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cat C7 problem 2 different engines

77K views 20 replies 13 participants last post by  Rufas 
#1 ·
C7 #1 acting strange,complaint loss of power.They took it to dealer.Dealer changed injectors,high pressure pump,pistons and rings,crank,cam,boost sensors.They took it for road test everything running fine than it started to push white smoke.Shut truck off restarted truck running smooth than started pushing black smoke.Any thoughts?Thats the 1st engine.2nd C7 rebuilt 3 years ago has about 40k on rebuild.Rering and replaced injector cups and o rings because of coolant loss.Engines been fine,last week was told that it sounded like it was back firing,when they started it up in the morning.Driver brought it to the shop,not missing just complained that every once in while has no power when pulling away from a stop or when you want to accelerate while moving.This engine has always had alot fo blow by comming from breather ever since new.After rebuild cleared up now its back.Thanks for any help.
 
#2 ·
the 2nd c7 sounds like the inj pump. The last one I worked on was doing kind of the same thing as the 2nd c7 and the pump was shot. Are you having any starting issues? The 1st c7 beats the **** out of me!
 
#3 ·
:bangit could be the kind of oil you used?:fanCATERPILLAR IS RECALLING CERTAIN C7 ENGINES MANUFACTURED FROM MARCH 3, 2005 THROUGH JANUARY 6, 2009, INSTALLED AS ORIGINAL EQUIPMENT IN VARIOUS HEAVY TRUCKS AND BUSES. THE #5 AND #6 FUEL LINES MAY CRACK AT THE FASTENING POINT TO THE COMMON FUEL RAIL AND CAUSE A FUEL LEAK.Consequence:
A FUEL LEAK, IN THE PRESENCE OF AN IGNITION SOURCE, CAN RESULT IN A VEHICLE FIRE.Remedy:
CATERPILLER WILL NOTIFY OWNERS AND REPAIR THE VEHICLES FREE OF CHARGE. THE SAFETY RECALL IS EXPECTED TO BEGIN ON OR ABOUT SEPTEMBER 1, 2010. OWNERS MAY CONTACT CATERPILLAR TOLL-FREE AT 1-800-447-4986.
OWNERS MAY ALSO CONTACT THE NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION'S VEHICLE SAFETY HOTLINE AT 1-888-327-4236 (TTY 1-800-424-9153), OR GO TO HTTP://WWW.SAFERCAR.GOV:thumbsup
 
#4 ·
The first truck I would do a back preasure reading, you could have a broken baffle, in the muffler.
The second one I would put it in the shop and remove the exhaust manifold, leave it sit for say 12 hours and then start it to find the cylinder, I would think you have a dribbling tip on at least one injector. That would give you fuel popping in the exhaust and pre ignition when trying to accelerate.
The blow-by, pressurise the Turbo outlet and I would be looking for worn valve guides.
 
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#5 · (Edited)
#2 has no injector lines just one from filter housing to front of head to supply the fuel to the fuel galley.Test drove truck today.When you mash throttle to floor engine will not increase in RPM just stumbles and bogs than gradually takes off.Checked fuel pressure between filter housing and head.60psi at idle and full RPM just barely 75psi.Isn't it supposed to be 105psi at full rpm.Going to check for air bubbles on the return tomorrow.No back fire when started and ran actually smooth.Just no acceleration at all just gradual.
 
#7 ·
Changed fuel and water seperator,and check valve on back of head.When truck was cold great throttle response and acceration.As soon as it started getting up above 150 degrees it started to stumble and fall flat.No acceleration just gradual.If you get kept the rpms up above 1400 it would accelerate fine when you hammered the gas.While i had gauge hooked up to fuel while this was going on fuel pressure would drop to 50 for a split second than right back up to 75.
 
#9 · (Edited)
i have a 2004 freightliner with a cat c7 on it. Experiencing strange beavior it idles fine up until it gets to 150 degrees from than on there is no acceleration. any ideas? Already went crazy with it. Changed fuel pump, changed fuel lines and filters, changed injectors o rings and still no luck. Would appreciate any sugestions.
 
#10 ·
From the other 2 guys symptoms, I would do what has already been suggested, change the muffler. It's a @$70 part that does wear out and/or get plugged up.
Granted most of my engine experience comes from gas engines, but an engine is an engine after all:) That's why I get top $ for the Range Rover engines I rebuild and sell, for some reason everyone is scared of what is basically a pushrod V8:roflol:

martin
 
#11 ·
:help Hi acegreaser , did you find the issue for the low power , as I'm having the exact same problem with my C7 , its not showing any codes, the fuel, oil, boost presure are all good , I've check the air to air cooler for restrictions , pulled the muffer off (ran it with straight pipe) not sure what to do next , my truck has power for about 1/2 mile pulls hard , then just falls off and can barely pull it self , my truck is an 07 335 peterbilt with an allistion transmission and it also has no codes , we scanned it a few times . I've changed the oil and fuel filters checked for air in the return line . :help
 
#12 ·
The first one sounds like a failed injector, Remember, just because its replaced does not mean it is not failing. I have replaced 6 injectors as a set in these c7's and had one fail running the engine up to temp......Second one sounds like the high pressure pump, need to check for faults.
 
#13 ·
I'm sure its not an injector failing, we've done injector cut out when on the scan tool and the cylinder balance is good , the only thing I can think of is the ecm but I was hoping that acegreaser had come up with a fix before I go that route, I may even remove the coolant temp sender from the eng and leave it out (still plugged in) and go for a drive . It seems as soon as it builds a little heat the power just falls off .
 
#20 ·
We did the injectors and Heui pump, the truck runs great lots of power as soon as you hit the throttle. Cat sells the pump and injectors as a kit and has great warranty as long as its installed by a Cat repair centre or Cat mobil repair, I had an issue 2 years later and Cat replace the complete kit again. what happens is the chrome starts pealing on the cam in the heui pump and the metal go's though the fuel system and scores the injectors.

Something else that can happen is injectors may start to misfire and can result in wiping out the torque convertor so now you end up buying a transmission, and in my case the mis was miner I could hardly hear it or feel, it felt like driving over a crack in the pavement, and to make things worse the trany I got was a Allison rebuilt and news to me they don’t rebuild the convertor, they only flush it and reinstall it, Allison does dyno the trany and they say if convertor has an issue they will see it on the dyno. Well 5 months later the convertor failed again in the exact same way, i was driving along the hwy at 100 kph let off on the throttle and the transmission seemed like it went into neutral making some strange sounds. So now I have warranty on the trany but they say its not the transmission that caused it to fail, in the end they did send me a replacement trany 3 weeks later and wanted to check out the truck as soon as it was installed. They didn’t find and fault with my truck so they covered the replacement trany but cost me 3 weeks of down time. So if you replace your Allison trany make sure you get a NEW torque convertor to save yourself anymore aggravation
 
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