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Engine Diagnostics / Re: CAT C7 350 HP lacking power (torque?)
« Last post by David.e.atherton on Yesterday at 04:14:35 AM »
Steve79, self maintance on you engine will give very good understanding ahead when
Traveling. One more thing I would suggest that is very important servicing your motorhome
Is taking of engine oil sample at each oil change peroids. Taking of oil samples sets up
first time a base line of anything wearing or breaking down within your engine via: of report
of particle count. You service of engine after that oil samples will give you a particle again
and is something is happening that component with excess wear particle count will increase.
If problem particle count gets high oil sample testing lab will let you know to check out what
is going on. What all this means like a fire contain it when it is small and little damage and
Cost. The same thing with oil sample on your engine something wearing or breaking down
Correct problem when it is small. Your engine has a DNA of all metals same as a person
going to Doctor for blood draw. Last thing Dave would suggest , take your hydraulic pump
that is fastened to your Air Compressor remove 2 bolts slide hydraulic pump back and
Check and lube the spline shaft on hydraulic pump. A Caterpillar 3126 E engine had metal
shaving spread throughout engine from hydraulic pump shaft in Air Compressor coupling
being dry over time . The results replacement of complete engine, this is a good case of
why oil samples pay to do each oil change peroids. Problem could have correct if a person
had been aware of this.  Staying on top on maintance with your engine we all can learn
the value of the Diesel Club Forum passing along information pertaining your engines.
Ask Dave, Dave Atherton Retired Cat Mechanic
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Engine Diagnostics / Re: CAT C7 350 HP lacking power (torque?) Update 2019
« Last post by Stevet79 on February 20, 2019, 10:09:32 AM »
Cat C7 350hp

Done and tested

New thermostats installed. Still runs same temperature + or - 190deg
Does not change even on long hills.
Saw it get over 200deg once when fan belt broke due to alternator seize up.
Installed dash gauge for boost and fuel pressure. Boost runs max around 26 psi, Fuel pressure seemed low around 72psi at cruise and dropped to 50 at idle when hot.
Replaced fuel return pressure regulator and now at 78psi cold idle and over 80psi at 1500rpm.
Will need to road test now. Noted pressure drop when driving hot and erratic gauge readings.
Fuel return bubble test shows NO bubbles at idle or 2000rpm in clear line installed for test.
Checked all wiring for problems. None found.
Removed radiator to repair rock ding from Alaska trip. Found radiator 1/3 plugged up with dirt and oil. Intercooler was probably 1/2 plugged up like radiator.
Cleaned both with soap and light pressure washer.
Radiator leaked after repair so replaced it.
Replace air filter. Didn't show as plugged on monitor
Back in Arizona now and the trip from Washington was much improved.
If I had to guess the Intercooler being 1/2 plugged with dirt and oil and the fuel return pressure regulator were the cause of lower power. Didn't see any more boost pressure but cooler air after intercooler would definitely increase HP.  Moderate hills doesn't even slow it down now. When I hit the 6+% it will drop to about 40 to 45 mph. Probably OK since we weigh in about 34,000lbs with the jeep behind us.
Many thanks to Dave Atherton for his help.
Ping me back if you have questions or suggestions.
Thanks ST
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Routine Maintenance / Re: reliable rv service
« Last post by David.e.atherton on February 15, 2019, 10:20:31 PM »
Charlie & Susie, here is my take on your problem . AC system will freeze up when
adding too much 134A coolant and even lock up the ACcompressor. Again vacuum
down system and let sit for 20/ 30 minutes to see if system will hold vacuum. If it will hold
Vacuum for 20/30 minute than open the low pressure or blue hose side to allow approx.
11/2 pounds of 134a and the reading on the blue gauge should read between 35 & 50
psi. Last be sure to disconnect the high limit while charging system than reconnect when
Reading on blue gauge falls Within the 35 - 50 psi. Ask Dave , Dave Atherton Retired Cat
Mechanic.




switch
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Routine Maintenance / Re: reliable rv service
« Last post by Charlie/Susie on February 15, 2019, 05:47:59 PM »
Phil and Ziggyh, the system has an expansion valve and dryer near the evaporator. Two things I failed to mention is 1; they found that there was to much oil in the lines and that was causing it to freeze up and 2; the high pressure line to the evaporator was old and had deteriorated inside causing another blockage and ice up. The system was drawn down and vacuumed twice and the old line replaced. All major components were replaced including a trinary switch?? The quantity of refrigerant added was listed as 1 which doesn't tell me anything. Was told it was cooling until it actually iced up. I will have all those things checked out, low refrigerant, air and/or moisture and air gap between clutch and compressor. Will update you all when system is finally functional. Thanks to all of you for your input, great to have a resource this rich in experience. Charlie.
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Routine Maintenance / Re: reliable rv service
« Last post by ziggyh on February 12, 2019, 04:37:41 PM »
Charlie
AC systems can be a orifice tube design or expansion valve type.  On a orifice tube type they use an accumulator with a cycling switch usually mounted on it. That switch cycles the compressor on and off based on the low side pressures. There is also a high pressure cut of located on the high side to protect the system and also a blowoff valve should pressures reach the blowoff point

An expansion valve system uses a valve on the low side line at the evaporater to regulate the low side pressure based on the temperature or the refrigerant leaving the outlet of the evaporater . There systems do not cycle the compressor on and off, the expansion valve just regulates the flow of refrigerant to maintain evaporater  temperatures. There usually is a low pressure cut off switch should the system be low in charge or outside temperatures are low enough. These systems also can use a evaporater  freeze sensor or switch to turn of the compressor should the evaporator  temperature get close to 32 deg F. The switch is sensor is usually located on the evaporator .

Expansion valve systems use a receiver/dryer mounted on the high side line mounted before the expansion valve.

Some systems also use a variable displacement compressor and orifice tube that also does not cycle on and off, it senses the low side pressure and changes the displacement of the compressor to control the.

When you say the system freezes do you mean it stops cooling or you see ice build up somewhere.

I'm heading south and stuck in a snowstorm and wifi is spotty. May not be able to reply back quickly


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Routine Maintenance / Re: reliable rv service
« Last post by antiqueclockservice on February 12, 2019, 06:00:38 AM »
It still seems you are low in charge...Did they pull the system down with a vacuum pump and then add refrigerant?  If not, you might have quite a bit of air and moisture in the system.  Also, it is sometimes necessary to replace the accumulator.   Pressures being good for the high side and low side do not indicate if the high side pressure switch is good or not, so did they actually test the switch or just read their manifold gauges?  Wish I could contribute more, but seems something is missing here...  Good luck!
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Routine Maintenance / Re: reliable rv service
« Last post by Charlie/Susie on February 11, 2019, 04:29:59 PM »
Thanks Phil and Dave, I was told that the high and low pressures were good while the a/c was running but would ice up because the compressor was not cycling off. So maybe the repair shop was talking about the high pressure switch since the coolant was charged, would high pressure cause system ice up? This thing is kicking my butt, and my wallet. Charlie.
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Routine Maintenance / Re: reliable rv service
« Last post by antiqueclockservice on February 02, 2019, 06:59:32 PM »
Hi,

Usually, evaporator freeze up is an indication of low charge.  So adding refrigerant might stop the continuous running and return to cycling on and off as necessary.  I have not heard of a cycling module.  A high pressure, low pressure cutout switch...yes...The system ran bascally continously cooling and to adjust temperature if too cold was to add heat from the cooling system via the "Blend" door.  Please let us know more about this module...I am always interested in learning about such things.  I spent 30 years as an automotive engineer and we never had a car/truck system with a cycling module, but my experience ended when I retired in 2002.... Even my 2016 Lincoln with dual temp controls for the driver and passenger is just two electrically operated blend doors... not a module that cycled the compressor.

best,
Phil Schilke
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Routine Maintenance / Re: reliable rv service
« Last post by Charlie/Susie on February 02, 2019, 09:07:51 AM »
Dave, sorry I didn't make myself clear. The compressor does not cycle on or off, it stays on all the time causing the system to freeze up. Was told that the cycling module/relay was bad but could not find out where that is located or what the part number would be. I have a call into Fleetwood but no reply yet. Thanks, Charlie
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Lubrication System / MOVED: Air Bag Replacement Gillig Chassis
« Last post by Brett Wolfe on February 01, 2019, 07:01:52 PM »
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