'56 leaky rear main, $%#!@*@!#$!!!!!!!!!!!!!!!!!!!

[Guest imported_NikeAjax]

Besides ripping the motor out, and restuffing new packing in, is there any way of fixing the rear main when it leaks???!?!?!?!?!? Razafraz freaking stinking, grrrrrrrrrrrrrrrr! Perhaps pull the pan then the rear-main-cap and repack that? This is pretty upsetting, it leaks like a stuck pig.

Thanks,

Jaybird

[Guest]

i did a repair on my rear main seal for $350 bucks with no warrenty from the shop.

The new cork gasket lasted three years with "car show" driving.

The truth is it's not your cork seal, but your warn out crank shaft.

[Buicksplus]

Ditto on that, though it's not just the crankshaft but also excessive crankcase pressure due to blowby past the piston rings. When that happens the oil runoff from the rear main bearing cannot easily fall back into the crancase and it gets pushed out past the seal.

That rear seal can usually be replaced, but it is difficult. I think Tommy1927 got a pretty good deal having it done for $350. But the chance of it significantly reducing your leak is poor.

If the car runs OK and you don't want to rebuild the engine, just bring along a little extra oil and a nice drip pan in your garage. Much cheaper and works every time. You might clean the oil filler cap and all the crancase vents too, that's usually easy and it might help a bit.

Good luck!

Bill

NM

[Guest imported_NikeAjax]

No, it's not that, but thanks. I just rebuilt the motor over the summer; everything is new. This flippin' thing has leaked from the get go, and I've read from other people's postings that it's not an uncommon happening on rebuilds.

Thanks,

Jaybird

[Guest]

well, that is a pisser!

Both my cadillac v8 and buick straight -8 don't lose a drop after four years since rebuild with high oil pressure.

I will add that my rebuilder shop did weld a metal collar around the crank shaft were the seals are.

I think they cut the crank down, and then weld the ring back up to spec.

[JohnD1956]

I thought my 56 rear main seal was leaking but found out it was leaking from the oil filter instead. Up against the block side, dripping like crazy and flowing down the back of the oil pan. May not be the problem, but if you've had a recent rebuild, I'd check on that.

Also, I forgot where I saw it, but apparently the oil filter housing has a stamped steel gasket originally? Did the rebuilder use one of those in this location?

JohnD

3757

[Guest imported_NikeAjax]

I've been cutting the gasket myself; is this one of those very rare aplications that I shouldn't? It kinda looked like this is where it was leaking from, oil filter area, but just couldn't see where it was coming from, by jings! Would RTV work, that being if I wait until it completly cured to torque the bolts?

Thanks fellers,

Jaybird

[Judd]

Jaybird

My AutoZone gasket set cam with paper gasket for the oil filter housing. I was told to use a 3.8 V6 rear main seal and 455 Buick front seal, I plan to try this set up on the 322 I am in the middle of rebuilding now.

[brad54]

I've heard the same thing about the later model rubber main seals. Give that a try--I need to do the same thing with my '54 264.

I don't buy the thing about high pressure in the crank case, caused from blow-by past the rings, "forcing" the oil past the seal--the last time I checked, the oil dipstick goes directly into the oil pan, and there is no gasket or seal on it--it just drops down into the hole in the block. If crank case pressure from the bottom end were a problem, any excess pressure would escape out the dip stick hole.

Plus, the lifter galley is open to the bottom end. And the heads have oil drain holes to the lifter valley, and on the '56 with valve cover breathers, any pressure from the crank case is going to escape there as well. On the '53-'55, it's just going to go out the road draft tube. Our engines aren't sealed--the oil being forced past seals would probably be an issue with later closed PCV systems--particularly with a plugged PCV valve.

-Brad

[old-tank]

Here is a method that I use that works for me.

Pull the pan and the main bearing cap (that is another story...ask and I can detail that later if needed). If the engine has a lot of miles replace the rear main bearing. Inspect the rear main seal for glazing, I a mean hard glass-like surface (some replacement seals are fiberglass are nearly impossible to cut with common tools and will glaze in a short time)...if glazed both the top and bottom will need to be replaced. Replace at least the seal in the main bearing cap, being sure that there is none clamped between the cap and the block. Put a thin coat of anerobic sealer on the clamping surface of the cap and install and torque to specs. Next pack the side grooves with cotton string and No. 2 Permatex (I use a nail and hammer it in tight)...donnot use the cork or rubber thingys that are supplied in the gasket set.

My bet on a new engine is: either the seals are glazed or the side seals and clamping surface is leaking.

I once tried to replace the upper and lower seals with neoprene on and installed engine and that leaked very severely

All of this is much easier with the engine on and engine stand.....

Willie

[Buicksplus]

Brad:

Since Nike's comments about his engine being rebuilt, I agree that crancase pressure is not the problem with this particular engine, assuming it was properly rebuilt.

But in general, the fact that the crankcase is vented via the dipstick and various other openings does not mean that it will not pressurize due to blowby. With major blowby, the flow through the vents is high enough so the crankcase develops sufficient positive pressure to block the return of rear main oil back into the crankcase. When that happens, the oil inevitably ends up getting past the rear seal. This only takes a tiny increase in pressure, since the normal oil return is through small passages by gravity.

Older engines often develop other oil control problems when the blowby gets too great for the ventilation system. I had one very warn engine that would collect large amounts of oil in the valve covers because the blowby flow up from the crankcase to the vent on the valve cover prevented rocker oil from returning to the crankcase. This led to plenty of oil consumption through the valve guides.

Bill

NM

[Guest]

bill is correct on the blow by issue.

my Cadillac v-8 with the $350 replaced rear seal had a BIG blow by problem, one cylinder was at 96 psi, when the other were 165 psi, and the oil filler cap would puff white smoke signals by the time the engine was shot. (the rear seal took four quarts of oil out of the engine before I got it home the 100 miles)

The theory behind the one bad cylinder is that gasoline when over floed out of the carborator would run into number one cylender and strip off the oil.

either way, this problem sucks, I hate to hear anyone having such a bad time with a re-build engine.

[jaxops]

Jaybird,

One other thing to think about is that the rear main seal should be a single piece, and it is usually a rope seal. A 2-piece unit might tend to leak. I wouldn't recommend RTV or a lot of gasket sealer to stop the leak. In my 56 Caddy (still a GM), it took about 100 miles of driving it around before it stopped leaking. Rubber and gasket seals tend to be more instant sealers, but rope seals have to wear-in. Not something that I was used to. Just something to consider.

Merry Christmas

[Guest imported_NikeAjax]

Thanks fellers! John D's old problem sounds like mine, so I'm gunna pull that oil filter dingus yet again, and see if'n that helps at'oll; razafraza stinkin, fragazaga! I did the rebuild myself, over the summer, and it has a couple of hundred miles on it, so I don't think any more miles on it will help the problem. I was very carefull to put the rope in and torque it to 110lbs. before cutting the stuff left over, so dang'it John, you'd better be right 'cause the smell of burning oil at stoplights is driving me nutz!

Hey, do they still use babbit in modern bearings? The engine on my Rambler uses aluminum bearings, it's a 1963 motor, and a Fiat, don't laugh at me, it wasn't mine, I worked on had the same? If not, when did they stop using it?

Thanks again gang!

Jaybird