Flushed Coolant - Need a sanity check

Run the heater with the engine on.

 

I've done 2 complete coolant drains on my 2015 V6. In both cases I drained the same amount:

- radiator - 3 qts. 10 oz.
- overflow tank - 24 oz.
- drivers side engine block - 4 qts. 10 oz.
- passenger side engine block - 24 oz.

Total 9 qts. 6 oz. drained from system

2015 owners manual shows the following capacity for the V6:

- automatic 10.1 qts.
- manual - 10.3 qts.

I suspect the remaining .5 qt. was still in the heater core.

 

For the issue you've run into, you should not use 50/50 pre-mix coolant. This type of coolant is good if only replacing coolant in the radiator. In a flush, you determine the coolant capacity of your vehicle. When you finish the flush, add concentrate antifreeze up to 50-60% of the vehicle's cooling capacity. Then, add distilled water until the system is topped off.

I can't believe Haynes doesn't say to use distilled water. It's gotta be in there some where.

 

Use this to burp your system - gets the air out and allow you to fill the system - air in the system will stop it from working correctly

https://www.youtube.com/watch?v=UpTntSoCWE8

Not sure why but Home Depot has a better price then the automotive stores like Advance.

https://www.homedepot.com/p/Lisle-Spill-Free-Funnel-LIS24680/206999882

$23 EPAuto Spill Proof Radiator Coolant Filling Funnel Kit

https://www.amazon.com/gp/product/B...&pf_rd_p=edaba0ee-c2fe-4124-9f5d-b31d6b1bfbee

 

Why does the heater need to be on?

 

To open the heater core valve (allowing coolant to flow through the core).

 

There is no 'heater core valve' in a Tacoma. Coolant flows continuously through the heater core. Cabin temp is controlled by an air blend door.

 

Lot of people think there is a heater coolant valve like the Old Systems used to have.

There is none as Curt stated constant flow through the heater core.

 

Then what purpose does it serve to have the heater on?

 

Continuous flow helps keep corrosion from forming in the core during summer months. Winter months as soon as the engine temp comes up you have instant heat. No need to wait for the core to heat up. I suspect blend doors are simpler (read cheaper) than valve controlled systems.

 

None.

Looks like the tech writer doesn't have a clue. But if you don't believe me you can hand over hand the heater hoses and see for yourself.

There is no valve. Not here to argue, just stating the facts.

You're welcome.

 

I replaced the heater hoses earlier this year, so I know there isn't a valve under the hood.
The question is, why does the heater need to be on?

 

I answered this question above. ^^^

 

And as I've already said the answer is: It Doesn't.

There is full flow through the heater core all the time. However it doesn't hurt anything to have it on.

 

I think this pretty much answered the question.
The answer? Because!

 

It seems to me like doing a flush, just a drain/refill and run for 10 min then redrain, with tap water instead of distilled water, can't be much of a problem. I re-drain all the tap water, blow the whole system out with low pressure air so no more drips from engine block or radiator, then refill with antifreeze/distilled water. Surely 10 min of run then full drain is fine?

You could even run a gallon of distilled through and let it drain out on the last drain, to push out any remaining tap water, before you fill with the good stuff?

 

distilled water is about a $1 a gallon so get 2 gallons at Walmart or the DOLLAR store

 

I've never used anything but tap water, never had corrosion or anything go wrong with my cooling systems. I flush, let the radiator drain, then add straight antifreeze and usually end up with -20f mix.