03 Tundra Overheating (Possible Head Gasket Issue?)

Please help! I'm trying to narrow down what the problem is with my 03 Tundra. It's not exactly a spring chicken anymore, the truck has 256K miles on it. I bought it about 7 years ago with 130K for a great deal and have had to do very little other than change oil/tires/brakes. The engine still purrs like a kitten, the power is great, it sounds healthy, but it gradually overheats. Here is everything that has happened so far. About 2 weeks ago, the top radiator hose blew a small split and sprayed coolant all over the engine, but since the truck is old I figured the hose might have just been bad and replaced it. It ran fine for two days and then started to overheat. It gets up to operating temperature, stays there for about 3-5 minutes of driving and then gradually begins to climb (over a period of 3-5 minutes,) until it's in the red. The heater blows either cold air, or mildly warm air while this is happening. If I stop and park when it starts to get hot and I rev the engine to about 3K+ rpms, it will cool back down a little bit, but this does not always work, and only works temperarily. I only figured out the engine reving trick on accident getting it home from work when this all started. It seemed to me that there was a blockage or water wasn't circulating, but I'm starting to worry it's the head gasket because I don't know what else it could be. Here's everything I've done so far in chronological order:

1. Chemical combustion leak detector test (came up negative, dye remained blue)
2. Replaced the thermostat (no change)
3. Burped the cooling system (no change)
4. Backflushed the heater coil (no change)
5. Replaced the water pump (no change) (pic related)
6. Backflushed the radiator (no change)
7. Burped the cooling system again (no change)
8. Bypassed the heater coil with a brass fitting (no change)

At this point I started to suspect head gasket problems so I rented a compression tester. Here is what came up:
Bay 1 (Driver's side):
(Front to back)
Port 1: 180
Port 2: 145
Port 3: 180
Port 4: 180

Bay 2 (Passenger):
(Front to back)
Port 1: 170
Port 2: 170
Port 3: 150
Port 4: 180

These are all within spec, but since the two problem chambers are so far off from the others I assume there is a problem there, but the chemical leak test (sign of cracked block,) came back negative. That was the first thing I tried so I wasn't wasting my time with the cooling system on a cracked block. I also don't have any other symptoms of a blown head gasket or a cracked block like poor performance or white smoke from the exhaust. The only other thing I can think to try is to replace the radiator, but It doesn't seem like the radiator to me because the overheating has been so consistent that I can tell you the exact intersection it will start to overheat at from my house. I've already put so much energy and money into this and I'm getting exhausted. Has anybody experienced these symptoms and found a solution? Any help is greatly appreciated. Thank you.
-Ron

 

Sounds like you’ve ticked a lot of boxes on the trouble shooting side. I can’t offer any solutions, but can tell you that I just swapped out a seemingly fine NAPA radiator with a new Denso radiator ($150) during a Timing Belt change.

I had monitored the temps prior and the old radiator would run around 195-200°. I had no problems. Put the new one in and she is cooler in the 183-185° range. I also performed a Prestone flush before new install even though my system was pretty clean. The flush did have some off color, but nothing major.

I remember a guy talking about a similar overheat problem as yours and he swapped in a new radiator after chasing gremlins. It solved his issue. He cut the old one up and found blockages in the middle which I suppose was causing the splitting top hose back pressure.

Hope his helps your trouble shooting.

 

I agree with PHM. If it were me, I would swap the radiator With a new one and while it's out, remove the thermostat and make sure it's working by dropping it in boiling water.

And welcome to the club!

 

Yup, I'm betting the radiator is blocked too. Especially if it's factory.

 

Here is what the service manual says on the compression test. It seems like it failed the compression test based on the differences between cylinders. I'm no expert, but I'm not sure how a radiator would fix that but since it's 17 years old it's probably a good idea to replace it.

Maybe @empty_lord has some advice.

 

The ones that are a fair bit lower would indicate a possible headgasket leak between the coolant jacket and combustion chamber. Exhaust gas testing for the coolant would let you know of combustion is getting into the cooling system. This can lead to air pockets and overheating

(sorry at work, missed that you did that test already)

 

The heater not blowing hot air when the engine is overheating is a sign that something is not circulating properly. The hose that blew out also signals too much pressure in the system, either from overheating or from a blockage in the system. Radiator is still suspect. Airlock of the system is also possible despite the burping of the system several times. They can be stubborn to get all the air purged out.

 

Thank you for the responses! I'm going to order a new radiator and keep my fingers crossed that it fixes the problem. If not we'll try running a head gasket treatment and see what happens. I will post updates on my progress.

 

Have you tried replacing the radiator cap? If not, then try a new OEM radiator cap. Make sure is the correct one for your Truck.

 

Did the radiator replacement fix the overheating problem?

 

I highly doubt it. But improperly filling your radiator, not burping it properly can lead to overheating. Along with a plethora of other things; like replacing the thermostat and not clocking it properly.

Chances are this guy isn't responding to you. As is typical around here, people are only here for quick advice and bounce once their problem is solved, usually without saying jack shit here which could really help the next person, like you.