300 TDI oil leak

portokali · 2024-11-23T15:59:35+0000

Hi everyone, I have an oil leak on the rear of the sump. My original sump was pretty dinged up and bent so I replaced it and resealed with Loctite ultra black according to instructions. However I am still getting the leak in the same place. The photos show the leak after resealing and no oil in engine and somehow it still leaks. I do have the engine tilted down as I am replacing the transfer case. The engine was recently rebuilt and new main seal was installed. There are no leaks upstream, it's between sump and flywheel housing.
Is there a trick to sealing the sump? Or is there something else going on?

D1Nut · 2024-11-23T16:20:37+0000

R u sure that's engine oil and not a mixture of "old" engine oil and diesel ?

I don't think you are ever going to get it completely dry. And if it doesn't drip after 1 hour of standing it's called a "sweat" of oil

portokali · 2024-11-23T16:33:55+0000

D1Nut said:
R u sure that's engine oil and not a mixture of "old" engine oil and diesel ?

I don't think you are ever going to get it completely dry. And if it doesn't drip after 1 hour of standing it's called a "sweat" of oil

Pretty sure it is engine oil. I've cleaned this up several times and it keeps dripping. The strange thing is that there is no oil in engine at the moment and it's still dripping. I see oil sheen between back of sump flange and bottom of engine and flows down flywheel cover.

portokali · 2024-11-23T16:38:04+0000

This are some photos of the old sump. The leak is in the same place. Between sump flange and bottom of engine.

Stanleysteamer · 2024-11-23T16:40:53+0000

It is probably due to the sump flange not being completely flat. This tends to happen when people overtighten the bolts and warp it a tad.
If you take it off to hammer it completely flat then you will have the opportunity to see where the oil is coming from.

portokali · 2024-11-23T16:53:54+0000

Stanleysteamer said:
It is probably due to the sump flange not being completely flat. This tends to happen when people overtighten the bolts and warp it a tad.
If you take it off to hammer it completely flat then you will have the opportunity to see where the oil is coming from.

The sump is brand new. I just installed it and has similar leaks

Stanleysteamer · 2024-11-23T18:35:13+0000

portokali said:
The sump is brand new. I just installed it and has similar leaks

Well if you fitted it and did the bolts up to the correct torque setting then either the leak is elsewhere and just looks like it is from the sump, or there is a source of a leak on the mating surface of the sump.
Or the sealant wasn't laid down evenly.
Best of luck finding it.

Stanleysteamer · 2024-11-23T18:43:57+0000

And when my new one was put on RTV sealant was used.
(My old one was replaced as it had started to weep oil through the base due to rust.)

Firebobby1 · 2024-11-23T18:59:59+0000

It can't be from the sump, if you haven't put oil in yet and it's a new sump??
It must be from another source.

portokali · 2024-11-23T19:01:14+0000

I didn't remove the paint from the sump flange. Will try again and remove the paint.

portokali · 2024-11-23T19:02:29+0000

Firebobby1 said:
It can't be from the sump, if you haven't put oil in yet and it's a new sump??
It must be from another source.

So maybe main seal or t seals?

Firebobby1 · 2024-11-23T19:15:16+0000

If from the rear, it could be from the main seal.
But you haven't run it up, because you have no oil in the pan.
Maybe remove it and see if you can see it tracking down

Stanleysteamer · 2024-11-23T19:26:08+0000

Firebobby1 said:
It can't be from the sump, if you haven't put oil in yet and it's a new sump??
It must be from another source.

Stanleysteamer said:
If you take it off to hammer it completely flat then you will have the opportunity to see where the oil is coming from.

See post #5

portokali · 2024-11-23T19:29:23+0000

Makes sense. Will drop the pan again. No oil is coming from the wading hole in bellhousing so didn't think it would be main.

Stanleysteamer · 2024-11-23T19:29:30+0000

Firebobby1 said:
It can't be from the sump, if you haven't put oil in yet and it's a new sump??
It must be from another source.

It can't be from the sump, even if he had oil in it as it would be below the level of the top of the sump!!!!
Unless he overfilled it like a complete maniac, which I don't think he is!!

Stanleysteamer · 2024-11-23T19:39:28+0000

Did you remove the oil filter at the same time as removing the sump?
could oil be draining down from there?

portokali · 2024-11-23T19:44:52+0000

I didn't overfill. The sequence of events is that I noticed a leak. Saw that the sump was dented so drained the oil and put in a new sumo with RTV - torqued to spec. There is no oil in the engine besides what might be in the oil filter. A few days later I noticed the same leak with the new sump. It may be between the flywheel housing and engine block.

portokali · 2024-11-23T20:49:28+0000

I spoke to rebuilder. Both t seals and main seals were replaced.

Stanleysteamer · 2024-11-23T21:18:45+0000

portokali said:
I didn't overfill. The sequence of events is that I noticed a leak. Saw that the sump was dented so drained the oil and put in a new sumo with RTV - torqued to spec. There is no oil in the engine besides what might be in the oil filter. A few days later I noticed the same leak with the new sump. It may be between the flywheel housing and engine block.

That all makes sense and I would have done the same things in the same sequence.
I am now thinking that the oil must be coming from what is in the oil filter housing, or else maybe some where in the cylinder head which only seeps down when the engine is tilted seriously down to the rear.

Firebobby1 · 2024-11-23T21:31:39+0000

Stanleysteamer said:
It can't be from the sump, even if he had oil in it as it would be below the level of the top of the sump!!!!
Unless he overfilled it like a complete maniac, which I don't think he is!!

If he's run the engine, the oil will splash about and could leak. But he's not put oil in so it can't be from the sump.

300 TDI oil leak

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