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Started By
Message
re: Idiot here, how complicated is a coolant flush?
Posted on 1/21/26 at 8:51 pm to terd ferguson
Posted on 1/21/26 at 8:51 pm to terd ferguson
quote:
You can also buy a container to catch the coolant and dump it down the drain later (handy for areas with more street traffic). Also works for oil, bodies, or anything else you need to dispose of.
Is there a brand or size that you prefer or would recommend?
Thanks.
0
Posted on 1/21/26 at 8:56 pm to WillFerrellisking
quote:
Why you wanting to do this?
No particular reason.
I just thought it was probably time to do it.
Like I said, I'm just trying to learn.
Posted on 1/21/26 at 8:57 pm to 308
Posted on 1/21/26 at 8:57 pm to 308
Replace belts, hoses.
That will require new coolant.
High-pressure "flush" isn't necessary, although some old coolant will remain in the block.
Are gonna DIY?
If so, watch some YT. Have a catch basin to dispose of old coolant properly. Don't over- tighten clamps.
That will require new coolant.
High-pressure "flush" isn't necessary, although some old coolant will remain in the block.
Are gonna DIY?
If so, watch some YT. Have a catch basin to dispose of old coolant properly. Don't over- tighten clamps.
This post was edited on 1/21/26 at 8:59 pm
Posted on 1/21/26 at 8:58 pm to 308
It depends on the condition of the system before procedure. It it's clean to start with drain and refill is OK. If it is solid rust/mud flushing is a must. Backflushing the radiator and heater core needs to be performed. You must understand that the greatest of flush jobs on a nasty system will NEVER remove all the crud.
Posted on 1/21/26 at 8:58 pm to WillFerrellisking
quote:
Why you wanting to do this? My truck has 273,000 miles and it’s never had a radiator flush nor does it run hot.
Yes, just like a transmission. If it’s working, leave it alone. Once you tap those closed systems, you open to leaks and problems everywhere.
Posted on 1/21/26 at 8:59 pm to bamacoullion
In addition, knowing how to remove air pockets is a must!
Posted on 1/21/26 at 9:00 pm to 308
Change the blinker fluid while you’re at it -
This post was edited on 1/21/26 at 9:07 pm
Posted on 1/21/26 at 9:03 pm to High C
No flush.
Drain.
Change hoses.
Refill.
Run 10 minutes or until warm.
Top off.
*If you want to get it all out and your engine is cold you can crank it without hoses and it'll pump everything out of the block real frickin fast. It'll make a hell of a mess but it'll work. Close the hood to help contain the spray. Then kill it.
Drain.
Change hoses.
Refill.
Run 10 minutes or until warm.
Top off.
*If you want to get it all out and your engine is cold you can crank it without hoses and it'll pump everything out of the block real frickin fast. It'll make a hell of a mess but it'll work. Close the hood to help contain the spray. Then kill it.
Posted on 1/21/26 at 9:11 pm to 308
It's NOT an easy DIY job if you don't know all the steps for your vehicle.
It IS an easy DIY job if you know all the proper steps for your make and model. You might want to get a special funnel to help bleed the air out of your system (and it can take a while to do this step). Some vehicles require extra steps for bleeding.
I would recommend finding a good video before attempting anything.
Home & Garden board will walk you though everything if you post this there. It's more active than you think.
It IS an easy DIY job if you know all the proper steps for your make and model. You might want to get a special funnel to help bleed the air out of your system (and it can take a while to do this step). Some vehicles require extra steps for bleeding.
I would recommend finding a good video before attempting anything.
Home & Garden board will walk you though everything if you post this there. It's more active than you think.
Posted on 1/21/26 at 9:22 pm to 308
It’s not as simple as draining and refilling. You have to burp the system. Air pockets will be introduced as you drain.
YouTube is your best friend. You’ll need a kit. Harbor freight sells a cheap one.
YouTube is your best friend. You’ll need a kit. Harbor freight sells a cheap one.
Posted on 1/21/26 at 9:22 pm to LSUFanHouston
quote:
He says a coolant “flush” is at best a waste of money, and at worse, can cause leaks due to too high pressure.
He’s correct. I got a coolant flush and a few months later my radiator exploded. Older car
Posted on 1/21/26 at 9:26 pm to 308
Your question is not stupid. Just draining and refilling the fluid is almost always acceptable. It is not hard. Minimal effort and financial investment. Taking it to a shop or a chain outlet is giving in to theft. YouTube is your friend on this topic.
Posted on 1/21/26 at 9:28 pm to jcaz
Plastic doesn't like sudden pressure.
Posted on 1/21/26 at 9:38 pm to 308
There are a bunch of questions that need answered first.
What kind of vehicle? Year and make. Newer vehicles have sealed pressure systems which is much more of a PITA than just pulling the peacock at the bottom of the radiator.
Are you having a cooling/overheating issue that you are trying to correct or are you just wanting to do general maintenance?
If you are just doing maintenance then a drain and refill is fine. (They also have test strips so you can test it fits and see if it needs to be done)
An actual flush is much more involved and I would never use an oil change place to do it (and a bunch would probably rip you off and just do a drain and refill and charge for a flush).
Depending on the vehicle, you can maybe do a flush yourself with water. The problem is that you really aren’t going to get much scaling out with just water and no chemicals. It’s going to be a mess because you really need to pull the thermostat. Then you need to do a final flush with distilled water because you should never use tap water in a a coolant system. Then you have to make sure that you drain the water out of your block because it’s going to dilute the new coolant - prob not a major issue in the south, but it potentially could be.
What kind of vehicle? Year and make. Newer vehicles have sealed pressure systems which is much more of a PITA than just pulling the peacock at the bottom of the radiator.
Are you having a cooling/overheating issue that you are trying to correct or are you just wanting to do general maintenance?
If you are just doing maintenance then a drain and refill is fine. (They also have test strips so you can test it fits and see if it needs to be done)
An actual flush is much more involved and I would never use an oil change place to do it (and a bunch would probably rip you off and just do a drain and refill and charge for a flush).
Depending on the vehicle, you can maybe do a flush yourself with water. The problem is that you really aren’t going to get much scaling out with just water and no chemicals. It’s going to be a mess because you really need to pull the thermostat. Then you need to do a final flush with distilled water because you should never use tap water in a a coolant system. Then you have to make sure that you drain the water out of your block because it’s going to dilute the new coolant - prob not a major issue in the south, but it potentially could be.
This post was edited on 1/21/26 at 9:42 pm
Posted on 1/21/26 at 9:54 pm to 308
quote:
2018 Dodge Ram pickup, 6 cylinder, 145k mostly highway miles.
Coolant never changed.
Yeah, it's past time. Modern coolant is GTG up to around 100k miles. After that, if you have any aluminum that it touches internally, the corrosion inhibitors are long depleted and it will attack that aluminum. The stuff that lubricates your water pump and keeps seals happy is also depleted.
Just draining the radiator hot works on SOME cars. Other cars, you can only get out a little at a time and you have to do this many, many times to get full coolant replacement or close to it. I recently did one for my family that took 10 drain/fill/warm up/drain cycles to get to 90% replaced. Some cars require you to burp their cooling system or do other weird things, just find a YouTube vid for your make and model to know for sure before you start.
BigBin and urtoosmall both have good advice in their posts.
This post was edited on 1/21/26 at 9:57 pm
Posted on 1/21/26 at 9:58 pm to BigBinBR
I would flush it with Prestone radiator flush if it had that many miles. Just follow the instructions.
Coolant has anticorrosives in it. They get used up over time and the "flush" removes that corrosion/scale which can block coolant passages or reduce heat transfer.
I would also replace the hoses, thermostat, cap, and the water pump.
If you just drain and fill, thats certainly better than nothing. You need the anticorrisives to be replenished.
I dont let mechanics near any of my vehicles, so no. I would not let Lube Express do it.
Coolant has anticorrosives in it. They get used up over time and the "flush" removes that corrosion/scale which can block coolant passages or reduce heat transfer.
I would also replace the hoses, thermostat, cap, and the water pump.
If you just drain and fill, thats certainly better than nothing. You need the anticorrisives to be replenished.
I dont let mechanics near any of my vehicles, so no. I would not let Lube Express do it.
This post was edited on 1/21/26 at 10:02 pm
Posted on 1/21/26 at 10:11 pm to 308
quote:
Would you trust the typical oil change place to flush the coolant correctly?
Coolant flushes (and all "flushes," for that matter be it engine flushes, radiator flushes, brake fluid flushes, etc.) are scams created by automotive service shops to generate revenue. If someone offers you one at a repair shop, just tell them "no" and then walk out, because they can't be trusted with anything else concerning your vehicle if they are willing to try to trick you with that scam. Ask yourself this question: have you ever heard of anyone's vehicle breaking down because it didn't get some kind of a flush? No.
Posted on 1/22/26 at 4:38 am to Trevaylin
quote:
eally easy to do a complete job
1 locate the car radiator over a street drain grate
2. open the drain valve at bottom of radiator
3. close valve and refill. Run engine for 10 minutes
4. Drain again to sewer
5. close valve and refill
easy peasy
This is why the Mississippi River in NOLA has purple catfish with feet isn't it.
Posted on 1/22/26 at 5:33 am to TheRealTigerHorn
quote:
Modern coolant is GTG up to around 100k miles.
Yep. We changed the antifreeze/water every year on our old junkers growing up.
Now my Toyota owner's manual says that the super long life coolant that comes with the car is good for 10 years/100K miles. Once you change it, you then need to do so every 50K miles. Check the manual for your vehicle.
Mine's at the 10 year mark, but with less than 80K miles. The coolant mix is still pristine and pegs the max protection level on two different testers. I'm going to let it ride a while longer.
I may let the dealer change it if/when the time comes before I sell it; it's probably something I'll do once while I own the car. An owner can do it, but it's not as simple as drain and refill with the garden hose. Distilled or deionized (highly purified) water is recommended.
Google and search YouTube for your make/model for the procedure and see if you want to tackle it.
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