I'm hoping someone with knowledge of the C-15 can help.
I recently bought an 04 KW with the C-15 twin turbo. My first trip out I noticed it didn't want to pull good and was very loud under a hard pull. I got out in the mountains of eastern TN going to Knoxville and it started shutting down on me. The check engine light came on and the engine sounded like the jake brakes were engaged.
Anyway i took it to a shop and they found that the exhaust manifold gasket was blown and a flex pipe was too. They fixed that and ran an overhead on it while it was apart.
Now for the issue i need help with. The guy that worked on it said it should average around 6.5 mpg. He used to be the foreman at KW in Knoxville. The truck is a T-600 and he said they get much better mpg's than say a 379 Pete or a W-900. Anyway.
I started writing my mileage down after repairs and it's been averaging 5.5 to 5.7 mpg. I called the mechanic back and he said I could be losing pressure in my fuel lines and suggested I replace them. I did. Still the same problem exists. Poor fuel mileage. Plus I've noticed it's getting hot pulling mountains with more than a 30,000 lb load. I asked him about that and he said C-15's run hot as hell anyway. He suggested anytime I downshift that I should flick on the manual fan switch to help keep it cool. I do this and it keeps it from overheating but sometimes I forget to turn it off and I end up driving for several miles with the engine fan on.
So if anyone can help me figure this out I would appreciate it. I would like to have more pulling power, better than 5.5 mpg and would like to find a way to keep it from overheating and not messing with the fan switch. Are these problems connected? Separate issues? Should I trade it off and get a Volvo with a Cummins like I almost got to begin with? Any ideas?
C-15 Cat Engine Problems.
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Ahhhh, the perils of a used truck. Cat's are notorious for poor fuel economy if driven hard so pretend there's an egg between your foot and the fuel peddle. When was the top set done last? Does the air to air leak?
As far as the over heating...is the air to air and rad clean? Can air pass through it freely because if it can't the radiator can't do it's job.
Just my initial thoughts.
Well it's clean...does it leak? I don't know. A trucker I was talking to on the CB said to take it to Kenworth and put it on the dyno. That should narrow it down maybe. I guess if it keeps doing it that's what I'll do.
The truck runs and sounds awesome. It idles like a brand new one without even a hick up. I think the engine will last me for a long time if I can find out whats wrong with it and get it fixed before it messes something up.
It sounds like a normal Cat to me. I dont know if Mr. Haney can help anymore with the acert as he is no longer a PDI dealer. If he can I would talk to him first if not get ahold of PDI. It makes an unbelievable differance in your truck.
Before I started making changes to my truck it sounded like yours it got 5.2 to 5.5 mpg. Now it gets close to 7 maybe better now I just put a differant manifold on and have not checked it yet. This is what I've done. I first changed the mufflers and installed a FASS. That improved it about .5 mpg I could almost get 6 mpg with it. Then I installed a PDI exhaust manifold and could easy get 6 ran 6.1 most of the time. Next (this is what I wish I had done first cause its the best improvment for the buck) I had Mr Haney who was a PDI dealer do a stage 1 tune on the ecm. Now all the power I want and it gets 6.6 to 6.9 mpg. Well worth the money!!! Just this weekend I installed a ported and coated manifold. I have only filled up once since then so I am not sure of the gains yet. I think from the looks of things I will be in the 7s. I love my acert!!!! I know there are other places that sell stuff to help with mpg and power for big trucks. I have heard good and bad. I can say from my experiance that PDI claims are true about what you gain with thier products. I am just a very happy customer.DisturbingThaPeace Thanks this.
Sounds like a typical ACERT to me. When you are pulling the hills what RPMs are you running? You can't lug a CAT up a hill, it will get hot on you every time. Downshift until you are pulling under 20 PSI on the manifold pressure and have your RPMs over 1600, this will cause the fan to spin faster and cool better. As for your fuel mileage, that is very common for an ACERT.
DO NOT follow follow this advice--->
You say it's getting hot but you never said what the temp is. It will run up around 220* easy and the fan should cool it down. If the fan won't cool it off then you have a problem, but over 200 is normal. I was flat on the floor today for over a mile doing 25mph at 117,000 gross and the water temps never went over 220 and the fan brought it back to 190*. If you losing power you could have low fuel pressure. What HP is it set at? How much boost pressure are you seeing? Is there smoke? What fuel filters are you using?
There is a reason Cat insisted on drivers learning how to drive the Acert's, and they insisted you have to gear them right. (I ordered mine with 3.73's which is the same as all the single turbo c15's I've had but since it was an acert they switched the gearing to 3.36's without asking, and it's perfect) Too many guys try to drive them like the older engines and find out if you do (over rev them) you will hate them and you will get no power and bad fuel mileage. Drive them correctly and they run great. And hopefully if I can talk Mr.Haney into doing one more PDI ecm in a few weeks mine will run even better.Bob's Buzz Thanks this.
Mine is definatly an Acert. It's the C-15 twin turbo. It's an 04. This is the first year of the Acert. The guy in Knoxville said it mine is the first model of the first year. He said it's a BNX or BMX. Soon after mine came out they changed to a different design and named it different. I forget the lettering but still it's an Acert as well.
The problems I'm having with low power and over heating is this. When I start to pull a hill I wait till it drops a few hundred rpm. For example if I'm running at 65 at around 1300 rpm I wait till it gets around 1100 rpm and down shift into 9th gear. It doesn't have the power to hold 9th very long if i'm loaded heavy and pulling a big hill. Then I do the same. Wait till I get down to 1100 and down shift into 8th. Each time I downshift the rpm's jump up to 1500-1600 but it won't hold the rpm's.
I went out west a few weeks ago with it and coming back I was loaded heavy. When I got into AZ pulling the mountains it would start overheating about 3/4 of the way up the mountain. By the time I crested the peak the lights was flashing and the engine would shut down on me.
Most of the time in flat land I'm not overheating. On smaller hills the temp comes up when I downshift but it doesn't overheat...just gets warmer than normal running temp. The normal running temp for my truck is around 200 and the fan doesn't kick in until about 235. I asked the mechanic about that and he said it's normal. He said the Acerts run very hot and that is the design to help burn the fuel with the new emissions.
If I let it go and don't turn on the fan manually then it kicks on about 235 and it is already too hot and still pulling. The lights start flashing and it shuts off on me. I can somewhat control the overheating using the fan manually but still it's not got any power.
I was sitting at CAT for a few hours Tuesday and I was reading all the pamphlets they had.
It was suggested that you can allow the engine to lug down and that by turning the fan on you actually lose 30-40 hp.
I drive an 04 KW with a C15 as well and it is not an ACERT engine. I haul pretty heavy, 140,000 and I don't have many problems. Mind you I am not hauling in the desert either.
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