Radiator Overflow

I enjoyed a few high RPM blasts down the highway while driving the '07 5.7L back from a friends house today, I stopped to top of the gas tank and thought I smelled anti-freeze. Nothing strong, just a hint of it in the air.

I popped open the hood after parking in the driveway and I could see where fluid had spewed out of the overflow tank sometime during the trip, I also noticed that the overflow tank was about 1/2 full.

I let it cool off for 2 hours and checked it again, the overflow tank is almost empty and the radiator is full. The coolant left in the overflow has returned to the radiator.

The radiator was flushed when I purchased the truck, and I've put about 20,000 miles on it since then. I believe the radiator is original, and I have no idea how old the water pump or thermostat are.

What could be going on here?

 

Anyone?

 

Could be that it’s time for a radiator or water pump or thermostat. But I would probably try a radiator cap first.

I put a TRD one on. Just for the hell of it. It had a few more psi threshold than stock. I want to say it was 18 psi instead of 15.

 

This^^^^.

I've had cooling problems eat my lunch before, and never found the problem. The one thing I didn't do, and I should have done, was change the freakin' radiator after everything else had failed. I relied on flushing and chemical cleaners to get the job done, and it just didn't. If a new radiator cap, then a new thermostat, doesn't work, then I would try replacing the radiator before tackling a water pump having no external signs of leakage. I have never seen a water pump failure from lack of pumping (worn or broken impeller), but my experience is not totally complete.

 

I feel the same way about the water pump, but I have seen them rotten on the inside without leaking. Like it was still doing its job just not well.

 

I ordered the TRD cap, and I have a new water pump sitting in a box ready to go. Since the factory radiator has 291k on it, replacing it with another OEM radiator seems like the most cost effective solution... and I guess an OEM thermostat is another good choice.

Neither of my temperature gauges indicated a problem.

 

This is easy and good to check before changing parts.

$38 Block Tester BT-500 Head Gasket Combustion Leak Test Kit - Made in USA

https://www.amazon.com/Block-Tester...a-570352767565&psc=1&ref=&adgrpid=61495038909

 

Ah, yes...Your comment about "rotten on the inside" restores my memory of 50K mile SBC water pumps after GM changed to sheet metal impellers from cast iron. Yep, poor coolant maintenance could lead to "rotten on the inside" water pumps. I'm guessing Toyota, and everybody else, is probably using erosion-prone plastic impellers now?

 

Yep! It was a SBC! Unsure of Toyota materials. Also a buddy of mine has a Dakota with the 4.7. The aluminum of the water pump had eaten away enough around the impeller pocket, that it looked like it wasn’t flowing properly anymore. The truck had over 200 K on it. We were in the engine doing the heads and upon removal of the water pump, which is huge on the truck, after inspection we decided to change it out. I laughed at my friend and said you should’ve planned on it anyways.

 

What thermostat works with the Towing Package? All of the OEM part numbers I have found are for 'without towing package'.

$31 AISIN THT-005 Engine Coolant Thermostat with Housing and Gasket - Compatible with Select Lexus GS F, GS460, GX460, IS F, IS500, LC500, LS460, LS600h, LX570, RC F Toyota Land Cruiser, Sequoia, Tundra

AISIN THT-005 / Toyota 16031-38010

 

Indeed.

 

Could be that the radiator is gunked up. This happened to me on an s10 years ago after flushing the cullant system.

 

How soon did you stop for gas after the few high rpm pulls on the highway ?

 

About 5 minutes after the last blast.

 

it could just be that the coolant heated up enough to go into the overflow but didn’t get a chance to cool down enough to go back into the rad .
I would put some coolant in the overflow and drive it on the highway without doing any high rpm pulls and then check it again after that .

 

But wait, there's more.

Whenever I cold start this truck on a really damp & foggy morning I hear a loud screeching sound that I assumed was fan belt noise because it would fade after about 90 seconds, so a new belt was placed on my list of things to do.

Today's cold start (60 degrees and low humidity) I hear a high pitched whine that sounds more like a bearing, it faded after about 2 minutes. This is the first time I have heard this sound, and I am thinking it's water pump related.

What are your thoughts after reading this new information?

 

Quite possible imo, but it wouldn't make sense as cause for overheating. UNLESS...the bearing is actually seizing and stopping pump rotation leaving the belt to slip on the pulley. If it's a water pump bearing, that problem will manifest quickly as visible leakage due to shaft vibration, which destroys the mechanical seal.

 

Do you think it’s possible you got coolant all over the pulleys and belt, and caused a squealing this morning.

 

Okay it's probably not the bearing... I am not experiencing an overheating problem in the typical sense, just this little bit of fluid escaping via the overflow tube.

Yes, but there really isn't much coolant loss. There was actually more coolant in the reservoir this morning.

 

Okay, before we start replacing water pumps and rads I will tell you that I was alarmed a few weeks ago when I noticed my coolant overflow near empty a few hours after a short drive. I panicked. But no signs of coolant loss.

Right after the next drive I noticed the coolant back up to half full in the overflow. It obviously varies based on heat, load etc.

My point is, you said you had the rad flushed. Any chance the tech just overfilled it, and you're heavy pedal just sent the excess our the overflow hose?

May be no issue here other than a tech being a little too liberal with the coolant.

 

He’s pretty meticulous about his truck. I can guarantee you his coolant overflow was probably at a perfect level LOL.

my suggestion would be start with the radiator cap.

 

The new TRD cap will arrive before week's end.

 

Update:
I cleaned all of the coolant off with Simple Green, and the belt squeak went away - good call Mr. Blonde. I talked with my tech while picking up a gallon of the pink stuff, he said that it sounds as though everything is functioning as it should considering the driving circumstances I described. The overflow tank is half way to the Max line, and I haven't added a drop.

 

I had a truck that did not like the max hot full line of the overflow tank. every time I would top it off it would spit a little out after a hot drive. Finally I quit touching it and it leveled off to a happy place. Never got any lower.

 

Looks like you might have resolved the squeak but through it this out there. I recently had a belt squeak during cold mornings for like a minute and it would go away. Ended up replacing my belt, tensioner and idler pulley. All was good after that.

 

It's on my list.

 

Correct i had mine always at full mark i checked one morning and most of the coolant was gone. I freaked out because i didnt smell or see any leak i thought i had a blow head gasket. I let the truck get to opreating temp and coolant is now at full mark. Remember coolant will decrease in volume when cold. Only thing i can think of is either it got to hot and overflow and got on the belts and bearing and thats the noise your hearing. Please dont replace parts if you have to only replace the broken one. I know you have a s*** ton of miles but its a Toyota not a ford lol. But if i was you i would get a pressure tester and test the coolant system and see if you have any leaks in the radiator or water pump.

 

Functional TRD bling under the hood.

 

I noticed in the first post that the foam strip that seals the frame and the top of the radiator was missing. I always wondered what that was for and why it was there. Does that help more air not escape over the radiator and force it to go through the radiator? I highly doubt that's your issue, but just saw that foam missing and wondering?