2008 tundra over heating issues

Hello all...i need help with this 2008 tundra that's over heating. Long story short...was over heating last month because of a bad radiator...fixed that and it ran great for a month...then just last week...started over heating again...both top and bottom radiator hoses were hot and building pressure. Stopped and added coolant...then lost every drop again in three miles.no external leaks that i could find...and no smoke out the tail pipe.figured i would do a leak down test...pulled all coils and plugs... Number three coil came out absolutely brown...i thought for sureis found a bad cylinder...but plug looks okay. Number 4 was a little brownon the coil and plug was wet coming out. I just wanted to get some opinions before taking the heads off...thanks in advance for your replies.

 

did you ever replaced the thermostat?

 

4 times in the last 2 month's.

 

did you check the oil for sings of water in it? ever replaced the water pump?

 

No signs of water in oil...never replaced water pump...no white smoke out tail pipe...but no apparent external leaks. Lost every drop of coolant in three miles...has to be going somewhere?

 

did you added the proper coolant or just water ? I'm not trying to say you didn't do it right, I don't know you or anything other that what you are describing here, so my comments are based on this conversation, just saying. lol

It could a blockage due to a faulty water pump, how many miles on that truck? and throwing it out of the coolant tank overflow

 

Added proper coolant....i don't believe it's the water pump as it has been fine and no signs of weeping. No offence taken...I've been wrenching on vehicles for 35 years...build custom motorcycles daily...this has me stumped though

 

if there's a blockage and the system is building up pressure, coolant could be going out thru the easiest exit point, the reservoir overflow onto the fan and that's why you don't see a leak, I would check for a spray pattern around the radiator area. About the water pump, it could not have signs of leakage but that doesn't mean is working properly, you don't say how many miles you got on that truck so it's hard to determine the condition of it.

 

105xxx miles...resivoir is empty. And it does have a spray pattern...

 

Did you install a new radiator or did you just cleaned the one you have? if so, It could be the radiator still has some blockage, based on the mileage the water pump should be still ok.

 

Brand new radiator...never has made good heat...could it be blockage in heater core?

 

I never really was sure that it was filled correctly... What is the proper procedure?

 

And a little off topic...but having wrenched on all kinds of different vehicles...i can't imagine what the dealer charges to change the plugs in this thing...i had to remove all sorts of things to get the plugs out....

 

Yep...did it right.

 

Fill up the coolant and idle to see if it still overheating and open the hood to see any leaking, also look at the bottom.

 

check the carpet inside your truck, if the heater core is leaking the carpet should be very wet

 

As for the plugs, my dealer wanted a little under $300 to change the plugs in my 4.7l. I had a local mechanic change them with the same Denso Iridium plugs for about $180.

 

Did you try replacing your radiator cap? I had similar problem with my 2005 Accord and it was a bad cap.

 

air bubble somewhere ?