new member here . coolant issues with my '06 tundra

good morning forum members . having coolant issues with my truck . first , let me give some background . i have 287k miles on her . i bought my tundra with 119k miles in 2011 . the truck has been a champ . all the usual maintence at the proper intervals has been done . heres my issue . i have a coolant leak somewhere and i cant find it ! this what i have done so far....
1. upper and lower radiator hoses have been changed out
2. new radiator installed last week ( my old radiator was about to give up the ghost )
3.thermostat and gasket changed last week
water pump is good . timing belt and water pump changed at 210k miles.
oil is clean so there is no coolant in the crankcase , so im thinking my headgasket is good .
no coolant smell in the cabin . carpet is dry so heater core is good .
what i have not done is change out the coolant recovery tank and hose ..
coolant loss is minimal .
the temp gauge reads in the 3oclock position but before these issues , it read lower say between the 3oclock and 4 oclock position . after driving it , i would pop the hood and eyeball the engine to see if i can see anything leaking - nope not a drop . ive left clean cardboard underneath the engine to see if there are any drops of coolant - none . so there you have it . any advice / comments are welcome . thanks

 

Have you checked the back of the engine? Several members have reported a leak towards the back of the engine that leaks down the back of the motor and is difficult to see. I believe its a an O-ring on one of the hard lines that failed them. Perhaps someone else will chime in. Welcome to the forum, and good luck with your problem!

 

Welcome....define minimal, cup in a day, week, month ?

 

Yup, have a really good look under the intake manifold for leaks. That pesky O ring might have failed.

 

May be able to search and find a couple of recent threads related to this.

 

Welcome from LA (Lower Alabama)!

Have you placed the cardboard further back, to check for the possible o-ring leak mentioned previously?

 

https://www.tundras.com/threads/coolant-leak-bypass-pipe-o-ring.81275/#post-2055606

Try here. Coolant bypass hose it's called. Worth a good inspection.

 

thanks for the replies . coolant loss is less than a cup over a weeks time . ill put the cardboard farther back and see if there is any sign of a leak towards the back of the engine and bell housing . if it is the " O " ring mentioned above , to change that out is beyond my automotive expertise .

 

less than a cup is going to be hard to see on ground but could be coming out the weep hole of pump. With ~80K miles on that pump, was it a good quality pump/installation as far you know ?

 

Park at an incline (nose up) and check if there is any any coolant coming out betweenWhere the transmission me the engine.

 

update on the coolant smell/leak . found it !!! i replaced my coolant overflow tank and tubing and the old tubing had a small crack right where the tubing inserts to the coolant tank . when i replaced my radiator , i had to move the hose off the radiator fill neck so im thinking when i pulled the hose of the radiator i mustve torn a small hole in the tube . by the way the tube was in bad shape almost rotted thru . hope this helps . thanks again for the advice .

 

Nice easy fix. Awesome!