smokey vs

Looks like a blown head gasket, the white smoke being steam.

Have you got a compression tester? If not, buy one or borrow one. Minimum compression of an Ecotec V6 is 100psi.

Compression Test Procedure.
1. Make sure you have a fully charged battery.

2. Run the engine until operating temperature is reached.

3. Turn the engine off and disconnect the spark plugs leads for the coil packs and spark plugs.

4. Remove the engine and fuel pump fuses.

5. Remove a spark plug and install the compression tester into whichever cylinder you want to start in. 1-6, 6-1, 1-3-5, 2-4-6. Whatever way you want.

6. You need another person to fully depress the throttle pedal and crank the engine over. Only crank the engine a maximum of four compression strokes (thumps) at a time, while observing the compression tester gauge and note down the highest reading.

7. Test the following other cylinders and compare all the readings at the end. The lowest reading on any given cylinder shouldn't be lower than 70% of the highest reading cylinder.

If a low compression reading is noted on one or more cylinders, you can 'wet test' the engine to isolate the issue even further. Add a small amount of engine oil in the combustion chamber of each cylinder and repeat the compression test again.

An large increase reading of compression pressure indicates that the piston rings, piston and/or cylinder bore are worn. A low increase reading of compression pressure can indicate burnt, obstructed or sticking valves or a leaking cylinder head gasket.

 

Check you fuel regulator too, sometimes the diaphragm splits and fuel enters the plenum via the vac hose. ( rich mixture black smoke )

 

As Jonah said - Check you fuel regulator too, sometimes the diaphragm splits and fuel enters the plenum via the vac hose. ( rich mixture black smoke )

With the engine running, remove the vacuum hose from the fuel regulator. If fuel spurts out, the regulator diaphragm is fingered.

 

valve sleam seals, inlet manifold gasket....i wouldn't be suggesting head gasket yet, plenty of other cheaper things that can cause this lol

 

Inlet manifold, which is located under the plenum.

Pressure test the cooling system too, that'll isolate if there is an internal coolant leak. Eg cracked inlet manifold gasket, cracked cylinder head, cracked cylinder block, cracked cylinder bore.

A perished valve stem seal will also produce white smoke out the exhaust as the oil is being burnt in the combustion chamber. It can be picked up by a dropping oil level measured on the dipstick. It would mostly produce a continuous small white smoke puff at idle though.