How to COMPLETELY DRAIN coolant from the radiator and block?

[maniskov]

Hi, All.

Well, I decided it was (way past) time to change my coolant (61k). So, I drained it via the petcock at the bottom of the radiator. Spec on my '05 says there's about 6 quarts, but I got *maybe* 4 out of there. Further research suggests that there is also coolant in the block that doesn't get released this way.

Can anyone tell me if there are coolant drain plugs on the block somewhere? Of, if not, how to completely drain the system of old coolant?

Many thanks!

[SuperGLS]

Welcome to EXD maniskov!

Help on the way about this.

[ricerrx7]

There's also coolant still in the heater core in the dash. Don't worry about getting every drop of coolant out of there. Get what you can out of the radiator, and that should be good enough.

[blmqzjc]

What I did on my Elantra was:

1) Drain radiator. Tighten petcock.
2) Fill radiator with deionized or distilled water (not tap water).
3) Run engine till thermostat opens (keep heater on during this step). It speeds up the process if you drive around the block a couple of times, as opposed to just idling.
4) Let car cool a few minutes, then carefully open radiator cap.
5) Drain radiator again - notice the coolant blend is getting weaker due to the added water in step 2. Tighten petcock.
6) Crank engine and immediately go back to step 2. Thermostat will open much quicker since engine already warm.
7) Repeat steps 2 thru 6 three or four cycles. The draining coolant should be almost all water by the fourth cycle.
8) When satisfied (or just tired of repeating the procedure ), add between 3 and 4 quarts of CONCENTRATED coolant to the radiator. There will still be 3 qts or so of almost pure water in there from the above steps.
9) Dont forget to drain and replenish the coolant reservoir as well.

Note: The reason I crank the engine in step 6 is that I dont like adding water to a hot engine unless it is running. For those that have a concern with this, they could simply let the engine cool longer before repeating the fill, run, drain cycles, but so doing will turn a one hour job into two or three hours.

You can do this yourself for around $10 for coolant and a couple gallons of water, or pay $100 for a machine flush - choice is yours.

[only1db]

that works...although i do not suggest driving it because if you have an air bubble in there who knows where its going to land...probably right over ther thermo...then your beat.


other then that pretty good.

you could also remove the water pump and cylinder head and turn upside down like a big motor bucket! haha it just gets a little messy

[blmqzjc]

that works...although i do not suggest driving it because if you have an air bubble in there who knows where its going to land...probably right over ther thermo...then your beat.


other then that pretty good.

you could also remove the water pump and cylinder head and turn upside down like a big motor bucket! haha it just gets a little messy

Could you reiterate on the air bubble, and what you mean by "then your beat"? I'm thinking that even if there is an air bubble (likely), it will work its way into the radiator. It will then be expelled either out the radiator top (if cap is off or only half on), OR if cap is on tightly, the air bubble will be forced by expansion into the coolant reservoir. Am I missing something? Thanks in advance.

[only1db]

the air bubble is going to sit right next to the thermosat and if it does that then the thermo will not open up because the hot liquid is not next to it..so you will overheat. by "beat" i mean your *** out and will have issues. bubble can be stuck almost anywhere...thats why capping it and then driving it around is just asking for trouble.


one more thing...turning your heat on will not do a damn thing...the only thing that does is open the actuator...not actually turn the HEAT on.

[Bunklash]

I'm the new owner of a 2000 Elantra. Great little car I bought as a daily driver to keep the miles off my fifth wheel tow vehicle.
I'd also like to drain and replace my engine coolant. With other vehicles, I have installed the tee fitting in a heater hose, removed the thermostat, and flushed with a garden hose before doing the drain-refill-drain-repeat process using distilled water. 1. Does anybody here have any compelling reason I shouldn't use this technique?
2. Also, nobody answered if there were block drain plug(s) or not.
3. What brand/type coolant does Hyundai recommend?
Thank you.
Bunky Jones

[ken2400]

You are SO far ahead of most people in just thinking about changing the coolant.
GOOD JOB.
So go ahead and ask your friends when is the last time they had it done. Most will not know or even have it written down.

So pull out what you can, change it out with what the owners manual says to use, and for the next week or so try to get the concentration right as best you can.

Good luck.

[blmqzjc]

The process I used in my post above (post #4) worked well for me. I've done it this way for decades on various cars, and never had an issue. I used the Texaco coolant (the old fashioned green stuff), cause that is what I saw a Hyundai dealer top mine off with when I first bought the car. Cheap green coolant is fine as long as you are willing to change it out every 2yr or 24k miles. Next time, I'm going to try the Genuine Hyundai coolant, which should last longer. The absolute "best" coolant for most Asian vehicles is a Phosphated OAT, with no silicates. Good luck finding that, as the only brand I've ever seen was Zerex Asian coolant, and nobody stocks it (it also only comes in 50/50 and I prefer concentrates).

I do not know about the block drains on the Elantra, and with my procedure I dont care. I used a tee on the heater hose on a Corolla I once owned to do back flushing, but it was probably more trouble than it was worth.

Most important thing is how often you change the coolant - same for oil, tranny fluid, brake fluid, and PS fluid - assuming you want to keep them forever like I do. The aforementioned Corolla I drove for 22 years.

[CornbreadXD]

i did pretty much the same thing blmqzjc when i flushed my coolant last summer on my z and elantra, just make sure you use distilled water because impurities in tap water can supposedly lead to rust, i'm not 100% sure but why chance it and distilled water is only like $.70 a gallon. you can drain your old coolant into the empty jugs too and take them to a haz-liquid place.

[soullesselantra]

ive always had the best luck just pulling the lower radiator hose at first to get everything out, then once its all out taking a garden hose to the top radiator hose and "flushing" the system that way then put it all back together and use a 70/30 coolant mix with some Gunk water pump lube and rust preventer

[blmqzjc]

I'd only do that if I was sure it was pretty soft water coming out of that hose. Or flush with a couple gals of distilled water after the hose water, just to get it out of there. Most city water is pretty soft, but it's not as good as distilled or deionized water.

[Bunklash]

I read my owners manual on coolant. All it said was use a coolant safe for aluminum. I chose Zerex G05. It's the least expensive and easy to find extended-life coolant I found while researching for my Ford diesel truck (which takes 3 gallons!).
Thank you all for the repllies.

[nathancarter]

Sorry to bump an old thread.

General consensus is that there IS NOT a coolant drain plug somewhere on the block? I didn't see one.

[songee623]

no there is just the radiator drain plug no plug on the engine.

[nathancarter]

Thanks. Well, I'm doing the water pump so I got most of it out anyway.... all over the garage floor, natch.

[songee623]

i did the same thing when i changed out the three radiator hoses. i thought once i drained the radiator i was good but nope lots of fluid from the hoses all over the ground.