Incoming New Radiator - 1997 FzJ80 - Coolant Type Question on NEW radiator (1 Viewer)

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DirtyPepper

DirtyPepper

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Oct 25, 2021
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Ok, so...not to beat a totally dead horse on the subject...don't hurt me, hahaha!

Yes, I read just about every post, old and new, about which radiator fluid to use, BUT...pretty much every post talks about an existing radiator and simply flushing the system and not dropping a new one in AND THEN adding coolant.

And I want to make sure I don't mess up, because I really don't want to take that HG "Rite of passage"...I want to delay it AS LONG as possible.

The new radiator arrives this Thursday and my 80 gets opened up the weekend of the 27th - there's nothing wrong with the current radiator but after 220K miles, I feel it's best to do PM...and since I'm replacing the entire cooling system, it was just a foregone conclusion to swap out the radiator and keep the factory one as a backup.

The system will be flushed to get any gunk or sediment of any kind out, sure...but when dropping the new radiator in, after reading the threads, I'm assuming green coolant is OK, yes? Prestone 50/50 is what's been in it since I took ownership (7 years ago).


Thanks in advance,
 
Marco Lau said:
make sure you flush the block too. Otherwise, you might be looking at HG replacement @ sub 250k
Click to expand...

Thanks, and yeah, planning on a complete flush with a flush system.
 
Which "flush system" are you using? Most flushing machines are just hooked up to tap water, which means you're introducing some Chlorine into the system.

Many of the MUD members use Distilled water at least for the final couple of flushes which include opening the block drain to remove traces of flush chemicals and tap water.

You have to be careful not to over pressurize the cooling system, specifically the heater cores. Everything else can be replaced fairly easily, but the main heater core requires the entire dash to come apart to replace if you blow that up.

Do you plan to replace the Thermostat, water pump, and heat control valve at the same time??

Big discussion on which Anti-freeze to use. FWIW I've used Toyota Red 50:50 (with distilled water only) in all my Toyota vehicles for a few decades with zero issues. Still running the original radiator on one FZJ80 with 377,000 miles. The core is still clean as a whistle (however the plastic tanks are done).
 
Kernal said:
Which "flush system" are you using? Most flushing machines are just hooked up to tap water, which means you're introducing some Chlorine into the system.

Many of the MUD members use Distilled water at least for the final couple of flushes which include opening the block drain to remove traces of flush chemicals and tap water.

You have to be careful not to over pressurize the cooling system, specifically the heater cores. Everything else can be replaced fairly easily, but the main heater core requires the entire dash to come apart to replace if you blow that up.

Do you plan to replace the Thermostat, water pump, and heat control valve at the same time??

Big discussion on which Anti-freeze to use. FWIW I've used Toyota Red 50:50 (with distilled water only) in all my Toyota vehicles for a few decades with zero issues. Still running the original radiator on one FZJ80 with 377,000 miles. The core is still clean as a whistle (however the plastic tanks are done).
Click to expand...

Thanks for the insight!

I was just planning on getting a standard flush kit from Napa…but that’s part of my question also, I guess…do I need to do a massive flush when replacing the entire radiator?

I planned on using distilled water…it’s pretty inexpensive and I’ve read that’s what most mud members use. Growing up, I came from the school of, “Eh, just use tap water in lieu of coolant…” but I haven’t done that since I was a kid (mid 40’s now).

I have no idea what the PO did other than some janky stereo work and a few hoses changed out. To answer your question, yes, the thermo and HCV are being replaced at the same time.

Cap, rotor, plugs, wires
Heater control valve, water pump, fan clutch, all heater/radiator hoses to include the PHH, oil change with OEM filter and Rotella oil…new radiator and radiator cap.

As I mentioned, my radiator doesn’t seem to have any issues on a general inspection level…coolant is still bright green but I’ve never flushed it in the seven years (20k miles) that I’ve owned her. With me wanting to baseline her, I figured I’d do the entire cooling system and then go from there 👍

As always…the words and guidance are all super appreciated!
 
Do not use any sort of flush kit that allows you to connect the garden hose directly to your cooling system. Our cooling system is designed for 13psi, the garden hose attached to your home plumbing will generate 4-5x's that and can blow out your heater cores, at the least.
 
I put a new radiator in a year or so ago. I flushed with the prestone kit from the local parts store. Used my tap water (which is a well so no chlorine but has minerals). Once the flush had been in there for the allotted time I pulled the radiator and then ran just water through the intake hose with the engine running for a while to make sure all the flush got out. After installing the new radiator I put in the universal color (it appears light yellow) mixed 50/50 with distilled water. It's been fine through one cold winter and two hot summers. I don't drive it daily anymore but it does get used several times a week. Nice thing about the universal is I can get it anywhere. Toyota red is hard to come by if you're in the middle of nowhere and need coolant.

Bottom line. Don't over think it. These trucks are designed to live in tough environments and can probably run a long time on dirty river water (not that I want to find out). Using tap water to flush and a different antifreeze than it came with from the factory isn't going to kill it.
 
Kernal said:
Do not use any sort of flush kit that allows you to connect the garden hose directly to your cooling system. Our cooling system is designed for 13psi, the garden hose attached to your home plumbing will generate 4-5x's that and can blow out your heater cores, at the least.
Click to expand...
Good to know!

What would be the route I would take, flush kit wise then?


Thanks,
 
Many ways to go about it but here's (roughly) the process I've used,
no kit, just elbow grease and getting wet a few times.

On a cold engine:

Adjust HVAC selector to the full hot position and leave it there for the entire procedure (this will ensure the rear heater is flushed also)
Remove the radiator cap
Open the radiator drain petcock
Open/remove the block drain
Allow the system to drain

Close the petcock and block drain
Add your cooling system cleaner and refill with water from the garden hose
Follow directions on the bottle including draining the system again
including opening/removing the block drain

But this time:
Disconnect the bottom radiator hose at the radiator
Disconnect the top radiator hose at the radiator
Remove Thermostat then put the housing back on (three nuts)

You can flush out the radiator at this point by putting the garden hose into
the fill port and top pipe of the radiator; do not stuff it all the way in and do not turn the pressure/flow all the way up.

Next you can (sort of) backflush the block/head by running water into the upper radiator hose (ie: flow toward the engine). Put the garden hose loosely into the top radiator hose, keep the flow/pressure low.

Open the block drain and radiator petcock again if they've been closed

Close all drains and reconnect all hoses (Tstat still removed)
Add 100% distilled water
Start engine and drive the vehicle, heat selector lever still on full hot
You don't have to turn on the blower

Allow engine to cool, repeat drain procedure.

If water comes out dirty, repeat flush above using Distilled water again
Some people repeat the Distilled water flush either way

It takes three gallons of distilled water (from Wally marts) for each flush

Install new Tstat (dingle ball at 12 O'clock) and any other parts you plan to replace (water pump, radiator, Heat Control valve, hoses, PHH, ---)

Final fill 50:50 Distilled water and compatible Anti-freeze/coolant

I overfill the the overflow tank by about two inches; the level will drop
over the next few days or so as trapped air is pushed out of the system
No need to "burp" the system IME

Note: if the system sat for a prolonged period empty while you replaced all the components you could wait to do the final distilled water flushes after putting it all back together as there will be some rusty water from it sitting open and unfilled with coolant IME.

Warning: important to resist the urge to turn up the garden hose pressure, don't do it, you don't need much to flush out the old fluid/water/cleaner.

-----------------------------------------------------------------

IMHO Toyota Red is the better choice, you can buy it from any Toyota dealer, and Amazon will ship it to you anywhere in the world if there's a physical address to deliver it to.

Your system shouldn't leak for the next 10-15 years minimum if you just replaced all the components and hoses with new OEM (or Gates Green Stripe heater hose where needed) so not much to worry about losing your coolant from a leak.

Some may say all the above is overkill, and it is a lot more work than a simple drain and refill. However I know from experience that the FZJ80 cooling system will stay clean for a decade plus if you follow that process or something close to it.

FWIW
 
Last edited:
If theirs already green in there and it still clean, like said before don't over think it.
Simple flush refill with more green 🤷‍♂️
FWIW been running the green for over 7 years with out issue, It's what was in there when I got the truck. and yes it's been changed but stayed with the green;)
 
Kernal said:
Many ways to go about it but here's (roughly) the process I've used,
no kit, just elbow grease and getting wet a few times.

On a cold engine:

Adjust HVAC selector to the full hot position and leave it there for the entire procedure (this will ensure the rear heater is flushed also)
Remove the radiator cap
Open the radiator drain petcock
Open/remove the block drain
Allow the system to drain

Close the petcock and block drain
Add your cooling system cleaner and refill with water from the garden hose
Follow directions on the bottle including draining the system again
including opening/removing the block drain

But this time:
Disconnect the bottom radiator hose at the radiator
Disconnect the top radiator hose at the radiator
Remove Thermostat then put the housing back on (three nuts)

You can flush out the radiator at this point by putting the garden hose into
the fill port and top pipe of the radiator; do not stuff it all the way in and do not turn the pressure/flow all the way up.

Next you can backflush the block/head by running water into the upper radiator hose (ie: flow toward the engine). Put the garden hose loosely
into the top radiator hose, keep the flow/pressure low.

Open the block drain and radiator petcock again if they've been closed

Close all drains and reconnect all hoses (Tstat still removed)
Add 100% distilled water
Start engine and drive the vehicle, heat selector lever still on full hot
You don't have to turn on the blower

Allow engine to cool, repeat drain procedure.

If water comes out dirty, repeat flush above using Distilled water again
Some people repeat the Distilled water flush either way

It takes three gallons of distilled water (from Wally marts) for each flush

Install new Tstat (dingle ball at 12 O'clock) and any other parts you plan to replace (water pump, radiator, Heat Control valve, hoses, PHH, ---)

Final fill 50:50 Distilled water and compatible Anti-freeze/coolant

Overfill the the overflow tank by about two inches; the level will drop
over the next few days or so as trapped air is pushed out of the system
No need to "burp" the system

Note: if the system sat for a prolonged period empty while you replaced all the components you could wait to do the final distilled water flushes after putting it all back together as there will be some rusty water from it sitting open and unfilled with coolant IME.



-----------------------------------------------------------------

IMHO Toyota Red is the better choice, you can buy it from any Toyota dealer, and Amazon will ship it to you anywhere in the world if there's a physical address to deliver it to.

Your system shouldn't leak for the next 10-15 years minimum if you just replaced all the components and hoses with new OEM (or Gates Green Stripe heater hose where needed) so not much to worry about losing your coolant from a leak.

Some may say all the above is overkill, and it is a lot more work than a simple drain and refill. However I know from experience that the FZJ80 cooling system will stay clean for a decade plus if you follow that process or something close to it.

FWIW
Click to expand...

Thanks for the super detailed write up! It’s appreciated 👍

Nothing is leaking…she’s as dry as a bone in that regard. In fact, she’s not even leaking any oil at 220k miles. There’s slight blowback oil from the distributor, and I already have the gasket ready and waiting for thst, among a slew of listed baselining parts ready to go.

Sometimes I wonder if I am overthinking the entire baseline…but what kicked it off for me was seeing the yellow coloring on my heater control valve and reading that the “arms” of it are probably disintegrating at that point. And after reading the horror stories of that going, I just decided it was better to do as much PM as I could, simply because it not only needed it, but because I don’t know what the PO did/didn’t do. I’d rather spend the money on PM and be 100% sure rather than jumping straight to sliders, or a lift, or any other big update.


Again, thanks 👍
 
Do your flush BEFORE replacing the water pump. Debris freed by the flush is hard on the water pump seals.

Afterwards, run whatever coolant you can easily get your hands on. I probably have Peak (green) in mine.

Personally, I don't think the heater cores are particularly fragile. If one lets go during a flushing process, it was about to happen while you're driving.
 
DC2NoVA said:
Curious, what radiator are you going with?
Click to expand...
I went with the DENSO via RockAuto - I wanted to go OEM but the price point was a little more than I wanted AND there was a helluva wait. So, after conferring with the Ih8mud forums of old, I went with the above mentioned DENSO.
 
DC2NoVA said:
Nice, same here.
Click to expand...
Yeah, I also spoke with another forum member that has a shop in Phoenix (where I grew up from 8 y/o to 29 y/o) who stated his shop runs these specific Denso radiators and no one has had a problem. If a Denso in a Land Cruiser can take he brutal Phoenix summer highway heat / stop and go in town traffic WITH the AC on, then I'm sure it'll be good in the PNW ;)
 
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