arj951

How much vacume should the engine be drawing? I searched the forum but with no luck...

Fireplug

18 to 20 hg at idle (vacuum)

arj951

I have about 10-12hg now. The dealer here told me 15-17hg. Any thoughts?
Any common causes for low vacume? Clogged rings or valves are always possible culprits.

94 4.3 vortec w/ 135k

chembrad

arj951, what is the configuration of your vacuum hoses going into the rear of your upper intake?

calgary_redneck

Low vacuum can be caused by late timing,bad rings,burned valves and big vacuumm leaks

arj951

Vacume lines are all in place and new. I just replaced them. the reading is from the manifold directly, bypassing any Hvac or tranfer case system.

I read in the Saturn forum that using "Mystery Oil" in the cyliders and letting it set for hours helps break up and remove deposits from the rings... any thoughts on this. I can see it being difficult with v6, maybe jacking one side up to level out the pistons? I don't know, has anyone tried this before?

wolfox

Pop your PCV valve off one side of the engine - preferably the side that is under manifold vacuum. Use a small piece of aquarium tubing to extend the tube over the fender, or off over the front of the engine in a safe location so as to not get it tangled up in your fan and serpentine belt. Suck up a light drizzle of the Mystery oil using the tubing until half of it is gone, or you start to see smoke billow out of the exhaust. The engine will stumble a little, but overdoing it will cause it to stall. You just want it to stumble a little as the cylinders will be loading up with the mystery oil. Turn the engine off after you have sucked up half of the bottle of Mystery Oil and let it sit overnight.

Restart in the morning, early - especially if this is your only vehicle. Sometimes the MO will foul the plugs just enough to keep them from firing. They can be cleared by just wiping clean with a rag and re-installing them. Once the engine starts - let it idle up to operating temp, and let it idle for about 10~15 minutes more. Take it for a gentle, slow drive around the block or across town. Make sure it is running and idling stable basically - then take it for a 10 mile trip down the highway. Bring her in the direction of home, but make a stop at the auto parts store to pick up things you will need for a complete oil change and oil filter swap.

The junk these cleaners removed dumps straight into the oil, and you have to remove it all before it may cause problems. Afterall, you do not want it ending right back up where you took it off from! Good luck.

lou S.

Be careful about adding ANY aftermarket lube to your oil. Wonder why they call it mystery oil?? LOL