Hi,
Since I have intake off on my DI car … thinking about cleaning the intake ports…
Car is V8 4.8 DI
I read somewhere to confirm that valves are closed, I should spray some wd40 if it’s stays they are closed and if it drains open…. Any opinion on this ?
Should I manually crank car after without plugs to blow things out ?
How many valves will be open and closed at any given time on V8
For cleaning I will do soaking + zip ties not media blasting
Ty
Would you spray the WD-40 into the intake port for each cylinder and look for it to dribble down into the cylinder (with the plug out)?
I would find out the engine's firing order - GM and Chrysler are usually 1-8-4-3-6-5-7-2. Ford is actually the same, but because they number the cylinders differently, the nominal firing order is stated differently.
I assume your 4.8 is a GM.
This used to be easier in the days of distributors, when you could turn the crankshaft pulley such that the timing mark was at TDC - at that point you could check the rotor position - it would point either to the #1 or the #6 terminal on the distributor cap. In any case. If the rotor points at #1, the piston in cylinder #1 is at TDC, and both valves are closed. (#6 will also be at TDC, but as the piston has just reached the very top of the exhaust stroke, the exhaust valve will be open.) Turn the crankshaft pulley another 360°, and the rotor will point at #6. Both of the valves for #6 will now be closed, as the piston is at the top of the compression stroke.
But how do you do that without a distributor to help you see which cylinder is to be fired?
If you have the valve covers off, you can see whether #1 or #6 has both valves closed, from the position of the rocker arms.
So, with #1 at TDC and both of its valves closed, you could do your cleaning.
Then you would rotate the harmonic balancer (crankshaft pulley) 90° CW (as seen from the front of the engine), at which point #8 would be at TDC, with both valves closed. Repeat, in turn, and with a 90° rotation each time, for #4, #3, #6, #5, #7, and #2.
