Where Is This Leak?

RBBailey

Well-known member
Callsign: KF7KFZ
OK, so I've long had a slow leak that I've really just ignored because it wasn't enough to worry about. But it's getting so that it drips every time I park.

I get motor oil coming off of the bolts that are on the bottom of the bell housing to engine. This is not a place that can leak on its own, so the oil is coming from up above someplace. It could be the vacuum pump, maybe the back side of the valve cover, or...? I do have seepage on these spots, but none of it is ever enough to make for what I see dripping off the very bottom. Any ideas?
 

Napalm00

Well-known member
It's most likely coming from the t seals on the rear bearing block or the rear main It's an engine out service to replace them .

Super common and shitty
 

Napalm00

Well-known member
Unfortunately age has really nothing to do with these rear main seals.

They are extremely sensitive for some reason.

It's more likely the t seals as they may be original and many don't replace them.


if you want a definitive answer where the stuff is coming from without any back and forth. Add UV dye that's made for air conditioning systems to your oil (available any auto parts store) , then power wash your engine and transmission or take it to the coin operated car wash and do the same, drive it for a day and then check it that night with a UV light. It'll be instantly obvious where the oil leak is coming from
 

RBBailey

Well-known member
Callsign: KF7KFZ
I can see that a few of the bolts on the pan do seep, but not enough to drip. The problem with seeing where it is coming from is that other than some minor seepages, I can't see anything. There isn't any oil anywhere on the truck except for on those two bolts, mainly the right side. I'd be expecting those two bolts to glow, but that doesn't show me anything new. Sounds like it might be fun anyway, so I'll see about picking some up later today.
 

RBBailey

Well-known member
Callsign: KF7KFZ
Let me expand a bit on this thread.

I usually spend a bit of time cleaning the underside of the engine once a week or two. I missed the last few weeks, and have noticed a few new leaks!

First, the drip from the bolts I described above might actually just be a culmination of a bit of a leak from here and there -- one from the back of the valve cover, one from the vacuum pump, and one from the back passenger side of the oil pan. None of these are too bad, I can easily clean the area of these leaks, and see right where they are coming from. But I think they are all adding up to the drips coming off that lower bolt. There doesn't seem to be any other place that it could be coming from. There are no seams on that side of the bell housing/engine/transmission. I hope the dye will help, but only if I am completely missing something. Like I said, it's easy to see where leaks are coming from because the engine is cleaned on a regular basis.

However! I just noticed a coolant leak that appears to be coming from right above the alternator. It could be the large hose right there. But it seems to be coming from the pump housing. Does this sound familiar to anyone?

I'll update once I get the dye running through in the next day or two and am able to use my new UV flashlight to check.
 
I had a horrific leak on my 300TDI that started about 50-100 miles after a full rebuild. I ended up pulling the pan, replacing the t-seals and rear main with a rear main from Turner. I didn't think it was worth my time to do the rear main and not the t-seals in-case I was wrong. I have put a couple thousand miles on her since and I have yet to see a drop of oil come out of the bell housing.

That being said, when I had my leak, the oil came out of the wading plug hole on the bell housing. I didn't have any oil coming from other spots. You might just have a combination of a few leaks from other places that just end up where you are describing.
 

RBBailey

Well-known member
Callsign: KF7KFZ
UPDATE:
The coolant leak decided to go away. I'll keep an eye on it in case it decides to come back after a long drive or something.

I can't get the glowing oil to glow. No indication of the UV stuff anyplace. However, I've been checking the drips before, and after every drive, and I can see a few specific things. First, the main drip is from the vacuum pump. It could be also contributing to the drip that comes off the bolt on the lower part of the bell housing. Second, there is oil coming out of the hole on the front cover..... Third, I can't yet tell if oil is coming out of the bell housing. There SEEMED to be a bit coming out of the bottom seam of the bell housing, but none is coming out of the drain hole itself, so I'm not sure what to think yet.

I'm driving it for a good 20-30 miles after work today, so I'll definitely see new developments this evening.
 

NPT90

Well-known member
front cover is a concern, there are seals along the cam and crank that are pretty easy to replace just have to get in there and pull the crank gear and the cam gear. If you have oil coming form there its worth doing the timing belt and giving it a good cleanout.

The vaccum pump is just a paper gasket I am pretty sure, might be worth replacing if you think it might be on its way out, makes sense you would have an oil leak if the gasket is shot or it could be a simple case of not tight enough.
 

Napalm00

Well-known member
agree with above. if you do pull the vac pump note the orientation of the gear that drives it and reinstall in the same fashion, it beds into the cam over time
 

RBBailey

Well-known member
Callsign: KF7KFZ
I’m not 100% sure which seals you are referring to because I’m not schooled enough yet. I know that before I had the engine installed the front and rear main seals, I think the t-seals, and the oil pan gasket were all changed. If this is something that happens every 10k miles, I can’t keep the truck. I’m not going to be removing the engine every year. There has got to be a better alternative.
 

RBBailey

Well-known member
Callsign: KF7KFZ
BTW, the vacuum pump is leaking out the top cover, not the gasket on the block. I've heard tell of people drilling out the rivets, and replacing with new gasket (right stuff) and then using small bolts to really close it tight. Anyone done this?

I think this is where I will start because it is an obvious leak, and it is letting enough oil out that I think it may be causing some of the other drips I'm seeing, mixing the results, and not allowing me to nail down exactly where the other leaks are coming from.
 
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