How thorough are coolant flushes at auto shops?

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150
Location
Minnesota
I need a coolant flush soon but I was wondering how thorough the auto shops do it? I know auto shops want the cars in the bays for the least time possible and a thorough coolant flush can take a couple hours or more (waiting for drainage/temps to be right in engine, etc). Do they just flush it once and put new coolant in or do they wait for it to drain fully and flush it again or? What is your experience? Also do they use tap water generally?
 
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2,021
Location
CA
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Messages
738
Location
New Hampshire
Depends if they have an exchange machine, if they do, then yes they will exchange all of the fluid. Problem is they will also use tap water unless they are using coolant that is already premixed. You probably should also ask what coolant they will be using, because more than a few shops will only use a universal coolant...not saying that's "bad", but if you want factory coolant you may not be getting it.
 
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25,980
Location
Upstate NY
Another case of the consumer needs to be informed. Whatever a shop does is probably better than leaving in coolant that is past its prime, but the service could be even better if the factory coolant and distilled water was used.
 
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1,307
Location
Ontario, Canada
Originally Posted by Whammo
I need a coolant flush soon but I was wondering how thorough the auto shops do it? I know auto shops want the cars in the bays for the least time possible and a thorough coolant flush can take a couple hours or more (waiting for drainage/temps to be right in engine, etc). Do they just flush it once and put new coolant in or do they wait for it to drain fully and flush it again or? What is your experience? Also do they use tap water generally?
As others have said if the shop has invested int a machine to do the exchange they'll probably do a good job and use pre mixed coolant. Many shops are short sighted and see the machine as an expense rather than an additional way to make money, as the mechanic can do other things while the machine does the emptying & filling. These days it seems that vehicles are made to be handled mainly by machines, we are supervising. wink
 
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You're using "shops" in the plural; to me, that's insinuating that YOU don't have a "favorite," or, worse, a TRUSTED shop in mind. All I can really tell you is my experience. A couple years ago, I got what I thought was too good a deal to pass up on a used car out of state. It took Herculean efforts ( I replaced upper & lower intake manifold gaskets in a hotel parking lot), but I got the car home....Told the wife that the cooling system (which looked like mud) was going to need a new radiator...I paid a local independent shop to "flush" my cooling system. They didn't know that I had already drawn a sample of the dirty coolant for comparison and baseline to see what they would accomplish. I wasted my money. Couldn't really see a lot of difference AFTER the "flush," so I went to few parts stores...Bought Prestone coolant flush, BG, Irontite, and a few I can't remember. I spent most of a day with a garden hose; removed my thermostat and flushed & flushed & flushed, saving samples each time in clear plastic cups to visualize what was happening, and I wasn't happy with my own work. Finally, I don't remember where I heard/read about it (maybe BITOG), but I went to a Farm store and bought some Citric acid. It's also available at Walmart, used for canning tomatoes. Citric Acid (and distilled water), without a thermostat, running my engine for an hour or so, cleaned my system so well that it now looks like new coolant, my digital readout on water temp runs about 15 degrees cooler, and I DIDN'T replace the radiator.
 
Messages
310
Location
Arizona
Originally Posted by Ihatetochangeoil
You're using "shops" in the plural; to me, that's insinuating that YOU don't have a "favorite," or, worse, a TRUSTED shop in mind. All I can really tell you is my experience. A couple years ago, I got what I thought was too good a deal to pass up on a used car out of state. It took Herculean efforts ( I replaced upper & lower intake manifold gaskets in a hotel parking lot), but I got the car home....Told the wife that the cooling system (which looked like mud) was going to need a new radiator...I paid a local independent shop to "flush" my cooling system. They didn't know that I had already drawn a sample of the dirty coolant for comparison and baseline to see what they would accomplish. I wasted my money. Couldn't really see a lot of difference AFTER the "flush," so I went to few parts stores...Bought Prestone coolant flush, BG, Irontite, and a few I can't remember. I spent most of a day with a garden hose; removed my thermostat and flushed & flushed & flushed, saving samples each time in clear plastic cups to visualize what was happening, and I wasn't happy with my own work. Finally, I don't remember where I heard/read about it (maybe BITOG), but I went to a Farm store and bought some Citric acid. It's also available at Walmart, used for canning tomatoes. Citric Acid (and distilled water), without a thermostat, running my engine for an hour or so, cleaned my system so well that it now looks like new coolant, my digital readout on water temp runs about 15 degrees cooler, and I DIDN'T replace the radiator.
I use citric acid in the dishwasher to keep soap scum off the dishes and the machine clean [along with vinegar]. It's what's called "Lemi Shine" in the stores. Bulk is much cheaper. Good to know it works to clean coolant systems too.
 
Messages
22,677
Location
Apple Valley, California
Originally Posted by Railrust
Depends if they have an exchange machine, if they do, then yes they will exchange all of the fluid. Problem is they will also use tap water unless they are using coolant that is already premixed. .
not me. we have a water filter system.
 
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2,021
Location
CA
It depends greatly on what type engine you have. An aluminum block and heads will pollute the coolant far less than cast iron. But that is not to say coolant exchange should be postponed or ignored just because it "looks good".
 
Messages
427
Location
Northeast Georgia
The difference in terminology can be a factor and sometimes gives an impression of false advertisement. When I ran service shops....we offered a coolant "flush" and simply a coolant "exchange". 2 different services with 2 different prices. The simple exchange service was done via a gravity fed apparatus. There were NO helper pumps or otherwise that could over pressurize the system. The water pump and thermostat of the vehicle did all the "work". On most vehicles, you simply made a connection to the upper radiator hose itself...then to the upper hose inlet on the radiator. Warm the vehicle up and allow the thermostat to open...it would evacuate old coolant into a waste tank. This made room for the new coolant to feed in....via gravity. We would let it run the cycle until we got at least a quart of clean coolant coming out the waste side. The "flush" service involved cleaning chemicals added to the vehicle and allowed to circulate for about 10-15 min. The machine was already hooked up, but it allowed the coolant to complete the circuit until you flipped it ON, then it evacuated the old and supplied the system with new. The hoses had clear sections so you could see the condition before, during, and at the end. We used Wynn's chemicals and machine for the "flush" service. Our coolant came 50/50 premixed in drums...whether it was conventional green or universal extended life. We never had to add water to the mixture. Both would always test at -34°F for freeze protection. If a customer wanted OE formula coolant, we would have it delivered or the customer was free to supply it. Didn't make financial sense to keep and dozen manufacturer specific coolants in inventory.
 
Messages
551
Location
South Wales, UK
Our Defender while maintaining it's coolant temperature perfectly fine was full of rust and scale. It's history unknown and the radiator fins were starting to rot out and the hoses were perished so I decided to do a full overhaul. I tee'd into the existing heater hose and removed the thermostat. I connected my household hose into the tee and run it at a very slow trickle with the header tank cap off. I started the engine and run it at a fast idle until the water started running clear our of the header tank. I then stripped down the cooling system, replaced the heater matrix, radiator, thermostat, all the hoses and the water pump and filled up with fresh coolant. That was a year ago and the coolant is still squeeky clean.
 

wtd

Messages
2,762
Location
southwest Mo.
Last year when it was time to have the coolant flushed in my Mustang, I decided to let the dealer do it because I didn't feel like it. For about $145, it was worth it to me not to spend time outside in the cold.
 
Messages
408
Location
Central NY
All depends on who does it. A flush could be drain, cycle thru distilled water, drain and fill with antifreeze. If you want it done right you gotta do it yourself or have someone you trust do it.
 

Whammo

Thread starter
Messages
150
Location
Minnesota
I did bring it to a shop to get flushed. I do have a concern though. I brought 2 bottles of Asian coolant in as I thought it would be better than universal coolant for my vehicle. When it was done they handed me back almost a full jug of one of the bottles which tells me that they must have put almost half of whatever universal coolant they use in the machine in it as well as a little more than a bottle of the Zerex stuff I brought in. Should I be concerned that these two might not mix well? I hope they wouldn't be too short-sighted to think about that...
 
Messages
25,980
Location
Upstate NY
Are you sure you need a flush or is the coolant just due for a change based upon mileage? A shop could have a tank of distilled water or a deionizer filter. The deionizer filter will make the water fine for use in the coolant system. We had a small one for my Mom's iron several years ago so I assume they make large ones. Premix coolant is fine but you need to make sure the freeze point is good when done. If you flushed with water it's likely the engine block is filled with water after the flush. Some use a flush tool that uses water and air to flush the system. If you use a chemical for the flush then you will need to flush it a few times to make sure all of the chemical is out and back to pure water.
 
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