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do you drain the engine block during coolant change?

  • I only change the fluid in the radiator but never drain the engine block

    Votes: 12 57.1%
  • I drain the radiator and the engine block always

    Votes: 7 33.3%
  • What's a coolant change?

    Votes: 2 9.5%
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Drain and fill @100k and then every 50k afterwards... only if you choose to do so.

I'm sure others will disagree with my above statement but to each their own.
 

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How much does the block hold compared to the radiator.....Could I do a few flushes (with running to temp to flush the block) and get the block essentially all water and then drain the radiator and fill with pure coolant to get a near 50/50 mix?

Or is there an easy way to drain the block.

I suppose the radiator holds a lot more and since I'm in the south, I'll probably just add 50/50 and not worry about the extra water in the block.

I haven't done a flush since the days when you used the prestone kit and put a fitting on the heater core lines for a garden hose. #oldschool
 
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Reactions: UNTMatt

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I have owned Toyotas that had drain cocks on the block. I don't know if the Tundra does or not. The coolant replacement section in the related Toyota Repair Manual specifically instructed draining of the block. I expect Toyota has continued that practice with later cars and trucks, but I won't know until I dig into it. When the time comes, I will drain the block if possible.

As for flushing the cooling system with tap water, then using coolant concentrate and the remaining water in the block to dilute, I would not. Tap water, depending on it's quality, has more-or-less minerals in it, and eventually those minerals can precipitate in your cooling system. Distilled or de-ionized water is cheap. If there is a price advantage to using Toyota long-life coolant concentrate (I assume it's available as concentrate), I would use that with distilled water. If Toyota's long-life coolant is only available as 50/50 mix, then I would use that believing that Toyota's water was distilled or de-ionized.

Current Toyota recommendations for the Tundra are to "inspect" Toyota "long-life" coolant every 15K miles or 18 months (Mmmm...Yep, looks like antifreeze to me.), and to replace the coolant at 100K or ten years. This is an extremely favorable recommendation, but I'm sure they have a solid basis for it. If you follow their "new truck" recommendation, I see no reason why you cannot repeat that recommendation and experience again, i.e. another 10 years with Toyota "long-life" coolant.

Finally, water and ethylene glycol may never wear out, but coolant does. All coolant, especially those products intended for aluminum engines, have corrosion inhibitors in the mixture to prevent corrosion. Pretty gutsy to intend to use the same coolant for the life of your aluminum engined truck...but then, the life of your aluminum engine might be shortened if old coolant isn't preventing corrosion. Your truck; your choice.
 
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Reactions: MetalMonkey

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I don't get it. At the beginning .001-.005 VDC is good and .07 and up is bad. He took his reading and said it's good. His meter read .03. That is not good and it's not bad? It's either good or bad. So his coolant is "almost bad or almost good"?
Looking at a couple web sites they say anything up to .3 VDC is considered acceptable.
http://www.ve-labs.net/electrolysis-101/how-to-test
 

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I don't get it. At the beginning .001-.005 VDC is good and .07 and up is bad. He took his reading and said it's good. His meter read .03. That is not good and it's not bad? It's either good or bad. So his coolant is "almost bad or almost good"?
Looking at a couple web sites they say anything up to .3 VDC is considered acceptable.
How to test for electrolysis | Vehicle Enhancement Labs
I think what the video meant to say is that 0.001-0.005 VDC is what should be expected from new coolant after replacement, and that anything between 0.005 VDC and 0.07 VDC should be considered OK.

This was the first time I had seen this test method. The potential measurement is determining how much electrolysis is occurring. If you have electrolysis, you have corrosion. I have always relied on the "clean and clear" method, and changing on recommended time interval to maintain corrosion protection. I'm guessing coolant has to get pretty foul to read 0.3 VDC.

Thanks for additional info from ve labs.
 
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I've done the radiator drain and refill a few times now. Cheap, easy, quick.

Coolant does not last forever. It does slowly become corrosive and its loses its lubricating properties over time.

I do not use Toyota's brand. I use Prestone premix.

160k+ now. 215k on an Accord doing the same thing.
 
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