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Radiator flushing methods

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If the coolant is clean and no major sludge or lack of maintaince then flush chemicals like that are not really needed.

My 99 Ranger looked like it never had the coolant changed when I bought it last summer, has 80k on it.
I drained it and filled with water. Drove it till it got up to temp and them came home.
Drained water and removed thermostat. Ran water through top of engine (where the thermostat went).
I then removed the lower radiator hose and allowed the engine and radiator to drain as much as possible.
I then put it all back together (New Radiator cap and thermostat) and filled with 50-55% long life coolant and the rest water.

Looks good now and no problems.
 
If the car is not that old/cooling system is in good shape, I would just drain and fill. Emptying the radiator and letting the engine drain out the lower hose gets the majority of the old coolant out (I'd venture a guess at 75-80%? Maybe a little less when you factor in the heater core).

It's definitely a good idea to change the thermostat. You can backflush if you want, but in the engine, IMO, it's not likely to accomplish much. Only thing where backflushing usually helps is the heater core, as it (hopefully) washes out debris clogging the inlet side.

Big thing about flushing the engine is that it you'll end up with water (or a very dilute coolant mix) in the engine. IMO not that much of a problem. I just initially fill with maybe a quart of straight antifreeze or thereabouts and then fill the rest with 50/50. The mixture doesn't have to be perfect; ending up 60/40 or so in either direction is highly unlikely to cause any issue.

Hydrometers are cheap insurance. Make sure you get the right one, IIRC they need to be calibrated differently for ethylene glycol and propylene glycol.

Oh, and you can also 'forward flush' the engine by putting water up the lower hose...but this is usually messy, as you need to devise a way to seal your your hose/sprayer with the lower hose. And obviously you can't use distilled water (if desired...frankly I don't think it matters much since 99% of shops use tapwater to mix antifreeze and it doesn't seem to cause issues).

Cliffs: 'flushing' chemicals are silly, so are 'cooling system conditioners' or whatever. Much more important to make sure you've got good coolant and a good thermostat.
 
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Only time I ever came close to need something like that is when I needed to clean that orange coolant fluid crap that turned in to gel out of a Jimmy. It was known Dex-Cool issue on those though. Granted I just replaced it with green after.
 
Do those additives actually work for dissolving Dex-gel? Never tried that. I'd almost be afraid of breaking all that crap loose...I'd have to be doing a REALLY thorough cooling system service.

Flushing with a machine cleans it out pretty well. Don't think I've ever tried cleaning one out in the driveway.
 
In my case it was a last ditch effort because the heater core was completely plugged. The heater core hoses didn't even get warm anymore. It was also acting like the cooling jackets may have been partly blocked getting things like pings from the rear 2 cylinders but the front four were ok. There was also nearly a 40degree delta on the temp probe between 2 and 6.

Ran some cleaner let it sit for a few hours / drove it to temp etc. Later we installed a heater line threaded connector and let the truck run on the driveway for about 30 minutes with city water pressure until the water dumping out radiator drain was running clear. We watched the engine temp like a hawk during this time but I guess 45 degree water being pumped right in to the engine keeps it pretty chilly.

I will have to see if I can find the pic we took of the driveway after. There was a "fan" of orange crap on the black top.
 
The heat worked afterwards? Typically a clogged core will cause the inlet hose to get hot, but not the outlet hose.

Logic says if the core has no flow at all, maybe the coolant will cool down in the inlet hose while it just sits there. But I've found completely inop heater control valves before (allowing no flow to the core), and the hose leading to it still got quite hot.

Not to derail, I just found that situation a bit curious...if you were feeling the hoses at the firewall, you sure the control valve further down the line wasn't simply closed?
 
phucheneh said:
The heat worked afterwards? Typically a clogged core will cause the inlet hose to get hot, but not the outlet hose.

Logic says if the core has no flow at all, maybe the coolant will cool down in the inlet hose while it just sits there. But I've found completely inop heater control valves before (allowing no flow to the core), and the hose leading to it still got quite hot.

Not to derail, I just found that situation a bit curious...if you were feeling the hoses at the firewall, you sure the control valve further down the line wasn't simply closed?
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The heatercore was completely plugged, zero flow. You could disconnect the return side and plug it with a wood dowel and the trunk wouldn't lose coolant. Unplug the feed side however and it would shoot water all over. This truck didn't have a control valve at all, source was the water pump and the return was up in the intake just past the stat. (completely from memory at the moment.)

--edit--

The chemical didn't really break it all free either. That was a combo of a high pressure water stream and an air compressor. Basically a pump that grabs house water and jacked the pressure up more to the water itself started knocking stuff around.

It made a rather satisfying "pop" when the goo let go the first time along with sloshing it everywhere.
 
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In EXTREME cases one can use oxalic acid at very low concentrations to flush dexcool thats gone poopoo.

I had a jetta that my nephew drove for some time that had coolant stop leak in it that ended up clogging his heater core. A heater core replacement on that car would double its cost so I flushed it for a while with Oxalic acid and ran a bunch of water in it afterwards under pressure. Cleared the core enough for the heat to come back. Never thought it would work.
Last resort kind of measure.
 
I flush my Dexcool every 3 yrs, it's supposed to be good for up to 100K but screw that, for me 3 years is plenty. IIRC most of the "Deathcool" problems were started by owners that never bothered to check the coolant level and wound up getting air trapped in the system which dex-cool didn't like..
 
It's actually a 99 camry. I bought it at 30K about 6 years ago. When I bought it the previous owner had the coolant system flushed and drained at toyota. They put in the "red stuff" (which I think is the toyota factory red coolant). I'm concerned now that I hear you guys talking about that stuff gelling? Is that one of the issues with the red stuff?
 
steppinthrax said:
It's actually a 99 camry. I bought it at 30K about 6 years ago. When I bought it the previous owner had the coolant system flushed and drained at toyota. They put in the "red stuff" (which I think is the toyota factory red coolant). I'm concerned now that I hear you guys talking about that stuff gelling? Is that one of the issues with the red stuff?
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No, the early Dexcool would gel up if air got into the system. The toyota Red is basic long life coolant with red dye.

Just buy some long life coolant and you will be fine.
 
Personally, I have completely stopped doing any flushing with hose or tap water and only use distilled. It costs more, and is a bit more of a pain (you can't just hookup a hose), but I feel like it helps keep a lot of corrosion out of the cooling system.

I basically drain, fill, drain, fill. Then run the car for a week or so. Then one more drain fill.

What is the make model and mileage? What is the history of the cooling system?
 
My beater I bought seemed to have never had a coolant flush in its life and it had around 230k miles on the odo.

The coolant was brown. It was supposed to be green.

Undid the radiator plug, opened the radiator cap and put a garden hose in.

Turned car on, started pumping water in from the hose as all this brown liquid came out from the radiator plug.

It took about 10, 15 minutes for the water to FINALLY become clear ...

It was insane.

Ended up with a 50% water, 50% antifreeze mix. Replaced thermostat. Driven it about 70k miles since.
 
SpatiallyAware said:
Personally, I have completely stopped doing any flushing with hose or tap water and only use distilled. It costs more, and is a bit more of a pain (you can't just hookup a hose), but I feel like it helps keep a lot of corrosion out of the cooling system.

I basically drain, fill, drain, fill. Then run the car for a week or so. Then one more drain fill.

What is the make model and mileage? What is the history of the cooling system?
Click to expand...

I generally use distilled. On the truck I was not willing to have a 1000 gallon distilled water tanker delivered so...
 
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