Coolant low. Pressure test? Radiator cap?

[zguy1]

Hello everyone. I'm planning to do a bit more maintenance on the 4Runner this weekend. I feel pretty motivated after just replacing the CV axles myself.

Here is the issue I have been noticing. I have 2008 V6 with about 260k miles on it. For the past 15k miles or so I have noticed some coolant loss in the overflow. I may have filled it up 2 or 3 times since. Prior to this, I didn't experience any coolant loss. I did a 10k road trip and the coolant lever was unchanged at the end of the trip.

I did check around the radiator. I don't see any crusty coolant underneath the radiator or on the front of the engine. I do see a bit of pink crust on the passenger side about highway down from the top under the radiator cap. It's very faint and hard to see. Maybe there is more visible once the shroud is taken off.

Any thoughts or next steps?
Should I replace the radiator cap? Pressure test the system? Remove the shroud?

Appreciate the suggestion as usual. Thanks!

 

[FordF150]

Just keep an eye on it daily for awhile.

I noticed my overflow tank being 1/4 inch low. I just checked it after a short drive and it is back to the fill line. Mysterious is all I can think. Now at 150,000 miles on our 2005 4runner.

I changed the radiator cap one time. Everything else is OEM.

Checked level just now in the overfill (again). It's a 15-year-old 4runner and starts and runs like new. Hate to lose it in an "overheat". Never have had an "overheat"!

260,000 miles is a lot of miles for any car, Zguy. I'd watch it carefully (every day). If it runs right at startup without a miss you are probably good to go, but you have to find out if the coolant is leaking into a cylinder or not. And, like where it is going?

Yes. Change your radiator cap. You probably will need a new radiator, but they are cheap ($100).

Find the leak anywhere yet?

Do not remove the shroud. You'll get an overheat for sure.

 

[Drcoffee]

Take off the skid plate and look up around the water pump and crank pulley. At 260k you are probably due for a new radiator and water pump. Might as well change the T-stat too.

 

[zguy1]

Take off the skid plate and look up around the water pump and crank pulley. At 260k you are probably due for a new radiator and water pump. Might as well change the T-stat too.

Thanks. I will take the skid plate off today.

I saw that Autozone rents cooling system testers. Was thinking about giving one a try. Figured I would try that with about 13 psi and see if I hear anything. With a leak as little as mine I am not sure if I would hear or see anything. I honestly have never used one before.

 

[zguy1]

I did some checking this evening. I was able to rent a cooling system tester from Autozone.

I tested my radiator cap and above 16 psi it started to lower pressure to about 15 psi. The cap has 108 kpa on it which is about 15.6 psi so it looks like the cap is fine. I also tested the radiator and system itself. When I put 15 psi on it, it would come down to about 13 psi after about 15 mins or so. It didn't seem to go lower than 13 psi though. I would assume there is minor leak as I would expect the system to hold 15 psi.

I also removed the skid plate and I could not see any leaking or pink residue on the engine or by the water pump.

Not sure what to do next. Maybe I will remove the shroud and see what is going on with some of that pink residue that is barely visible below the radiator cap on the passenger side.

 

[Drcoffee]

Take the two bolts holding the radiator shroud off and lean it back to check out the radiator for leaks. How does the engine oil look? In some cases it can be a head gasket. Or a leak in the trans cooler inside the radiator. The oil would be milky if the cooler is leaking.

Head gaskets generally blow coolant out the overflow tank. It doesnt sound like your problem.

 

[UrbanRunner651]

If you can see any visible crust on the radiator it is leaking and should be replaced. It is a common failure on the 4th gens to see a small weep off the ends where the shroud meets the body on the passenger side. Grab the Denso replacement off Amazon for <$100. Swap only takes an hour or two.

 

[zguy1]

Take the two bolts holding the radiator shroud off and lean it back to check out the radiator for leaks. How does the engine oil look? In some cases it can be a head gasket. Or a leak in the trans cooler inside the radiator. The oil would be milky if the cooler is leaking.

Head gaskets generally blow coolant out the overflow tank. It doesnt sound like your problem.

Thanks. I will be unbolting the shroud today to take a closer look at the bit of crust that I can see. Oil engine is fine and has been unaffected since I started noticing the coolant lever dropping. My overflow tank is clean.

 

[zguy1]

If you can see any visible crust on the radiator it is leaking and should be replaced. It is a common failure on the 4th gens to see a small weep off the ends where the shroud meets the body on the passenger side. Grab the Denso replacement off Amazon for <$100. Swap only takes an hour or two.

Thanks. Unless it's leaking elsewhere that I can't see, I really believe it has to be the radiator at this point especially from the tiny bit of crust I can see. Going to take a better look today.

Is the Denso a direct replacement? I just checked Amazon I did not see any Denso that fits my 08 SR5 V6.

Also, I would suspect that I will need to check the trans fluid once the swap is done regardless of any fluid leaking from the lines going to the radiator. I would assume the radiator is holding some trans fluid regardless of whether any leaks out during replacement.

 

[UrbanRunner651]

Yea, if you can see crust just replace it.
Direct replacement. Not exact same as OEM but good enough. Here is the listing I bought back in 2019.
Amazon.com: Denso 221-3117 Radiator: Automotive

You should have an external trans cooler in front of the radiator so any fluid loss should be negligible. Just use the butt end of a sharpie marker or something similar to plug the lines when you disconnect.
Also don't really need to bother draining the block as there is only minimal fluid in it when cool.

 

[Drcoffee]

Check rockauto.com. Lots to choose from. I have used Denso, koyorad both about $100

Im one of those people that does not trust amazon suppliers.

 

[zguy1]

Yea, if you can see crust just replace it.
Direct replacement. Not exact same as OEM but good enough. Here is the listing I bought back in 2019.
Amazon.com: Denso 221-3117 Radiator: Automotive

You should have an external trans cooler in front of the radiator so any fluid loss should be negligible. Just use the butt end of a sharpie marker or something similar to plug the lines when you disconnect.
Also don't really need to bother draining the block as there is only minimal fluid in it when cool.

Well I got the Denso from Amazon today and put it in. It was a perfect fit. Hardest part for me was getting to the hose clamps using pliers and channel locks. I ended up taking out the battery and tray to have some more room.

Barely any trans fluid came out after removing the hoses but I suspect the radiator contained some. I have about 1/2 quart of Toyota WS trans fluid and I hope that it is enough to bring the trans level back up.

I also need to fill the coolant up as I forgot to pick up a gallon. Coolant seems very expensive. $20 for 50\50 mix whether it is dealer or an aftermarket brand. I would not want to do a flush.

Btw, after removing the shroud it was easy to see that it was leaking.

 

[Drcoffee]

Now is the time to add a tranny cooler. The ATF flow is IN the top, OUT the bottom. Because its a vertical cooler. The fluid drains back to the transmission. Unless you are adding an external cooler, there is no need to top off the ATF.

BTW coolant is cheap compared to head gaskets. Buy two gallons and flush it now while you are in there. I go the extra step and disconnect the top heater core hose and blow compressed air to empty the core. Be careful to gently blow air in it, you dont want to blow out the core. When refilling, leave the top hose disconnected (engine off) until coolant comes out to purge air from the system. That is the highest point in the system.

 

[zguy1]

Now is the time to add a tranny cooler. The ATF flow is IN the top, OUT the bottom. Because its a vertical cooler. The fluid drains back to the transmission. Unless you are adding an external cooler, there is no need to top off the ATF.

BTW coolant is cheap compared to head gaskets. Buy two gallons and flush it now while you are in there. I go the extra step and disconnect the top heater core hose and blow compressed air to empty the core. Be careful to gently blow air in it, you dont want to blow out the core. When refilling, leave the top hose disconnected (engine off) until coolant comes out to purge air from the system. That is the highest point in the system.

I didn’t check the trans fluid level. I tried even tilting the radiator sideways and barely nothing came out from the two transmission lines. Maybe a drop or two if that. Your explanation makes a lot of sense.

With that said, does my base SR5 even have a trans cooler then? If the trans fluid doesn’t even pass through the center of the radiator it sounds like the transmission fluid is not being cooled at all.

I already put everything back together so unfortunately I didn’t drain any additional coolant or add the external cooler yet. My radiator only took about a gallon to bring the level back up. I drove it once after finishing the job yesterday so I’ll check the level again this morning.

 

[waypoint]

With that said, does my base SR5 even have a trans cooler then? If the trans fluid doesn’t even pass through the center of the radiator it sounds like the transmission fluid is not being cooled at all.

Yes, the cooler circuit in your radiator is effective at maintaining trans fluid operating temp (and helping to warm it up to operating temp). The optional auxiliary cooler is fluid-to-air type and plumbs in after the radiator to spill off additional heat.

 

[firebirdguy]

Well I got the Denso from Amazon today and put it in. It was a perfect fit. Hardest part for me was getting to the hose clamps using pliers and channel locks. I ended up taking out the battery and tray to have some more room.

Barely any trans fluid came out after removing the hoses but I suspect the radiator contained some. I have about 1/2 quart of Toyota WS trans fluid and I hope that it is enough to bring the trans level back up.

I also need to fill the coolant up as I forgot to pick up a gallon. Coolant seems very expensive. $20 for 50\50 mix whether it is dealer or an aftermarket brand. I would not want to do a flush.

Btw, after removing the shroud it was easy to see that it was leaking.

you can get valvoline zerex asian coolant at walmart for about $12/gal. its great stuff & 100% approved for use in these toyotas.

& as you found there is very little ATF that comes out the the lines when diconected, the trans cooler in the radiator is very small & the lines are thin, it holds maybe a few ounces of fluid or like 1/2 cup. the trans is probably fine if its a few ounces low but always a good idea to recheck the fluid level using the factory temp check procedure.

Valvoline Zerex Asian RED Vehicle Antifreeze / Coolant - 1 Gallon - Walmart.com - Walmart.com

 

[zguy1]

you can get valvoline zerex asian coolant at walmart for about $12/gal. its great stuff & 100% approved for use in these toyotas.

& as you found there is very little ATF that comes out the the lines when diconected, the trans cooler in the radiator is very small & the lines are thin, it holds maybe a few ounces of fluid or like 1/2 cup. the trans is probably fine if its a few ounces low but always a good idea to recheck the fluid level using the factory temp check procedure.

Valvoline Zerex Asian RED Vehicle Antifreeze / Coolant - 1 Gallon - Walmart.com - Walmart.com

That's good to know about the coolant. About 1.5 years ago I bought a gallon of Valvoline Asian (pink) from Menards just to have and it was much cheaper than Toyota's then. I was going on a 2 month road trip and assumed I would need to add coolant every now and then. Turns out it didn't use any over the 10k mile trip.

Fast forward to now and my local Menards no longer carries it. I went to Autozone and bought a gallon of what they carry but it turns out Toyota Long Life was the same price so I returned it and got the Toyota one.

 

[firebirdguy]

That's good to know about the coolant. About 1.5 years ago I bought a gallon of Valvoline Asian (pink) from Menards just to have and it was much cheaper than Toyota's then. I was going on a 2 month road trip and assumed I would need to add coolant every now and then. Turns out it didn't use any over the 10k mile trip.

Fast forward to now and my local Menards no longer carries it. I went to Autozone and bought a gallon of what they carry but it turns out Toyota Long Life was the same price so I returned it and got the Toyota one.

the zerex is very high quality just like any valvoline product. its 100% compatible with toyotas coolant to top off or do a full flush. best price for the asian coolant.