16 year old coolant 179K miles Toyota 2.4l 2AZ-FE. A few questions about changing coolant.

[Owen Lucas]

I plan on flushing my coolant soon, about time. Noticed the level has been gradually getting lower in the reservoir over the last few years. It’s completely empty now, and have a few questions.

1. I’m pretty sure the engine isn’t consuming coolant (waiting on 1st UOA) based on clean oil filler cap. Where has it been going over all this time, evaporating?

2. I’m thinking of using Liqui-Moly radiator cleaner, is there any benefit to flushing coolant or is this stuff snake oil?

3. Should I run a garden hose through the radiator to get the flush residue out?

4. Since I have the coolant system open, should I change the thermostat? Haven’t had any issues with overheating but maybe as preventative maintenance.

5. Anything else I should look into while the system is open? Coolant cap? I will probably use some left over condenser cleaner since and power wash the radiator / condenser while I have the bumper off (changing headlights) as well.

 

[zzyzzx]

3. Should I run a garden hose through the radiator to get the flush residue out?

Yes.

 

[mk378]

Look for very small leaks, like at the ends of hoses.

 

[zzyzzx]

5. Anything else I should look into while the system is open? Coolant cap? I will probably use some left over condenser cleaner since and power wash the radiator / condenser while I have the bumper off (changing headlights) as well.

Coolant cap is really independent of anything else and should be checked periodically anyway.

Pressure washing a condenser or radiator is a great way to bend all the fins.

 

[khittner1]

1. After 16 years, some evaporation of the water content might be expected. Check your water pump's weep hole to see whether there's been leakage there.

3. If you're replacing the OE Toyota SLL pink coolant (which is 50/50 from the jug) with the same, I wouldn't bother with the cleaner and flushing with water. Drain and fill the system with 50/50 SLL, and do it again at 50K intervals thereafter.

4/5. A new OEM thermostat and filler cap would be OK, but you're probably past the point of viewing it as preventative maintenance. Rinsing the condenser and radiator fins with a garden hose would be a good move to remove whatever accumulated bugs & grunge it can, but I wouldn't be using a power washer on the feeble, thin fins of either the condenser or radiator.

 

[zzyzzx]

Even if it has the original hoses, compare them to new ones. Even if they aren't leaking and look good, they can be swollen in which case I'd replace them.

 

[The Critic]

I plan on flushing my coolant soon, about time. Noticed the level has been gradually getting lower in the reservoir over the last few years. It’s completely empty now, and have a few questions.

1. I’m pretty sure the engine isn’t consuming coolant (waiting on 1st UOA) based on clean oil filler cap. Where has it been going over all this time, evaporating?

2. I’m thinking of using Liqui-Moly radiator cleaner, is there any benefit to flushing coolant or is this stuff snake oil?

3. Should I run a garden hose through the radiator to get the flush residue out?

4. Since I have the coolant system open, should I change the thermostat? Haven’t had any issues with overheating but maybe as preventative maintenance.

5. Anything else I should look into while the system is open? Coolant cap? I will probably use some left over condenser cleaner since and power wash the radiator / condenser while I have the bumper off (changing headlights) as well.

1) Water pump, head bolts (common on early 2az's) and/or radiator.

2) No

3) No

4) Your call

 

[WobblyElvis]

Keep in mind.
If you flush out any part of the system with water, some straight water will remain inside. This means you will not be able to bring the mixture back to 50/50 if you purchase the coolant in a 50/50 mix.

 

[Owen Lucas]

Even if it has the original hoses, compare them to new ones. Even if they aren't leaking and look good, they can be swollen in which case I'd replace them.
View attachment 79491

Great point. They are $15 and $21 OEM so I might as well replace those. Had a pinhole leak a few years back on another vehicle, would like to avoid that again.

 

[Owen Lucas]

Keep in mind.
If you flush out any part of the system with water, some straight water will remain inside. This means you will not be able to bring the mixture back to 50/50 if you purchase the coolant in a 50/50 mix.

Alright, makes sense. I would rather have some old coolant than a diluted mixture.

 

[nwjones18]

Alright, makes sense. I would rather have some old coolant than a diluted mixture.

I feel like everyone has their own way of doing this, but the way I fill after I flush with water is I add enough full strength antifreeze to cover system capacity then top off with water. That way there is enough antifreeze in there to cover whatever water remains from the flush.

 

[Jake_J]

16 years on a modern Toyota P-OAT coolant is not that much, there's plenty of Toyota's at 16 years and 180K miles with the original coolant that are fine. Unless you see sediment, or any other problems with the old coolant I would just refill with new P-OAT coolant and call it a day.

 

[JustinH]

Those Toyota 2.4L's and 1.8L's of the same vintage are tough to get filled unless you fill them under vacuum.

I would pressure test the system while off to find a leak, if it is that low you have a problem.

This is looking less and less like a DIY job to me, unless you have those two items in your home garage.

I had several cars with 2.4L and 1.8L 4 cylinder Toyota engines.

 

[Owen Lucas]

16 years on a modern Toyota P-OAT coolant is not that much, there's plenty of Toyota's at 16 years and 180K miles with the original coolant that are fine. Unless you see sediment, or any other problems with the old coolant I would just refill with new P-OAT coolant and call it a day.

Thank you for the advice, I thought I was pushing it with the original coolant. I would rather top the system off than take it all apart.

 

[Owen Lucas]

Those Toyota 2.4L's and 1.8L's of the same vintage are tough to get filled unless you fill them under vacuum.

I would pressure test the system while off to find a leak, if it is that low you have a problem.

This is looking less and less like a DIY job to me, unless you have those two items in your home garage.

I had several cars with 2.4L and 1.8L 4 cylinder Toyota engines.

I have an HVAC vacuum pump but it sounds like automotive systems use something different? I think I might as well avoid the whole disassembly and overhaul and just top off the coolant and monitor the reservoir level. What’s the longest you had the OEM coolant on your Toyota engines?

 

[madeej11]

Even if it has the original hoses, compare them to new ones. Even if they aren't leaking and look good, they can be swollen in which case I'd replace them.
View attachment 79491

If it's swollen then it definitely cannot look good.

 

[Jake_J]

I have an HVAC vacuum pump but it sounds like automotive systems use something different? I think I might as well avoid the whole disassembly and overhaul and just top off the coolant and monitor the reservoir level. What’s the longest you had the OEM coolant on your Toyota engines?

There's no need for filling the those engines under vacuum, profession tech's use them to save time but you can get the system perfectly bled out without them. Just raise the front in the car (or park it on an incline), get a funnel that fits the rad opening well, and let the engine warm up to temp while checking the level and adding coolant as you go. I've changed coolant on a few 1.8L (1ZZ-FE) and 2.4L (2AZ-FE) Toyota engines and never had an issue using the normal method. Even if you skip the bleeding procedure most engine will bleed the air out during the first few drive cycles, so you'll just need to add coolant later.

 

[zzyzzx]

If it's swollen then it definitely cannot look good.

The thing is that hoses can be swollen and still look good until you compare them to a new hose. That and part of the swelling process I swear makes the hose a little longer too. When looking in your engine bay, your basis for comparison is going to be other swollen hoses.

 

[eljefino]

You can get concentrated aftermarket red coolant-- Recochem makes it, Pep boys used to sell it. Red isn't as great as pink but mixes and is compatible. This would be for if you had to flush with water. You shouldn't need to clean out the inside of your rad, assuming you never topped off with tap water and its high mineral content (which varies by region.)

I would punt-- get 50-50 premix, drain what you can, refill, inspect the hoses, leave the rest alone. Thermostats are one of those things that the aftermarket doesn't make as well as OE. Gently cleaning the condensor and rad is a fine idea.

If you have a scan tool, watch how closely your car follows t-stat temp. Your dash gauge will be dampened so this is the only way to really know.

Coolant does evaporate. It's honestly a miracle it disappears as slowly as it does in many cars.

 

[Oliveoil2]

I have never “flushed” a coolant system. Ever. Just drain and refill every 2-3 years with OEM coolant mixed with distilled water.