Multiple oil leaks 1964

Joined
Sep 8, 2021
Thunderbird Year
1964
Just curious... having my Bird in the shop for losing oil... many seals, gaskets leaking. Rear main seal, valve covers, pcv blowing out all over engine...too many to list. My guy feels it is because there is a pressure issue, oil being forced out everywhere it can, intk the starter, over the front, down the block because it can't go to where it needs to properly. Going to replace all seals and gaskets, pcv, whatever it takes to stop the bleeding. Only 61k miles, sat a good while before I got it. Everything, absolutely everything, is original, never been touched nor fixed nor repaired previously on this engine. As I said, just curious as to dealing with a car with so many leaks and any feedback as to what else we should be looking into?Thanks!
 
Joined
Aug 14, 2019
Thunderbird Year
1957
I can't figure out why there would be so much pressure in your block. I think your diagnosis is correct but how is the engine designed to breath? In my 'Y' block it is pretty simple, breather up top and an exhaust tube out the back.
 

74 Harley

Active Member
Joined
Jul 8, 2020
Thunderbird Year
1962
Pcv? Not in '64 to my knowledge. If this car is truly original and untouched then it's leaking because the gaskets and seals have simply died. They would be 57 years old, and the valve covers, oil pan, & intake end seals are cork. Rear main is probably a rope seal.
While you have the engine out replace the transmission seals also.
 
Joined
Sep 8, 2021
Thunderbird Year
1964
I can't figure out why there would be so much pressure in your block. I think your diagnosis is correct but how is the engine designed to breath? In my 'Y' block it is pretty simple, breather up top and an exhaust tube out the back.
Ty. Not sure myself, he was puzzled too. Gonna start with compression check then trying to figure out why all the oil so under pressure. Definitely spraying everywhere under the hood...

Pcv? Not in '64 to my knowledge. If this car is truly original and untouched then it's leaking because the gaskets and seals have simply died. They would be 57 years old, and the valve covers, oil pan, & intake end seals are cork. Rear main is probably a rope seal.
While you have the engine out replace the transmission seals also.
Not sure if he meant it to be what we think of as a modern pcv set up but definitely a positive crankshaft ventilation mechanism he spoke about. There was some non-standard other owner rigging involved in which some meshing had been fitted into the unit and he thinks thats playing a part. Ty for the feedback!
 

74 Harley

Active Member
Joined
Jul 8, 2020
Thunderbird Year
1962
If stock it will have a "road vent" tube from the back of the manifold down the right side. The oil fill tube has a vented cap, and a sheet metal wing to deflect air into the vented cap.
"Positive crankcase ventilation" is air drawn by vacuum from either the valve cover or manifold.
Any pressure in the crankcase is the result of faulty rings.
How long had this engine/car been sitting? With some running it may clean up some, but I will still stand by my original post about the age and materials used. Good luck, keep us posted.
 
Joined
Feb 9, 2019
Thunderbird Year
2002
Even a new engine has some "blowby" and running the engine pressureizes the crankcase; these engiens are big air pumps after all.
However that pressure should be either scavenged out by the old road draft tube or siphoned out by a PCV system.
Many older cars were converted to PCV and it often wasn't done properly....some got pressurized so much the dipsticks were blown out of their holes. It was not uncommon for the worng PCV valve to get installed.

Frankly, I would be tempted to run the car a few hundred miles with some Marvel Mystery Oil in it and see if things got better.
 

ducksface

1963 Sports Roadster 3x2
Joined
Oct 27, 2021
Thunderbird Year
1963
If they're blowing oil, the new gaskets are needed.
However,
Buy a cheap valve cover, with the oil filler cap in it.
This should vent the oil chambers enough to stop the blow by. It'll make a mess if it's an air pressure in the oil system problem, wont make a mess if it's just the gaskets are ruined.
Also
Check your current oil filler while the car is running. If it pulses, you have a compression or exhaust leak into the oil system.

Do an oil pressure check. Too high of an oil pressure will have pushed out any press-in pressure limiter you have in the block(though I think 64 was screw in limiter)

There are many things to diagnose BEFORE the gasket changes,
 
Last edited:
Joined
Jun 3, 2020
Thunderbird Year
1955
There is another possibility unfortunately. Run a compression test and look for a weak cyl. A cracked piston can make all kinds of blowby (pressure) in the engine. Also stuck rings caused by decades of sitting.
 

doug7740

Active Member
Joined
Dec 29, 2014
Thunderbird Year
1955
If you perform a cylinder leak down test test you will know for sure if the piston rings are the cause of your problem. By placing each cylinder at Top Dead Center and applying 70 psi of shop air into the cylinder, if the piston rings are defective when you remove the oil filler cap you should hear the air entering the crankcase.

doug7740
1955 Thunderbird Blue
 

64ZCODE

Active Member
Joined
Aug 18, 2018
Thunderbird Year
1964
Just curious... having my Bird in the shop for losing oil... many seals, gaskets leaking. Rear main seal, valve covers, pcv blowing out all over engine...too many to list. My guy feels it is because there is a pressure issue, oil being forced out everywhere it can, intk the starter, over the front, down the block because it can't go to where it needs to properly. Going to replace all seals and gaskets, pcv, whatever it takes to stop the bleeding. Only 61k miles, sat a good while before I got it. Everything, absolutely everything, is original, never been touched nor fixed nor repaired previously on this engine. As I said, just curious as to dealing with a car with so many leaks and any feedback as to what else we should be looking into?Thanks!
Yes to what everyone is saying. I would also replace the PCV valve and make sure the associated tubing isn't plugged. If the PCV system isn't pulling fumes out of the crankcase, they have to go somewhere.
 
Joined
Sep 5, 2018
Thunderbird Year
1955
Just curious... having my Bird in the shop for losing oil... many seals, gaskets leaking. Rear main seal, valve covers, pcv blowing out all over engine...too many to list. My guy feels it is because there is a pressure issue, oil being forced out everywhere it can, intk the starter, over the front, down the block because it can't go to where it needs to properly. Going to replace all seals and gaskets, pcv, whatever it takes to stop the bleeding. Only 61k miles, sat a good while before I got it. Everything, absolutely everything, is original, never been touched nor fixed nor repaired previously on this engine. As I said, just curious as to dealing with a car with so many leaks and any feedback as to what else we should be looking into?Thanks!
I
 
Joined
Sep 8, 2021
Thunderbird Year
1964
There is another possibility unfortunately. Run a compression test and look for a weak cyl. A cracked piston can make all kinds of blowby (pressure) in the engine. Also stuck rings caused by decades of sitting.
Thanks. Pistons, rings, all fine. Compression check great. Changed out all the gaskets, seals, unclogged the blowby, removed meshing someone stuffed up the pcv...all seems good now.
 
Joined
Oct 10, 2021
Thunderbird Year
1964
Just curious... having my Bird in the shop for losing oil... many seals, gaskets leaking. Rear main seal, valve covers, pcv blowing out all over engine...too many to list. My guy feels it is because there is a pressure issue, oil being forced out everywhere it can, intk the starter, over the front, down the block because it can't go to where it needs to properly. Going to replace all seals and gaskets, pcv, whatever it takes to stop the bleeding. Only 61k miles, sat a good while before I got it. Everything, absolutely everything, is original, never been touched nor fixed nor repaired previously on this engine. As I said, just curious as to dealing with a car with so many leaks and any feedback as to what else we should be looking into?Thanks!
I would first check the Breather off the back if in take that goes to carb. Pull all the plumbing off of in take and clean insides or replace. the metal piece that reduces down to make flow less is gummed up on the in side. and check of course breather/oil fill cap
 
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