oil Pump - Remove".

       

    2. Oil pump gears that have too much wear will cause a reduction in oil pressure. Repair the engine oil pump. For information on the repair of the engine oil pump, refer to Disassembly and Assembly, "Engine Oil Pump - Remove".

     

  7. Excessive clearance at engine bearings will cause low engine oil pressure. Check the engine components that have excessive bearing clearance and make the necessary repairs.
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Customer reply replied 1 year ago
No fuel contamination oil he's just been changed with cat oil
Mechanic: catmastertech, Technician replied 1 year ago

Ok, I haven't seen this cause be oil pressure directly. I have always found it was the injectors.

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Customer reply replied 1 year ago
Just started all of the suddenRuns good under throttle when you get it cranked
Mechanic: catmastertech, Technician replied 1 year ago

I would go back and look closer at the fuel supply and transfer pump pressures.

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Customer reply replied 1 year ago
Transfer pump is new
Mechanic: catmastertech, Technician replied 1 year ago

Then, I would go back and look closer at the fuel supply

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Customer reply replied 1 year ago
Thank you
Mechanic: catmastertech, Technician replied 1 year ago

You're welcome. I will be glad to help as much as I can.

Thank you for using JustAnswer, if you do need further help please let me know.

If you are satisfied with my service, please take a moment to provide a rating.

Thanks again, Don

CATMASTERTECH

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Category: Construction and Road Equipment
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