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RichKimball · 03-26-2018, 08:31 AM

Hi. I have a 2008 6.7ISB on a Freightliner chassis. Recently, while in higher altitude (5000+ft) I had a STOP ENGINE light flash and then the engine would go into derate mode and shut down. No other light or warning. This was while climbing hills.
When i restart the engine, I would get a warning lamp of Exhaust Hi Temp and then go out. My year model doesn't use DEF and this Hi Temp lamp is supposed to be from DPF regen. This happened about 4 times. All other engine functions are normal...coolant temp etc. Thoughts? I posted a pic of the fault lamp.

2 Stroker · 03-27-2018, 10:24 PM

Quote:

Originally Posted by mevman

Hi. I have a 2008 6.7ISB on a Freightliner chassis. Recently, while in higher altitude (5000+ft) I had a STOP ENGINE light flash and then the engine would go into derate mode and shut down. No other light or warning. This was while climbing hills.
When i restart the engine, I would get a warning lamp of Exhaust Hi Temp and then go out. My year model doesn't use DEF and this Hi Temp lamp is supposed to be from DPF regen. This happened about 4 times. All other engine functions are normal...coolant temp etc. Thoughts? I posted a pic of the fault lamp.

Well I will take a shot at it. Kind of like have a pyro telling you the exhaust is to hot, drop a gear. I have a pyro on my 06 Ford 6.0 and when it get to 1350deg I drop a gear to get the exhaust out quicker and less strain on the motor. 1400+ may melt a piston. Don't know what kind of gauges you have but I would get some. I run the EDGE CTS in my Ford and the SilverLeaf in the MH.
2 stroker

RichKimball · 03-31-2018, 07:40 AM

Hi Stroker.
Yes, I believe you're correct regarding the turbo EGT. It is concerning as I have run the mountains before even towing and never saw this trouble.
It's fairly expensive to install and run an EGT probe to the turbo on a MH.
Others on a FB group mentioned EGT high temps also.

In all the manuals I have, nothing talks about warning lights on the Freightliner dashboard. Thanks again for your input.

RichKimball · 02-27-2021, 07:21 AM

As a follow-up to this I queried my Cummins dealer. They thought the aftertreatment DPF in the muffler was partially plugged. A nearby truck shop wanted $750 to bake and clean the DPF. With some new gaskets and the help of a motorcycle jack and YouTube videos showing how to self clean a DPF I proceeded. It took a day or so for the DPF to full dry out using compressed air and a dryer on the airline...but I finally felt confident to re-install. What a pain that was. Anyway....having no way to test to see if the high temp light would come back....
I also noticed that my exhaust manifold was leaking at a couple of cylinders. Contacted a local shop to do the work for me...as i feared of broken bolts etc. the shop was great and had it repaired in a couple of days, even with sending out the manifold to be planned.

I have never seen the High Temp Exhaust fault since and I have towed on the way to Las Vegas though the mountains with good performance. It could be that the manifold leak was causing the high temp....not sure. And other than my time and $60 for new aftertreatment muffler gaskets, the cleaning of the DPF was free.

Happy guy....engine runs great.

HolllywoodGT · 03-29-2021, 11:06 AM

Had the same issue on a new used coach I bought about 6 months ago. One was a turbo clamp failed fixed that. Then got about 40 miles down the road and the tail pipe folded over causing a High exhaust temp from lack of flow. Still didn't run tight until I did a full Regen. Heading back out in a week so I hope I doing have any issues