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Cat Man
Cat Man, Caterpillar Engine Expert
Category: Heavy Equipment
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Experience:  23 Years Caterpillar Engine experience.
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C7..2005, we have resealed the injectors..valve cover..bubbles

Resolved Question:

how can fuel get into the oil cat c7 2005, we have resealed the injectors.did not fix,had valve cover off put shop air to the fuel entrance no visable there a chance for the fuel to be mixing in a injector body not to be seen.took head to machine shop to magnaflux said no problems.any suggestions?
Could the head be internaly leaking that fuel in oil but the oil prssure is so high,huey pump that the oil would go into the fuel.Thanks .
Submitted: 5 years ago.
Category: Heavy Equipment
Expert:  Cat Man replied 5 years ago.

Hi. Thanks for using JA! I will try and help you out.


It is not possible for fuel to get into the oil from an injector. The High pressure oil is much higher than the fuel so the oil will always go into the fuel.


Since you have had the head check for this problem, the only thing left is the fuel transfer pump. It is located on the back of the HEUI pump. I would recommend replacing the pump.


Please let me know if you have more questions.

Customer: replied 5 years ago.
we have already replaced the transfer
Expert:  Cat Man replied 5 years ago.
Thanks for the information.

Since the tranfer pump has been replaced already, the problem must be in the head somewhere. I know that you had it checked but there is no other place that fuel can enter the oil.
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