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Forza4us · 06-14-2015, 08:45 AM

I recently purchased a 2007 Magna (50k mikes) with the Cummins ISX 600 engine. While driving up from Dallas to Yellowstone I noticed that the entire back side of the coach was covered with a thin layer of black soot. Is this something that I should be concerned about or is it normal? Should I check the air filter to see if it's clogged? One last note, on the last leg of the trip up I noticed a slight loss in power. Sorry for what might be dumb questions but I'm new to diesel engines and just want to make sure that I ward off any potential issues before they become a problem.
Many thanks!
Rick

Skip426 · 06-14-2015, 09:49 AM

Air filter would be the first place to check and with the noticeable drop in power , fuel filters as well. Even it you have service history on the fuel filters, it only takes one tank of bad fuel to plug them up.
JMHO: Don't trust the " air filter monitor " most are not accurate.

Forza4us · 06-14-2015, 11:01 AM

Thanks Skip. I checked the air filter and air filter monitor and both look good. How and where do I check the fuel filters? Headed to Jackson Hole in the morning will check again when I get there.

Skip426 · 06-14-2015, 11:16 AM

Depending on the coach/chassis/and Cummins installation of filters you will probably have 2 filters , maybe even 3 ; so I'll have to let someone with your exact coach answer that question.
Cutting the filters open after a change is the best way to determine if they were plugged, but most owners won't go that far and rely on improved performance to tell them if fuel filters were the problem.

tom chelbana · 06-14-2015, 02:42 PM

We have a 04 500 ISM Cummins and the side were the exhaust comes out there is a thin layer of soot for the about 3 feet forward and 2 feet high. Have over 115K miles on coach and runs good and don't think you have a problem. Wipe right off.

TQ60 · 06-16-2015, 08:31 AM

Isx engines are prone to valve issues...

Ask mr d...

Loss of power indicates problem that could be simple but given isx do some homework to confirm if it is in group sensitive to issues.

If fails it is a 30k problem.

Forza4us · 06-17-2015, 12:15 AM

Thanks all for the input. On the trip yesterday from Yellowstone to Jackson Hole the engine seemed to be running ok. That said, I'm definitely going to have the engine checked out when I'm back in Dallas. I believe Mr D's engine was an ISX 650. As far as I know the 600 hasn't had the same valve/engine issues as the 650. Nonetheless, I won't be taking any chances with it.

Mr_D · 06-17-2015, 12:44 AM

Quote:

Originally Posted by TQ60

Isx engines are prone to valve issues...

Ask mr d...

Loss of power indicates problem that could be simple but given isx do some homework to confirm if it is in group sensitive to issues.

If fails it is a 30k problem.

Yes, the ISX 600 is also prone to the problem although the 650 seems to be worse. I've seen some of the ISX 450's do the same thing but at much higher mileage in class 8 trucks.
Boy, are they ever and yes more than 30k.

We never got any soot like that though, even after the valve broke. I do see some soot discoloration in the closet lining though. It was therer when we bought the rig so no idea when or how it happened.

We got a lot of "regen" notices on the panel before the valve went. Seems like several times a day. Turns out the DPF was also cracked which might have caused some of the warnings.

Our first warning of the valve breaking was the engine lost power and threw a check engine light. I was able to drive it a few more miles to a truck stop. I was really low on fuel so I added a few gallons thinking I was sucking air. No such luck either.

Forza4us · 06-17-2015, 10:17 PM

Thanks Mr D for the heads up. I will have a Cummins service center look over the engine.

Mr_D · 06-17-2015, 10:48 PM

Quote:

Originally Posted by Forza4us

Thanks Mr D for the heads up. I will have a Cummins service center look over the engine.

I know of one ISX that was worked over by Cummins to get it running correctly then blew up less than 50 miles later. No warranty coverage either.
So, don't expect Cummins to pick up impending problems! We had an oil analysis done and the engine blew 2,600 miles later. There is not much of any way to predict a valve breaking off.

Peralko · 06-18-2015, 12:07 PM

All the more reason we're leaning towards an older Prevost!

Mr_D · 06-18-2015, 10:07 PM

Quote:

Originally Posted by Peralko

All the more reason we're leaning towards an older Prevost!

With a DD?
Our ISX, when running correctly is a monster! Now if they really did get it permanently fixed we'll be OK, but if I have to shell out big $$ to fix it again I'll hope someone starts a class action over the problems!

Forza4us · 06-18-2015, 10:30 PM

There's no sure bet with any brand of engine. That said, I'm confident that I'll get it sorted out when I get back to Dallas. It's not running that poorly. Today I was going up 6% grades with ease. Thanks all for your input.

Peralko · 06-18-2015, 11:58 PM

Quote:

Originally Posted by Mr_D

With a DD?

Have any experience with Detroit Diesels? In a Prevost, power to weight ratio is about the same as our coach, and we are doing fine with the power we have.