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Cat 120m won't start and is leaking fuel around #1injector…

Customer Question
Cat 120m won't start and...
Cat 120m won't start and is leaking fuel around #1injector line .
What should I look for to stop the fuel leak and get it to start?
Submitted: 9 months ago.Category: Construction and Road Equipment
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Answered in 5 minutes by:
9/24/2017
Mechanic: catmastertech, Technician replied 9 months ago
catmastertech
catmastertech, Technician
Category: Construction and Road Equipment
Satisfied Customers: 2,526
Experience: Field service technician for CAT 19 years.
Verified

If this is the C6.6 or C7.1 engine, you have high-pressure rail fuel system and these lines must be replaced if normal tightening does not stop leaks. These lines are never to be loosened for purging air from the lines. The system will self-purge any air in the lines.

Be sure to check the rail for damage. I have seen one of these break off the fitting at the center rail.

If you need more help, please post the complete serial number of this machine.

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Mechanic: catmastertech, Technician replied 9 months ago

Please note, you will need to return to the site chat page to reply.

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Customer reply replied 9 months ago
s/n D9W147
Is it just the lines to be replaced and what happens to them if loosened? I did loosen them
Mechanic: catmastertech, Technician replied 9 months ago

The lines are designed for a "CRUSH" to fit seal. CAT always recommends replacing any line that is removed. It is also imperative that all fuel system components be kept clean and sealed in their bag to prevent contmination.

I have re-used lines when making repairs and lines are not available. However, if I am making a repair that requires removal of a line, I will order a new replacement line.

The common rail should be fine if you did not cross thread the fitting or break it trying to over-tighten the line to stop the leaks.

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Mechanic: catmastertech, Technician replied 9 months ago

Below is the exact information from CAT

Cleanliness of Fuel System Components

Cleanliness of the Engine

NOTICE

It is important to maintain extreme cleanliness when working on the fuel system, since even tiny particles can cause engine or fuel system problems.

The entire engine should be washed with a high-pressure water system. Washing the engine will remove dirt and loose debris before a repair on the fuel system is started. Ensure that no high-pressure water is directed at the seals for the injectors.

Environment

When possible, the service area should be positively pressurized. Ensure that the components are not exposed to contamination from airborne dirt and debris. When a component is removed from the system, the exposed fuel connections must be closed off immediately with suitable sealing plugs. The sealing plugs should only be removed when the component is reconnected. The sealing plugs must not be reused. Dispose of the sealing plugs immediately after use. Contact your nearest Caterpillar dealer in order to obtain the correct sealing plugs.

New Components

High-pressure fuel lines are not reusable. New high-pressure lines are manufactured for installation in one position only. When a high-pressure line is replaced, do not bend or distort the new line.

All new fuel filters, high-pressure fuel lines, tube assemblies, and components are supplied with sealing plugs. These sealing plugs should only be removed in order to install the new part. If the new component is not supplied with sealing plugs, then the component should not be used. The technician must wear suitable rubber gloves. The rubber gloves should be disposed of immediately after completion of the repair in order to prevent contamination of the system.

Refueling

In order to refuel the diesel fuel tank, the refueling pump and the fuel tank cap assembly must be clean and free from dirt and debris. Refueling should take place only when sheltered from dust, wind, and rain. Only use fuel, free from contamination, that conforms to the specifications in the Operation and Maintenance Manual, "Fluid Recommendations" Fuel Specifications.

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Customer reply replied 9 months ago
When replacing the lines in our cleanest environment the connections under the valve cover are ok to connect to? Those don't need to be replaced?
Mechanic: catmastertech, Technician replied 9 months ago

The Quill tube is held in place with a locknut. It also has a locating tab on the tube to prevent it turning. As long a the threads are clean, you should not have any issue. The quill tube is like the common rail, the metal is harder than the fuel line.

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Mechanic: catmastertech, Technician replied 9 months ago

Sorry, that is for the larger engine. This one is slightly different. Let me get the instructions to help you with that.

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Mechanic: catmastertech, Technician replied 9 months ago

Here is the correct installation instructions for your fuel lines.

https://drive.google.com/open?id=0B8Gc4s_tr2LzYmw0dUwxcFFhNXc

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