Only after driving long distances the bottom of the vehicle is covered in oil

Tiny
CANNON1349
  • MECHANIC
  • 2005 GMC ENVOY
  • 4.2L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 203,000 MILES
This car has a strange problem. When city driving, daily routines, and small trips, this car will not lose a drop of oil between oil changes. But, when driven on a 700 mile + trip, the entire bottom half of the car becomes soaked in about two quarts of oil (still a little bit on the stick after round trip). I can't see anything actively leaking, the pan gasket is dry and eventually all of this oil will cook off and it'll seem spotless again. I'm really racking my brain about it.
Tuesday, July 2nd, 2019 AT 7:12 PM

33 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Good morning,

Can you post a picture of the bottom of the engine with the oil showing?

Roy
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Wednesday, July 3rd, 2019 AT 1:10 AM
Tiny
CANNON1349
  • MECHANIC
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I tried. Basically droplets of oil everywhere. The AC compressor and alternator were soaked. Eventually all of this will cook off and it'll be like it never happened.
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Wednesday, July 3rd, 2019 AT 4:34 AM
Tiny
ASEMASTER6371
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Thank you.

The leak looks like it could be from either the front oil seal on the crankshaft or the oil filter. Since it does it when you are on the highway, that is when the pressure is at the highest.

I would add an oil dye to the oil and then drive it a couple of days and use a LED light to spot the source of the leak.

Then we can discuss options.

Roy
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Wednesday, July 3rd, 2019 AT 4:40 AM
Tiny
CANNON1349
  • MECHANIC
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Just re-bumping this for discussion. Since the oil change 2,000 miles ago, it hasn't leaked any oil, to my knowledge. However, the new belt has begun to "glaze"? I guess from something leaking on it? Or maybe it's lack of tension. What I'm trying to say is that the belt no longer has the nice hard rubber outside and is now soft and stretchy, can almost pull it off the pulleys.
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Thursday, November 7th, 2019 AT 2:07 PM
Tiny
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Change the belt and tensioner.

Roy
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Thursday, November 7th, 2019 AT 2:12 PM
Tiny
CANNON1349
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Quick question, could lack of tension cause the vehicle to just quit at random?
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Thursday, November 7th, 2019 AT 2:13 PM
Tiny
ASEMASTER6371
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No, it will glaze the belt.

Roy
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Thursday, November 7th, 2019 AT 2:21 PM
Tiny
CANNON1349
  • MECHANIC
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I've had dye in this car for 2 oil changes now. The front seal should be glowing under the UV light right? There is only oil on the front frame, the skid plate, and a drop on the bottom of the oil filter. No oil around the oil filter base plate. The pan gasket area is dry.
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Sunday, November 24th, 2019 AT 4:11 PM
Tiny
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Okay, is the oil on the frame have oil dye in it or is it leftover from before?

Roy
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Sunday, November 24th, 2019 AT 4:30 PM
Tiny
CANNON1349
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Oil on the frame does have the green tint to it with UV Light. Yes
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Sunday, November 24th, 2019 AT 4:38 PM
Tiny
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Then it is coming out of the engine.

Did you check the top such as the valve covers, intake manifold, and the oil fill cap?

Roy
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Sunday, November 24th, 2019 AT 4:40 PM
Tiny
CANNON1349
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There's a slight valve cover leak up top, but no dye came out of it. Nothing down the exhaust, and certainly not out of the cap. There's a puddle caught in the skid plate, took that out. And a green bit on the head of the drain plug put not the seal around it.
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Sunday, November 24th, 2019 AT 4:41 PM
Tiny
ASEMASTER6371
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It has to be leaking from somewhere on the motor.

Either that or it is burning it out the tail pipe.

Roy
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Sunday, November 24th, 2019 AT 4:54 PM
Tiny
CANNON1349
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I'll keep looking. But if it burned it out like that there wouldn't be other evidence right?
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Sunday, November 24th, 2019 AT 4:56 PM
Tiny
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You might see something at the exhaust manifolds.

Roy
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Sunday, November 24th, 2019 AT 5:03 PM
Tiny
CANNON1349
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I attached here the best picture of the crank seal I can get. It looks wet to me. But not showing up florescent green from the dye.
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Monday, November 25th, 2019 AT 4:09 PM
Tiny
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Yes, that looks like it is seeping but has not actually become a leak.

Look at the rear of the engine as well for the rear main.

Roy
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Monday, November 25th, 2019 AT 4:23 PM
Tiny
CANNON1349
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The rear main is leaking, but it never has been a problem, just a brown wet spot on the trans bell housing, I can't really see that blowing up to the front during normal driving, especially on long trips.
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Monday, November 25th, 2019 AT 4:27 PM
Tiny
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How much oil do you use between changes?

Roy
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Monday, November 25th, 2019 AT 4:37 PM
Tiny
CANNON1349
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That's what's funny. Every time I change the oil the level is full. When we drive it to Louisiana, which is 1,400 miles round trip it will use 2 or 3 quarts.
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Monday, November 25th, 2019 AT 4:42 PM

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