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WillTory

Fuel Injectors

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(Specifically the HEUI injectors used on the CAT 3126E engine)

How does B-20 fuel impact injector performance/life?

What is the mean time between failure (MTBF) of the injector?

What is typical failure mode of injector? Solenoid? Burned or carbon tip? Sludge? Plugged?

My 3126E engine (with 114K miles) exhibits a slight shudder on acceleration around 1400 RPM. When monitoring RPM with my VMSpc, I do not detect a fluctuation, and at steady speed, all is well. Based on that, I am not suspecting ride-height adjustment or tires, and the universal joints have been replaced during transmission overhaul. My mechanic told me it was possibly an injector, and he has test equipment that can selective turn on/off solenoids. (Must complete body work first, however) 

Have viewed numerous injector operation videos on U-Tube, but have not found answers to the above questions.

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Official answer from Caterpillar (Percent biodiesel permissible):

For engines built prior to 1/1/07 up to 30%

For engines built after 1/1/07:

C7 and C9 up to 5%

C13 and C15 up to 20%

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Red,  There are a number of variables.

How does B-20 fuel impact injector performance/life?

    B-20 has good and bad effects on items.  Offers a higher degree of lubricity, but at the same time it tends to clean out the system and that process can increase the amount of items that can be collected in the fuel filters. 

What is the mean time between failure (MTBF) of the injector?

      I have not found any real good information that charts the number of failures do to specific categories. Water in the fuel, algae build up, the brake down of fuel lines and seals caused by Bio fuel, Electrical issues in the injector or issues with the electrical connections. Injector pump pressures affect injector life.  

      Injectors have failed due to all the listed items regardless of miles driven from a few thousand miles to 200,000 miles. Same engine can have one fail with in a month of service - while the other OEM injectors last for years.


What is typical failure mode of injector? Solenoid? Burned or carbon tip? Sludge? Plugged?

         All the above.

Rich.

Edit, This is a chart of the different Diesel fuel suppliers Cetane levels - Fuel mixtures involve a lot of Chemistry. all these fuels will work in Diesel engines, but it is only a small part of what can effect engine operation.

Cetane-werte der Diesel-Marken:
BP (Amoco branded), 51
Chevron, 49 (51 with Techron D)
ConocoPhillips, 48 (California 48-53)
PetroCanada, 47-51
Shell, 46;
Sinclair, 46
Marathon 45
Exxon/Mobile, 43-46
BP, 40-42 (Powerblend 47)
HESS, 40-45
Husky, 40 (Max 41-45)
Sunoco, 40 (Sunoco Gold 45)
Holiday Stations, 40-43
Love's: 40
Pilot: 40
Valero: 40
Sheetz: 40
Flying J, 40

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3 hours ago, Hermanmullins said:

Will,

What happened to your Transmission? 114K miles seems to be very low mileage for an overhaul.

Herman

Seemed to me also! Sold the motorhome in March 2016, bought it back (long story) in September 2017. Transmission shifting hard, sometimes slipping. Shop said teardown was necessary. This was found. Transmission was rebuilt, replaced engine front seal, universal joints. Motorhome was delivered new in October 2003 with ATF-III, fluids and filters replaced on Allison recommended frequency by me. After overhaul, tranny filled with Transyn. 

What caused failure? Don't know. Theory was possibly rocking the transmission. Stuck in snow or mud? Never by me, but don't know about previous owner. 

 

UNTITLED.jpg

Edited by WillTory
correct spelling

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Let me guess, you sold it and retained the note, they defaulted and you took unit back?  Or was it a brother in law deal?

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15 hours ago, manholt said:

Let me guess, you sold it and retained the note, they defaulted and you took unit back?  Or was it a brother in law deal?

Not quite. Rapidly approaching 80, we decided to hang up the keys, and sold it. After one year, realized that we were RVaholics and started to shop for a replacement. I considered downsizing, but SWMBO refused, comparing every coach to "my Meridian"!  So, I contacted the new owner, consummated a deal and bought it back!! I trusted the new owner when he told me it was "just like you sold it to me" and drove it home without a thorough inspection. Caveat Emptor! 

I will bring it back to the condition it needs to be, and we will continue to enjoy it.     

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On ‎12‎/‎20‎/‎2017 at 8:31 AM, WillTory said:

What is typical failure mode of injector? Solenoid? Burned or carbon tip? Sludge? Plugged?

Most common, clogged or plugged on the oil side. Reason; motor oil is not often designed to be utilized as hydraulic oil, when pressurized to over 3000 psi to actuate the injectors on a HEUI engine it sludge's up, usually within the injector. There are products out there to clear the crud created but often it can be too late. This situation is often amplified on an engine that idles excessively, as the extreme oil pressure entering can help blast the crud out, at idle it just stacks it on. I have had some success in disassembling the CAT injector, cleaning out the oil side, replacing the poppet valve seal and reassembling/reinstalling in the engine.

Here is an explanation on how yours work. FYI the 7.3L powerstroke ford and CAT 3126 series use the same injectors (appearance) just some internal stuff is different.

http://www.trucktrend.com/how-to/expert-advice/1304dp-heui-how-high-pressure-oil-injection-systems-work/

 

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 To diagnose a Cat Engine it is imperative to have a diagnostic tool like Cat ET. It will run an automated Cylinder cut out test to check injector balance and see if one or more injectors are not supplying enough fuel. Also a test for the high pressure oil. The Cat ET can graph the output and many other parameters. I believe there is also an upgraded Oil pressure sensor and I've changed many pump solenoids for hard starting issues on the 3126. Mostly on the C7 I have seen Oil leaks at the injector O ring also.

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Megadiesel, Welcome to the forum !

Your thoughts are in line with cat injector problems. Fallows what Joe L. posted earlier in this thread. 

Thank you for sharing .

Rich.

 

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