I am getting a moderate amount of oil leakage focused at the rear passenger side of the engine. It tends to accumulate on the frame rail on that side, but it’s hard to pinpoint a focal area. The highest and farthest forward point I see oil is the lower passenger side spark plug guide bracket.

My first though was valve cover, but it is not wet. Second thought was rear main seal, but why would oil chiefly accumulate on the passenger side, and show evidence ahead of the block/bell housing seam? I should note that there is no flywheel dust cover installed and no gasket/seal on the starter where it bolts to the bell housing.

So, does this scenario sound familiar to any experienced y-blockers out there?

1954 Crestline Victoria 312 4-bbl, 3-speed overdrive

Check that the most rear threaded holes in both cylinder heads behind the intake manifold have bolts in them.  In your particular case it would be the 3/8-16 threaded hole under the distributor.  The end holes on the intake side of the cylinder heads are open to pushrod holes.  If no bolt in the hole, then make sure the bolt that's being installed is short as too long will cause pushrod damage.

Lorena, Texas (South of Waco)

Kinda like a SBC threaded hole to hold the fuel pump push rod up when you’re changing a fuel pump. Some trucks and all 55-57’s used the hole for a mount. Leaving it out gives you a built in oil leak. GMC 6’s do it with side mounts. They even use copper washers.

56 Vic, B'Ville 200 MPH Club Member, So Cal.

I checked and both holes have bolts in them. On the passenger side, the bolt is holding the upper spark plug wire bracket. On the driver side, the bolt is securing a ground strap. It didn’t look like either was a leak source, but if you think it’s worthwhile I could pull them and apply a bit of thread sealant.

I was under the car for an oil change tonight and noticed quite a bit of oily sludge on the driver side rear of block as well, running down to the oil pump from somewhere above the head/block seam. The car usually leaves a few drops of oil when parked after a drive. When I did the clutch a few months ago I degreased and power washed the block, so I believe this is new accumulation over the past couple hundred miles. Maybe I need to degrease it all again, drive a small warm-up loop and check everything before it has a chance to spread all over everywhere.

1954 Crestline Victoria 312 4-bbl, 3-speed overdrive

Back of the valley pan? You running a clean, well maintained road drift tube or have you fitted a PCV system?

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

It’s a road draft tube. I do periodically check the block-mounted filter. For a tired engine, there really isn’t much blow-by.

The area around the distributor behind the valley pan looks dry to me. I’ll see if I can get some decent pictures on here.

1954 Crestline Victoria 312 4-bbl, 3-speed overdrive

Y-Block valley pan leaks are notorious. Once it’s overtightened/warped, likely only RTV can seal it.

6 VOLTS/POS. GRD. NW INDIANA

When I rebuilt my last 292 I drilled and tapped around the Valley Pan for short Machine Screws. Cast Iron was easy to drill and Tap. No leaks from the Top of Motor.

  

I inspected the valley cover area as best I could today. It really does not appear to be a leak point. Looking more closely, I observed that the top and sides of the bell housing are completely clean. The flat area of the block behind the valley cover isn’t exactly clean, but it doesn’t present like an active leak. The area between the passenger side head and the distributor was the dirtiest, but again, didn’t look like an active leak area.

This sent me back to the valve covers. Looking from below, I could see some glistening around the perimeter of the driver side valve cover gasket. I think perhaps I didn’t have the valve cover nuts as snug as they should be, or that the relatively new cork gaskets had settled in some and required retorquing. I removed the covers, wiped down the mating surfaces, and reinstalled at a measured 2.5+ ft-lbs. I’ll report back whether it makes any difference.

1954 Crestline Victoria 312 4-bbl, 3-speed overdrive

Mine has always had minor leaks from the rear area. I have had the oil pan off on occasions and can never see where a leak is or coming from. The top off-the engine is tight. The best thing I did was add a PCV system that put a slight vacuum on the engine. The other is run the engine 1/2 qt low on oil. Don’t know why that helps but it does. I installed positive oil seals when I had the heads off and lapped the valves which had 10K miles. It uses no oil that I can tell and I change once a year @ 1000-1500 miles. Good luck. 

56 Vic, B'Ville 200 MPH Club Member, So Cal.