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Cat Man
Cat Man, Cat Engine Expert
Category: Medium and Heavy Trucks
Satisfied Customers: 8870
Experience:  I am ASE Master Truck Certified.
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Customer Question

MR. CAT-MAN...PRE EXISITING CONDITION: HELP PLEASE!! We thought we had this truck properly repaired, only to find out that the unit is acting the same way as before! 2002 Caterpillar C7 3126 7.2 liter Engine Engine Serial Number: C7KM44559 COMPLAINT: Of
the mornings truck has plenty of power, runs great. The longer the day goes by making deliveries,the engine struggles for power. Many times late in the afternoon running several hours the truck will hardly pull a hill, not getting over 10 MPH. This seems to
occur ONLY when you are CLIMBING A HILL. You LOOSE POWER. Straight-away on level surgace, runs fantastic. When your loosing power, the valves rattle...low oil pressure on dash gauge shows low. We did notice WHITE SMOKE when we first drove truck out of our
shop, AFTER we got engine to normal operating temperature.
Submitted: 1 year ago.
Category: Medium and Heavy Trucks
Expert:  Cat Man replied 1 year ago.

Thanks for asking your question and requesting me. I will try and help you out.

If I remember correctly, the engine light does not come on and the fuel pressure is within 65-85 correct?

Customer: replied 1 year ago.
to both. No engine light comes on and fuel pressure is at 65-85 after the initial repairs.
Expert:  Cat Man replied 1 year ago.

I see. Thanks for the information.

I would suspect you have a low boost condition. This can be caused by a leak in the air piping or air to air aftercooler on the truck. I would first inspect all of the piping to see if there is a hole in any of the rubber boots that hold the pipes. From there you may want to cap off one side of the air to air cooler, and pressurize it. They have been known to crack and leak and cause low boost. You could also have a faulty turbo.

Please let me know if you need more help or have more questions.

Customer: replied 1 year ago.
Will check boot. Will pressurize Charge Air Cooler to 35lbs and see if I have a leak.what should I check on the Turbo to determine if turbo is going bad?
Expert:  Cat Man replied 1 year ago.

Ok sounds good. Look for exhaust side fin damage and excessive turbo shaft end play. It should only move in and out about an 1/8 of an inch.

Please reply back if you need more help or have more questions. I am happy to assist.

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