Radiator flush or not??

[smtrader]

I'm totally confused...after reading just every posts on flushing (or not) a Prius radiator! Some say flush, others say drill/fill only.

So...is there a concensus on this, please? I found an independent shop that did an excellent job with my other car and I'm wondering if I should do the same with my 04, 80K, Prius. Though my baby has never had any overheating problem, but I believe strongly in preventive maintenance.

Your thoughts please?

[Patrick Wong]

Drain/fill is fine. However, an independent shop not specializing in Prius may have trouble due to the coolant heat recovery system which includes an electric pump and the thermos container.

[edthefox5]

Its hard to do properly unless you have the proper equip. You need this:

MityVac - Automotive Vacuum Pump Kits - Radiator Adapters - Cooling System & Pressure Testers Kit - Fluid Evacuator

to properly vac. If you dump all the motor coolant including pulling the thermostat it will be an overheating/ sloshing sounds under the dash nightmare unless you evacuate all the trapped air. Its a dealer or a very savvy mechanic deal. Do what I do yourself. Dump the rad.contents only. Put just distilled water back in it. Run it till it reaches op temp with heat on full blast. Let it cool down. Repeat.
Then final rad dump then fill up with factory coolant. That will get you real close to a complete flush.But stay with it. Do what I've listed all in one day. Don't let it slide and run it without factory anti-freeze as it might corrode.
Done this in alot of cars and had good results and will save you some money and horrors of horrors will keep it off the dealer rack.Good luck

[smtrader]

Thanks...I might try to do the "flush" myself! A few more questions:
1. How do I dump all the coolant? Is there a valve underneath the radiator to let out the coolant?
2. When I fill, I have to do so through the resovior, right?
3. Change the thermostat too or not?

[rumpledoll]

In the old days coolant was based on Inorganic Acid Technology (IAT) for corrosion protection. It was great stuff and offered very good corrosion protection. It did have one major drawback - a 30,000 mile 2 year service length. When it was let go longer, as many consumers did, bad things could and did happen.

In order to get a longer life, GM lead the way to longer service life with Organic Acid Technology (OAT) antifreeze. GM's version, brand name DexCool can last 5 years/150,000 miles. There was one problem - DexCool can weaken certain rubber and plastic gaskets/hoses/parts due to one of the major ingredients (2-ethylhexanoic acid known as 2-EHA ). So nobody but GM (and Saab, IIRC) uses coolant with 2-EHA in it. BTW, Preston long life any color any make uses 2-EHA.

Toyota switched to a long life antifreeze using a Hybrid Organic Acid Technology, and like all Japanese manufacterers they use no silicates and they do use phosphates. The Toyota Pink is good for 100,000 miles/10 years and 50,000 miles/5 years afer that.

So, at 80,000 miles you still have 20,000 miles of life left in your antifreeze. I would not worry about until the 100,000 mile mark.

The longlife HOAT technology variations that everybody besides GM went to contains silicates and no phosphates (European makers do not like phospahtes) - Ford's G-05 is an example. GM's DexCool has no silicates and no phosphates but has the dreaded 2-EHA that everyone else hates. Only the Japanese make a HOAT based longlife antifreeze with no silicates, no 2-EHA, no amines and low phosphates (the Japanese have long used phosphates).

The only place to get a Japanese style longlife antifreeze is the dealer, and given how hard it is to remove all the old antifreeze from the Prius, I would recommend staying with the Toyota "pink" longlife antifreeze when your Prius hits the 100,000 mile mark. Under no circumstances should you risk using a 2-EHA based antifreeze with it's known gasket compatibility issues in your Prius - which rules out DexCool and Preston long life any color any make coolant.

Rumple

Originally Posted by smtrader

.. I'm wondering if I should do the same with my 04, 80K, Prius.

[Patrick Wong]

Originally Posted by smtrader

Thanks...I might try to do the "flush" myself! A few more questions:
1. How do I dump all the coolant? Is there a valve underneath the radiator to let out the coolant?
2. When I fill, I have to do so through the resovior, right?
3. Change the thermostat too or not?

1. Yes, the radiator has a drain cock. The engine block also has a drain cock on the side that faces the rear of the vehicle. Further, the coolant heat storage tank (which contains hot coolant) can also be drained, and the associated coolant pump should be disconnected during this process so that you don't have an accident. When refilling, one challenge will be to run that coolant pump so that the tank can be filled and air can be purged out of that system.

2. Yes

3. Since your car has 80K miles, this is a good idea. You will also need to replace the rubber O-ring that seals the thermostat housing.

I suggest that you use Toyota Super Long Life Coolant which is premixed with distilled water. This has the correct pink color and is ~$20 per gallon.

I also suggest that you download and study the Hybrid12 Engine Control System.pdf file that can be found at Automotive Training and Resource Site, especially pages 2-4 to 2-7. If you need more tech info after reading that, go to techinfo.toyota.com and download relevant repair manual pages for your model year.

If you are still inclined to DIY, you may decide to forego draining the coolant heat storage tank; however this will result in keeping ~30% of the old coolant in the combined system.

Good luck.

[Patrick Wong]

Originally Posted by edthefox5

... If you dump all the motor coolant including pulling the thermostat it will be an overheating/ sloshing sounds under the dash nightmare unless you evacuate all the trapped air. Its a dealer or a very savvy mechanic deal. Do what I do yourself. Dump the rad.contents only. Put just distilled water back in it. Run it till it reaches op temp with heat on full blast. Let it cool down. Repeat.
Then final rad dump then fill up with factory coolant. That will get you real close to a complete flush...

Hi Ed,

A problem with this suggested approach is that the correct coolant is the pink Toyota SLLC which is already premixed 50%/50% with distilled water. Hence the use of distilled water during the intermediate drain/flush steps means that at the end, the coolant that remains in the system will have an insufficient % of antifreeze and an excess % of water. This results in reduced anticorrosion and antifreeze protection.

[V8Cobrakid]

you must have missed the last line about adding factory coolant in the end...

i like that approach... a distilled flush.

[rumpledoll]

The problem is you will have great trouble getting the proper 50/50 distillation with the water "flush". Since there is a significant amount of water in the coolant system, when you add 50/50 you will end up with something *less* than the required 50/50.

Rumple

Originally Posted by V8Cobrakid

you must have missed the last line about adding factory coolant in the end...

[V8Cobrakid]

then don't add 50/50... buy pure. they sell it.