Codes on Cat 3126

[John White]

I have a 2003 KW and recently have been having some problems. The engine has 80k miles. Truck has 300k. It is a septic pumper truck and will idle for 30 or 45 min while pumping a septic tank. I have heard that Cats don't like to idle for a long period of time. After finishing up and starting out it will smoke like a injector is bad for about a mile or two and no power. First time it has ever done that I turned the key off and back on and and it seemed to clear up. Thought it was just a one time situation. It ran ok for several more days. Then a day or so ago I pumped a tank and did same thing, smoke finally cleared up but no power all the way back to shop. Next morning it started up fine, ran to the dump station and went on another pump job, ran fine, pumped tank and set idle higher this time, started out, no smoke but no power for about 5 miles, then started running fine. About 5 years ago I replaced the engine, old engine had a bad cylinder on #6, had to replace engine, (block had a big ridge they said from injector failure) I never had Cat cleat the codes. I checked the codes yesterday and it says code 74 which is#5 or 6 bad injector. Could these codes still be there from old engine failure?. No engine lights have come on. If it is a injector sticking sometimes could I put some Lucas or some other injector lube in the fuel and clear it up? I checked my mileage and it fuel filters were replaced at 30K . I think that is way past due. I can't find a good answer on how often they should be replaced. Some say every 10k, some say 30k, some say every other oil change. Cat can't get me in for two weeks. I am going to replace the fuel filters and try pumping another tank and see what happens. If it doesn't run right I will just have to let it set till I can get it into Cat and run a scan. I can replace the injector myself but I want to know what one it is and if the codes are from old engine failure. Any help appreciated.

 

[crane operator]

Replace your fuel filters every oil change. Filters are cheap.

3126 likes clean fuel and clean oil. 200-250 hour oil changes wouldn't be out of line. I don't know your daily usage, but just guessing (using the 80k in 5 years on the new engine), you should be changing oil every 2 months or so. At least quarterly.

If a injector is bad, I doubt any lucas is going to fix it, just replace it. If you do pull a injector, I think I would pull all of them, and have them all tested.

 

[John White]

I change oil every 3 to 4 k miles due to the idling. I figure 1\2 hour for each job (200 in a years time would be the same as 8k miles. Again, could this code be from old engine failure or would it have erased itself in 30k

 

[Nige]

Stored (aka Logged) Codes never erase. Someone has to go in there with Cat ET and erase them.
It's SOP to clear Codes after an engine change at a dealership because a lot of the Codes are created by the change itself. If the engine replacement was done somewhere else then I guess you'd have to ask to get it done.

 

[John White]

Thanks Nige for your information. You probably don't remember it but you steered me in the right directions about 5 years ago when I bought this truck and was having trouble with it. Finally found out the engine was bad. I purchased a used engine and installed it myself.. So I never had the codes erased by Cat. I used mu original ECM. The fellow I bought it off of wasn't sure of the millage but said it was under 100k. I took the ECM to Cat and they scanned it. They said it had 65K on it and even showed me the average speed it was driven at and idle time. But I used the ECM from my old engine. So I will change my fuel filters and hope that fixes it. I can see how a plugged filter could cause a no power problem but could it make it smoke as I described. I will change filters next week and keep you posted.

 

[Nige]

Really the only sure way to is to clear all the Codes that are there now, then run it and see what (if anything) comes back.

 

[Nige]

Oil change recommendations as follows: -

Engines with a shallow oil pan. 11k miles or 1100 gallons of fuel burned, 250 operating hours, or 6 months, whichever comes first.
Engines with a deep oil pan. 15k miles or 1500 gallons of fuel burned, 400 operating hours, or 6 months, whichever comes first.

 

[John White]

I changed filters, went on a job today, seemed to run fine. I did notice one thing when changing secondary filter was not even finger tight. Just spun off with no effort. I don't know if it if it could have been sucking air. What caused it to smoke?