460 Rear Main Seal

[ArdWrknTrk]

I'll read up on the oil pressure switch and how to rule that out. Are there any other things I should rule out that would be easier to get to? I just fixed one valve cover gasket leak and there's no evidence of any leak from the other one.

If you've observed the oil pressure sender/switch at the back of the block there is little else.

There could be a leak from the rear of the intake manifold at the china wall seal, but you would have noted that while looking at the sender.

My truck has a weeping RMS too.

It's not something I'm going to address until I can figure out a time and place to pull the engine.

I'll replace the oil pump -and the pan gasket, obviously- when I have some way to do that.

[Gary Lewis]

I'll read up on the oil pressure switch and how to rule that out. Are there any other things I should rule out that would be easier to get to? I just fixed one valve cover gasket leak and there's no evidence of any leak from the other one.

Yes, where the rear of the intake manifold hits the wall at the back of the block. I've had two engines where someone did a very poor job of installing the intake and there was a leak there. It is right in front of the oil pressure switch, and if either of those are leaking the oil will run down and look like a rear main leak.

If I were you I'd pull the air cleaner to get access to the rear of the intake and the oil pressure switch. Check to see if there is any oil puddled on top of the block right behind the manifold. If so you have to figure out from whence it came, but it'll be either the switch or the intake/block interface.

And while I can tell you are thinking "Please, not the intake!", I'll assure you that R&R'ing the intake is far easier than the pan.

[Bullnose Gator]

Yes, where the rear of the intake manifold hits the wall at the back of the block. I've had two engines where someone did a very poor job of installing the intake and there was a leak there. It is right in front of the oil pressure switch, and if either of those are leaking the oil will run down and look like a rear main leak.

If I were you I'd pull the air cleaner to get access to the rear of the intake and the oil pressure switch. Check to see if there is any oil puddled on top of the block right behind the manifold. If so you have to figure out from whence it came, but it'll be either the switch or the intake/block interface.

And while I can tell you are thinking "Please, not the intake!", I'll assure you that R&R'ing the intake is far easier than the pan.

Got it. Is there documentation here that would help me with a visual of where that is? As you must know by now, I know my way around a 460 as well as a politician does the truth, so any additional hand holding would be much appreciated.

[Gary Lewis]

Got it. Is there documentation here that would help me with a visual of where that is? As you must know by now, I know my way around a 460 as well as a politician does the truth, so any additional hand holding would be much appreciated.

Here's a shot of the oil pressure switch on the back of Big Blue's old engine. You can see the brass tee that screws into the engine, the steel tee on top of it, and the oil pressure switch coming in from the driver's side. But that isn't the standard setup as you'll probably just have the steel tee and a switch screwed into it.

And the intake manifold is literally an inch in front of the brass tee. It is the light gray thing. The block is dark blue. And where they meet is where that engine was leaking.

So you want to check out that area very, very closely. If you have a leak there then do a happy dance 'cause fixing that is far easier than fixing the rear main.

[Bullnose Gator]

Here's a shot of the oil pressure switch on the back of Big Blue's old engine. You can see the brass tee that screws into the engine, the steel tee on top of it, and the oil pressure switch coming in from the driver's side. But that isn't the standard setup as you'll probably just have the steel tee and a switch screwed into it.

And the intake manifold is literally an inch in front of the brass tee. It is the light gray thing. The block is dark blue. And where they meet is where that engine was leaking.

So you want to check out that area very, very closely. If you have a leak there then do a happy dance 'cause fixing that is far easier than fixing the rear main.

Perfect, thanks. I'll try to check it out this evening, fingers crossed.

[Bullnose Gator]

Perfect, thanks. I'll try to check it out this evening, fingers crossed.

I didn't see any evidence of a leak near that area, or anywhere near the upper half of the back of the block. The rear half of the oil pan gasket on both sides has fresh, wet oil. Is there any point in determining if it's just the pan gasket or the RMS, or would you just replace both since I'd have to yank the engine either way?

[Gary Lewis]

I didn't see any evidence of a leak near that area, or anywhere near the upper half of the back of the block. The rear half of the oil pan gasket on both sides has fresh, wet oil. Is there any point in determining if it's just the pan gasket or the RMS, or would you just replace both since I'd have to yank the engine either way?

If you are pulling the pan I'd replace the rear main seal at the same time. The seal's cost is minimal and the labor cost for just getting to it will be significant.

[fryntrz]

If you’re going to change the seal, consider checking the seal crush. Nothing worse than rework!

460Ford.com Oil Leak at RMS