2009 Fleetwood with 8.3 cummins

[Toribk]

Someone correct me if I'm wrong, but I would think if it was related to the turbo or the actuator malfunctioning, their would be a very noticeable decrease in power, hesitation and the like.

Presumably this would set off a MIL icon on the dash and would normally derate your engine to eventually illuminate a red "stop engine" light.

Even if it IS a malfunctioning EGR cooler, I'm surprised the temperature/pressure sensor has not triggered an engine Code there or further downstream via the cross over tube at the EGR valve?

Thinking out loud???

[FleetProv40X]

That’s what I thought too. I have power, but not like on big or long inclines. It will get down to 40 to 45 mph. On the other hand it runs so smooth.

[TexasTom]

The "retarder" switch on mine acts like it just downshifts the transmission. I don't know what the actual mechanical process is, but it does increase the RPMs significantly if I hit the switch. So the only time I use it is going downhill in the mountains to help control speed.

[wolfe10]

Originally Posted by TexasTom

The "retarder" switch on mine acts like it just downshifts the transmission.

Indeed, having the transmission downshift to keep engine RPM toward the upper end of its allowable range IS part of engine braking-- whether an exhaust brake, VGT brake or engine compression brake.


But, it is only part of what is/should be happening.


To determine whether your "engine part" is working is pretty easy.


At, say lower highway speed, down arrow the transmission to select the gear at which the engine is at the upper end of it allowable range. Let off the throttle and note deceleration. Turn on/off/on the engine brake. You have taken the transmission out of the equation-- it will be in the same gear whether the engine brake is on or off. If there is no discernible difference in braking performance, something is wrong and needs to be addressed. At this point, you must know exactly what type of engine brake you have to know how to proceed.

[Toribk]

From Cummins:

The VGT Braking Assistance (ie Retarder)works in conjunction with the engine and transmission to provide an integrated braking system to help slow the vehicle. This is commonly referred to as exhaust braking. Braking power is achieved by modulating the sliding nozzle ring to restrict the flow of exhaust gasses from the engine, this will create high back pressure on the engine. The high back pressure creates a high level of resistance to the motion of the pistons within the engine and this resistance is used to reduce engine speed and thus vehicle.

The exhaust brake feature will only function when the Exhaust Brake Switch to the ON position. With the switch in the ON Position and the vehicle moving faster then 5 MPH; the exhaust brake will automatically operate when pressure is removed from the accelerator pedal allowing the ECM to see 0% throttle and 0% fuel delivery.

Now in real world experience with my Cummins ISC 8.3 over the past twelve years, the VGT works most efficiently at speeds under 45-50 MPH so keep that in mind in hilly terrain or steep descents.

I follow the practice of climbing at the same speed you intend to descend to keep the pucker factor to a minimum.

TexasTom....are you going to take the coach in to a Cummins Service Center so they can connect it "Insite" for a diagnostic evaluation?

[FleetProv40X]

I’m sorry I didn’t look back at the thread until now. I’m home and the engine would twice I believe produce smoke without the retarder switch on. I would crank the engine get ready to leave idle out to the highway and when I got on the throttle it smoked pretty bad for about 45 seconds and then slow the smoke down to none by two minutes. After finding a place to stop I noticed light oil or fuel spots on the front of my truck I am towing.

[Toribk]

Well, if you have white smoke and oil droplets emitting from the tailpipe you are burning engine oil which is certainly not normal.

I think it is wise to have it evaluated at a Cummins Service Center and proceed from there......just my opinion.

We'll be standing by.

[Caliber]

Symptoms point to a cracked EGR cooler. When you changed the coolant did you vac fill it? Air pockets get trapped within the cooler, causing spot overheating, cracking the stainless steel core.

[FleetProv40X]

Thanks guys. I’m going to try and get into the Cummins shop here in Ft Worth. It was smoking before coolant replacement. I didn’t use a vac on coolant I kept draining at the thermostat housing. It finally got all the air out. Temp is working fine.

[Toribk]

Just curious, how many miles on the coach and has the Crankcase Ventilation Filter (CCV) ever been changed or the vent tube inspected that your aware of?

[FleetProv40X]

42,056 miles
No filter hasnt been changed that I’m aware of.