Dirty cooling system?

[Full-Timers]

Does your coolant filler neck look like this?



The coolant looks clean but the inside of my filler neck looks dirty. Do you think the whole system is this dirty? I don’t think a simple flush will remove this slime. What would you do?

[DriVer]

Originally Posted by Full-Timers

Does your coolant filler neck look like this?

No

The coolant looks clean but the inside of my filler neck looks dirty. Do you think the whole system is this dirty? I don’t think a simple flush will remove this slime. What would you do?

Keep flushing Don't use any type of cooling system cleaner.

[max49]

Mine does'nt look like that. But I live in a dry climate where rust is not nearly as big of problem as back east. I guess , as Driver said, keep flushing and maybe add a rust inhibitor.

[iRV4FUN]

Um, this is exactly why I dumped the Dex-Cool

[DriVer]

Originally Posted by iRV4FUN

Um, this is exactly why I dumped the Dex-Cool

After 93,000 miles and 8+ years of ownership, why would my DexCool not present in the same manner? My coolant is clean and no sludge. The problem as presented is manifest is due to a mechanical anomaly and not due to the coolant itself. Air getting in the system will do this. This can happen at the radiator cap, low fluid levels also contribute to the problem. DexCool is an extended life product and as such would be grossly inadequate if it sludged up like that across the entire fleet of vehicles that it is installed in. We're talking 100,000s of cooling systems or even millions.

[BCooke]

I do not know what it is out of.
There are issues with newer engines with the complexity of their castes parts and removing all of the undesirable material. Just did a flush and refill on a freightliner chassis this year after a radiator replacement due to failure ( 5 year old chassis ). Found out information from Cummings cooling engineering, performed flush and refill. Filter is now supose to have blanks changed at 3, 6, and 12 months ( I think is was ).

[M&EM]

Originally Posted by Full-Timers

Does your coolant filler neck look like this?



The coolant looks clean but the inside of my filler neck looks dirty. Do you think the whole system is this dirty? I don’t think a simple flush will remove this slime. What would you do?

FT you recently show on another post that your over flow tank cap had cracked and allowed air to get sucked back in to the sealed system? A non full radiator might well present crud like shown but only at the level it has air in it. I would flush several times using distilled water and maybe a radiator flush ( I did just that in my last cooling system saga) and run up to temperature each time. I did not have any sludge or air in my system before or after but I felt better doing the DI water and flush. I have changed the coolant on a 4 year schedule using Dex.

[Full-Timers]

Originally Posted by M&EM

A non full radiator might well present crud like shown but only at the level it has air in it.

I thought about that myself. I was wondering if the whole system looks like that or if I could just get away with carefully running a bottlebrush down the filler pipe to clean it out. I do need a complete flush and will be doing that soon also.

[iRV4FUN]

Originally Posted by DriVer

After 93,000 miles and 8+ years of ownership, why would my DexCool not present in the same manner? My coolant is clean and no sludge. The problem as presented is manifest is due to a mechanical anomaly and not due to the coolant itself. Air getting in the system will do this. This can happen at the radiator cap, low fluid levels also contribute to the problem. DexCool is an extended life product and as such would be grossly inadequate if it sludged up like that across the entire fleet of vehicles that it is installed in. We're talking 100,000s of cooling systems or even millions.

I agree… there are millions of Dex-cool systems on the roads without any issues. My research into this coolant has led me to believe that there is a narrow Ph band that must be maintained in order for optimal Dex-cool performance. That said, our spark plugs were designed for 100,000 miles and I’m pulling mine out at 40,000!

DEX uses OAT, or organic acid technology to extend the service life of the product. But one of the primary ingredients is thought to soften plastics (i.e. polymers that may be found in an intake manifold gasket) if not kept in Ph balance. One of these imbalances is due to air being introduced into the system. Air can be introduced through very small leaks in a cooling system. These leaks, or improper 50/50 mix ratio, or using “ordinary tap water”, or other failures, IMHO can cause DEX to turn acidic over time.

Properly maintained, in a perfect world or near-perfect system, this SHOULD never be an issue. This is why we see millions of Dex-cooled vehicles achieving long lifetimes. They lived in a perfect world. Unfortunately, some of our Dex-cooled systems aren't nearly as perfect under the hood as most of us would like to believe.

I’m not advising people to change out their Dex-cool. Several years ago I simply Googled this issue and made a decision to convert to a Universal coolant which uses a different corrosion inhibitor that is NOT known to soften plastics. My coolant is on a timed-out basis of every ~3 years. Not 100,000 miles!

[BCooke]

You can send your coolant for testing and they can tell you if the additive is required. The filters for the Fleet Guard come in 2 flavors a standard filter (has additive for coolant system) and blanks (just a filter) if they are used you have to get the coolant tested to assure the system is within tolerances.

[ArmyMPFromMO]

FYI. Make sure you never mix DexCool with non-DexCool anti-freeze. It will turn into a highly corrosive cocktail and destroy your cooling system. If you plan on switching, make sure you throughly flush all the DexCool out.