Engine running too hot only under load - TundraTalk.net - Toyota Tundra Discussion Forum

User Tag List

 
LinkBack Thread Tools
post #1 of 7 (permalink) Old 10-03-2018, 05:54 PM Thread Starter
Junior Member
 
Join Date: Oct 2018
Posts: 3
Thanks: 0
Thanked 2 Times in 1 Post
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
Engine running too hot only under load

Hello all,

I'm struggling with an engine cooling issue. I have an '08 Tundra Double Cab SR5, 2WD, 5.7L, with about 85,000 miles on it. Bought it used, drove it 1200 miles home without issue. Everything seemed great with the truck, until I hooked up my 7,000lbs travel trailer. Once i got it up on the interstate, the engine temperature gauge began to move toward Hot. It never completely gets there, stopping a little more than 3/4 of the way. Note the transmission temperature gauge never moves, and stays at normal.

Further experimentation revealed that not only does this only happen when towing at interstate speeds (e.g. greater than 55 MPH) but only in 5th gear. When I put the transmission in S Mode and in 4 range the temperature drops back to normal. Air temperature was around 80 the first time, and in the low 60's subsequent times.

The dealer found a leaky water pump, and pointed to that as the culprit, and replaced it. However even with the new water pump in place, I had the same issue the next time I hooked up the trailer. The dealer now sounds a bit stumped, and is thinking the thermostat is the next likely culprit... maybe.

The puzzling thing seems to be that this only happens under towing conditions. That also makes it challenging for the dealer to verify its fixed. I've been searching the forums and haven't found anything that sounds similar. What else could it be?

Thanks in advance!
Tundra513 is offline  
Sponsored Links
Advertisement
 
post #2 of 7 (permalink) Old 10-03-2018, 09:36 PM
Member
 
Join Date: May 2015
Posts: 50
Thanks: 0
Thanked 5 Times in 5 Posts
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 15 Post(s)
Sounds like the thermostat possible partially not opening up all the way but enough to keep engine cool when not under load. I would have that changed out and it should of been looked at when changing out the pump and at least checked for leakage. I think it's the next logical step.
Joseph is offline  
post #3 of 7 (permalink) Old 10-04-2018, 08:15 AM
Senior Member
 
Join Date: Dec 2013
Posts: 1,975
Thanks: 349
Thanked 648 Times in 487 Posts
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 599 Post(s)
Yep. Thermostat. AISIN THT005

About $29 on rock auto and $39 on Amazon. One piece housing and all. Little aggravating to change out. It would have been much easier if they'd done it when they changed the water pump.

Either that or you've got a restriction in the block or radiator. More rpms more water moving through the system. That is why you can down shift and temp will go down. That is also a good sign that you don't have an engine issue of some kind.
sundance is offline  
 
post #4 of 7 (permalink) Old 10-04-2018, 02:37 PM
Senior Member
 
Join Date: Jun 2009
Posts: 2,329
Thanks: 431
Thanked 1,548 Times in 1,073 Posts
Mentioned: 22 Post(s)
Tagged: 0 Thread(s)
Quoted: 562 Post(s)
check fan clutch also.
if cooling in 4th with higher revs but not in 5th or 6th then it could be too much slippage,although at 55mph ram air should be sufficient.
check coolant flow in radiator as well or for any obstruction in hoses.
restosud is offline  
The Following User Says Thank You to restosud For This Useful Post:
24hrsparkey (10-11-2018)
post #5 of 7 (permalink) Old 10-05-2018, 02:41 PM Thread Starter
Junior Member
 
Join Date: Oct 2018
Posts: 3
Thanks: 0
Thanked 2 Times in 1 Post
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
Thanks all. Since the thermostat seems to be the next logical (and easier) thing to try I'll start there next. I'll post the end result.
Tundra513 is offline  
post #6 of 7 (permalink) Old 06-05-2019, 09:00 AM Thread Starter
Junior Member
 
Join Date: Oct 2018
Posts: 3
Thanks: 0
Thanked 2 Times in 1 Post
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
Just to tie this thread off, last fall I changed the thermostat hoping that would do the trick, but had parked the trailer for the winter without a chance to test the change. Finally got it back out again a couple weeks ago, and the final result is the engine temperature is now right where its supposed to be regardless of speed, gear, uphill, or down. Sometimes the simplest solutions are the best. :-)
Tundra513 is offline  
The Following 2 Users Say Thank You to Tundra513 For This Useful Post:
Powertechn2 (06-05-2019), riccnick (06-10-2019)
post #7 of 7 (permalink) Old 06-05-2019, 11:41 AM
Senior Member
 
MetalMonkey's Avatar
 
Join Date: Feb 2012
Location: The San Diego Bay Area
Posts: 9,107
Thanks: 5,234
Thanked 6,507 Times in 3,901 Posts
Mentioned: 18 Post(s)
Tagged: 3 Thread(s)
Quoted: 366 Post(s)
Garage
Thanks for wrapping it up ~ we can all learn something here. @Tundra513

A picture is worth a thousand words
But your smile is worth a million
MetalMonkey is offline  
Sponsored Links
Advertisement
 
Reply

  TundraTalk.net - Toyota Tundra Discussion Forum > Tundra Discussion > Tundra Problems: Maintenance, Repair & Dealer/Warranty Issues

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the TundraTalk.net - Toyota Tundra Discussion Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome