Nitrites in HD Coolants..

[George7941]

Nitrites are used to protect cylinder liners against cavitation erosion. The older fully charged coolants come with the nitrites in them but the nitrites get used up fairly rapidly and the coolant has to be monitored frequently(with test strips) and the nitrites(and other additives) replenished with SCAs.

The HD ELCs are NOAT(a prime example being CAT ELC) and the coolants are supposedly good for 300k miles or more without any extender added.

So, coming to my question - how come nitrites last so well in NOAT coolants but not in the old inorganic additive coolants?

My best guess is that the 2-EHA in NOAT lays down a good protective layer to protect against cavitation erosion and the nitrites is only called upon when this 2-EHA layer is breached due to some unusual circumstance.

 

[Wilhelm_D]

Originally Posted By: George7941
The HD ELCs are NOAT(a prime example being CAT ELC) and the coolants are supposedly good for 300k miles or more without any extender added.

So, coming to my question - how come nitrites last so well in NOAT coolants but not in the old inorganic additive coolants?


CAT actually issued an explanation in 1999.

“ELC utilizes patented carboxylate inhibitors that allow the coolant to go at least 600,000 miles, 6,000 hours or 6 years before a coolant change. No SCA’s are needed. A single addition of Cat Extender is all that is required at 300,000 miles, 3,000 hours or three years. It eliminates the need to use supplemental coolant additives (SCA’s).”

“The carboxylate inhibitors in ELC deplete very slowly. Furthermore, the carboxylates provide protection of wet sleeve cylinder liners, which eliminates the need for routine testing of coolant for nitrite and/or molybdate levels. When the cooling system is maintained properly and ELC (or equivalent) is used for top up, there is no need to conduct routine testing for inhibitor levels.”

Given the cost of sleeve damage, most fleets use an ELC Field Test Kit on an interval shorter than the 300k – 3k hr – 3 yrs schedule to be on the safe side.

 

[tdi-rick]

FWIW Cummins/Fleetgaurd's new HOAT/propylene glycol ELC (PG Platinum) doesn't use 2-HEA in the formulation AFAIK and doesn't contain any nitrites at all.

It is supposedly good for 500,000km/6000 hours before testing/replenishing.

 

[Coolant_Man]

More enough on nitrites and ELC diesel coolant...

http://www.ford-trucks.com/forums/960812...nformation.html