2008 Tundra 5.7 temp issue.

this whole thing has been a pain in the ass, I should replace the belt tensioner and idle pulley but I wont, this is my short term tow vehicle and plan to sell it when im done. For now it works and I wont feel guilty selling it, I put enough time and money into the rig and have learned much about toyota tundras/sequoias.

Zeekevin, put foam above and below the radiator gap to help direct the airflow to rad. check your thermostat like I did w/ boiling water and measure temp maybe w/ cooking bbq meat probe to be more accurate and see if it is opening. you said yours was a OEM thermostat from the dealership so I assume it would be okay if it was new but could be wrong. I noticed when I replaced my clutch fan w/ oem fan from toyota I can now hear the fan roar when it is hot outside while idling, sometimes when driving slowly, before I could not hear my fan. My final thought if i still had the temp issue with all I have done, I figure the Catalytic converter was clogged causing back pressure making more engine heat or our high millage engines are just worn and create more heat w/ usage and age.

 

Fantastic. My guess is the fan clutch was main culprit but the t stat was also probably causing restriction.

 

@busterg

I found my problem. I had a piece of the old radiator cap stuck in the system, it only took tearing it apart 3 times to find it after a year.

 

Wow. That is crazy.

fantastic news though!

 

Now that we've read of this a few times, it sounds like checking the condition of the radiator cap condition should become a more frequent check...

 

Or just replace it as preventative maintenance even with less than 100k miles

 

A friend of mine just purchased a used 2010 and I messaged him that very suggestion.

 

I have been driving the truck the last few days a can confirm I no longer have any more temp issues.

water temps hold steady between 185-190°f now due to the bigger koyo aluminum radiator

 

fantastic.

 

I'm having the same exact issues you were having and I took my radiator cap off and it's broken too. Was the plastic piece just laying in the thermostat housing or was it wedged somewhere? I've gotta get this issue fixed before the next camping trip and hunting season is starting.

 

It was just laying in there.

 

Hi I'm also having this issue with my 2008 tundra.
When I drive over 50 mph the needle goes over the middle..
Did you ever figure out what the issue was..??
I replaced water pump.
Radiator is new.
Hoses are new..
Cap is fairly new.

 

My issue was a broken radiator cap exactly like posted above. It might be a good idea to drain the antifreeze, pop the hoses off and look down in the thermostat housing and see if there is something blocking the flow.

I'm not a mechanic, but after my experience that's where I'd start. And probably replace the thermostat while I was at it.

 

I just wanted to bump this old thread to say thank you to those who struggled with this problem and pointed me in the right direction. Last week my truck started get about 3/4 on the temp gauge occasionally when pulling a trailer. It would cool down for a while and then creep up again. I checked the coolant level and it was fine. When I went to put the cap back on I looked at it and saw that it was missing the center part.

I remembered reading this thread before so I knew right away where to look. Today when I got back home I drained the coolant and pulled the top hose. Sure enough, the center of the radiator cap was blocking the bypass port in the cross over pipe. Removed the blockage and refilled the system with coolant. New cap and all good now. This could have been a real head scratcher.

 

Nicely done

 

I’m glad you found the problem right away vs dumping money into parts that didn’t need to be replaced haha.

 

I have a 2008 Tundra Limited 2WD towing a 6000 lb travel trailer. I have towed it thousands of miles through desert heat and in mountains, never seen the temp move...until yesterday.

On Tuesday before our trip, I checked the coolant and found reservoir was empty. Filled it with the wrong coolant (green), but didn't realize yet that was a problem mixing the two differing types of coolant. I got the coolant level back up to full before I started this trip.

Yesterday I towed the trailer up to Big Bear and it was behaving normally until I got to the climb. I had to stop four times because coolant temp got up to 3/4 on the gauge. I popped the hood and it was boiling water into the overflow. It cooled, sucked coolant back in, then I added regular water back in and filled it up each time (twice poured water directly into radiator, but never burped it, so could have been water pockets). I recall thinking the radiator cap looked "flat". The center wasn't completely missing like y'alls photos, but it didn't seem to stick out either (like a smaller piece had broken off).

I am on a time crunch (short trip, heading home tomorrow after only two nights) and didn't have time to deal with it so took it to a local shop. It was indeed a bad radiator cap, and they are replacing the thermostat for good measure (110K miles). I didn't ask if it was oem thermostat, but I will.

I will also ask if they found the missing/broken piece when they drained it. If not, I won't be surprised if I see higher than normal engine temp towing home, but should be able to limp home now that a good cap is on it. Then I go on the mission to find the missing piece.

Additionally, I am getting three gallons of the red coolant to carry with me, both home tomorrow and in all future trips where I'm towing. I'll let AAA handle anything non towing in the future.

This and the other overheating thread slightly more recent have been marvelous threads. Thank you all for the discussing AND PICTURES of the process. I feel like you have all made my coming days much easier to diagnose if I experience further heat issues.

...Todd

 

Thanks for the recent bumps on this thread. I just experienced the same symptoms for the first time after thousands of miles towing, and I'm going to pull the cap tomorrow morning. The bumps def helped with search results. Thx!

 

Were you guys able to resolve your problems?

 

Nope, not yet. Mine hit while towing to the second leg of.our vacation. Spent 3 hours at a dealership to tell me they couldn't find any leaks and continued to tell me it was the hills in the area despitee.telling them it's never done this. So I have a tstat, cap and coolant ready for pickup when I get home next week. Asked them to test the cap and the notes show "all is clean and closes tight."

I'll report back again in a week or two. 200 mile tow early next week and then a 575 mile tow next weekend.

 

How many miles do you have? Maybe it could be a fan clutch issue.

 

Rolled 34k the day the temps spiked

 

We'll, long saga, but here it is:

My truck has always run warmer than what everyone discusses on this forum. Even the trans cooler shows 15 degrees warmer than everyone else. After the dealership said nothing was wrong when I saw a spike to 240, I proactively replaced the cap. No joy. Replaced the thermostat today and it is running 20-25 degrees cooler than it ever has and the trans temps are 15 degrees cooler.

$26 bucks, about an hour of time, and 1.75 gallons of coolant. Glad it wasn't any of the other issues. I did pull both hoses to insure nothing was missed.

Thanks for this thread, everyone. Happy to be seeing coolant temps running 188-192 on average. Literally have never seen this on this truck before.

 

Glad you fixed your problem, kinda rare to hear a t stat failing so early on.

 

The broken radiator cap ended up being my issue as well. The bottom part had created a blockage in the bypass. Below picture shows what a broken cap looks like.

 

Another victim of a broken radiator cap

 

I wanted to bump this thread as I'm having very similar issues. Replaced all the things to no avail.

How do y'all reckon the broken cap made it past the upper radiator tank since that's the direction of the water flow? Where many of you are finding it, it seems it went backwards through the upper hose.

 

Thank you all for all of the advice and testimonies of what you are dealing with. Long story short, these are still the best trucks out there.

Ok so I drained the radiator, flushed it really good. Couldn’t find the broken pieces. I doubt that it has gone thru the t stay at this point. Maybe it’s been the cap the hole time. Not keeping good enough pressure to push thru the radiator into the lower end to the t stat ?

I was using green coolant, so I guess I need to go to red?

I pull a work trailer too. So should I go ahead and replace the radiator again? It’s under a warranty and It won’t cost anything. I’m getting a new cap too.

I don’t h
Think the water pump is bad. I feel like it was working just was getting backed up and stopping at the bottom hose. The lower hose was really cool and the upper one was extremely hot.
Thoughts?

 

I'd see what a new cap does for you first. Without the smaller gasket that's missing, there's no way for it to seal and build pressure. Quick and easy.

 

So took the bypass hose off. Everything is clear. Do you all think that the loose cap would cause this. I think if it was loosing that much pressure that some coolant would seep out the cap a little. That never happened