Smoke and knocking

Hello there everyone, new member here. I have a 2006 Toyota Tundra 4.7 with 275k miles. My truck has started emitting smoke during startup, I want to say a gray/blue smoke. It definitely has a burning type of smell when the smoke is coming out. After about 30 seconds, the smoke goes away and truck drives normally. After driving for a while though, the smoke will come out again and the engine will start making a knocking/backfiring type of noise and lose power. I can’t even take it on the freeway as it will do this when I drive above 50 mph. Any ideas? Dealership unclogged the fuel injectors and replaced spark plugs. They said the smoke was carbon buildup. Was charged $500 for that job. Please help, your comments are appreciated.

 

@empty_lord

 

Never had a 4.7 do this. Have you been losing oil? Typically blue smoke is oil.

 

Head gasket maybe?

 

I have been losing oil, but I also had the rear main seal done too as that was leaking A LOT of oil. Too early to tell, just had the truck worked on yesterday

 

(1) Your dealership is more dishonest than I thought Toyota would allow. They're thieves...don't go back.

Carbon buildup? Fuel injectors unclogged? Sparkplugs replaced? I doubt anything was done except let your truck rest in the parking lot sunshine all day, then collect $500 for bogus work not done. Had they at least done a compression test, you would have gotten something useful for your $500.

(2) At 275K miles, I would lean toward your truck simply being worn out. A compression test would go a long way to confirming that fact about the engine. It's true that some Tundras last a million miles, but most of them won't. Having to replace the rear main seal is further evidence that your truck is becoming a money pit. That's the reason they keep making new trucks...eventually vehicles will have to be replaced.

 

I am at a loss. I really want to hang on to this truck, it’s my favorite body style of tundras. Im going to check for coolant in the oil and have a compression test done. Thank you guys for your replies.

 

Pop open your radiator and overflow tank. If you see black specs in there it's a possible sign. But, if it is your exhaust would have a sweet smell. You can check the under side of your oil cap too.

 

PCV valve?

 

I know in small block Chevy's that could also be a sign of leaking valve seals. The truck sits and oil leaks down through the valve seals. When you start the motor, that oil that has leaked down is burned off. After it is burned off in the 30 seconds or so, you are good to go. This process will repeat itself once the truck sits long enough for the oil to get past the valve seals. Usually sitting overnight or longer.

Not as familiar with 5.7 Toyota engine, but possibly valve seals?

 

Valve seals will cause smoke cold for sure. But what he’s describing sounds a bit worse than that

 

Okay guys. i assessed the coolant tank and found nothing unusual. However, I assessed the oil dipstick and oil fill cap and found this strong scent of gasoline. This would be indicative of a gas-oil mixture and since the spark plugs can’t ignite can’t ignite oil and fuel, hence the knocking at higher speeds. I’m going to take this truck to a different mechanic and see if they can check the valves. Today I was able to drive the truck on a hot day with the ac on at 70 with no issues. I am pretty positive there’s something up with the valves.

 

If you can find a independent Toyoya master tech, or at least a Toyota enthusiast mechanic, that would be great. I found a local guy who did me right on my sequoia, so happy I did. His motto was not selling any shit I didn’t need. Well he found a repeat customer when he said that to me, especially after the proper quote and awesome work his team did for me.

I really hope it is something simple that has just been overlooked for you. Definitely in for results.

 

Doubt it will be the valves. My prime suspects would be the newly "unclogged" fuel injectors and plugs. If you have a leaking injector, or a non-firing spark plug the fuel will not be ignited in the cylinder and the buildup in fuel will wash down past the rings and end up in the oil. Using straight gasoline as a lubricant doesn't work. You could severely damage the cylinder. I wouldn't drive it until you get this sorted out.

 

Bump for updates. My curiosity is piqued.

 

Maybe possible fuel filter is clogged , that would cause fuel starving. ie can't go faster than 50mph. Just a thought..

 

So guys, the culprit was the pcv valve. I was able to drive it today with no issue on the freeway. Thank you all for your contributions. Anyways it turns out some shop put some chinese aftermarket pcv valve and the hoses came loose. Again, thank you all for the support.