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Garrett County, MD | So this might be a long post but if you know about jakes on cat engines I could really use your help.
One of our trucks is an International 9400 2002 model I believe. Has a cat c15 6NZ in it. When we bought it a few years ago the previous owner had it turned up a lot and we didn't realize how much. We we put it to work in our hills and proceded to have head cracking issues. Finally figured out why and turned it back to stock 550 (reflashed ecm) and put a slightly larger non-wastegate turbo on it to keep it cool. When I had the head off I noticed the liner protrusion was out of spec so I pulled the motor and did a major overhaul. I have done these cats before. No big deal. We have multiple of these motors. Anyways to the original question. It has been running quite a while since the overhaul and runs good with no issues. Before the overhaul the drivers always said the jake was awesome. After the overhaul they complain that while it works it is not as good as it was before and when you are going down a hill with a load and flip it to the 3rd stage it doesn't seem to change how it feels from the second stage. During test driving empty it feels and sounds as if all three stages work but there is probably a 2 second delay when going from 2nd to 3rd stage until it really kicks in good. You also have to basically rev it up all the way and let off to get the 3rd stage to work(no load). I have no idea how it was set before we reflashed the ecm and majored the engine.
What I have done.
Replaced the 3 position switch.
Tested the on off switch.
Confirmed the computer is seeing all switches working and high/med/low in Cat ET. Computer knows what is should be doing basically.
Set the mode to manual in Cat ET.
Tested wiring going from valve cover plug to jake solenoids for continuity. Good.
Manually activated each of the three jake solenoids and watched them work.
Visually watched the jakes work in the shop with someone else revving it up and letting off.
Completely rebuilt the jakes with a tune up kit.
Readjusted the top end and set brake spec to Jacobs spec of .037
Changed the setting in ET so that the fan kicks on when 3rd stage is activated.
Not sure what else there is. Also occasionally when you are coasting and hit the pedal to accelerate it will act like the jakes are still on(even if they werent) ( not really full bore jake noise but just a little bit of that sound) and have no power for a couple seconds and then clear up and take right off. Not sure if this is related. Has always done this.
I'm not sure what else to do. Is there another electronic controller for the jake somewhere on the truck? Could it be something different in the reflashed ECM? I believe all the mechanical things are good so I feel it must be electrical.
I have to be missing something. We have other 3406s and they all work better than this one and I have rebuilt or adjusted all of them. This one seems to work fine except it just doesnt hit that 3rd stage properly. Also not sure how that could be as stage one controls the center jake and stage 2 controls the outer two jakes. So if they both work then how could stage 3 not work because it just combines the two.
Thanks for any advice. We are going through brakes at an alarming rate without that good 3rd stage jake.
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Cat C15 jake brake question
