OAT Carboxylate coolants and solder protection

[FCD]

Browsing old threads regarding coolant on BITOG i noticed that time and time again, OAT coolants are accused of poor protection of Lead solder, brass and copper.
What gives?

https://www.sae.org/publications/technical-papers/content/2000-01-1979/

This SAE study while old, does not make it less relevant, it says that Carboxylate OAT coolants provide SUPERIOR protection to Solder than conventional IAT Silicate coolants.

Yet there are many albeit anecdotal accouns of people seeing badly degraded lead solder due to using OAT coolants.

OAT coolants are also accused of poor protection for Copper and Brass, the primary corrosion inhibitors that protect copper and brass are Azoles in their various forms such as Mercaptobenzotriazoles.

I don't know of any coolant formulation that does not contain them, so in theory any coolant that contains some form of Azole , wether organic or inorganic, or a HOAT should keep the copper and brass heater cores or even radiators happy...
I have also read that Silicate helps to some degree to protect solder and copper / brass.

Right now i am running VW G12++ im both my Fords, it's an OAT Carboxylate coolant with Sebacic as the main OAT inhibitor, and between 400-500ppm of Silicate. ( Apparently no 2-Eha )

It claims to protect Cast Iron, Alu, Copper, Brass and Solder for up to 5 years before needing changing, and claims total neutrality regarding rubber seals and hoses.

Coolant experts, chime in with your knowledge, can an OAT Carboxylate coolant protect Solder, copper and brass well or no?

 

[Chris142]

I work at a radiator shop. Dexcool and the dexclones will make a soldered radiator or heater leak in a very short time. Eventually destroying the part.

We do not cover repairs if the wrong coolant is used. Every customer that leaves with a soldered radiator gets the talk.

The hoat coolants like GO-5 are supposed to be OK but we have not tried it.

You can see me @ :14...... https://youtu.be/5yG4zxz8CvE

 

[FCD]

I've been reading a series of 3 books on Google which are called "Engine coolant testing" and they seem to suggest that OAT Coolants which contain 2-Eha and or Octanoic acids, will corrode solder, but ones that don't have 2-Eha perform equally well compared to "traditional" coolants or even better, meaning theat they will not corrode Solder.

I am aware that Dexcool uses 2-Eha which might explain why you have seen bad results with Dexcool and solder, Volkswagen's OAT coolants, including the Silicated OAT coolants they have been using since 2005 model year cars do not contain 2-Eha from what i've gathered, and Octanoic acid inhibitors don't seem to be at all common in modern OAT coolants.

In fact i have a pdf ( in Spanish ) that explicitly states that the type of Silicated OAT Volkswagen uses, is in fact compatible with solder, copper brass etc.

So far i have no problems to report, both my cars are running fine on it, and ofcourse with the youngest being from 1988 they do contain lead solder, copper and brass in the cooling system.

 

[StevieC]

Solder is mainly Tin with some lead if it's the leaded type. It's most likely the Tin that isn't compatible with the coolant in the "lead solder" Perhaps this is why?

 

[Chris142]

Originally Posted by StevieC
Solder is mainly Tin with some lead if it's the leaded type. It's most likely the Tin that isn't compatible with the coolant in the "lead solder" Perhaps this is why?

Ours is 40/60.

 

[StevieC]

After looking it up it appears it can be either way (Heavy lead or heavy tin). Cool.

 

[Dan55]

I have personally observed this in my 1995 Pontiac Bonneville with a Harrison brass radiator at around 50k. I think they referred to it as Solder Bloom! GM had just recently switched to dexcool at that time.

 

[FCD]

As i said Dexcool does contain 2-Ehexanoic acid which has been said to increase solder corrosion substantially.

 

[nthach]

Prestone, who is still a 2-EHA stalwart reformulated Cor-Guard to be friendly with controlled-atmosphere brazed heat exchangers. The trend towards reducing lead is a European/Chinese requirement and looks like brazing is the most popular way to build Al-based heat exchangers. We don't know what metals are used in CAB, typically yellow metals or SnAg alloys are used in brazing.

Ford is having a rash of issues with orange Dex-Cool, but they are split on the fix for it. The F-150s will get converted over to their yellow DY coolant, the Transits will get Prestone Cor-Guard and my homework tells me Prestone has sold Ford on Cor-Guard for OEM on certain applications.

The Japanese seem to found a way to keep Pb-based solder protected with their PIAT coolants, and it seems like their POATs are OK with solder as well.

 

[FCD]

I've read in the past that Silicates are the most effective inhibitor of solder ( in all its various types )

But azoles also play a role in inhibiting the solder?

 

[George Bynum]

Originally Posted by Chris142
Originally Posted by StevieC
Solder is mainly Tin with some lead if it's the leaded type. It's most likely the Tin that isn't compatible with the coolant in the "lead solder" Perhaps this is why?

Ours is 40/60.

Lots has changed since the hate of lead became mainstream ... In my youth (say 1955-1975), 63:37 (the eutectic alloy) was considered optimum for hand-soldered electronics. 60:40 was more commonly used. Plumbers used the stronger 40:60 alloy. It was considered bad to do a water heater replacement with 60:40 ... weaker especially at the higher temperatures ... but I did 2 with my electronic solder that held until I sold the houses.