Possible Head Gasket Leak, seeking advice

2003 Tundra AC 4.7L 350km

Driving home tonight had the stereo flip off and back on again and suddenly the smell of burning coolant after about an hour of consistent driving. Was a minute away from home so pulled in.

Oil looks normal, consistency normal
Coolant looks normal with normal consistency but has a gassy smell
Engine otherwise sounded happy

No codes, misfires, overheating, etc. everything operating as normal. Starts fine, runs great.

About 2 months ago I had a collapsed upper radiator hose and I burped the system and added some extra coolant to the reservoir. Noticed today that I overfilled it by about an inch but not to the top or anything.

After about 45-60 seconds after start I'll hear a small whine but assumed that was the heater core or a pulley suffering because it's cold as piss this winter in Canada. Couldn't hear it in the cab and wouldn't hear it after it had run for a bit.

Prior to this I had experienced a rad failure but caught it and had it towed in, replaced the radiator and they flushed both systems thoroughly. No issues since. However I'm thinking there's potential of warping due to the excessive heat that would've been created.

My guess is that there's an HG leak allowing exhaust fumes into the coolant. Unless someone has experience of it being something else, posting just to see if there's any niche tundra things that could cause this.

My course of action is gonna be to use blue devil and then change the oil and coolant. I'll see about doing the HG this spring potentially over a weekend but would likely lean towards a used engine out of a yard for a few hundred bucks with lower KMs

 

Go get yourself one of these first.



That'll tell you if you have exhaust gas in your coolant. Have you been loosing any coolant? Check underneath your oil cap for frothing, but since your oil looks normal I doubt it will be. Any overheating at all? High temps?

 

No coolant loss, no excessive frothing, a small amount of residue that's still much less than others have posted here that's within *normal*. No overheating, it's winter now so I don't monitor things as close except when I can crank my heat but it never goes past the halfway mark, no high temps. I also smelled the radiator and there's zero exhaust smell from it. The reservoir smells of gas and that's it. I talked to my mechanic and we both think it's worth draining the reservoir and refill with fresh prestone. I have a short trip coming up - 450km, I'll check for smell after and I'm going to order a kit like the above to test the rad.

 

Be sure and use the Aisin pink. What color coolant is in it now? Also, Run the truck a bit and smell the exhaust. A semi sweet smell will mean coolant is getting in there. And come down to TX and take your air back. I don't like being 3 with a wind chill of -15.

 

Aisin brand pink, for sure, but if he is currently using Prestone, which I don’t think makes a pink SLLC coolant as Toyota recommends, he needs a full flush before installing or it could make the problem worse. He may already have buildup in the engine from using the wrong coolant, or if the genius who swapped it to yellow coolant didn’t fully flush the block first, they may have amber sludge throughout the block like Noah had. He shouldn’t be using the yellow nor the so called “universal” coolant in the 2UZ-FE engine.

I’d also install a new OEM radiator cap while in there, if he’s still running on the original.

 

Yeah, I shoulda mentioned that. Don't mix coolants, regardless of what the jug says. Good catch.

 

I wouldn’t use Blue Devil if you plan on fixing it the right way. That will destroy the rest of the cooling/heating systems.

 

So after a lot of poking around the conclusion that I came to is that the res didn't get emptied when the system got flushed. I don't have a good sense of smell so I had to get some assistance but the reservoir pink coolant has a touch of oil residue, likely whatever came out of the system with all the flushing. The yellow prestone in the system is clear and has no gelling or anything of that nature. The exhaust is fine, there's no exhaust bubbling through the radiator, it's just the reservoir.

What I did smell last night though was electrical not coolant. So the coolant can get resolved at the very least as a separate thing. It seems like the factory amplifier fried.