Several manufacturers built 3800. Without that information no answer can be given
You will need a intake manifold set and possibly a plenum gasket set.
Bend over the mechanics counter.
replace the water heater inlet pipe on the intake manifold on a 3800
If it is a gm 3800 you need to replace the upper intake. It has a crack in it.
What was the situation with DexCool and the Chevrolet 3800 series II engine and how do i get the replacement intake manifold from Auto-zone and what is the part #
front side of plastic intake manifold
In my Chevy 1500 with the 305 Vortec, the problem was the lower intake manifold gasket, which is the one that seals it to the engine block. On your 3800 V6 (in a Silverado? I didn't know that; I thought it was the 4.3, maybe it's an older or newer year than my body style), it could very well be the same. There is also a coolant line coming out of the manifold, if I'm not mistaken. Could be to the thermostat, but I don't have the truck anymore. To the best of my knowledge, that would be the easiest and cheapest thing to check.
The Manifold Absolute Pressure (MAP) sensor is located near the throttle body on the intake manifold.
The lower intake manifold gaskets on 3800 engines are likely to go bad at around 80,000 miles. This is caused from the gaskets being made with rubber and being eaten away by the "So-Called Dexcool" coolant. It is best to replace this gasket as well as the upper plenum gasket with a metal gaskets and change from dexcool coolant to regular antifreeze. This is an expensive repair...so be prepared.
A gm 3.8 l v6 or 3800 cc engine cannot have antifreeze in exhaust without first getting into the engine. If its getting into the exhaust it may be entering the cumbustion chambers through a damaged cylinder head or head gasket. Also this engine depending on the model year may have issues with the intake manifold gasket, that can cause antifreeze to leak into the engine oil.
This question references General Motors built FWD vehicles with the 3800 Series supercharged engines. Sensors included the O2s in the exhaust manifold and the downstream of the catalytic converter pipe. knock sensors in the block, and the manifold absolute pressure sensors in the intake manifold.
The cooling temperature sensor is located on the drive belt end on the intake manifold on 3.0 and 3.8 liter motors. On 3800 motors it is located on the opposite end of the intake.