2016 Silverado 5.3 exhaust manifold wet?

[Rickyace09]

So I was doing my spring/summer oil change and noticed this stain on the drivers side head/block. I don’t think it’s oil but I’m also not sure why it is. I sprayed it down with brake cleaner and it left like a water line stain. I also noticed it coming from the rear location of the exhaust manifold on the driver's side. I also see some burnt spots in the middle of the manifold. The rear manifold bolt looks wet when the truck is running but not oil cause it doesn't smell. 

[Rickyace09]

So my exhaust manifold on my drivers side has been wet around the rear bolt and gasket area. I’m not sure if it’s oil or condensation? The reason I say that is it doesn’t burn or smell like oil but looks like it or a rust stain color. It only happens when running and dries up quick. The truck drives fine. Also no smoking at the exhaust pipe. What could this be? I purchased a new manifold, arp bolts, gaskets and valve cover gasket just to replace it but doesn’t look bad. Truck has 101k on it. 

Edited May 24, 2024 by Rickyace09

[Rickyace09]

So I was able to get under the truck this morning and noticed that it is Oil. The level is normal and its not smoking. Hoping its the valve cover gasket. 

 

Edited May 28, 2024 by Rickyace09

[CamGTP]

Could be coolant then, these trucks run dexcool that is orange so the rust color make sense for coolant.

[Rickyace09]

Definitely oil. But not sure if its the valve cover. Crossing my fingers. 

[txab]

Do not create a new thread on the same subject. Use this thread

[richard wysong]

Oil would not dry up. Looks like coolant to me. Pressure test the system hot and cold

[Rickyace09]

Definitely oil and coming from the last bolt on drivers side. Is that bolt going into an oil gallery? Seem worse last night that usual so definitely getting worse. 

[CamGTP]

The head bolts go in dry or they may come with a little thread locker. They don't require any special sealant for coolant or oil as far as I know. There is oil passages in the cylinder heads for oil to make it back into the crankcase. Those passages are sealed by the head gaskets.

[richard wysong]

No oil gallery in the heads. The bolt may have penetrated into 1 of the drainback channels, remove it and put some thread sealer on it. Again oil is not going to dry, it will collect dust and turn to greasy sludge. Where it is getting worse it is probably coolant, are you still running Dex-Cool or has someone switched it to green?

Edited May 30, 2024 by richard wysong

[Rickyace09]

42 minutes ago, richard wysong said:

No oil gallery in the heads. The bolt may have penetrated into 1 of the drainback channels, remove it and put some thread sealer on it. Again oil is not going to dry, it will collect dust and turn to greasy sludge. Where it is getting worse it is probably coolant, are you still running Dex-Cool or has someone switched it to green?

Yeah it’s not drying up and to answer the coolant question it’s still running Dex-cool. 

[Rickyace09]

Removed manifold to replace gasket and ports are dry as well bolt holes. Mechanic mentioned valve over was wet on edges so that was replaced as well. Hoping it’s that. Will keep an eye on it.