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Cat Man
Cat Man, Caterpillar Engine Expert
Category: Heavy Equipment
Satisfied Customers: 6444
Experience:  23 Years Caterpillar Engine experience.
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installed # 4 injector in c-15 cat 6nz motor also removed other

Resolved Question:

installed # XXXXX injector in c-15 cat 6nz motor also removed other 5 injectors and replaced all o-rings installed all injectors. we set all injector heights with tool we borrowed also checked valve & jake settings. started truck and motor is smoking bad & missing. This is the first injector ever replaced in this motor. Truck had fuel pressure turned to 130 lbs. about 3 yrs. ago. Could this be a problem? . What could be the problem?
Submitted: 3 years ago.
Category: Heavy Equipment
Expert:  Cat Man replied 3 years ago.

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

 

The first thing I would recommend to do (if you haven't already) would be to go back through the over head. Anyone can make a mistake, you may have adjusted something on the wrong engine position.

 

As far as the 130 psi fuel pressure, it should not cause this problem.

 

Did this start out with the engine just having a "Miss" on number 4?

Customer: replied 3 years ago.
truck had been smoking & missing when starting cold after warming up for 15 min. truck ran fine. exhaust manifold gasket was leaking we took exh.manifold off to replace bad gasket. started truck with exh. manifold off & found excessive smoke from #4 cylinder this is why we replaced #4 injector . when pulling injector we noticed o-rings were cracked & broken tnen we decided to replace the o-rings on all of the inj. put excessive STP on o-rings before installing.
Expert:  Cat Man replied 3 years ago.

Thanks for the information.

How long have you let the engine run? The reason I ask is because if it is only for a short time, possibly the STP is in the fuel system and just needs to be ran out.

Customer: replied 3 years ago.
we let it run for 10 to 15 min. we thought there may have been air in the system . we also noticed oil in exhaust pipe after turbo took exhaust pipe loose from turbo & inspected turbo noticed no oil in turbo . We think oil came from when we had turbo off and any oil laying in bottom of turbo may have been disturbed . WE also took turbo loose from exhaust manifold to make sure no oil was coming from exhaust and going into turbo.
Expert:  Cat Man replied 3 years ago.

Thanks for the information.

 

I would think that 10 to 15 minutes would be long enough to get rid of air and/or STP.

 

Have you been back over the overhead?

Customer: replied 3 years ago.
not completely after replacing all injectors we set all injector heights . We then checked all valve and jake settings with feeler guage and they seemed all in spec.
Expert:  Cat Man replied 3 years ago.

Thanks for the information.

 

If you have been back through the overhead and it is correct, you may have to remove the injectors and inspect. Since the engine was not smoking like this until the injectors were removed, there may be a cut O ring on one of the injectors.

 

 

Customer: replied 3 years ago.
we replaced all o-rings on all injectors and reinstalled them . Do you think we could have damaged the new o-rings when reinstalling them ? this does not seem likely considering all the STP we used. Should we take exhaust manifold off to see which cylinder we may have a problem with ?
Expert:  Cat Man replied 3 years ago.
Yes, it possible that there is o ring damage. It may be a good idea to drop the exhaust manifold. This way you can pinpoint the cylinder that is the problem.
Customer: replied 3 years ago.
could they have sold me the wrong injector . I gave them the engine serial # XXXXX I was told to get all the numbers off the top of the injector and stop at a cat shop or truck dealer to have the computer hooked up to the truck in turn this new injector must be fine tuned to the trucks computer is this true?. how important is this?
Expert:  Cat Man replied 3 years ago.

Each injector has what is called a "Trim Code" on it. When ever an injector has been replaced, this code must be changed in the ECM. However, I can't say I have ever seen an incorrect trim code cause an engine to smoke though.

 

Get me your complete engine serial number and the part number of the injector. I can find out if it is the correct one.

 

 

Customer: replied 3 years ago.
engine serial # XXXXX XXXXX . Injector part # XXXXX
Expert:  Cat Man replied 3 years ago.

Thanks for the information.

 

The 10R8501 is the correct part number for your engine.

 

Maybe you should go ahead and drop the exhaust manifold and see if the smoke is coming from number 4?

 

If it is not, at least we will know that the problem is not the injector. If it is smoking on number 4, they may have gave you a faulty injector.

 

 

Customer: replied 3 years ago.
the increased fuel pressure should not be a problem . When i had this done a few years ago they said they had to go into the computer and make changes to make it seem like they were changing the injectors so they could increase the fuel pressure . This work was done at a certified cat shop which i have been going to for years
Expert:  Cat Man replied 3 years ago.

Thanks for the information.

 

So what exactly did they do re increase the fuel pressure?

 

I'm not sure I follow what you are saying. Could you elaborate on:

 

they said they had to go into the computer and make changes to make it seem like they were changing the injector??????

 

Customer: replied 3 years ago.
they put a spring or something in the fuel transfer pump . then they went into the computer and changed codes on all injectors maybe to accept the increased fuel pressure im not sure. Would this need to be done when you increase the fuel pressure ?
Expert:  Cat Man replied 3 years ago.

Thanks for the information.

 

I see. They put the new spring in the transfer pump. I am aware of this. But they should not need to adjust anything in the ECM.

 

This new spring was just designed to weaXXXXX XXXXXke before. This in turn helps the system maintain adequate pressure in the system in order to keep the injectors full after injection.

Customer: replied 3 years ago.
if they did change something in the computer for the injectors could this be a problem replacing this # XXXXX injector now ? . Also we have a hand held computer to hook up to the truck to check for problems but one of the prongs is broke on the computer hookup under the dash of the truck, is there anywhere out on the engine to hook up this computer ?
Expert:  Cat Man replied 3 years ago.

If they did change something in the computer, it could very well be a problem with now replacing #4 injector.

 

Unfortunately, there is no place other than on the dash of the truck to connect tooling. Sorry.

Customer: replied 3 years ago.
when they hooked a laptop computer to the truck the last time i was in for service they hooked up somewhere out by the ECM because they said one of the prongs was broke under the dash . i thought maybe there was somewhere else to hook up ?
Expert:  Cat Man replied 3 years ago.

If they hooked up out near the ECM, they would have had to use a bypass harness. Cat makes a bypass harness that connects directly to the ECM. It connects where the truck harness connects to the ECM.

 

The bypass harness is used whenever there is a problem using the dash connector.

Cat Man, Caterpillar Engine Expert
Category: Heavy Equipment
Satisfied Customers: 6444
Experience: 23 Years Caterpillar Engine experience.
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