Choreo

A few months ago I noticed that I started getting drops of oil on the floor right after an oil filter change at the local Avis-Lube. I took the car back and I went down in the pit and could see oil dripping off an Oil Filter bolt next to the where the oil filter attaches. Therefore they agreed to change out the filter again at no charge.

Next day - oil on the floor again? So, guessed it was not the oil filter after all.

I took the car back again and followed them down into the pit and he said I had a blown Main Seal. I could see some oil on the top of the Bell Housing so my first guess (hope) was the Oil Pressure Sensor instead. It looked like the oil was dripping from a bolt head next to the Oil Filter and maybe the middle of the Bell Housing, but the Oil Pan, etc. looked clean.

Since I threw my back out, I have been putting off tearing into the cowl to see if I might get lucky and it just be an Oil Sensor or Cam Sensor issue. I had an oil sensor fail on my previous engine with the usual pegged out pressure reading, but it never leaked oil. I did however perform the Under-Cowl mod by cutting out the plenum, so I could at least get to the sender this time much quicker (without having to pull the Intake Manifold, etc.).

I kept checking the dipstick over the past few weeks and even up until today it showed FULL. I am amazing how many oil spots you can leave on the floor without the level going down at all!

This time my Oil Pressure Gauge readings all looked reasonable for the past few weeks, so I was fearing a Rear Main Seal $$$$. I finally got up the drive to tear into the cowl 3 days ago and just held my breath when I checked it out (praying that is was just a leaky sensor connection to the block itself). The Oil Sensor connection WAS LEAKING FOR SURE (but the sensor electronics were still taking a reading). I replaced with a NEW sensor and torqued it to 15-ft-lbs, then headed back to the Oil Change Pit for another oil change. The guy shouted up from the pit again (same as a few months ago) - "Did you know you have a blown Main Seal?". I told him that I just replaced the Oil Sensor and that is where I thought all the oil was coming from that he was seeing. I went down in the pit again to double-check and there was oil everywhere - all over the bottom of the pan, a drop on the oil pan bolt, a drop on the same bolt as before by the oil filter and even some oil on the Starter Motor?

Since I had just reinstalled a new Oil Sensor that day, I was still hoping that was the only leak, so I cleaned the oil off of everything under the car and waited to see. It has been 3-days so far and the bottom of the engine is still dry and clean and not a single drop on the floor (yet). Before I was getting a small puddle about 2"x 3" EVERY night.

Here is what I found when I checked the Oil Pressure Sensor:




Guess I will know for sure in the next few days if that was the "only" problem, but I suspect that it was the main source due to all the oil around the sensor hole and on top of the bell-housing.

I had my long block replaced under warranty 3 years ago, and I know for a fact that they re-used my new oil sensor (at the time) during the re-install. Guess it lasted about 2-1/2 years before springing a leak.

If this was the only leak (as it appears to be so far), how would the oil get from the OPS to the "front" of the Oil Pan - even the the front cross member and all over the bottom of the Oil Pan unless I was doing 70MPH in reverse???

striper

It's amazing the mess leaking fluids can make. I had a badly leaking clutch slave. My oil sensor and my rear main seal are not leaking as I did the clutch repair myself and have been able to examine everything under the car. However, there is a liquid mess on my oil pan which is clutch fluid that has somehow managed to blow forward.

m6 c5

I had my oil pressure sending unit on my camaro blow out and lost and entire quart of oil in just a few min. You could see a steady drip of oil on the road where I had driven along with a puddle of oil on the road where I pulled over....
On the other hand it kinda sounds like you have a power steering leak being that its all over the front of your cross member, unless I read it wrong.

dezcapt51

Mine did same thing replaced ops no leak

bburn

Just went through this exact same thing about two weeks ago. Yes, my leaking oil pressure sensor made a mell of a hess. I first changed mine out in 2010 when the gauge reading became pegged out at full pressure. That sensor lasted all of 16 months before I started smelling an awful burning oil smell a couple of months ago. I could smell it while idling at a red light or in my garage after getting home from a drive. Then I noticed numerous oil drips right below the rear of the engine where I park.

I feared the worst (main seal, etc.). After inspecting the mess at the back of my intake manifold, it became clear that my sensor had failed again. Fixed it in 30 minutes since I had previous experience and had already done the cowl mod. As soon as I pulled my cover plate off I could see a huge oil mess all around the sensor. I'm almost a pro at changing it now. I place black duct tape back over both sides of the piece I cut out. I layer it like shingles so that water will shed over the successive layers of tape. It's pretty much waterproof that way and keeps dirt and grime from the engine bay out of the cowl area. Once the wiper cowl is back on, everything is perfectly hidden.

rebelheart

Moving air spreads oil everywhere!We always clean the engine first,then look for leaks from the top down.

pewter99

you may also want to look at the plastic hoses back there for the PCV valve...all these cars have them and they crack and leak...

10yrPlan

I know this post is 3+yrs old - but it was very helpful to me. I recently bought my first corvette and it has an oil leak. After researching oil leaks and finding this post, it fit the description of my oil leak. Just took off the intake manifold and found that the root cause is the oil sender. Thanks!

Armand Gagnon

How exactly do I do the cowl mod? I have the same exact systems and have only owned my 2002 C5 Convertible for less than a month. Do I still have to remove the intake to do the modification? Is it possible to change the OPS without the Mod or removing the intake?

ant-knee470

You do not have to do any mods to your car to do this without removing the manifold.. I did mine today and it was easy to do and I did not remove the manifold or drill holes in my car..

The hardest part is getting the plug off, The trick to that is have a long long long flat screw driver , Push the clip that unlocks the plug and pry up at the same time and the plug will come right off.. Go to youtube and search c5 corvette oil pressure switch and there are some great videos of xactly how to do it...

hope this helps,,

Ant...

ant-knee470

Number 3 is the way to go, Just have a little patience and you will get it..
Just my opinion..

Ant...

ant-knee470

Forgot to mention, If you are going to attempt to do it without removing the manifold get yourself a MAC Oil Pressure switch removal socket, The number is sc46 this will make life much easier.. It is a 3/8 drive which is much better then using a 1/2 drive the extra room is nice..

Thanks,

Ant...

WetMountainMan

Thanks to all for this information. I have a rear engine oil leak and hoping this is it, instead of something more serious.

RedBoy504

I've watched the video over and over again. I tried everything. It's not working. Can anybody tell me what I'm doing wrong? I have the plug off I can't get the socket to go onto the sensor to save my life. I've literally been trying for months. Thanks

feeder82

just remove the intake, its not that hard, the time you wasted you could have had it off

ant-knee470

DID you get the socket I told you to get? There on e-bay for 12 - 15.00 well worth it.. I tried with a 27mm and could not get it either, Could not get socket to go over sensor. There is a bolt that is right next to the sensor and the 27 mm will not fit good nor will a 1-1/16 socket... you will end up stripping it.. Get that socket I told you to get, and you will get it... It is made for the oil sensor switch and is much thinner then the 27mm,

Thanks,

Ant...

helga203

JMBickel

I am relocating the oil sensor without removing the intake. I have the fittings and braided line for relocating the sensor. I have mated the brass fitting with the tubing adapter and installed into block. Now I need an "L" shaped open end wrench to get in there to tighten the hose and can't find one. Any suggestions?

emptnest

WetMountainMan

Maybe try something like this with a short extension, a swivel joint, and ratchet...
Open End Crowfoot Wrenches