Radiator drain advice, please

[wavinwayne]

I'm going to drain & re-fill the radiator on my wife's Expedition this evening. The radiator is cold as I type this. I assume that the radiator cap needs to be off when I remove the drain plug, so that the radiator will be properly vented. Is this correct???

Sorry for the stupid question, but I don't want to screw anything up.

 

[Sumerduckman]

It will drain fine either way. You can leave it on while you back off the drain/petcock, and then remove, to slow down the intitial flow.

 

[Donald]

You realize you most likely will not get all the AF out of the engine block by just draining the radiator. The engine block may have drain plugs that can be removed to drain out most of the AF in the block. Most people these days seem to be getting a radiator flush which pushes a cleaner and fresh AF throughout the system.

 

[wavinwayne]

quote:

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Originally posted by Donald:
You realize you most likely will not get all the AF out of the engine block by just draining the radiator....

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Yes, I am aware of this. I just want to introduce some new AF/Coolant to the system. I'll just do this 2 or three times over the next few weeks until I'm happy with the color of the mix in the expansion tank. Unscientific, yes, but that's the way I like it.

 

[Donald]

Also (because I did this) you realize that some of the newer cars take fancy AF, not the plain green AF we have all been using for years. They market a "global" AF that says it can be used with any of the newer (and older) AFs. And then there is some specific AF for VWs for example.

 

[wavinwayne]

The Expedition in question specifies good old green Ethylene Glycol anti-freeze, so no worries there.

 

[blupupher]

I just did this to my car the other day. Only 21k on it in a year, but I figure if I do this yearly, I really won't need to do a complete drain and flush till, well, who knows. I guess in about 4 more years when I replace the hoses and t-stat.

 

[ex_MGB]

Modern anti-freeze in a new vehicle is good for 100k miles. Just draining the radiator and what drains out of the rest of the system and re-filling every two to three years thereafter will keep plenty of corrosion protection inside the system.

Biggest challenge is getting the air out. After filling, leaving cap off, bring engine up to temp and add as required. Have fluid in the overflow. Go for a short drive and park overnight. During cool down fluid will be sucked from the overflow tank back into the radiator.

This is why people get a radiator service and then car overheats on a trip. some cooling systems are difficult to get all the air out.

 

[Winston]

Drain and refil every 20k or 2 years. Flushing s a waste of money. Use distilled water only. A lot of cooling system build up is due to hard water deposites.

 

[muddawgs]

one time i had to put the nose up on ramps to get the air out of my tacoma. once i did that it burped just fine after heating and letting it cool. the radiator on my wifes cobra had a soft white nylon like drain plug. of course it broke as soon as i loosened it but was easily extracted using a 10mm allen key and AZ had a replacement that was much stronger. just repeat and cycle the heat and you'll be all good. so be careful and good luck..

muddawgs

 

[blupupher]

quote:

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Originally posted by ex_MGB:
Modern anti-freeze in a new vehicle is good for 100k miles. ...

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For most vehicles, not all. I know Hyundai still uses the older green stuff.

 

[TallPaul]

Here is an article that promotes the "just drain and refill the radiator" method.

 

[Matt_S]

quote:

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Originally posted by TallPaul:
Here is an article that promotes the "just drain and refill the radiator" method.

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I have a gripe with this article. He doesn't address the significant number of car owners who wind up with horribly corroded cooling systems because they never even look at the coolant, much less consider changing it. Does he only do a drain and refill on those cars too? I hope not. He also doesn't give any guidance as to how often this drain and refill should be done. Does one simply follow the owner's manual? Does one do this more frequently? Less frequently?

 

[wavinwayne]

In keeping with my style of being behind schedule, I finally did the radiator drain & re-fill today on my wife's Expedition today. The project was a little messy, but on a difficulty scale of 1 - 10, it was a 1.

Here's exactly how I did it:

With the engine cold, I opened the petcock on the passenger's side/bottom of the radiator, & let the old coolant drain until the radiator was empty. This turned out to be right at 2 gallons. It took approx 20 minutes for the radiator to drain.

Next I re-tightened the petcock. Then I poured into the coolant reservoir approx. 1.75 gallons of a 50/50 mix of coolant/distilled water. I started the engine & let the it warm up (approx. 15 minutes) with the reservoir cap off.

As the engine warmed, the coolant level dropped a little. I kept adding coolant until it was at the full hot mark in the reservoir & the level wasn't dropping anymore. I then put the cap back on the reservoir.

Lastly, I took it for a 20 mile road test & re-checked the level when I got home. All is well. I will re-check again in the morning with the engine cold.

I'll do this process again in a couple of weeks, just to use up the remainder of the Texaco antifreeze/coolant that's now taking up space in my garage.

Thanks for your helpful tips, BITOGers.

 

[eljefino]

I take it your expedition has no actual "radiator" cap but rather a pressurized "surge" tank with cap that is the high spot in the system?

I only ask because someone with both a radiator cap and nonpressurized overflow tank might see this thread, and get confused.

 

[wavinwayne]

quote:

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Originally posted by eljefino:
I take it your expedition has no actual "radiator" cap but rather a pressurized "surge" tank with cap that is the high spot in the system?....

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Yes, that is correct.

 

[LubeOiler]

I found this on the Subaru site after reading of a sealent they supposedly use for the cooling system.Coolant Check and Fill

It is very important to displace any air in the cooling system to ensure cooling system efficiency. First of all, make sure the radiator cap seals up and works properly to maintain cooling system pressure. Having a pressurized cooling system allows for a higher boiling point. It is recommended that the coolant be changed every 2 years, as it contains a zinc content that is used up by electrolysis of the dissimilar metals in the engine and radiator to prevent corrosion.

From a dry system, fill the radiator completely with the proper mix of antifreeze coolant. Once the radiator is full, start the engine. Watch for air bubbles to rise as the engine takes up the coolant. Add coolant as the motor runs, keep watching for air bubbles, and to see if the coolant level goes down. Squeezing the radiator hoses will help “burp” any remaining air

Let the engine run to operating temperature, allowing the thermostat to open. The thermostat will only open if there is enough coolant flowing through it. Watch for the temperature gauge to stay steady at a comfortable temperature. Top off any more coolant and put the cap on. Drive the car to see if it maintains steady temp. If it wants to get hot, there is still air in the line. If that is the case, let the car cool off and then top off the radiator.

As a safe measure, check the coolant level before driving the car the next time.

The entire cooling system uses approximately 1 ½ gallons

The radiator itself uses about ½ to ¾ gallon I know once the thermostat opens the air will work its way out so squeeze the hose

and help the air escape may be a better method.

 

[VelociRacer]

Don't forget to set the heater control to full hot so that you can get all the coolant out of the heater core. You need the ignotion switch set to "ON" (not running) on vehicles with motorized HVAC actuators (vs. cable).

 

[wavinwayne]

UPDATE:

I did the same procedure over again on Saturday. I've included some pics of the materials used.

After I purchased a gallon of Motorcraft coolant & read the ingredients, I realized it's nothing but plain green EG coolant. So went to AAP & purchased the Texaco coolant sitting next to it in the pic. Over the course of two drain/re-fills I used approx. 2.75 gallons of coolant & an equal amount of distilled water.

Coolant Reservoir Cap:

I love the smell of ethylene glycol in the morning; It smells like.........victory.