I have a 96 2DR 4x4 blazer with the 3.6L w/ aluminum oil pan. She has been leaking oil for quite sometime now. When I first got her, she leaked about a quart a day. I tried some additives to resolve the problem and was able to slow the leak down considerably to about a quart a week. I figured there was a bad seal somewhere and finally got around to cleaning everything up to try and figure out where. I have narrowed it down to the area around the crankshaft positioning sensor. Cant tell for sure if its the timing cover gasket or the main seal. I am curious to know what everyone thinks would be a good solution to resolve this problem with little money and little time.

 

3.6L huh...?

It probably is leaking where the timing cover, block, and oil pan all come together. I would recommend you degrease the area and maybe put some of those fluorescent dye tablets into the oil. That would allow you to really pin point it. If it is the oil pan gasket, it could be problematic to replace with the engine in. The timing cover is equally as difficult. The front seal or the seal on the CKP sensor are not too bad to do.

 

There's an S10 crew cab down the street from me with 4x4 and a 4.0L!

Wouldnt a complete clean up and short run time give you more of an example of where it coming from?

 

My bad...the engine is a 4.3 not sure wth i was thinking. Its been a long week. I cleaned everything up with brake cleaner and let it run. It does not leak while running. Once the engine is turned off it starts coming out right around the Crank Sensor. There is no seal on the sensor just an o-ring. The sensor is built into a bracket, the bracket screws onto the timing cover and the sensor pushes into the cover. I can not see the main seal in this area because the part of the cover that houses the sensor extends over top of it. It is my understanding that to replace the main seal i would have to drop the pan, which is a pain in the *** with the aluminum pan; practically have to pull the engine. The timing cover is just as bad, having to remove the entire front end.

I just happened upon this stuff...Permatex Spray Sealant has anyone ever used it?

 

o-ring = seal...

You need to remove the balancer to replace the front seal. To get the balancer off, you may have to remove the fan and fan shroud, but that should be about it.

 

My terminology may be incorrect. Im not referring to the seal in the middle of the timing cover. I am referring to the half circle seal in the front of the oil pan

 

The crankshaft position sensor O ring can be replaced, but I would also suggest checking the front two oil pan bolts...make sure they are there and tight.

I am not sure if these engines use the one piece oil pan gasket or not which would include the half circle one at the front oil pan. And yes getting the oil pan off on these vehicles is not easy as everything is in the way. Probably is easier to lift the engine especially if this is a 4WD vehicle.

 

Its the 2 piece gasket that has the half circle in front. It seems to be leaking from the half circle gasket in the area behind the timing cover where the crank sensor is. It is not leaking from the crank sensor. I will check the bolts and make sure they are tight. Does anyone know what the torque specs are on them? If that doesnt fix it I think I may need to get some sort of sealant like I found above. It has to be able to get behind the timing cover to be able to get to the area of the half circle gasket that is leaking.

I have attached a pic to kind of show what I mean. In the pic the yellow area is the timing cover. The area that jets out at the bottom is where the senor is at. The blue area represents the half circle gasket. The black is the oil pan. As you can see the area for the sensor is blocking access to the half circle gasket in that area. This is where the oil is leaking.