jtramont

Hey guys looking for an opinion here.... I have a '73 L82 4spd

I have an oil leak that is pretty severe and I'm trying to isolate it. I've got it narrowed down to one of three things:

1. Rear Main Seal
2. Oil Pan Gasket
3. Oil Filter Gasket (possible miss-thread but I did that 10 years ago and have been ultra careful when installing the filter plus when you miss-thread it you get oil blown everywhere when you start it)

I lost about 1.75 Qts of Oil in 750 miles and the thing that perplexes me is that I have motor oil on the driver's side and center sprayed back to the rear support for the transmission and up the firewall to about the clutch linkage which is equal to about the top of the oil filter.

I think this seems to indicate that it's either under pressure, it's mainly leaking when the car is running or both. In my limited experience, I think a rear main seal simply drips unless it's totally blown in which case then I think you lose oil really fast. (let me know your thoughts here).

All of this started after I changed the clutch and the oil/filter. Before that I had some minor dripping at the back of the oil pan by the crank but it was like two drips in a week not a minor puddle like I'm getting now. BTW, when I reinstalled the flywheel cover I installed the tabs by the crank over the lip of the oil pan...let me know if I screwed up here.

Because the oil is all over it's tough to isolate it but whenI cleaned it up and found that there were heaviest drips at the bottom of the oil plan, the bottom of the bell-housing at the flywheel cover and at the rear mount for the transmission.

Thoughts and experiences very welcome!

Happy Holidays to all

Jim

MelWff

after you cleaned it, you didnt put it up on a lift with the engine running?

fanmanbd

My guess would be the filter but wash it down good and you should be able to see a bad leak like you describe.

jtramont

Now for the punchline.....

I took it out for the last run before the snow started flying (I live outside of Denver) and when I was waiting for the garage door to go up she stopped running....not a stumble and stall, just a sudden dead with zero power anywhere. There is another post out for that one...this has NOT been my month!

In the process of eliminating the variables there I pulled the starter to test the solenoid (I realize that that would typically prevent it from running not usually kill the engine while running but I but I figured while I'm at it I may as well make sure I have all the bases covered). That's when I noticed that I had oil everywhere. As a result, putting it on a lift or looking for it while running is not presently an option.

The oil filter did appear to have some oil on it and there was a drip on the very bottom of it although not as heavy as others....I'm off to the parts store to get a new oil filter and oil as I may as well change those while I have the front up.

Jeff_Keryk

Oil pressure sender unit?

stumpshot

You've already checked this I'll bet, but, running a clean rag under the bottom of the valve cover gaskets will show leaks that can go right down the back side of the heads, down the block and trash the underside of the car. Also, rear intake manifold leak that hugs the top ot the bell housing and shows up on the oil pan, trans, rear end, blah,blah blah.
Just thinking of all the weird leaks I could have SWORN were coming from the oil pan (yeah, sure enough to yank the pan and replace the gasket) only to have the leak show up at the bottom of the timing chain cover or somewhere else.
Good luck!
Stump

73, Dark Blue 454

Clean all the leaked oil on the engine, then purchase and run one of the dye kits for finding oil leaks ($10).

I just saved you hours of time.

Also, it's my experience most oil leaks occur at the back of the valve covers (the ends closest to the firewall). Oil can pool up in that area then crankcase pressure pushes it out. Leaks from this area can fool you into thinking your rear main seal is leaking or the pan gasket.

Speaking of crankcase pressure, which aggravates oil leaking, are you running the PCV equipment?

Good luck!

sly vette

Since you stated that this started after you changed the clutch and oil filter make sure the gasket from the old filter came off with the old filter. Sometimes they will stick and when you install the new filter you will have two seals,between the filter and the housing,and they will leak. It's a long shot but I have seen it happen.

Peterbuilt

Your 100% correct! Two gaskets will leak A LOT! Found that out the hard way after changing an oil filter on a DC-3. Talk about a mess!

JimT

I have had leaks at the rear of my valve covers, oil pressure line/fitting, blowout at valve cover breathers (valves needed adjusting and no pcv), and the rear seal. I've also fought a leak on my old XKE oil cannister - this arrangement used an "O" ring that has to be changed. I found an old, dry "O" ring had been left in the ring groove - so it can happen.
good luck

jtramont

Thanks guys....

I checked the oil pressure line, valve covers and for the infamous second seal...think we've all been there on that one at one point! I also cleaned up everything I could under the car and so far, no more drips. I am almost certain it was coming through at the oil filter gasket. Although I had to use a filter wrench to remove it, I found it intially tightened easier than loosened. If that didn't fix it, the dye is a great idea.

JimT

An overtightened oil filter will also leak!

scottyp99

When I'm looking for an oil leak, what I like to do is clean everything up as well as I can, and then spray the whole thing down with aerosol spray foot powder. Makes even the smallest leak stick out like a sore thumb.


Scott

LS4 PILOT

Oil pan gasket fails with age, had to have mine replaced on the 454 , it was dripping out in several spots . While you replace the pan gasket , do the front and rear seals .

jtramont

Thanks Guys....

I took the old filter off and found that there was a tiny nick on the mounting surface. Don't know if that caused the leak or not but I switched to a PureOne filter where the gasket is slightly wider than on the Bosch or K & N and the problem went away....some days you just get lucky!

Hope everyone had a tremendous New Year holiday!