Radiator Always Full / Reservoir Always Empty

So I've had my 2001 Tundra since 2016 now and I've always had this issue. Anytime I add coolant to the overflow, it will disappear within a few days. The radiator is always full and in fact I've driven about 30,000 miles this way, with the overflow empty and the radiator full. I actually just completely forgot about it for the past 5 years or so until I added more coolant this year and the same thing happened. It's like a thorn in my side and I'd like to get it fixed if I can.

I've never seen any coolant under the reservoir nor around the line running to the radiator. That would be pretty obvious.

After I put in the coolant this year I did notice liquid under the truck but it was dark like oil or steering fluid, not green. The leak came and then went, it's not continuous.

I do have a steering leak ( supposedly ) but I've never had to add steering fluid in the 7 years I've had the truck and it's full to this day so who knows. I guess I just assumed it was coolant leaking out and getting dirty before hitting the ground.

I don't think I have an oil leak because the level never drops, plus the leak stopped for whatever reason.

Anyone have any hunches where it could be going? I've not dug in too much, just looking for direction first.

 

Are you filling it to the fill line or to the top of the res?

 

What's your exhaust and oil change look like? Also what part of the country do you live in?

 

Filling it to the fill line.

Exhaust is clean from what I can tell I can't see it. Oil is also good.

 

And you’re sure there’s no air in the system? Like, none? Heater on full blast to ensure water and air has pushed out of every line, and there hasn’t been some trapped which is slowly letting out? And you’re using red (/pink) coolant?

 

No I'm not sure of that, as I've just started thinking about the issue again. Using green coolant that is compatible with a 2001 Tundra. Not sure the brand off hand.

 

There are no green coolants compatible with the 2UZ-FE I'm aware of.

 

Thats why the rez is there. The water is going somewhere. Cracked tank? Any heat on the gauge?

 

And for the record, I'm not saying this will happen to you. Just saying, red is what is prescribed by OEM. Coolant is colored for a reason, each color has different properties which make it compatible or incompatible with different engines (i.e. making it compatible with seals and block/heads being either alloy or iron, since some coolants react with alloy, or react with iron)

Here's what yellow coolant precipitate from using green/yellow coolant in 2UZ-FE, and/or mixing green/yellow with other stuff looks like in a 2UZ, worst case I think any of us have ever seen:

https://www.tundras.com/threads/crackhead-resurrection.94083/page-25#post-2424817

https://www.tundras.com/threads/crackhead-resurrection.94083/page-13#post-2396026

https://www.tundras.com/threads/crackhead-resurrection.94083/page-25#post-2424634

https://www.tundras.com/threads/crackhead-resurrection.94083/page-25#post-2424716



What came out after flushing:

https://www.tundras.com/threads/crackhead-resurrection.94083/page-26#post-2426208

If I were you, I sure as hell would NOT be running green/yellow coolant in that engine, and if your mechanic told you it's "compatible", it's time to find a new mechanic.

Whatever you do, when you go to replace with proper coolant, make sure you fill/flush with distilled water after getting the green/yellow out, or if you just intend to run-flush it with hose water like I would to save time, hook a water hose up and leave it running with the engine running to dilute every last bit of what's in there before letting the engine cool down, and flushing the water, then filling up being careful to burp things properly as you go.

I'd surely hope your truck isn't "losing" coolant because it's eroding the internals (seals/passages) that'll ultimately clog stuff up like what you see in the pics above. Or because something already got eroded and you're not seeing the drip.

 

So the owners manual states -

Coolant type:
“TOYOTA Long Life Coolant” or equivalent
With ethylene–glycol type coolant for a
proper corrosion protection of aluminum
components


I'm running Walmart's Supertech coolant which is rated for all makes and models and contains ethylene-glycol.

I've only been running it for about a year and less than 1000 miles. Can't remember what I used before that.

 

No cracked tank, there is never anything leaking in that area. Gauge reads normal, right in the middle when it's heated up.

So I guess if there was air in the system I could expect some over heating right?

 

Here is what confuses me the most - if I have a leak, why is the coolant not disappearing from the radiator?

 

For your 2000 the Owners Manual is correct.
Toyota OEM for 2000-2003 was their Long Life RED. That changed starting for the MY 2004-2006 when they changed to Super Long Life PINK with a longer change interval.

From Owners Manual

"Toyota claims that their Pink Coolant is good for up to 160,000 km (100,000 miles) or 10 years for the factory fill and then needs to be changed every 100,000 km (60,000 miles) or 5 years after that. The red coolant has a much shorter life and needs to be changed every 50,000 km (30,000 miles) or every 2 years."

 

Ok so since no one is clicking the link above, I'll just post this here.

From what I can tell, my coolant looks perfect when I look in the radiator. It's as bright as the stuff in the bottle and I see no signs of sludge or anything. If I end up doing a coolant flush I'll post pics of what it looks like.

 

Ok so considering that your exhaust is not continuously white or the dipstick doesn't look like chocolate milk then everything should be good regarding any leaks through the heads. What part of the country are you in?

 

Minnesota.

 

I’m with ‘Shifty on this. My truck came with Green when I bought it in 2005 but I flushed and went with pink. Look carefully in your valley with a flashlight for small leak from one of the o-rings, also check the coolant crossover gaskets front and rear, and look under the water pump pulley. I would also look along the lower radiator tank where it’s crimped to the core and where the transmission line barbs are threaded into the plastic tank.

 

Taken from the info dump thread:

Recalls, TSBs, and annoyances - there are quite a few, here are some big ones that generate threads​

• • .....
  • .....
  • .....
  • ....
  • ....
  • ....
  • Water leaks, from rain, car wash, or otherwise: Check this thread for the common ones you may find, the cowl leak into the passenger side is hugely common and very easy to fix.
  • Coolant leaks: Three common causes: One is the is the gasket behind the thermostat housing, another is the coolant crossover at the rear of the block, and last but not least, old radiators is another source. Here's a list of things to check if you're losing coolant. For repairing the leak behind the t-stat housing, check this out. For the coolant crossover tube issue, you'll likely find coolant at back of the block, near where the trans and engine meet, check this reply for video/fix. This reply contains links to three other off-brand/odbball leak cases. For radiator leaks, this is one example of a tiny one - always replace with Denso brand radiator, and know different cab types use different sizes, careful where you order, scAmazon especially tends to deliver damaged products often (RockAuto has a spotless record with forum members). Proactive radiator replacement is wise. The transmission line routes through the bottom of the radiator ... go look up "pink milkshake", it happens in these trucks.

 

Just keep filling the over flow in-between the two marks until it stops being empty. Do it over a few days just to see if it makes a difference. I also think it's definitely possible that there is a hairline crack in your overflow and it's leaking back out very slowly.

As for coolant type green/yellow is not technically correct. If the system was flushed of all old coolant properly before switching I don't see there being any issues short term. If there has been yellow/green mixed with red/pink then yeah that's a big problem the two coolant types can and will react with each other and clog up passages. Just something to be aware of.

 

Well I'm trying to do a flush but only a bit over 1 gallon of liquid is coming out at a time and that's it, I'm assuming from the radiator. I've let the engine heat up so the thermostat should be open, but it seems like 2 gallons is stuck in the engine.

What's the proper way to get all of the liquid out of the system?

 

You can’t get it all out. Be sure heater control full hot and warm engine till thermostat opens. Open the draincock on the bottom of the radiator and catch in a buck. Remove lower radiator hose and catch in another bucket. Open two 10 mm block drains under engine. That’s best you can do. Listen to Shifty’ and use only Zerex Asian Pink. Make sure jingle valve on thermostat is clocked at 12:00. Read Shifty’s post about just bout FGT and check common leak point like coolant crossover pipes

 

Thanks, didn't know about the block drains. Are there any air bleeders on the V8 engine?

 

My reservoir has always been empty for the last 150k miles since I replaced it.

 

Just picked up a "new to me" 2019 Tundra and after owning 3 previous 4Runners I noted the odd issue of an "always empty" coolant resovoir but always full radiator. No leaks noticed and the truck has just over 70k miles on it, one previous owner always maintained by the dealer since new that I bought it from. My 4Runners never did this. I won't get into the color of coolant issue but as I see no leaks, no issues with gaskets blown anywhere etc...it is a bit of a mystery...

 

If it's something you may want help with info on, highly recommend posting over in the 2.5 generation forums here: https://www.tundras.com/forums/2-5-gen-tundras-2014-2021.27/

(This post is in the 2000-2006 year subforum)

 

No, there are not. I’ve always filled mine on my driveway which is nearly level. Some advise an uphill. After having the system open, I start the engine before the radiator is topped off. Turn heater control full hot. Squeeze upper radiator hose several times to purge air. Watch radiator for circulation indicating thermostat open. Again squeeze upper radiator hose and top off. File reservoir to fill line. Close radiator cap. Be sure your cap is good. I seen some where the center disc has fallen out. Drive it for a couple miles and recheck level in fill tank. Recheck reservoir next day. I’ve never had a problem with trapped air doing this.

 

Encountered the strangest thing while pouring the new coolant into the truck this afternoon. I bought 7 jugs of Supertech Toyota coolant (red!) so I could do a coolant flush to remove any trace of distilled water and then fill it up after the flush. I poured the first bottle and it was red. The next bottle was pink. The next was red!

Looking at the jugs, I finally found some subtle differences between the pink jugs and the red jugs. I guess Supertech is changing the color to pink or something since I believe it is formulated as per Toyota's Super Long Life coolant.

I doubt there is any other difference between the two but who knows. I'm glad that this round is getting flushed out in the morning.

Besides that it's gone well. I did 3 flushes with distilled water and managed to get about 2.9 gallons in and out each time I think. The last one looked like slightly used dishwater. I never found anything bad like rust or sediment.



Last question I guess - can a 2001 4.7l tundra run pink coolant? Or do I need to actually find red?

 

I just bought an 02 about 6 weeks ago and to much my horror the reservoir came up empty and popped the cap the radiator needed half gallon...
I started looking around the radiator.... It was blowing coolant without per se leaking!! mostly around the bottom and little bit on the top.... significant build up. Started going away with a distilled water petcock drain and fill flush (7 times) over a weeks time, while waiting for new radiator to come in. Changed it out 2 days ago and refilled almost empty reservoir and radiator is still full....
I grabbed a Denso from Rock Auto only 137.00 and also replace upper and lower hoses, also new radiator cap and thermostat...

these radiators need updated time to time and the aftermarket ones have a lot of connectivity issues from my research!
I will probably change out my radiator every timing belt change... or every other one? just as preventive maintenance

The transmission cooler is in the bottom of these radiators so that's why someone asked if you had the pink milkshake in your transmission.... ;-)

all I got.... hope you remedy your situation cost effectively!!