Coolant replacement - how well am I doing?

[NoVA_T4R]

Hi,

My engine coolant drain and refill schedule has been as follows:
64,xxx (bought used)
100,xxx
124,xxx
145,xxx
192,xxx
216,xxx
243,xxx (first time doing multiple drain and refill; used BG Products Engine Cooling System Cleaner after first drain, then multiple drain and refill with distilled water until clear - 3 times, then 50/50 with Toyota Red). Not any brown fluid, just gradual lightening from red to pink to light pink....
All the previous services were Toyota dealership drain and refill. Probably not used with distilled water.

I'm currently at 266,xxx miles. For my next coolant service (around 280k miles), I'm contemplating pulling the thermostat and doing a garden hose flush in both the upper and lower radiator hose openings to get out any accumulated sediment and get anything out of the heater core. Have not experienced any high temps on my dashboard thermometer or experienced any loss of heat from heater core, just considering this to be OCD/extremely proactive to check "sediment in heater core or engine block" off and take me through the rest of my anticipated life with this T4R.

I'll also being putting in a new water pump and thermostat (replacements for both are due).

Your thoughts? Removing thermostat and garden hose flush too much?

 

[pokeyman]

If you are going to change the water pump do the timing belt too

 

[LittleCaesar]

I would just wait until you replace the water pump, TB, and the like. Just make sure you burp the cooling system well to get rid of all the bubbles in the system.

 

[gamefreakgc]

Wow yeah you are OCD lol! However, fresh fluids definitely help prolong the life of an engine so can't really say you've done anything wrong or wasted money. Most dealerships will now put the pink Long-Life fluid in and works great but Toyota Red is also good, just doesn't last as long.

Normally a flush is only necessary if the system has contaminates (scale, rust, changing fluid types like from green to red etc.) but it certainly can't hurt anything. Also, take a look down the opening under the radiator cap and that will give you a clue as to the health of your engine's coolant passageways. If you see clean, shiny alimunum you're doing great. If you see rust and scale buildup on the fins to the point you don't see any shiny aluminum you might want to consider a new radiator. They are a point of failure on these engines since the plastic tops will fatigue over the years, as well as the metal separator between the coolant and transmission fluid (although rare).

 

[NoVA_T4R]

The short duration (~20k miles) intervals were when I was towing a fully loaded UHaul trailer going cross country in the summer. So, doing coolant and transmission fluid flushes was something I did right after arriving.

Most recently I had aux trans cooler issues (Aux trans cooler stealth leaking?). I didn't post an add-on comment, but I'm getting trace leakage of ATF fluid so ordered a new radiator so I could reset my radiator age to "new" and put that worry behind me.
So my coolant flush question was in conjunction with my near future radiator replacement.

 

[4runnerbemore]

This is totally fine and I believe it is recommended procedure by Haynes manual (Who the hack reads it nowadays, we have Google right?).

 

[nobb]

It seems you are changing it out fairly regularly so there really should be no gunk/sediment in the coolant. IMO your flush procedure is a bit overkill...I would just drain it from the bottom radiator hose and top it off with new coolant.

One reason why I don't like the garden hose method is because the water is hard and you can get contaminants from the hose. You also have to pay special attention to get the concentration perfect right after.

 

[gamefreakgc]

It seems you are changing it out fairly regularly so there really should be no gunk/sediment in the coolant. IMO your flush procedure is a bit overkill...I would just drain it from the bottom radiator hose and top it off with new coolant.

One reason why I don't like the garden hose method is because the water is hard and you can get contaminants from the hose. You also have to pay special attention to get the concentration perfect right after.

There is a coolant drain plug on the block itself to remedy this issue. But to be honest its location is a bit of a mystery, even when I had my engine on a stand I couldn't identify which one was the plug.

 

[nobb]

There is a coolant drain plug on the block itself to remedy this issue. But to be honest its location is a bit of a mystery, even when I had my engine on a stand I couldn't identify which one was the plug.

Yea I know about that one but never managed to find it. We are supposed to be swapping out coolant every 2 years anyways so I'm not too concerned about a tiny bit of left over coolant in the block. I almost never use the radiator drain because it's too slow and if there's sediment, I don't feel like it does a very good job getting it out.

 

[Brian.]

I just replaced my radiator and did 4 flushes between the old and the new. Since it was an unknown vehicle with no records, I was going to go overboard, but this is just for reference sake.

So, the coolant that came with the car, to that I added a Prestone coolant flush and drove it for a few days running front and rear heaters.

Drained the coolant and filled with distilled water and a second bottle of coolant flush (wasn't needed, but I'd already bought it) and again drove for a few days.

Then I did 3 more distilled water flushes, driving just long enough to get the thermostat to open and circulate through the whole system. Each time I had a little less green tinge, till the last I had none. I was prepared to do one more flush, but opted not to.

Replaced the radiator and filled with Zerex Asian.

Personally, I wouldn't flush with a garden hose unless you're Also going to do a distilled water flush after that. I take that back, I simply wouldn't do a garden hose flush on anything I owned.

 

[TheDurk]

There is a coolant drain plug on the block itself to remedy this issue. But to be honest its location is a bit of a mystery, even when I had my engine on a stand I couldn't identify which one was the plug.

Yea I know about that one but never managed to find it. We are supposed to be swapping out coolant every 2 years anyways so I'm not too concerned about a tiny bit of left over coolant in the block. I almost never use the radiator drain because it's too slow and if there's sediment, I don't feel like it does a very good job getting it out.

This thread should allow anybody to finally locate that elusive plug, It IS there.

Location of engine block coolant drain plug on '97 V6 - Toyota 4Runner Forum - Largest 4Runner Forum

 

[TheDurk]

I just replaced my radiator and did 4 flushes between the old and the new. Since it was an unknown vehicle with no records, I was going to go overboard, but this is just for reference sake.

So, the coolant that came with the car, to that I added a Prestone coolant flush and drove it for a few days running front and rear heaters.

Drained the coolant and filled with distilled water and a second bottle of coolant flush (wasn't needed, but I'd already bought it) and again drove for a few days.

Then I did 3 more distilled water flushes, driving just long enough to get the thermostat to open and circulate through the whole system. Each time I had a little less green tinge, till the last I had none. I was prepared to do one more flush, but opted not to.

Replaced the radiator and filled with Zerex Asian.

Personally, I wouldn't flush with a garden hose unless you're Also going to do a distilled water flush after that. I take that back, I simply wouldn't do a garden hose flush on anything I owned.

Been doing it for 50 years on my 1966 Farmall 140. No issue on a cast iron block and all brass rad. I use the same water to mix the coolant. Also, I have very soft mountain well water. Hard stuff is down in the flatlands.

Aluminum 4Runner and BMW are a different story.

 

[gamefreakgc]

This thread should allow anybody to finally locate that elusive plug, It IS there.

Location of engine block coolant drain plug on '97 V6 - Toyota 4Runner Forum - Largest 4Runner Forum

Eureka!

I definitely don't have the little tube on my current engine, I would have spotted it.

 

[T4R2014]

I don't think you need any chemicals. Just some gallons of distilled. I wish every 4Runner had coolant changes like this.

For really bad systems, it turns out Pinesol works amazing.