Odd coolant issue in ISC 8.3

[stooks]

Our 2013 Tiffin Phaeton (Freightliner Custom Chassis and 380 Cummins ISC engine) has been in the local Freightliner/Cummins shop for a week with an odd coolant issue that started about a month ago.

We seem to be getting additional pressure into the coolant system somehow. This is causing the pressure cap to release periodically and along the way we lose coolant out the overflow. Which eventually leads to a low coolant light. Top the tank off and repeat ever couple of hours while driving.

Freightliner CC Support has me check a few things before we checked it into the shop.

• Tried 2 new surge tank caps rated at 16psi. (Confirmed by Freight liner)
• Oil dipstick looks clean, no additional fluids noticed.
• No condensation on the oil fill cap.
• No white smoke at startup
• No leaking coolant under coach except for the overflow tube.
• Engine has not been overheating

Once in the shop the checks continued:

• Exhaust gas test done on coolant system - Negative
• Pressure test of EGR was also done, passed.
• Air Compressor and Head leak are still on the board to check.

The other odd bit:

- Shop noted an ammonia smell to the coolant when they first checked it. Appeared to have DEF in the system. They did a basic test of putting some coolant on a surface and letting it evaporate. Crystals appeared so they continued with the assumption it was DEF.

• The coolant system was flushed in May and new coolant along with a new Surge Tank put in. The only coolant added thereafter was from a gallon (50/50 mix) the shop gave me to top it off and some distilled water.

• As for the coolant that was removed, it appeared to be a little more of an orange tint than original pink and had a white film floating on the surface. This white substance would collect on your finger as you skimmed the surface. No oil or exhaust debris was noted.

The current direction is to change out the thermostat and coolant and test. Appears some tech have seen a thermostat going bad cause similar issues. But unless the coolant is breaking down in the system due to heat, etc, (saw that in a forum post somewhere) the residue in the coolant is still not explained.



I may have left out something here that was checked or tested so bear with me. But as the FLCC shop is scratching their heads I wanted to see if any of this sounded familiar to anyone.

[vettenuts]

Are you the original owner? Has the SCA level been maintained over the life of the coach? Sure wish you had the coolant that’s was removed, your answer may have been there.

[stooks]

Originally Posted by vettenuts

Are you the original owner? Has the SCA level been maintained over the life of the coach? Sure wish you had the coolant that’s was removed, your answer may have been there.

We are not. It is a 2013 and we purchased it in mid-2019 with 18k miles. The coolant was checked a few months later and a coolant flush and new surge tank was installed at the end of April this year.



The recently removed coolant was still in a tub behind the RV this afternoon. What did you have in mind for a sample?


-greg

[jacwjames]

Are you sure its a ISC engine.

Have they done a compression test on individual cylinders. Almost sounds like you have a leak on the compression side into the coolant circuit. It would explain both the pressure and the DEF in the coolant. Could be a head gasket.

[OldWEB]

Originally Posted by jacwjames

Are you sure its a ISC engine.

Have they done a compression test on individual cylinders. Almost sounds like you have a leak on the compression side into the coolant circuit. It would explain both the pressure and the DEF in the coolant. Could be a head gasket.

That is what I thought, but... No white smoke at startup When shutdown, the leak usually flows 'the other way' and coolant enters the cylinder and you get the white puff of burning coolant at start up. But stranger things....

[vettenuts]

Originally Posted by stooks

We are not. It is a 2013 and we purchased it in mid-2019 with 18k miles. The coolant was checked a few months later and a coolant flush and new surge tank was installed at the end of April this year.



The recently removed coolant was still in a tub behind the RV this afternoon. What did you have in mind for a sample?


-greg

Think I would send a sample to JG Lubricants. I would call them and get their sample kit and explain about the coolant now in a tub. Ask them the best way to take the sample.


I was worried about cavitation pitting of the liner..



https://jglubricantservices.com/home.html

[Ljwt330]

Originally Posted by jacwjames

Are you sure its a ISC engine.

Have they done a compression test on individual cylinders. Almost sounds like you have a leak on the compression side into the coolant circuit. It would explain both the pressure and the DEF in the coolant. Could be a head gasket.

Just a question for understanding.


How would a compression check, or any engine check, account for DEF in the coolant? From what I understand, which is admittedly limited, the only contact where DEF could enter the coolant is through the DEF heater coil inside the tank, but that is shut off in warm conditions. I cannot see the possibility of DEF in the coolant outside of the DEF heater tube as it is exclusively part of the exhaust system.


I am a bit skeptical that the shop actually found DEF in the coolant, given the way they "tested." I think it may be a red herring.


I am wide open for additional information that could explain how DEF could enter the cooling system.


Pressurizing of the cooling system is the question, and worn liners could be a strong possibility.

[vettenuts]

I don’t think their method of testing for DEF was adequate. I would get a sample tested. That will not only provide information on contamination but iron content, which may point to a liner issue. It will also provide SCA level, which will show whether or not it was maintained.

[Toribk]

We just had a member on our private forum with the identical symptom ( coolant loss via the overflow tube) you are experiencing.

After all testing was completed and a few parts replaced, it eventually turned out to be the compressor.

I'm glad you have it on the list yet to be examined.

Let us know how you make out.

[vettenuts]

I would be real interested in finding out what you eventually find out is wrong with it.

[mjeffrey]

Here is a reference I found online...CP7F1B.pdf

[mjeffrey]

Trying again...CP7F1B.pdf

[Toribk]

mjeffrey,

Copy the Link to the information, I don't think the website is allowing you to post yhe file.

[OldWEB]

Both work for ME.