Why won't the heatercore coolant drain out?

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I'm getting ready to do a little routine maintenance on my 2WD 2004 Toyota Tacoma with the 2.4 motor.

I'm planning to change my coolant and it seems like most people say that you shouldn't expect to get *all* of the coolant out by draining the radiator and even opening the block drain plug. *Most* people think you're only going to get about, maybe, 80%-90% because the heatercore will still have some in it that's just not going to drain out.

I'm wondering why it won't drain? Is it just a gravity thing in that it sits lower than other stuff and that's why it won't drain, or...??? Should I lift one end of the vehicle to try and get it to drain?

Thank you,
Ed
 
There are too many variables in heater core placement and line configurations to say if it will drain or not.
If the core is side mounted with the lines up and down it will drain, if its vertical with the lines side by side it wont drain unless you turn the car upside down.

You can disconnect the hoses at the engine and flush it with water and refill it with coolant, the new coolant will push the plain water out as its heavier.
I wouldn't recommend removing the hoses from the core itself as too much movement can cause a leak, they can be very fragile. When removing clamped (not disconnects) hoses from a core its best to carefully cut them off with a razor knife.
 
Originally Posted By: Trav
There are too many variables in heater core placement and line configurations to say if it will drain or not.
If the core is side mounted with the lines up and down it will drain, if its vertical with the lines side by side it wont drain unless you turn the car upside down.

You can disconnect the hoses at the engine and flush it with water and refill it with coolant, the new coolant will push the plain water out as its heavier.
I wouldn't recommend removing the hoses from the core itself as too much movement can cause a leak, they can be very fragile. When removing clamped (not disconnects) hoses from a core its best to carefully cut them off with a razor knife.

+1. A shot of WD40 on the hose/pipe "interface" will make thing go better. I agree, don't mess with the heater core end.
 
Looking at yours, it will not drain, it appears to be hung inside with both pipes side by side.
99287_LEF_P05__ra_p_zps1rpharlq.jpg
 
Generally speaking I think lifting an end of a vehicle results in little height difference but you have nothing to lose but the effort and time necessary. I didn't think of that "side-by-side" vs. "high-and-low" layout stuff.

Disconnecting the hoses mightn't be worth it as there isn't that much coolant in the core. Drain your radiator and possibly your block (remember, block drain plugs are as dangerous to touch as core nipples), fill with water and run the engine for 5 minutes. Do that 'til clear; finishing with distilled water.

Calculate a 55% coolant to 45% distilled water concentration and measure out the coolant. Separate a pint of that coolant and mix with a pint of distilled. This quart of mixed coolant will be what you put into the reservoir as you shake the bubbles out of your system.

Did you state the age of your vehicle or its coolant? What's its condition?

You may be flushing so much that everything will be cleared and your mix of new coolant will eliminate your concern.
 
For a perfect flush I disconnect one or both coolant hoses to the heater core. Flush in both directions. Contaminants can accumulate there. I also run the engine for a short bit while flushing to get the dead spots in the water pump.
 
Originally Posted By: Trav
Looking at yours, it will not drain, it appears to be hung inside with both pipes side by side.
99287_LEF_P05__ra_p_zps1rpharlq.jpg




Nice pic thanks....

In this case, putting a hose to one of the openings, run till clear, then put the hose to the other opening and repeat is going to get it as clean as possible.
 
Originally Posted By: Kestas
For a perfect flush I disconnect one or both coolant hoses to the heater core. Flush in both directions. Contaminants can accumulate there. I also run the engine for a short bit while flushing to get the dead spots in the water pump.


+1. Back flush the core with hoses still attached to it. Finish flushing with 3 gal distilled water.
 
Originally Posted By: Kuato
Originally Posted By: Trav
Looking at yours, it will not drain, it appears to be hung inside with both pipes side by side.
99287_LEF_P05__ra_p_zps1rpharlq.jpg




Nice pic thanks....

In this case, putting a hose to one of the openings, run till clear, then put the hose to the other opening and repeat is going to get it as clean as possible.


That's it, just flush back and forth then fill the core through the hose with coolant, no need to get the tap water out with distilled the coolant pushes the water out without mixing.
 
Originally Posted By: Trav
Looking at yours, it will not drain, it appears to be hung inside with both pipes side by side.
99287_LEF_P05__ra_p_zps1rpharlq.jpg




Thank you all.

I don't understand what this picture is and/or its orientation?

Ed
 
Originally Posted By: Kira
Did you state the age of your vehicle or its coolant? What's its condition?


My truck is a 2004 Toyota Tacoma with appx. 163,000 miles. I'm the 3rd owner - my Sister gave the truck to me.

She bought the truck from my former employer who purchased the truck new from our local Toyota dealer. The truck had been maintained "by the book" by the dealer.

My fluid visibly looks like the Toyota Super Long Life coolant ( http://www.amazon.com/Toyota-Genuine-Fluid-00272-SLLC2-Coolant/dp/B004SL8568 ) and that's what the parts department of the dealer sold me. Based on it's visible condition, I'm guessing the coolant has been changed at one point, but since I'm not exactly sure when that was...I'm going to do it myself.

smile.gif


Ed
 
Are you trying to change the coolant chemistry to a different type, or just do a thorough flush and re-fill?

If the former, getting it 100% clean is important. But if the latter, it's kind of overkill to mess with heater hoses unless they are readily accessible. it is smart to inspect them anyway, though. And on several Toyotas I have serviced, they never have been readily accessible (V engines, though).

What I do in this case is drain the rad. and block, fill with dH2O until the heater valve opens and mixes. Stop, drain the block and rad. again and repeat. This will get out all but a very few ounces of old fluid in the system; fractional dilution is your friend (if you want to do the math yourself, the nominal heater core volume I have found for most Toyota applications is 1.7 qts; compare that to your total system volume - easy to find).

If your heater hoses are readily accessible and you can pressurize dH2O to flush, then that's not unreasonable.
 
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I have just blown them out by mouth when replacing heater hoses.

Normally after a radiator flush I will run several cycles of water to operating temps which means no old coolant is left in the system. I did this when I moved the Blazer from Dexcool to old Green because it did not have the pressurized coolant tank that let the Dexcool contact air and do bad things. If it is a four gallon system about 50% will drain out without draining the block so I just go back with 100% antifreeze to get the 50/50 mix.

Had to do the same for the 1992 P30 Chevy motorhome chassis because a long life antifreeze help weaken the joints in the copper radiator. When I had it recorded I went back to the OEM Green antifreeze.
 
Originally Posted By: Ed_Flecko
I'm just doing a drain and refill for good measure I guess you'd say.

Ed


In that case I would do what I was saying and what Kira outlined above.

Check the heater hoses are good (not overly soft or bulging), then drain block and radiator. Fill, get hot, run heater, then let cool a bit and drain again.

Then fill 50/55/60% straight coolant (if you use Red), then dH2O to top off. The spec for total volume is usually easy to find in a manual or online. Your year I think has red Toyota coolant and not pink. But that was the year they started transitioning. This is available in concentrate from the dealer or CarQuest, or Pentofrost A1 is the same from Napa, O'Reilly, etc. The pink is only available pre-mix as AKAIK and in that case, I would not flush the core as then you end up a lot less than 50/50 which is undesirable to me unless I lived in Florida.

After getting it fresh, then I just drain/fill the radiator every 30k miles. My oldest car I've treated like this is now 18 years old and the system is spotless and never needed any other maintenance. I change uppper/lower radiator hoses at t-belt changes as a preventative item, but not because they were soft or bulging.
 
Originally Posted By: oldhp
Originally Posted By: Kestas
For a perfect flush I disconnect one or both coolant hoses to the heater core. Flush in both directions. Contaminants can accumulate there. I also run the engine for a short bit while flushing to get the dead spots in the water pump.


+1. Back flush the core with hoses still attached to it. Finish flushing with 3 gal distilled water.


Im assuming you guys use a low pressure garden hose first?

But then with the distilled water, do you just dump it in and let gravity do its thing?
 
Originally Posted By: Trav
I wouldn't recommend removing the hoses from the core itself as too much movement can cause a leak, they can be very fragile. When removing clamped (not disconnects) hoses from a core its best to carefully cut them off with a razor knife.

Considering how big of a job a heater core replacement can be, I'd agree with that. A day's work in the LTD wasn't fun.

When the old F-150 years ago had a heater core leak, I was concerned and told my dad I'd need help, of course. He said, no, go take a look again. Grab your sockets and screwdrivers and a knife and you'll be done in under fifteen minutes without any help. He was not kidding.
 
Those were the easiest one i ever did also. IIRC they were right under the hood on the right side and the cover was held on by some small sheet metal screws right?
Today some cores can take 4 hrs or more even if you have done them before.
 
Yep, there were some screws, a couple bolts, hose clamps, and that was about it, and the location is just as you said. The blower motor was in essentially the same spot and just as easy to change. Heck, for the cost of a heater core and the effort involved, one could change them as preventative maintenance, rather than use a heater core failure as a reason to dump a vehicle.
wink.gif
 
I thought book time on my 2004 Jetta was like 8 hours. When people started saying that it was becoming a common repair item MkIV cars, I took it as a sign to move on. I didn't have a place to store the dashboard and everything else that had to be removed.
 
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