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Old 02-24-2020, 12:52 PM   #1
Junior Member
Join Date: May 2014
Location: Simpsonville SC
Posts: 15
Cummins ISM Internal Coolant Leak

We have a 2008 Newmar Essex with a Cummins 500hp ISM engine. No DEF or particulate filter. Early this past fall I started noticing a lot of thick whitish smoke upon starting the engine anytime it had sat for several hours or longer. The smoke plume would disappear after about 3 minutes with engine idling. I was having to add about a quart of coolant every 1000-1500 miles. The coach had about 85k miles on it when we purchased it 2 years ago and now has about 125k. It did not consume any noticeable engine coolant until late this past summer.

A little over two weeks ago took in to nearby Cummins Atlantic in Spartanburg, SC and they found combustion gasses in the engine coolant as well as a small leak in the EGR cooler. We had them then pull the head and they found low cylinder liner protrusions. They advised replacing the liners which would then also require replacing the pistons. Also they advised that the head should be also replaced as they had no way to pressure test or magnaflux the head to assure it also wasnt contributing to the coolant issue. Sending the head out for testing would end up costing nearly as much as a remanufactured head. Of course the EGR cooler would also have to be replaced. The engine has had OAT antifreeze (no SCA issues with OAT) since birth, and Cummins did confirm to me that there was no sign of liner pitting or corrosion, but to date, they have not been able to provide any explanation as to why the low cylinder liner protrusions. We have authorized the above repairs which total in excess of $20k.

I am wondering if all the issues were having are common place or if we just drew the short straw, and any thoughts about why the low liner issue.

Ward J
2008 Newmar Essex 4502 (500 hp ISM), 2010 Honda CRV toad
1999 Monaco Executive (450 hp M11)
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Old 02-24-2020, 06:07 PM   #2
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Newmar Owners Club
Join Date: Aug 2015
Location: Ponchatoula,Louisiana
Posts: 699
We had a boat with twin QSM11s. We had the white smoke at start up and could tell the engines were not in sync. Called out diesel mechanic and it was diagnosed with a leaking head gasket. Best of luck on this!

David and Sharon
2017 Newmar LA 4519
2020 Jeep Wrangler Rubicon
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Old 02-24-2020, 06:17 PM   #3
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Join Date: Aug 2015
Posts: 492
Of course Cummins is gonna rape every dollar they can. Exhaust gasses in coolant and leaking egr cooler is pretty common. Have you physically seen the spec and low liner condition? Dropped liners is usually a condition found on trucks with manual transmissions and usually caused by lugging up a hill.

What was there determining factor to dig deeper than egr cooler failure?
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cummins, leak

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