Cummins ISL 400 HP

[JerryD]

my cummins ISL 400 hp pusher emits blue/grey smoke whenever i press the brake pedal, at idle it nearly dies, but the exhaust brake or the emergency brake does not cause the smoke. as quick as i push the accelerator it emits a black cloud and all seems fine. no noticeable difference in power. Any ideas?

 

[Rich W.]

what year which chassis?

 

[JerryD]

2003 Spartan chassis

 

[Rich W.]

Ok well first a couple things - it has nothing to do with the brake system, service or emergency, but braking (forced deceleration) may be creating a situation which contributes to visible oil smoke, causing some confusion there. Your black cloud is just unburnt fuel during initial acceleration and unrelated to the problem.

Also I’m guessing the engine brake is a Jake (compression) brake and not an exhaust brake (has a high/low or high/med/low) - is this correct, or is it just on/off?

Two possibilities are rings and the crankcase vent system. It would be good to have someone follow you around a bit to get a better idea of when it smokes and how much. They will be able to see a lot more than you can from the driver’s seat.

A couple questions:

1. Any oil noticeable in the exhaust system?
2. How long have you owned the coach and is this a new condition?

Also you might add “smokes“ or “smoking” and “2003” to the title to get experienced mechanics interested, and note the manufacturer and model in your next response.

 

[JerryD]

Ok well first a couple things - it has nothing to do with the brake system, service or emergency, but braking (forced deceleration) may be creating a situation which contributes to visible oil smoke, causing some confusion there. Your black cloud is just unburnt fuel during initial acceleration and unrelated to the problem.

Also I’m guessing the engine brake is a Jake (compression) brake and not an exhaust brake (has a high/low or high/med/low) - is this correct, or is it just on/off?

Two possibilities are rings and the crankcase vent system. It would be good to have someone follow you around a bit to get a better idea of when it smokes and how much. They will be able to see a lot more than you can from the driver’s seat.

A couple questions:

1. Any oil noticeable in the exhaust system?
2. How long have you owned the coach and is this a new condition?

Also you might add “smokes“ or “smoking” and “2003” to the title to get experienced mechanics interested, and note the manufacturer and model in your next response.

I’ve owned the coach for 5 years (20,000+- miles) now has 60,000. It’s an exhaust brake, thers a valve that actuates in the exhaust pipe. My back up camera is set to work all the time, so I can watch the exhaust discharge.
The shop tells me it’s a problem with the ECM. Does this sound feasible??

 

[Rich W.]

Ok, older in-manifold exhaust brake. And when its switched on and you brake it activates automatically? And thats when it smokes? And when its switched off and you brake, no smoke? It would be nice if its just an ECM thing, I just dont know what that would be.

 

[Buly]

Usually blue smoke indicates oil is getting into the combustion chambers.
Broken or worn out rings?
Black smoke, indicates very rich mixture, and unburned fuel goes thru the exhaust.
In a diesels, it happens if the injectors are fouled, and instead if creating fuel mist, they dribble fuel that can not fully burn.
The other cause is restricted air intake affecting fuel / air ratio.
But in your case, someone should do a hands on troubleshooting.
We are just guessing.

 

[Rich W.]

I’m also concerned that the ECM answer is a guess and it could be an expensive one. If they want to start swapping parts I would get an agreement in writing that there will be no charge if it doesn't solve the problem. Ive seen far too many posts on forums about people paying for unnecessary repairs and parts because the tech was guessing.

 

[JerryD]

Ok, older in-manifold exhaust brake. And when its switched on and you brake it activates automatically? And thats when it smokes? And when its switched off and you brake, no smoke? It would be nice if its just an ECM thing, I just dont know what that would be.

No, it makes no difference weather the exhaust brake is turned on or off. The only thing that causes the smoke is when I apply the brake with the brake pedal.
It smokes when I apply the brake weather the exhaust brake is turned on or not.
The way this exhaust brake is set up, when turned on, it’ll come on when ever I take my foot off the accelerator, or when going down a grade and the RV is trying to coast factor than the speed it’s set at, but that doesn’t cause the smoke issue either.

 

[Alex.isl400]

No, it makes no difference weather the exhaust brake is turned on or off. The only thing that causes the smoke is when I apply the brake with the brake pedal.
It smokes when I apply the brake weather the exhaust brake is turned on or not.
The way this exhaust brake is set up, when turned on, it’ll come on when ever I take my foot off the accelerator, or when going down a grade and the RV is trying to coast factor than the speed it’s set at, but that doesn’t cause the smoke issue either.

 

[Alex.isl400]

No, it makes no difference weather the exhaust brake is turned on or off. The only thing that causes the smoke is when I apply the brake with the brake pedal.
It smokes when I apply the brake weather the exhaust brake is turned on or not.
The way this exhaust brake is set up, when turned on, it’ll come on when ever I take my foot off the accelerator, or when going down a grade and the RV is trying to coast factor than the speed it’s set at, but that doesn’t cause the smoke issue either.

 

[Alex.isl400]

My isl400 started doing the same thing smoking while applying service brakes it would even choke out the motor most of the times so I did digging and unplugged the auxiliary brake wire from the head and no smoke or choking I don't get what's wrong with the engine brake why would it be doing that? Any help plz thanks

 

[Rich W.]

No, it makes no difference weather the exhaust brake is turned on or off. The only thing that causes the smoke is when I apply the brake with the brake pedal.
It smokes when I apply the brake weather the exhaust brake is turned on or not.
The way this exhaust brake is set up, when turned on, it’ll come on when ever I take my foot off the accelerator, or when going down a grade and the RV is trying to coast factor than the speed it’s set at, but that doesn’t cause the smoke issue either.

Ok re-reading this and given Alex’s experience, maybe your exhaust brake is sticking or over-actuating. Try disconnecting it as he did and see what happens. If thats it, a good cleaning and service as necessary of the exhaust brake will probably clear up the problem.

 

[JerryD]

Ok re-reading this and given Alex’s experience, maybe your exhaust brake is sticking or over-actuating. Try disconnecting it as he did and see what happens. If thats it, a good cleaning and service as necessary of the exhaust brake will probably clear up the problem.

No, when I apply the exhaust brake, the engine actually changed pitch and when I release the brake it goes back.

I’m also concerned that the ECM answer is a guess and it could be an expensive one. If they want to start swapping parts I would get an agreement in writing that there will be no charge if it doesn't solve the problem. Ive seen far too many posts on forums about people paying for unnecessary repairs and parts because the tech was guessing.

well it turned out, the Spartan service (Boarder Engine Rebuilding) in Mission Tx replaced the ECM $5K , cured the smoke issue.