Dex-cool

Reply

  #1  
Old 11-01-04, 04:25 PM
Sparky-L.U.697's Avatar
Member
Thread Starter
Join Date: Feb 2003
Location: Indiana
Posts: 328
Dex-cool

Is it common for DEX-COOL to plug up a radiator (5yrs old)? I have a 99 Chevy Suburban 5.7l and developed a leak around the oil cooler when I took the radiator to the radiator shop to fix the leak they called to tell me I had a 75% blockage and they were unable to clean it or rod it. When I questioned them they said it may have been caused by the leak allowing air into the radiator causing the DEX-COOL to oxidise and plug up the tubes(aluminum radiator). They also said there was no chemical to remove this oxidation only recourse was new radiator ($300). I said to just fix leak as the trk only runs 205-210 degrees in the summer w/ the air on, then they sugguested I try to buy radiator flush and flush kit from parts store and see if that would help (even after telling me there was no known cure for that substance left from the DEX-Cool)

Any help or sugguestions will be apreciated
thanks, Jay
 
Sponsored Links
  #2  
Old 11-01-04, 05:06 PM
Desi501's Avatar
Member
Join Date: Oct 2003
Location: Boynton Beach Florida
Posts: 2,207
Yep, that's pretty common if you leave that stuff in there for 5 years. Sometimes you can flush it out and sometimes you can't. Do whatever you have to, even if it means changing the radiator. It's much cheaper that ruining an engine. In the future, flush it out by 3yr of 50K, whichever comes first.
 
  #3  
Old 11-01-04, 07:53 PM
Member
Join Date: Aug 2003
Posts: 478
Dexcool is not solely to blame. I feel the problem is mis-leading claims by GM of 5 years or 150,000 miles. Antifreeze degrades at different rates under different driving conditions just like motor oil. People are not being told that the antifreeze condition needs to be periodicly checked to keep the cooling system in good shape.

Many GM vehicles have ran hundreds of thousands of miles with Dexcool and clean cooling systems if they were properly maintained.

The problem you have is linked to allowing the mixture to become diluted to where you have less than 50% Dexcool (-34 degrees farenheight freeze protection) allowing the coolant level to run low and allowing the EME activity in the cooling system to get over .5 volts.

GM is now recomending to keep the coolant level above the full cold line to help prevent running low on coolant.

The secret is proper MAINTAINENCE just like many items on the vehicle. If neglected you will pay the price as you are learning. You can safely go 5 years or 150,000 miles IF you do not let the mixture get less than 50% Dexcool, do not let the coolant level get low, and you do not let the EME voltage rise over .5 volts.

This is all easy do it your self preventative maintenance. All you need is an antifreeze tester and an inexpensive digital volt meter. EME can be checked by setting the volt meter on the lowest scale, put 1 probe in the coolant in the radiator (or the coolant in the coolant recovery tank if the radiator has no cap) and put the other probe on the engine block or head. You will get a voltage reading anywhere from about .1 volts or higher. If you are .5 volts or higher it is time to change coolant and it is best to use distilled water anytime you mix anytype of antifreeze.

There have also been problems linked to certain types of radiator caps (that go on the radiator not on the reservoir) that are allowing not allowing the coolant in the reservoir to keep the radiator full. You can be tricked into thinking the radiator is full because there is coolant in the reservoir. On occasion you need to take the radiator cap off when the engine is cold. If there is coolan in the reservoir and the radiator is not completly full there is a problem that needs correction. Unless you have a leak somewhere you probably have a bad radiator cap.

I hope this helps you understand what happened.
 
  #4  
Old 11-02-04, 05:16 PM
Sparky-L.U.697's Avatar
Member
Thread Starter
Join Date: Feb 2003
Location: Indiana
Posts: 328
THX for All the info I appreciate your time.
 
  #5  
Old 11-12-04, 11:35 AM
Handyman1950's Avatar
Member
Join Date: Nov 2004
Location: Springfield, MO
Posts: 36
Wow! I'd never heard of EME voltage or how to check it. I'll give it a try. I just had the AF changed on my 99 Grand Prix with 100K on it. Everything seems to be fine--just normal maintenance.
There is a Sunday morning radio mechanic--I forget his name--that is a proponent of flushing the Dex-cool from any car, new or old, and replacing it with conventional fluid. Reason being that the stuff destroys gaskets. Is this gasket destruction due to lack of maintenance? Any thoughts?

H
 
  #6  
Old 11-12-04, 02:01 PM
Member
Join Date: Apr 2002
Location: Pittsburgh,Pa
Posts: 2,417
Dexcool can get dirty like any other coolant lack of flushing will cause problems.If you run a vehicle low on dexcool it will affect gaskets and most likely make the coolant dirty for lack of a better word.As with any coolant the only water to be mixed with it is distilled water.I would bet 99.99 percent of people use tap water to mix with coolant and it contains minerals bad for a cooling system which speeds up electrolisis causing corrosion.The amount of time any coolant lasts depends on how the vehicle is maintained and driven the same as a brake system for example.Most Dexcool clogging can be traced back to a cooling system that was run low at some point and not repaired right away.
 
  #7  
Old 11-12-04, 06:35 PM
Member
Join Date: Aug 2003
Posts: 478
Davo is right. The key is lack of maintainence that causes problems. Like I said above I think GM has misled people into thinking you can forget about your Dexcool for 100,000 to150,000 miles (depending on the year & make of car) or 5 years. I am looking at the owners manual for a 96 blazer. It says the coolant is designed to last for 100,000 miles or 5 years. The manual for a 2002 corvette says to change it at 150,000 miles or 5 years. What they fail to say is you need to check the condition of the coolant on occasion.

If the coolant has degraded it needs to be changed, and Davo is right it has been determined that low coolant levels contribute to the clogging and deterioation of aluminum, gaskets annd even plastic intake manifold failures.

If you follow the tips in my other post you stand an excellent chance of good service from a dexcool system.

Another tip. If a cooling system has ever had regular antifreeze in it there is no benefit to putting dexcool in it and trying to get extended change intervals.

Also like I said above you can be tricked into thinking the radiator is full if the coolant reservoir is full. This is where the bad radiator caps or leaks in the system cause problems.

I would be wary of taking advice from your saturday morning radio mechanic. He seems to be un-informed and giving bad advice. Yes dexcool has had problems but there is a reason. It does not mean dexcool is a bad product.

It sounds to me like that guy would tell people to never buy a Toyota if he knew some one who had a Toyota that the engine blew up. Of course he probably forgot to ask if the engine had oil in it when it blew up.
 
  #8  
Old 11-14-04, 04:36 PM
Handyman1950's Avatar
Member
Join Date: Nov 2004
Location: Springfield, MO
Posts: 36
My step-daughter was here with her 99 Cougar which she just bought this summer. I don't know what the af change history is on this car so I did the EME test on it. It was +.15. I tested my 99 Grand Prix which just had the af changed--it was -.15. Does this make sense?

You're right about actually checking inside the radiator for coolant level--always do. If there was a leak between the radiator and the overflow, the radiator would suck air as it cooled.

Don't know what to think about the Sunday morning "mechanic-in-a-radio". But my car has 116K on it and is doing fine.

HM
 
  #9  
Old 11-14-04, 06:40 PM
Member
Join Date: Aug 2003
Posts: 478
Handyman---yes it makes sense. You simply had the polarity of your probes reversed when you did the tests. If you put the negative probe on the engine you will get a positive (+) voltage reading and if you put the negative probe in the coolant you will get a negative (-) voltage.

For those who think dexcool is bad I just put a thermostat in my daughter's 96 blazer with 117,000 miles. It measured .250 volts. and -34 F The coolant was getting a little dark but the inside of the radiator and the inside of the intake manifold looked brand new.
 
  #10  
Old 11-15-04, 07:32 AM
Handyman1950's Avatar
Member
Join Date: Nov 2004
Location: Springfield, MO
Posts: 36
[QUOTE=car nut]Handyman---yes it makes sense. You simply had the polarity of your probes reversed when you did the tests. If you put the negative probe on the engine you will get a positive (+) voltage reading and if you put the negative probe in the coolant you will get a negative (-) voltage.

Sorry, Car Nut. I always put the neg on the engine, or various other ground points, and the pos in the coolant. I just went out and tested in the radiator. I had previously tested in the overflow. The reading eventually stabilized at -.15.
I had it flushed and refilled at the dealership. Do you think they used distilled water?
 
  #11  
Old 11-15-04, 11:19 AM
Member
Join Date: Jul 2002
Location: Kansas City, KS
Posts: 588
Thanks for the tip with the voltmeter. I assume you test the DC voltage? not the AC.
 
  #12  
Old 11-15-04, 08:32 PM
Member
Join Date: Aug 2003
Posts: 478
[QUOTE=Handyman1950]
Originally Posted by car nut
Handyman---yes it makes sense. You simply had the polarity of your probes reversed when you did the tests. If you put the negative probe on the engine you will get a positive (+) voltage reading and if you put the negative probe in the coolant you will get a negative (-) voltage.

Sorry, Car Nut. I always put the neg on the engine, or various other ground points, and the pos in the coolant. I just went out and tested in the radiator. I had previously tested in the overflow. The reading eventually stabilized at -.15.
I had it flushed and refilled at the dealership. Do you think they used distilled water?
I was wrong. Handyman you are correct. I just checked 2 Hondas, 1 Acura, and a Corvette with Dex Cool. They all read - voltage when the - probe was on the block. I dug out the instructions from NAPA and they said to put the - probe on the block just as I thought I remembered it.

However when ever I reverse the polarity on the volt meter leads the measured voltage is always almost identical except it is either + or -. I can only gather from this that the NAPA instructions are wrong.

I would be extremly surprised if a dealership would use distilled water. They should know distilled water is best but it is something that will not have an immediate effect and most customers would not know the difference. It would cost them a dollar or so more per car. Call them and ask what kind of water they used and see what they say. They may try to tell you it does not make any difference. And if so you will know they either don't know any better or they are to cheap to use it.
 
  #13  
Old 11-15-04, 08:33 PM
Member
Join Date: Aug 2003
Posts: 478
Originally Posted by kuhurdler
Thanks for the tip with the voltmeter. I assume you test the DC voltage? not the AC.
Yes you are testing DC voltage.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes