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 Tim Your Own Question

Tim
Tim, Foreman
Category: Heavy Equipment
Satisfied Customers: 356
Experience:  23 Years Heavy Equipment and Truck Repairs Shop and Field in the Minning and Construction Industry
16986108
Type Your Heavy Equipment Question Here...
Tim is online now
A new question is answered every 9 seconds

My c12 cat engine for a 1999 freightliner..low oil pressure..gages

Resolved Question:

my c12 cat engine for a 1999 freightliner keeps warning that i have low oil pressure and my gages indicate the same. i have all ready replaced the oil pump ,sensor, by pass valv, oil base filter pan, buchings are new the crank shaft is good, and yet still the oil pressure is low when i turn it on cool the pressure marked good the psi is on 45 when the temp hits 200 it comes down to 35-40 psi but when i run it and hit about 40-55mph the oil pressure goes down to like 10- 20 psi and the low oil pressure alarm comes on and it stays like that it wont come back up also the check engine light comes on to
Submitted: 5 years ago.
Category: Heavy Equipment
Expert:  Tim replied 5 years ago.

Hello, welcome to JA , my name isXXXXX will try to help.. It looks as if you have covered all your bases, from your symptoms I would be leaning toward a couple things more so even though they have been checked, worn bearing and bushing clearences. ( especialy if you have only low oil pressure at high idle) I once had a 3508 that was oversped and the Idler bearing clearence was increased and the oil pressure was fine except at high idle, when the clearence would open. your specs at normal oper temp is 40-60 at 1800 rpm and min of 10 psi at idle. the other thoght I had was the possibilty of a pump suction problem from a crack or restriction. It may be worth taking a oil sample and sending it in.. they can tell you if you have metal showing and that could help it narrow down to the worn parts, and fuel or coolant containinant.. here is Cats list of possibilities, hope this helps..

  • 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 pickup 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, "Refill Capacities and Recommendations" 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. Refer to Operation and Maintenance Manual, "Refill Capacities and Recommendations" for the recommendations of engine oil.

 

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. New engine oil filters will prevent more debris from causing this problem. 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. Determine the reason for an open lubrication system of the engine and make the necessary repairs.

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 pickup 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.

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".

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.

 

Thank you,

tim

 

Tim, Foreman
Category: Heavy Equipment
Satisfied Customers: 356
Experience: 23 Years Heavy Equipment and Truck Repairs Shop and Field in the Minning and Construction Industry
Tim and 2 other Heavy Equipment Specialists are ready to help you

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

What Customers are Saying:

 
 
 
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
< Last | Next >
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
  • used your service this weekend with "Trecers" help. thank you ,thank you, thank you. replaced an A/C fan motor. Local Auto Zone had part. $15.00 "tracer" fee and $40.00 for parts, I saved several hundreds of dollers at a shop. i will recommend you and use you in the future. David L. Richmond, TX
  • 9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much. Phil Marysville, CA
  • Lurch. Thank you very much. I had real doubts about this website but your promptness of response, quick followup and to the point answer with picture was incredible. Charles Walnut Creek, CA
  • As a single woman, I really appreciate an excellent and affordable opinion.
    Thank you Geordie, I will not hesitate to contact justanswer in the future!
    Sue Charleston, WV
  • Another great insight to what may be the problem. I will have my mechanic take a look at it tomorrow. Thanks again, Frank...you do indeed know your stuff. Jim Castleberry, FL
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
 
 
 

Meet The Experts:

 
 
 
  • Chris (aka - Moose)

    Technician

    Satisfied Customers:

    112
    16 years of experience
< Last | Next >
  • http://ww2.justanswer.com/uploads/MU/muddyford/2012-6-13_1204_1.64x64.png Chris (aka - Moose)'s Avatar

    Chris (aka - Moose)

    Technician

    Satisfied Customers:

    112
    16 years of experience
  • http://ww2.justanswer.com/uploads/Boxerman1969/2009-06-22_213107_ja_avatar.JPG Tim's Avatar

    Tim

    Foreman

    Satisfied Customers:

    338
    23 Years Heavy Equipment and Truck Repairs Shop and Field in the Minning and Construction Industry
  • http://ww2.justanswer.com/uploads/jrwhitey2000/2009-01-03_193237_me.jpg J.R.'s Avatar

    J.R.

    Technician

    Satisfied Customers:

    148
    13 years as warranty technician for Detroit Diesel
  • http://ww2.justanswer.com/uploads/yellowman99/2010-03-20_033822_Marshall_Pete_Furr.jpg Cat Man's Avatar

    Cat Man

    Caterpillar Engine Expert

    Satisfied Customers:

    3714
    23 Years Caterpillar Engine experience.
  • http://ww2.justanswer.com/uploads/WT/wtolkson/2012-6-8_12723_JApicture2012.64x64.jpg Wayne's Avatar

    Wayne

    Journeyman

    Satisfied Customers:

    3023
    34 years experiance as engine rebuild and problems.Thermo-King repair and trouble shooting.
  • http://ww2.justanswer.com/uploads/cumminsdr/2010-7-20_204410_ja.jpg DR.Cummins's Avatar

    DR.Cummins

    FIELD SERVICE TECHNICIAN

    Satisfied Customers:

    2354
    16 Years working on Cummins Diesel engines,
  • http://ww2.justanswer.com/uploads/KO/koboma/2012-6-6_20917_DSCF1022.64x64.JPG Curtis B.'s Avatar

    Curtis B.

    service manager

    Satisfied Customers:

    2229
    30 years exp. with diesel engines, heavy equipment and forklifts, including lp forklifts
 
 
 
Chat Now With A Technician
Tim
Tim
Technician
356 Satisfied Customers
23 Years Heavy Equipment and Truck Repairs Shop and Field in the Minning and Construction Industry