Hello All! I bought my 94 Z28 w/ 6 speed tranny over a year ago. I've had issues... Car started running rough, I found that someone had criss crossed two plug wires. I replaced the plugs and plug wires. A couple of times the dipstick would come out of the tube and spill oil on the motor. It was an aftermarket dipstick so I got a factory dipstick and tube and put it in. Then the power steering pump went out, replaced it. Couldn't get it started after that. Had it towed to a shop, they said timing chain broke. They replaced the timing chain, I had them do the water pump and distributor while they had it torn down. Got it out of the shop, ran great for a day. Next day, I heard a pop and I saw oil. Pulled it over, oil was dumping out the front seal. Called the shop, they towed it back in, replaced the seal and started it. The seal blew again. They think the rings were put in wrong or are bad and I'm getting too much back pressure. They replaced the seal and told me there was no warranty on that. Low and behold, seal blew again. I paid the shop a lot of money for nothing and I don't know if I should trust them. The car will run, but it gushes oil from the seal. It also pushed the PVC out. I am at a loss.. The car has aftermarket headers, no cat and Magnaflow muffler. The air injection tubes are not in place, I don't know if that would have anything to do with it or if it is an internal engine problem or what... I have no clue, someone please help.

 

Excessive crankcase pressure will cause seals to blow out and the dipstick to pop out. Simplest thing to do is check your PCV system to make sure it isn't plugged. Worst case scenario is that your rings are shot and that it's time for a rebuild.

How many miles on the engine?

 

I replaced the PCV valve and the hose, but I don't know if the hose is ran to the right spot. The hose from the PCV runs right back into the manifold... I can't tell in my Chiltons where it's supposed to go.. It's a mess, apparently the previous owner didn't know what he was doing. The harness is all chopped into, fan is on a manual switch, etc. The crappy part is - the shop I paid to do the timing chain had the motor out and didn't even catch the "ring" problem.. Is the air injection pipe just an emissions thing? Or do you know?
The engine has 135K on it, but they had the valve covers off and the heads looked new. They even had the pan off...

 

If the rings were worn enough to cause blow by as bad as you describe, it would also be smoking bad and fouling plugs to the point of non-drive ability in just a few moments. Not to mention the fact that the engine would be significantly down on power. To the point of even a child being able to identify the loss of power.

Besides that, it is extremely easy to find bad rings with a leak down tester.

Also the crankcase can be tested for proper vacuum level with a manometer.

It seems that you didn't have the pressurized crankcase issue until AFTER the shop did the timing chain.

Pull the plugs and do a leak down test on the cylinders that show oil fouling. If you don't have any bad cylinders, find out why the PCV system is screwed up with the use of a crankcase manometer.

 

Your PCV hose routing sounds correct for a 1994.

 

As Rob noted, 94 PCV valve vacuum comes from a C-shaped hose that bends backward to a vacuum nipple on the drivers side of the intake manifold, a few inches behind the grommet for the PCV valve. You can see it below the EGR vacuum nipple and hidden partly by the brake booster hose in this photo:

http://www.injuneer.com/images/photo.../dOptivac1.jpg

You should have an AIR injection tube to each exhaust manifold. The AIR pump only runs for a few minutes at startup to help the cats heat up and operate sooner..... emissions only. Does not affect how the enigne runs, unless the pipes and/or check valves are leaking.

Why did the "shop I paid to do the timing chain had the motor out"? You don't need to remove the engine to change the timing chain.

You had signs of excessive crankcase pressure when the aftermarket dipstick started blowing out. It didn't suddenly start after the timing chain replacement. The crankcase pressure should also vent through the hose that connects the passenger side valve cover to the side of the throttle body. Pull that hose off and look for signs of oil in the hose, and then look under the plate on the top of the throttle body for oil builup. If the blowby is bad enough, you may be able to feel and/or hear it by taking the oil fill cap off and putting your hand over the opening, then listening near the opening.