I suspect a rear main leak has developed

[DoubleDingo]

I took the dogs for a ride to our favorite spot for them to get out and run. I stopped at a store to get some beverages and I smelled fresh oil coming from my truck. No smoke so it isn't coming from the valve covers onto the exhaust manifolds. And nothing from the sides or the front of the block.

I only saw a small spot under the truck. Keeping an eye on the oil pressure, it started out at 40 psi going to the spot to run them. Coming back it ran at 20 psi and would sometimes go up to 30 psi. But the smell of oil was definitely noticeable coming through the vent. I got home and checked the oil, it was full, but there is definitely a leak, and I think it is the rear main. Looking at the attached picture, what do you guys think? I figured with the top end being all new, and the truck sitting for so long without being driven most of its life, that the bottom end seals and gaskets being old and brittle cannot hold up to the pressures being generated from a fresh top end. Does that make sense? There isn't any red in the small puddle to indicate front trans seal and with it coming out of the hole in the dust cover, it is probably not the oil pan gasket.

 

[bigcountryguy19]

I would say it's the rear main, or pan gasket. Could possibly be the rear intake gasket, maybe it slipped out.


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[DoubleDingo]

I would say it's the rear main, or pan gasket. Could possibly be the rear intake gasket, maybe it slipped out.


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Originally I thought it may be the intake too, but with the drip coming from inside the dustcover, that is what makes me lean more towards rear main. If it was the rear of the intake, I think it would run down the outside of the tranmission. I would hate to be driving along and have that seal blow out completely. Guess I better switch vehicles at lunch today.

 

[DoubleDingo]

The more I think about it, the more I am just going to bite the bullet and replace the rear main. Is it a difficult job without pulling the engine? I figure while I am at it, I will replace the timing cover gaskets, and oil pan gasket and be done with the bottom end seals. I will change the timing set while I have the cover off. And since the transmission will be coming out, those seals will get replaced too, and the transmission will get degreased and I will dump out the ATF in the torque converter and replace that too. What are your thoughts on the oil pump? Replace it while I am in there, or leave it alone? The engine only has 78,*** on it. I am okay with it pumping at 40 psi. But that 20 psi yesterday had me worried. I am guessing it was lower because the oil was leaking out and pressure couldn't build in the engine. The engine ran fine, just had lower than normal oil pressure when fully warm.

 

[bigcountryguy19]

I would replace the oil pump, for one it's not that expensive, for two do you really want to tear it all back apart again if it does take a dump? When I replaced my rear main I had to losen all the main caps and slightly drop the crank to get the upper seal in, it wouldn't rotate out. I highly suggest a one piece oil pan gasket if you are doing it under the truck, will make life much easier lol. Replacing the seal with the engine in is easier on a 4x4. It might just be easier to pop the engine out an put it on a stand. Since your going to replace all the bottom en gaskets, I would just pull the engine, you have to take the whole front of the engine apart anyway to get to the timing cover.


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