Oil leaks to bell - no clue about cause

65Fastback

Active member
Hello,

I have an oil leak on my 68 block and I dont have a clue regarding it’s cause.
Oil leaks on the bell side of the block.
Last weekend we had the bell and flywheel off because we suspected the rear main seal to be the cause. It appeared to be dry so we didn’t replace it. Furthermore oil was visible at the top of the block rear side, running down and on the inner bell walls. We thought it could come from the rear side head gasket, dropping into the bell from the top. Today I powdered the whole area, drove around and found the headgasket/block area completly dry.
Fresh leaking oil can be seen around the lower starter screw/mid-right bell screw (seen from the back) and on the lower areas of blockplate/bell. And it is engine oil, no trans oil.

I assume that the rear main seal is okay because oil appears much highter between block and blockplate. Head gasket is okay for sure.
Where are other possible routes for engine oil into the bell?

Any hint is highly appreciated.

Cheers
Joerg
 
way outside the box thinkin:
Valve cover gasket? Driving can press the oil far from the original leak source…
Would a steam or power wash help? Clean and don't drive, wait then observe. Trace the run line UP!
This way U only have gravity to consider> C "quote" in my sig,

Next run the engine (no movement) 2 C if it's pressure related?

(sorry but my off hand thoughts w/2 beer in me)
:beer:
:eek:opsie:

BTW: like pikesan (da guy & his) suggestion.
 
Hey Fish!
Spring sprung yet?
 
To sum up the previous posts--all excellent suggestions:
Valve Cover--Oil gallery plugs--Thread sealer on flywheel (flex plate) bolts.
....I'll add another--oil pressure sender unit
 
sure, alldem & more…
:LOL:
BUT
try it w/o movement (or even running (for a day or so).
Put a big cardboard, sheeta cloth, newspapers (I need sompin cuz I 'm on dirt, weeds'n gravel) weighed down by rocks/bricks/etc (so as to not blow away or move).
Come ck later to C what gravity dun. If notin, just start/run 10 min (in that same spot) 'n C. (heat'n pressure)
Next - Rev it up. (strain/power).
Each has a different story 2 tell ya for better diagnosis.
The movement seems to spread the stuff around & obscure the real location…

Let us know how U do~
;)
 
Put some dye in your oil & a black light should pin point your leak.
 
Hello,

thanks for all your suggestions. I was a few days offline so I just saw it. Highly appreciated!

Well, I think I can exclude as cause:
- Oil pressure sending unit (no oil in this area)
- Valve cover gasket (completely dry)
- Flywheel bolts (sealed, no oil on pressure plate)

The oil galley plugs (I saw 2 plugs at the block: top and left) appeared to be not the cause, because no excessive oil there. Now I'm not too certain about it.

The leak must be in the upper area of the block. I seems that it collects between block and block plate.
Digging into my memory, when we removed the block plate, I saw most oil on the block around the top bellhouse dowel, which is in my case a cutted screw (installed by original owner). Maybe this thread goes through the block as it seems that somebody cutted the thread in at that time.
As it was late at night and we were certain that the oil comes from the head gasket above (now I know, it doesn't), we didn't examine the screw/thread or even took a photo.

I think I need to pull the toploader once more to have a detailled look on oil routes and all possible passages to the block. Before that I will clean everything up again, cover all relevant areas with baby powder and execute the gravity and idle test.

Cheers
Joerg
 
That threaded screw may be the oil galley plug? it is under oil pressure, it will leak if not right and sealed. It is 1/4 ''pipe .The large knock in plug for the cam can leak oil. The other plug goes to the water jacket.
 
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