Any Partial Coolant Drain Advocates ?

[ChrisD46]

*Great Info !
Originally Posted by doitmyself
Originally Posted by FordCapriDriver
Now what do we exactly mean by partial drain.

On nearly all vehicles approximately 1/2 of the coolant is in the radiator/overflow tank and the other 1/2 is in the engine block. Most here refer to a partial drain as draining and replacing the 1/2 that is in the radiator/overflow tank only. Because today's coolants keep the systems so clean, it is felt unnecessary to do an entire coolant flush. It's similar to just doing a pan drop and refill on a transmission, where 1/2 (+/-) of the old fluid remains in the torque converter, etc..

The logic of the partial drain done more often is that it is just so easy to drain and refill the radiator compared to attempting to flush out the entire engine. And again, we just don't seem to see the crud buildup in cooling systems with the newer coolants like we did several decades ago. Save the complete fluid exchange for neglected systems or when changing coolant types.

 

[Propflux01]

By draining the radiator, are you not draining the block as well, considering the lower radiator hose gets drained along with the radiator, and the lower hose drains what's in the block? Seems to me the only thing that should be left is maybe what's in the heater core, and the top hose at the thermostat.

 

[Olas]

partial drains are very uncomfortable.
cooling systems probably don't mind as much as we do

 

[Urshurak776]

My Dad taught me to do nothing but check level until 60K-75K. Somewhere in that range. Do a complete drain and flush with DI water. Refill system and overflow with 50/50. So now you are fresh again. Then, every Spring (or fall, you pick) drain radiator and overflow, then refill with 50/50 (Usually about a gallon or so drained from system.) Do that until you get rid of the vehicle. Systems have looked squeaky clean doing that. Overflow tanks look brand new inside.

 

[nthach]

I was a believer in that until recently, given Astro14(or whoever maintains a fleet of GM vans) has seen no spectacular cooling system failures with Dex-Cool. The Toyota and Hondas I've worked on for friends and family all had pristine cooling systems, provided the OEM fill wasn't molested with dissimilar coolant. Another friend had a Subaru that was filled with universal coolant and that looked good on the inside when the water pump and T-stat was removed. I think modern xOATs are capable of long service lives.

However, coolant is cheap and if the car has an easy to access cooling system with no complicated bleed procedure it doesn't hurt to do a periodic drain and fill. Keeping the inhibitors fresh and in sufficient concentration is never a bad thing.

 

[JHZR2]

Water doesn't degrade, shear, or oxidize. Additives deplete, and the metals can shed ions and sometimes metal into the solution.

Vastly different situation than lubricating oils. And now that the amount of silicate is low, gone, and where it's used, seems to be more stable...

The radiator drain works just fine. When the system has to be opened up for a legitimate reason, then drain it in full.

 

[talest]

Originally Posted by slacktide_bitog
Once you open the radiator drain, you might as well do it all

Only open (cap) cold
Replace with same fluid as is in there
Then.. exchange some.

 

[nthach]

Originally Posted by JHZR2
And now that the amount of silicate is low, gone, and where it's used, seems to be more stable...


Mercedes, BMW, Tesla and VAG is calling for SiHOAT coolants, either G-48 or G-40(G-12++)/G-13 - and they call for long or no drains. In the case of Mercedes, there's a silica pack in the coolant surge tank that helps keep a constant level of silicate in the cooling system.

 

[ctechbob]

Mine get new coolant when its timing belt time. I get approx 1.5 gallons out of a 2 gallon system, which is what comes out when I drain the rad and take the water pump off. Both cars are spotless inside the radiators.

 

[doublebase]

I absolutely only do drain and fills with my coolant. At the 100k mark, drain and fill. And every 30k thereafter. Simple. Never an issue.

 

[mdboulier]

I’m a fan. Time will tell. Here’s what I do. Replace coolant in reservoir, then without opening radiator cap I open the petcock. This begins to siphon throughout the whole system without introducing air. I keep reservoir topped up as the new coolant siphons through and close the petcock when coolant reservoir is at the appropriate level.

 

[MRtv]

I drain my radiator once a year and refill it. Keeps the chemistry fresh. G-05 in my 97 Ford F150. One gallon bottle of the 50/50 does the job.

 

[doublebase]

I’m a fan. Time will tell. Here’s what I do. Replace coolant in reservoir, then without opening radiator cap I open the petcock. This begins to siphon throughout the whole system without introducing air. I keep reservoir topped up as the new coolant siphons through and close the petcock when coolant reservoir is at the appropriate level.

I have never seen or heard anyone doing it like this, so you just add coolant to the reservoir and open the pet cock? It’ll pull the coolant out the reservoir without removing the radiator cap? And no air will get in/no bleed necessary? I like it, might give that a try!

 

[ctechbob]

I drain whatever comes out when I do a timing belt on my 2 J-Series cars. Usually works out to about 1.5 gallons out of 1.8 give or take. It gets replaced with either Honda OEM or one of the aftermarket ones. The TL got the Pentofrost last time, and the Accord got Zerex Asian Blue a few months ago when it got serviced. Between changes I will keep an eye on the cooling system and if I see any kind of funk in the radiator I will take steps. So far, nothing to report. Both cooling systems are just fine.

The Accord I've owned from new, and it had coolant done at the first and second TB change. First time was at the dealer, so no idea what their procedure was. Bought the TL with 129k on it and had no service record of TB or coolant, so it got done then with the Pentofrost.

Didn't realize I'd already replied to this post. Ohh well, this post has more information in it. *sigh* getting old sucks....

 

[mdboulier]

I have never seen or heard anyone doing it like this, so you just add coolant to the reservoir and open the pet cock? It’ll pull the coolant out the reservoir without removing the radiator cap? And no air will get in/no bleed necessary? I like it, might give that a try!

Yep. works depending on how your system is plumbed. Keep the reservoir topped up as it siphons through.

 

[Hogwash]

Yep.....in fact this is how I do it on all of my vehicles. Valoline Zerex pink for my Toyotas.

Though recently I did a more comprehensive flush on a buddy's RX300 because the coolant looked like prehistoric dinosaur piss. Filled with Autozone premixed green found on sale

 

[Snagglefoot]

Interesting that folks talk about opening petcocks. Gm trucks have not had petcocks for over 10 years. You have to pull the lower radiator hose using a spring compressor.

 

[Kira]

What kind of spring compressor?

I've been keeping systems clean with radiator + reservoir drain & fills for a while now.

 

[Snagglefoot]

Here are two spring compressors. I guess the proper name is hose clamp pliers. The one on the left works best. It is very difficult to get a pair of normal pliers into the area around the lower hose area so you have these remote “pliers” to get into the small space, fit on the clap and compress the ends so that the spring clamp on the hose opens up. The hose clamps are reusable.

 

[Snagglefoot]

Where is a similar set on Amazon.