1956 engine oil leak

[Mr. Bill]

My mechanic says that these old cars had many leaks because the gaskets were rope and not the type of gaskets they use today. Has anyone else had this problem and should I have the faulty gaskets replaced with the modern type gaskets or as a friend suggested a heavier cork gasket which was available for the older corvettes of the same vintage. Have others with 55, 56, and 57 T birds had similar engine oil leaks and from where mostly? the valve covers seem OK the oil pan is where I suspect the leaks but I have not had the car up on a lift yet. Any suggestions or ideas would be greatly appreciated.

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[rponfick]

Very common problem. I think there are two types of seals available: the older rope type, and a newer composite. Some speak highly of each type, and is a matter of installation.

 

[1957Bird]

Most common 312 Y block oil leak is unfortunately the rear main seal.
IMO the only replacement kit worth the time to install is from Prestige Thunderbird in California. Definitely not the cheapest but in my opinion the best available. Can be done with engine in the car but you need to pack a fair amount of patience.

 

[doug7740]

When I replaced the rear oil seal I followed these instructions and had great success.

https://www.Thunderbirdforum.com/ne...stallation-plus-other-key-points-to-consider/

doug7740
1955 Thunderbird Blue

 

[Mr. Bill]

I asked this question before about the engine leaking and members all suggested replacing the main seal. The suggestions were to get the seal from Prestige, either a graphite seal or a neoprene seal. Now my question is, which seal graphite or neoprene is better and which is easier to work with and last longer?

 

[doug7740]

I can only speak from my own personal experience and I have always used neoprene and had great success.

doug7740
1955 Thunderbird Blue

 

[intlhud]

I’ve owned my ‘56 since July. The previous owner kept the car parked for the better part of 14 years, and claimed little to no oil leaks over that time. Visual inspection beneath the car supported his claim. Of course there should be little leakage if the car hasn’t been used. But I saw little evidence of long term staining or caked on oil/dirt.. The car has 83k miles. Since buying I replaced some external components, changed oil and filter, installed new gas tank. In the time since July I’ve drivien little more than 100 miles. More serious oil leaks started to show up during my first “big” road trip last week. Prior to the road trip I discovered that all the bolts on the oil pan were quite loose. I tightened them all, but not necessarily to torque specs. During my 300-odd mile road trip last week, oil leaks began within 60 miles, and grew worse as the week wore on. When I returned home I noticed considerable oil on my shop floor that occurred overnight. Some appears to be new oil, as I would expect from the recent oil change. Some is dirty oil, which may be oil dripping from the dirtier parts of the undercarriage. Or, maybe not. Is my sudden leakage the result of the car sitting up for more than a decade? The former owner says he cranked it occasionally, adding a gallon of gas from time to time to let it idle for awhile. I would think that should keep seals and gaskets somewhat pliable. Putting the car on a rack revealed a considerable amount of leakage from my initial 100-mile drive about. I strongly suspected the loose bolts on the oil pan as being the source at that time. So, my question is where do I start? I don’t have a rack, so I’m limited to Jack and Jack stands. That doesn’t allow for much old body (mine) flexibility and poor lighting. Should I try some Lucas oil leak stopper to give it some time to heal? Is there any way to isolate the source of the leak(s) other than visual? I don’t plan any lengthy road trips in the upcoming 2-3 months, maybe pressure wash as best I can and start looking? Any suggestions are appreciated! Thanks, Bob

 

[Ward 57]

I believe there is a dye you can put in the oil that shows up under a black light. Don't know how available it is but pressure wash and then any source of the leaks should show up.

 

[74 Harley]

A lot of the gaskets in that car are probably cork. Over time they will deteriorate,shrink,crack, or harden like a rock. Oil pan and valve cover gaskets are probably going to be required. There's no easy way out.

 

[Brax]

My mechanic says that these old cars had many leaks because the gaskets were rope and not the type of gaskets they use today. Has anyone else had this problem and should I have the faulty gaskets replaced with the modern type gaskets or as a friend suggested a heavier cork gasket which was available for the older corvettes of the same vintage. Have others with 55, 56, and 57 T birds had similar engine oil leaks and from where mostly? the valve covers seem OK the oil pan is where I suspect the leaks but I have not had the car up on a lift yet. Any suggestions or ideas would be greatly appreciated.

 

[Brax]

My mechanic says that these old cars had many leaks because the gaskets were rope and not the type of gaskets they use today. Has anyone else had this problem and should I have the faulty gaskets replaced with the modern type gaskets or as a friend suggested a heavier cork gasket which was available for the older corvettes of the same vintage. Have others with 55, 56, and 57 T birds had similar engine oil leaks and from where mostly? the valve covers seem OK the oil pan is where I suspect the leaks but I have not had the car up on a lift yet. Any suggestions or ideas would be greatly appreciated.

Only use the neoprene seal the joints with RTV and the side seals with RTV. These rear main seals are available at most auto parts stores gel pro and cost about $15 . Always check the bearing clearance and replace if border line . Also only use cork for valve cover.

 

[Ward 57]

Only use the neoprene seal the joints with RTV and the side seals with RTV. These rear main seals are available at most auto parts stores gel pro and cost about $15 . Always check the bearing clearance and replace if border line . Also only use cork for valve cover.

True mechanics HATE RTV on the gaskets. A light coat of spray gasket adhesive is all that's needed to set the gasket and let it do it's job. Lots of discussion on the use of neoprene or original cork gasket material, no judgment.
The biggest reason for pan gaskets and steel valve cover leaks is that the mating surface has been bent due to overtightening. Plenty of time with a ball peen hammer on a proper surface will be your friend.

 

[Brax]

True mechanics HATE RTV on the gaskets. A light coat of spray gasket adhesive is all that's needed to set the gasket and let it do it's job. Lots of discussion on the use of neoprene or original cork gasket material, no judgment.
The biggest reason for pan gaskets and steel valve cover leaks is that the mating surface has been bent due to overtightening. Plenty of time with a ball peen hammer on a proper surface will be your friend.

RTV is used to seal the joints of 2 main seal pieces and the 2 cap seals. Think you misunderstand you’re not making a gasket just sealing. As for a ball peen hammer leave it in the box where it belongs.

 

[doug7740]

When replacing the rear main seal I have always followed Gil Baumgartner's instructions and never had a problem.

doug7740
1955 Thunderbird Blue

 

[Ward 57]

There are definitely uses for RTV But slathering it on in place of proper gaskets or surfaces is not recommended is the point I was trying to make.

 

[Frankie the Fink]

Well - I'd be surprised if you had the original rope seals - but maybe. If not, the try some Blude Devil Oil Stop Leak. I'm not usually a fan of additives (many are snake oil) but this stuff cured a rear main seal and crank snout seal in my 63 Corvette and an oil leak in the daughter's 2014 Jeep Hemi. It won't hurt a thing to try it; it actually re-vitalizes seals and gaskets:

Amazon.com

Many FLAPS also sell it locally.