What happened to my coolant?

Dave Kay

Adventurer
FWIW thinking back it was the prestone 10 minute stuff they had me use. They just had me do it for 30 minutes to really break it down.

You might call a lube place. It only ran me $100. You could get there just buying all the supplies trying to do it yourself and you have all the crap left over in a bucket or two.
Thanks Matt, am glad that Prestone treatment worked good for you--- and believe me, I would luv a quick simple solution. My Problem is that I'm a fanatical direction-following over-doer from way back--- and if it ain't done by the book I ain't gonna' sleep well at night. (some people in my trade sometimes hate me for it)

And anyway, the GM tech article says other flush products are not reccomended for this Dex-cool-mud-problem so I'm taking the long, hard road home... and when I finally gets there, I know I'll be sleeping well.:wings:

P.S. check the 4th post down: http://www.corvetteactioncenter.com...erformance/24337-cooling-system-question.html
 

coreys88burban

Adventurer
i put dexcool in my motor in my chevele after 3 years of hard work and $4,000 in parts and it did the same thing...needless to say i was overheating myself. id never use dexcool agian.
 

4x4x4doors

Explorer
Obviously, YMMV.

In my 91, I had the glycol (green) flushed well and replaced with Dexcool at 100K. It was absolutely fine for the next 50K miles I kept the truck. My thinking was more along the lines of what I might be dumping in a stream if the cooling system went on me. My 99 still had the original dexcool at 113K when I totaled the truck and the 01 had the original dexcool still in it at 134K and 8 years when I sold it.

Sorry it's not working out for you.
 

PirateMcGee

Expedition Leader
I used to work at an oil change place, we used to see this all the time. Terrible coolant and if there is even remnants of the green stuff left you can end up with problems as they do not play well together. Also if it comes in contact with air, over time it gels. Your're going to need to go get this flushed out someplace. We used to only charge $69 for a complete flush which is pretty reasonable and it worked great.

One other thing, do not put soap in your cooling system. You are not trying to remove any oils, and you will just be asking for trouble. I worked on multiple cars that tried this and even with our flushing machine it was extremely difficult to remove all the remnant soap.
 

Dave Kay

Adventurer
Well, I stayed up kinda' late last nite doing some research and IMHO, this Dex-cool-turns-to-mud thing is a total ripoff-scandal. The companies that make the stuff should put a warning label on the jugs because by now THEY WELL KNOW this product is faulty and causes untold million$ in repair costs. But of course they won't because that's how you do business these days; ignore the glaring problem and just keep marketing it like it's perfectly fine. Then when they finally get hit with a class-action lawsuit and the product is either fixed or taken off the market, or whatever, the board of directors and investors could give a damn becasue they've made their profits, the share holders are happy and it's on to devising the the next scam to be sprung on the un-informed American public. (that's you and me!)

(For a perfect example of my thesis do a search for nVidia & Dell laptops and you'll see what I mean.)
 

motorking

New member
Can anyone explain this; Installed a bigger, re-cored radiator in Jan '09, all new hoses, flushed the system, filled w/50-50 Dexcool and distilled water. First time using this stuff but for some reason I was told it's better than the green stuff even for older rigs. (GMC 1986) The truck hasn't been driven more than 10k miles since that work was done and the cooling system was full whenever I popped the cap...

Fast-forward to today----- I'm changing out the thermostat and to my utter shock and amazment I discover that my entire cooling sytem is FULL of some kind of rusty residue--- clinging to everything--- I mean the stuff is thick! What the???? Inside the radiator walls it's coated with this stuff and YET, the coolant that I drained into a bucket looks clean and new.

What have I got here and how do I get rid of it? Help, anybody?
Hi,
I am the technical manager at Prestone. What you are seeing is rust based corrosion. It is not caused by the dex cool. It is caused by air ingestion into your cooling system, most likely from the raditor cap. is your coolant recovery system/bottle intact? Make sure it is and you have a good quality rad cap. Use prestone super flush, clean it out really good and make sure the recovery system is working and this should not reoccur.
 

dwh

Tail-End Charlie
Hi,
I am the technical manager at Prestone. What you are seeing is rust based corrosion. It is not caused by the dex cool. It is caused by air ingestion into your cooling system, most likely from the raditor cap. is your coolant recovery system/bottle intact? Make sure it is and you have a good quality rad cap. Use prestone super flush, clean it out really good and make sure the recovery system is working and this should not reoccur.
I've never used Dex-Cool. I have however owned over 40 vehicles with radiators and have always done my own mechanical work. Buying and fixing up older trucks has been a hobby of mine for over 30 years. Many of my vehicles were older and never had recovery bottles. Most had some air in the system at one time or another.

I've seen plenty of rust-based corrosion and scale and most all of the other problems that engine cooling systems can experience.

None of my vehicles have -ever- had thick, oily, gunky sludge like that described by the OP and many others on the Internet who've described their experience with Dex-Cool. (EDIT: Amended - I have seen such sludge from blown head gaskets - but that's a different kind of sludge.)

This makes me think that what the OP (and others) have described is in fact, NOT what is normally called "rust based corrosion".
 

motorking

New member
I've never used Dex-Cool. I have however owned over 40 vehicles with radiators and have always done my own mechanical work. Buying and fixing up older trucks has been a hobby of mine for over 30 years. Many of my vehicles were older and never had recovery bottles. Most had some air in the system at one time or another.

I've seen plenty of rust-based corrosion and scale and most all of the other problems that engine cooling systems can experience.

None of my vehicles have -ever- had thick, oily, gunky sludge like that described by the OP and many others on the Internet who've described their experience with Dex-Cool. (EDIT: Amended - I have seen such sludge from blown head gaskets - but that's a different kind of sludge.)

This makes me think that what the OP (and others) have described is in fact, NOT what is normally called "rust based corrosion".
Hello,
Not here to argue with you at all. The industry issues with dexcool are not the fault of the coolant. Air ingestion, poor gasket materials and people randomly mixing different types of coolant when they had leaking intake gaskets ARE the cause of dex cool issues in the industry.
FACT- GM still uses dexcool in every vehicle they build. In 2011, Ford and Chrylser have started using dexcool in all of theor vehicles. Mercedes, BMW and VW are now all using it. I am a mechanic with a shop, well aware of issues with certain vehicles out there, that said, its not the coolant. I just drained the dexcool in my 2004 cadillac, it is crystal clear as is the inside of the radiator. This is after 6 years and 60k miles of use. Looking at the picutres provided, it does not look thick, oily, it looks like a typical OAT coolant cleaning rust from the cooling system. Its pretty easy to see what it is, Polaris labs will analyize the coolant for 20$. Then you would know for sure whats going on. Anything else is just speculation. The fact remains that most all automakers are transitioning to OAT type (dexcool) coolants simply because it is the best technology out there.
 

dwh

Tail-End Charlie
The industry issues with dexcool are not the fault of the coolant. Air ingestion, poor gasket materials and people randomly mixing different types of coolant when they had leaking intake gaskets ARE the cause of dex cool issues in the industry.
Right. No disagreements on that.

My point was that this problem is not the same as other "rusty cooling system" problems.

Perhaps it would better for you to refer to it as "'Dex-Cool type' rust based corrosion" or "OAT type", rather than make it seem like you are pooh-poohing the problem by equating this particular issue to the "normal" rust based corrosion that is common to radiator cooled vehicles. This certainly appears to be a different breed of animal.



Looking at the picutres provided, it does not look thick
Perhaps not, but the OP -described- it as thick.

"I mean the stuff is thick!"


it looks like a typical OAT coolant cleaning rust from the cooling system.
Could be. That doesn't really jibe though with the description in the OP, which describes the system as pretty clean before he put the Dex-Cool in it.

Also, "cleaning" would seem to imply that the rust would be in solution - i.e., when you drain the coolant, the rust is mixed in with it. That's not the situation described in the OP, where the coolant was clean and the gunk was -deposited- on the walls of the cooling system.

Depositing the gunk on the walls to where it doesn't flush out with the liquid (not in solution) is not what I would refer to as "cleaning".

EDIT: Unless you mean that the coolant self-cleans by depositing the gunk on the walls...
 
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Dave Kay

Adventurer
Hi,
I am the technical manager at Prestone. What you are seeing is rust based corrosion. It is not caused by the dex cool. It is caused by air ingestion into your cooling system, most likely from the raditor cap. is your coolant recovery system/bottle intact? Make sure it is and you have a good quality rad cap. Use prestone super flush, clean it out really good and make sure the recovery system is working and this should not reoccur.
Dude, everything in the system was brand new as of Jan 2009. The truck has less than 10K miles since the work was done. The block was drained and back flushed seperately from the radiator. Nothing out of the ordinary was done to make this cooling sys different from the one I did for my 1977 C-20 and that rig STILL has it's orginal radiator that's clean as a whistle. I never used Dex-cool before and was unaware of the potential problems. The stuff SHOULD NOT be used in older vehicles and that's the lesson here.

BTW; GM DOES NOT reccomend cleaning up this problem with the diluted products such as Prestone becasue it will not get resuts--- read the 15 page remedial procedure.
 

Dave Kay

Adventurer
Ok, I DO appreciate all the comments and shared knowledge, thank you all. And I'm not knocking anyone who uses the Dex-cool in their newer rigs heck--- I've got the stuff in my 2000 Pontiac Grand Prix and it's not been a problem. So 'nuff already of my gripin' and moanin', I'm getting to work on this mess this weekend and doing the 61-step GM procedure to the "Tee." So far I've got most of the supples/chemicals together, (less than $50 bucks so far) and now my question IS; what coolant do expedition-folk use in their rigs today? In particular, for their older (pre-millenum) rigs?

(aside from my current dex-mudd debacle) Used to be I'd just go get some of the green stuff, mix it 50/50 and it's good to go for a couple years, never a problem even if you spring a leak. But since I made the mistake of buying into hype and used something I should not have for my year truck, I don't want to gum-up the works again.

So I'm shopping for coolant and I'm seeing something called RV coolant, then there's extended life coolant, mix-it-with-anything-any-color coolant, super-safe-your-dog-can-drink-it-coolant and maybe a few 'eco-green' type coolants. Is it all marketing BS? Or does any of this stuff have an advantage over the other? Or is good old green stuff the way to go for pre-millienium rigs?
 

HenryJ

Expedition Leader
I held off for as long as I could :)
API said:
Associated Press
GM Settling Suits Over Engine Coolant
By DAVID TWIDDY 03.26.08, 5:11 PM ET

KANSAS CITY, Mo. -

General Motors Corp. has agreed to settle a series of class-action lawsuits claiming a faulty engine coolant damaged thousands of customer vehicles.

Under the settlement, GM would reimburse class members between $50 and $800 for repairs linked to Dex-Cool, an orange coolant that GM included in cars and trucks beginning in 1995.

The total cost to GM will depend on the number of customers claiming damages, but the plaintiffs' attorneys estimate the settlement could cover up to 20 million initial and secondary buyers of GM vehicles that used Dex-Cool. They also say the price tag could reach the hundreds of millions of dollars.

A California state court gave preliminary approval to the settlement last week and a Missouri court plans to consider it Friday.

"We fought for about five years to recover monetary damages for people that would be meaningful and I think we achieved that," said San Francisco plaintiff attorney Eric Gibbs, who estimated most people spent between $600 and $900 for repairs. "The recovery for most of the people will be pretty good."

GM spokesman Tom Wilkinson said the company was not admitting any wrongdoing but is settling the case to cut down on legal bills.

"Our experience with Dex-Cool is that when the cooling system is kept full and properly maintained we haven't seen any problems," he said. "These kinds of things appear to be issues of low coolant, which isn't unusual with high-mileage vehicles, so we decided to agree to the settlement."

GM owners have filed a dozen breach-of-warranty lawsuits in state and federal courts across the country, including California and Missouri, where one of the earliest cases was filed in April 2003.

The cases all claim vehicles with Dex-Cool often damaged the engines or created a rusty sludge in the radiators that caused the vehicles to overheat.

Under the agreement, GM will reimburse some of the cost for intake manifold gasket replacements, cooling system flushes and heater core repairs sought during the first seven years or 150,000 miles, whichever came first, that the class member owned the vehicle. Considering that some vehicles may have been sold and the new owners also paid for repairs alleged to have been caused by Dex-Cool, individual vehicles may generate more than one settlement.

Negotiations on a settlement began shortly before the Missouri case was scheduled to go to trial in November. They culminated with the agreement being filed in Alameda County Superior Court in Oakland, Calif., on March 20. That settlement covers 49 states.

A separate Missouri settlement, with the same terms as the California one, is scheduled to go before a judge Friday in Jackson County, Mo. Missouri had a separate settlement as it was the first states to grant class-action status to the claims, said Jack Brady, a Kansas City-based attorney and co-lead counsel.

"It could be multiple nine figures; it depends on how many people make the claim," Brady said. "I think it could be a huge settlement."

Gibbs said the attorneys will receive up to $23 million in fees and $2.8 million for expenses.

The settlement covers GM vehicles with 3.1-liter or 3.4-liter V6 engines for model years 1995 to 2003; those same brands with 3.8-liter V6 engines for model years 1995 to 2004; and small trucks and sports utility vehicles with 4.3-liter V6 engines for model years 1995 through 2000.

The deadline for submitting claims is Oct. 27 for states outside Missouri and a week later in Missouri, assuming the judge grants preliminary approval Friday.
http://www.dexcoolsettlement.com/ I have heard no more on this and all the information seems to be disappearing. Swept under the rug as the issue is now past a decade old now.

Too late to jump on that bandwagon.

Dexcool has two main problems. Heat and air. Unfortunately the cooling system tends to be prone to both. Older systems more than the newer.

It is true that the radiator caps were a contributor in earlier models. The stock GM cap is was poor. This was the case even into the early 2004 models.
The problem is that the upper gasket was made from a fiber base, which is nice because it doesn't crack like the rubber based seals, but it does shrink a little and just by its nature does not seal well.
The next problem is that the ID of the upper seal is barely smaller than the rad opening, so there is very little contact. If the gasket (seal) shifts even a little, air can enter the system.
Next is the check valve. Some were not spring loaded and would allow air to pass after cooldown. For the Dex users all these issues were VERY bad! (Dex + air = contamination)

More on the cap here: All” about DEX-COOL®
All” about DEX-COOL® said:
MACS 2001: GM and Texaco “Bare All” about DEX-COOL®
by I.M. Cool
Appeared Jan/Feb 2001 Cool Profit$ Magazine
© 2001 All Rights Reserved
As in the past, the MACS 2001 Convention and Trade Show in Orlando provided some very interesting and helpful air conditioning information. However, the sleeper presentation at this show was not about refrigerant, but—of all things—engine coolant! (Sleeper does not refer to making you sleepy; it was anything but boring.)

Marketing departments of major consumer goods manufacturers are known for their attempt to conceal even a shred of negative publicity about their products. You can’t blame them; you do the same in your business. That’s why it was refreshing to witness a candid GM/Texaco presentation about DEX-COOL coolant and its related field service problems. I give the big guys credit for even bringing up the subject because, well, let’s face it, there are not a lot of kind words being spoken about this coolant at automotive service shops today. (Especially at radiator shops.)

GM Cooling System Contamination Video @ $10 +S&H - Call 800-393-4831Left: 14-Minute GM Training Video is now available to help technicians service known cooling system contamination problems in specific GM vehicles.

GM’s Jay Dankovich and Equilon Enterprises’ (Texaco) Stede Granger directed a 2-year study of thousands of DEX-COOL cooled vehicles. Armed with the results, they really didn’t have anything bad to say about the coolant. In fact, they strongly defended the product’s reputation. What they revealed to the audience is that specific models of GM vehicles have specific cooling system contamination problems. And essentially, that DEX-COOL is not the culprit!
Their presentation started with a 14-minute video that is now being circulated to technicians at GM dealers nationwide. In the video, GM’s trainers succinctly described the problems that have been found and the corresponding corrective actions to be taken by technicians.

Suggestion. This video is a “must see” for all technicians considering themselves antifreeze/coolant experts. Without this information, your cooling system service knowledge of late model GM vehicles is severely limited. Seriously!
Fortunately, you can buy the video for only $10 (plus S&H). Call MSX International of Auburn Hills, Michigan at 800-393-4831. Ask for the DEX-COOL Video: “Understanding Radiator Cap and Cooling System Contamination.” Part number: RADCAPK. Immediately following this article is a report on this training video by John Brunner, recently retired GM field service representative.

What was said at the presentation? Besides the video, Jay and Stede included their personal observations about the study. At the end, they fielded several questions from the audience. Here’s a recap of their entire presentation.

1. Keep the cooling system filled. In fact, fill the reservoir bottle to “Hot” level when the system is cold. Problems arise when a system’s coolant level is not maintained. (Fleet vehicles receiving regular maintenance, and with reservoirs kept slightly above normal, do not show signs of contamination. This even applies to the specific “problem” vehicles.)

2. The coolant problems found in this survey were caused by system contamination, and not due to the breakdown of DEX-COOL.

3. Check and keep the pressure cap clean and functioning. A contaminated and/or malfunctioning cap causes low coolant levels, which in turn causes overheating and a greater loss of coolant: the notorious vicious cycle. No matter what the vehicle, if the cooling system acts suspiciously, test the pressure cap.

4. On the ST vehicle models mentioned in the GM DEX-COOL video, you “must” replace all suspect radiator caps, especially those with a Drop-Center design, with a Stant Model 10230 or 11230 (Spring-Center type). (Just do it.)

5. Make sure that the coolant is at a 50-50 mix. Often, the flush water was not being removed from the engine block. Consequently, when a 50-50 mix is added to the system the resultant mixture could approach 30-70. Like any fluid that has been diluted beyond its recommended levels, the lowered level of inhibitors will not be able to protect the coolant system effectively. Low levels of inhibitors can cause pitting on aluminum surfaces and general corrosion of cooling system metals.

Cutaway of Drop-Center CapLeft: Drop-center, “vented” radiator pressure cap. GM found this cap (like the Stant 10231) to be less helpful than a Spring-center cap (shown below) in controlling the formation of contaminants in the cooling system. If contamination forms, the debris fouls the valve and restricts its ability to seal. In turn, the coolant boils at a lower temperature. Coolant loss is accelerated and so is the accumulation of contaminants.

Cutaway of Spring-Center CapLeft: Spring-center, sealed radiator pressure cap (like the Stant 10230). This is the preferred cap for GM applications that are more prone to accumulating cooling system contaminants.

6. A safe method of achieving a true 50-50 mix is to first determine the actual capacity of the system (use the owner’s manual). Then add 50% of “that” amount of undiluted DEX-COOL (or any coolant), and top it off with water.

7. Mixing a “green” coolant with DEX-COOL reduces the batch’s change interval to 2 years or 30,000 miles, but will otherwise cause no damage to the engine. In order to change back to DEX-COOL however, the cooling system must first be thoroughly drained and flushed.

8. Bacteria cannot live in a hot, Ethylene Glycol environment and is therefore not a threat to DEX-COOL.

9. While there have been intake gasket failures on CK Series, V8 powered vehicles for various reasons, DEX-COOL has never been found as a cause.

10. Use a refractometer to check the condition of DEX-COOL. Its inhibitor package is strong enough that if the batch still provides proper freeze protection, it is probably still providing proper corrosion protection as well.

11. DEX-COOL can handle the minerals in hard water better than silicated conventional chemistry coolants. Drinkable water is suitable for top off.

12. In ST Blazer applications where the radiator cap is mounted at an angle to the ground, the vehicle is more susceptible to radiator cap contamination and its related problems. The Stant 10230 is a wise choice for these vehicles.
Another article:
Dexcool was developed specifically to protect aluminum engines. As any engine that is primarily made from aluminum the key word here is "primarily". The engine still has lots of small parts touching the coolant that are made from ferrous metal. Stuff like bolts, the water pump impeller, headbolts, gaskets, cylinder bore liners, etc.

The protection level of silicated coolant is dependent on a coating of silicate on all of the parts of the engine blocking electrolytic reactions. This is a hit-miss kind of thing and you can see the effects of electrolysis on the intake manifolds on mid-80's Oldsmobiles and Chevys. They will be eaten away wherever they were in contact with a ferrous metal part. The way Dex-Cool functions is that it actually changes the molecular structure of the surfaces of the aluminum in contact with the coolant. (Sometimes this will appear as a black or dark gray coloring of the aluminum inside the cooling system.) This is a similar process to bluing of ferrous metals to prevent rust.

The drawback of silicates is that over time they flake off leaving unprotected areas of the engine open to electrolytic action. They also have hard debris floating around in the cooling system. (The Silicate coating is that white flaky stuff you see in a used engine block at the junkyard.) Pieces of it find their way into the water pump seal and wear it out much earlier than if you use Dex-Cool. They also build up in the radiator and block the flow of coolant through the tubes slowing cooling. And as if that were not enough, the silicates act like insulation keeping heat from transferring from hot parts to the cooler liquid and from the hotter liquid to the cooler radiator surface to be carried away.

Dex-Cool has had some issues with solids forming in the coolant. Those issues are caused by two things.
1. Air trapped in the pressure side of the cooling system.
2. Over-concentration of coolant.
You can mix them but you lose the benefit of the Dex-Cool (mixing is not what turns the coolant into "mud") Never go higher than 50/50 and always make sure the system is full and is not losing coolant. Also, when you do this, replace the Radiator cap, preferably with a new one from GM. GM used to use Stant caps until they found out that they were getting air in the cooling systems from them. Look at your cap and if you see a Stant brand "Block S" on the stock GM cap, toss it and get a new one from a GM dealer. As long as it does not have that "Block S" on it when you pick it up, you are good to go. Some of them may have the small letters "TVS" on them, these are the good ones.
That is all good, but the biggest offender is the cap for most systems.


Above: Drop-center, “vented” radiator pressure cap. GM found this cap (like the Stant 10231) to be less helpful than a Spring-center cap (shown below) in controlling the formation of contaminants in the cooling system. If contamination forms, the debris fouls the valve and restricts its ability to seal. In turn, the coolant boils at a lower temperature. Coolant loss is accelerated and so is the accumulation of contaminants.


Above: Spring-center, sealed radiator pressure cap (like the Stant 10230). This is the preferred cap for GM applications that are more prone to accumulating cooling system contaminants.

There is also a problem with cavitation on the impeller in the older engines. Specifically the 5.7L and 4.3L GM engines. A redesign of the pump impeller in newer models seems to have cured that contributor.
Add to those issues an incompatibility with the intake gasket materials used in 1999-2002 models and the whole thing is a real mess.

GM distanced itself from the problem by selling the Dexcool problem to Havoline who currently manufactures Dexcool.

I would say that I have seen 20 yr old green coolant that never posed a problem even when subjected to air , and creek water. Yet I have seen numerous cases of sludged , corroded, damaged parts , etc. in systems using Dex with very little neglect. The extended life Organic Acid Technology (OAT) coolant was a good idea, but just didn't pan out in my book.

Can OAT coolants work? Yes.
The newer cooling systems have changed to meet the problems head on. Starting with the 5.3L engine family.
A new coolant reservoir expansion tank that is baffled and contains the fill / pressure cap. At the highest point in the system and open to circulation flow to scavenge air in the system.
Newly designed heads and water pump.
Are there still problems? Sure. The stuff is still sensitive to contamination. The extended service interval may not be as long as advertised.

How do I fix it? flush , flush, and flush again. The Prestone cooling system flush seems to do a good job. I follow the directions and then fill and drain at least three times after each warm up, until it runs clean.

Nothing transfers heat to the airflow better than straight water. It conducts very well. We add "coolants" to improve protection of the cooling system components and add freeze protection as well as raise the boiling point.
Straight water and a corrosion inhibitor are all you really need if it doesn't freeze in you local. An additive that breaks the surface tension is a good idea too. Royal Purple makes "Ice" and Redline has water wetter. That stuff is just good science.

What do I use?
In older vehicles, pre 2002, I use a 50/50 mix of green and distilled water. To that I add a bottle of Redline Water Wetter. This additive breaks the surface tension and aids in the heat transfer. Service this combination every two to four years, although I have seen some go much longer with no ill effects.

If the vehicle is newer than 2004 and uses extended life coolant. I watch it close and add nothing but a clean 50/50 mix of that coolant and distilled water. Serviced at no more than a four year interval. What am I watching , or looking for? White waxy crystals at or around the air coolant interface, This residue is an indicator. Milky opaque coolant. An over heat, or boil over. All would be reasons for a flush and refill.

Moral of the story: Service your cooling system. Treat it as needed and protect it from contamination. Use distilled water and a 50/50 mix.
Older systems should use the Green coolant (alkaline based)
Newer systems may work fine with extended life (acid based) red, orange coolants.

Knowledge is power. If you don't know ask questions. Sorry for the long post, but this is not an easy one to answer.
 
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