I've replaced the O ring on the CPS twice but it keeps on a leakin. I've cleaned everything as well as I can prior to placing the O ring on the sensor and installing the CPS. I installed it with the O ring dry once and with a light coat of oil once. But it still leaks. Any advice? :(

 

I'm guessing you're assuming it's the CPS 'cause when you look under the car there's a single drip hanging off the sensor ;) I had this same annoying leak. Turned out that the seal in the front cover had worn a groove in crankshaft hub. Replaced the hub and seal, no leak for the last 30k miles :)

Waterpump driveshaft seal and Opti seal are two other potential culprits for a lone drip.

 

I'm curious how many miles were on your vehicle when the hub was worn enough to cause a leak?
My '92 LT1 has about 85000 on it, and I imagine I will be replacing the hub and seal before long. I even ordered the LT1/LT4 hub puller/installer tool from Kent-Moore.

Tom Piper

 

~40k give or take a couple thousand miles.

 

I have looked and felt around at every spot I can and I can not find any trace of oil except at the CPS. BTW this car has less than 5000 original miles on it. The guy I bought it from never used it. So I doubt if there has been time to wear a groove any where. :)

 

Anytime I have an oil leak that doesn't make sense (meaning the leak is there, but I have tried every logical method to eliminate it), I start looking at crankcase ventilation -- if pressure builds in the crankcase, it has to go somewhere, usually taking some oil out with it.
The best way I have found to check the crankcase ventilation system is to block the tube where the fresh air enters the crankcase with a vacuum gauge and, at idle, view the vacuum reading. There should be some (about 5") vacuum at idle caused by the vacuum through the PCV valve from the intake vacuum.
If you don't have some vacuum, you need to find out why.

I had a problem with a Ford 5.0 engine once where I had chronic oil fouling of the #8 plug. The problem was the neoprene grommet that the PCV valve was in became brittle over time and did not seal properly. This meant that there was no flow of fresh air through the crankcase. This caused crankcase pressure (this only happened at highway speeds ~70mph) to build and blow oil down the #8 intake valve stem and foul the plug. (On a Ford 5.0, the last valve on the driver's side is an intake valve, and since the engine slops downward toward the rear, the oil builds toward the back of the head.)
After replacing the PCV valve grommet (about $3.00), I haven't had a problem in 35K miles -- I used to have to clean the plug about every week.
A Ford mechanic told me the engine was worn out and needed replaced. So, ($2000 - $3) means I saved $1997.

Tom Piper

 

Probably no groove worn in the hub, but with that few miles it wouldn't surprise me if the seal is bad. Sometimes sitting is harder on them than driving.