01 5.3l oil leak/pressure issues

[01SLE]

Hi, I'm new to this forum and unfortunately my first post is not about how great my truck is lol. I just picked up a 01 Yukon 5.3l 4speed this weekend and I knew ahead of time it probably needed a rear main seal. Prev owner said oil pan but I know better. Oil is leaking pretty profusely from between the pan and bell housing and splashes back onto the trans and exhaust while driving. While parked and turned off, some oil leaks out but not much after sitting a while. Sucks but at least it's a cheap fix if I'm willing to sacrifice a weekend under the truck.

Last night I noticed another issue. The oil pressure is sitting about right from what I can tell at idle, ~35psi. But it "searches" a lot. It's wobbling as much as 5psi up and down at idle fairly rapidly and doesn't get much higher than about a little over 40 at higher rpms.

In the past ~5 years I've had an OBS 07 Silverado 5.3, 08 Silverado 5.3, and 09 Yukon Denali 6.0 and none of them had the oil pressure bounce around and from what I remember and at higher rpms while accelerating, the oil pressure would raise at least towards the ~60 mark.

Also when I started it for the first time, the check oil pressure light came on and as I thought "oh !@#$!" and went to turn it off, the oil pressure jumped up to where it was supposed to be. Nerve racking...

So basically I'm wondering if these pressure symptoms are related to the main seal leak, the oil pump, or something else. Obviously if i'm going to pull the transmission I'd like to replace everything that may be messed up at once. Or if you guys know anything to check before I dig into it, let me know. Thanks!

 

[YukonXL04]

Also when I started it for the first time, the check oil pressure light came on and as I thought "oh !@#$!" and went to turn it off, the oil pressure jumped up to where it was supposed to be. Nerve racking...

My 00 6.0 Sierra used to do that when it was under 30* outside. But it had 300,000 miles. However it didn't leak a drop of anything. It did burn oil though. It did it for 2 years and never died lol. I was waiting for it to die so I could rebuild it.

 

[01SLE]

And to top it off, a P0301 Cyl #1 misfire. Hopefully the complete lack of maintenance is to blame on that one and it's a bad plug or wire... hopefully.

 

[bottomline2000]

check your oil pressure sensor. Mine developed a leak and oil actually leaked up through it and back down on the trans. It was quite a bit of oil, enough that if the truck sat the oil that sprayed out dripped on the ground. I knew it wasn't my rear main seal since it was done 20k ago.

its a lot easier than a rear main seal and you only have to reach behind the top/rear of the motor and feel for the oil leak around the sensor. this would explain both problems you are having.

 

[SLCHOE]

check your oil pressure sensor. Mine developed a leak and oil actually leaked up through it and back down on the trans. It was quite a bit of oil, enough that if the truck sat the oil that sprayed out dripped on the ground. I knew it wasn't my rear main seal since it was done 20k ago.

its a lot easier than a rear main seal and you only have to reach behind the top/rear of the motor and feel for the oil leak around the sensor. this would explain both problems you are having.

I agree. Check this first. It would explain the fluctuating oil pressure gauge as well as the oil leak in that area.

 

[01SLE]

I was just reading about that in another thread, thanks guys. I'll check it out and report back.

Anyone have a cylinder fire order diagram on hand? Going to pull this cyl 1 plug and check the wire.