2010 T660 with ISX 450 Mystery Coolant Loss

It's been losing about 1 liter per day. no sign of external leak. Loss only occurs during engine operation. The company shop worked it for 8 hrs and documented that they repaired a leak in the overflow tank. No change.
As of yesterday, it seems to be getting worse. I added 2 liters in Durant,OK. I had to add 2 more when I got to Tulsa...
No sign of water in the oil.

 

I've got the same problem in a pete 386, same engine and year.

I never felt confident in the threads on the overflow cap. I sometimes see coolant beads around the filler neck after idling overnight.

It seems like the more often I top it off, the faster it vanishes.

 

I had an '07 Volvo once with VED12 engine doing the same. Kept consuming coolant and getting worse. No leaks anywhere. This a company truck, the shop was like, just drive it and keep the water topped off... ha!! Eventually the egr valves went bad and the engine had a huge loss in power. The wrench at the Volvo dealer who fixed it told me my coolant loss was thru the egr valves and out the smokestack as water vapor was why I never saw any leaks.

 

My guess would be EGR cooler too. Wish somebody could come up with a definitive exhaust test for antifreeze!

 

Yep thats classic EGR Cooler symptoms. I'd get it to a shop and get it checked out and changed. It will destroy the motor if it is and it goes on to long.

 

I did find a reference on google to the EGR cooler being a well-known issue. Too bad the "techs" at the company shop haven't heard about that.
I'm just keeping it documented to cover my six if the coolant hits the fan in the future....

 

DISCLAIMER: THIS MAY NOT APPLY!

I'll just toss this out there FWIW....at least in the W900s like me and a few others that own them..

They use coolant coolers for the transmission. We call them Coolant KILLERS.
They leak internally and start tossing coolant into the transmission.
The coolant level drops with no explanation...and you search and search to no avail.

Then the trans starts a nice whine...you pull the oil fill plug and coolant gushes out.

...just something for anyone else reading this thread to at least consider.

-JD

 

I know kw uses the same style cooler on there power steering as well atleast ok the heavy duty trucks

 

Mine had a leaky water cooled transmission cooler when I bought it but the dealer swapped it out at no cost for an air cooled when I bought the truck. Was leaking underneath the truck not into the transmission fortunately.

 

Mine blew the day I bought the rig. Fortunately, like Rollin Coal, it leaked externally and not internally.
In my case, it was OIL - but still better than the worse.

I have an external cooler installed and working on plumbing it and then removing the original coolant cooler.