My first vehicle! 1956 CJ5

[bmorgil]

Looking good 56"! What a great time with three generations, favorite cars, at the show!

Nicely done 56', way to go man!

It is a big job to go after that oil leak if it is the rear main seal. Nothing you cant handle however. It could also just be the pan. Since the issue seemed to occur after a "High RPM" run down the hill, it could be the oil pan seal. Old motors with some ring bypass, combined with the oil splash from high RPM, can cause a lot of oil splash and pressure in the pan.

The rear main seal will always leak the most under pressure. If it is loosing that much oil, if it is coming from the rear main seal it will leak when it is idling with a steady drip. If you increase the oil pressure by holding the engine RPM up enough to achieve good oil pressure, the seal should start to pump out the oil. If the oil leak becomes significant while you hold the pressure up, but is not so bad when the engine is idling, it could definitely be the seal. If on the other hand there doesn't seem to be a big difference between idle and holding a high enough RPM to hold good pressure, I would suspect the oil pan gaskets and seals.

In our shop, we use air pressure to quickly identify leaks. You can seal up the engines openings and apply air pressure at about 3 to 5 psi. The leaks show up very quickly that way. Similarly, pressurizing the oil system will identify any pressure leaks. Lets see what you come up with on a preliminary look over.

Here is an excerpt from gizzard's build: https://willysjeepforum.kaiserwillys...toration/page2
The rope seal will eventually weep oil. Just the nature of the beast. I have seen them properly installed go past 50,000 but not much more. The rubber seal is going to be a less touchy installation and a better bet at a good seal the first try. It is important to check the dimension of the seal O.D. in the block. Not all blocks are the same. Not all seals have the same O.D..

The best tip I can give about leaks is to do it the way the factory does it. This technique is used by the top engine builders in the world. Seal up the obvious "holes" in the crankcase and apply about 3 to 5 psi of air to the crankcase. I have several "Jerry rigged" adapters set up with an air regulator. By applying a few PSI to the crankcase you will quickly find any leaks. You will hear the air seeping by the ring gaps and that should be it. The crankcase should hold a little pressure for a just a second or two. The air pressure should only be escaping past the ring gap and out through the valves. Blocking the exhaust and the carb and any other vents, should produce a fairly leak free crankcase, If you hear air hissing out from anywhere besides the ring path, its a leak. A little dish soap and water on a brush and watch for bubbles.

Here is info from Mark J's build: https://willysjeepforum.kaiserwillys...that-is!/page2
Mark, A quick diagnosis is to see if it drips more when it is running as opposed to when it just sits. The oil of course blows all over as you drive so it can be very dificult to find the leak as you know! When there is oil pressure, the rear main seal is going to leak if it is going to leak. If it is as bad as you indicate (3 pints yikes) I would expect a steady drip at 20 to 30 psi of oil pressure. In neutral have someone hold the rpm up so you can build some pressure and peer underneath. If the main seal is pumping oil it will start to drip at the bell housing to block.

I think there is a very good chance it is leaking at the rear main. You really cant install the wick seal (rope) without removing the crank, unless you like main seal leaks. To do it right it has to be "packed" into the cap and block then the crank is installed. You can use a new style metal backed seal (be sure you have the right one). You can do this one with the motor in the vehicle. You carefully and with a lot of lube, being careful not to cut the seal, work it around the crank in the block then reinstall the cap. The side packing on the main cap and the interface between the cap and the block are also common leak points. Don't trim the side rubber too far and use black silicone sparingly where the cap and block and side seals all come together. The service manual will help you here on the seal points. And as Larry said do try to use a torque wrench on the oil pan bolts if you can. Over torquing ruins it all. Though you can pound the pan back into shape, it is now weak around the holes and will probably just dent when you try to re-tighten it.

Keep us posted on your progress Mark. This is a common attempted thing changing the rear main in the vehicle. I have accomplished it on a few different types of motors. The Willys does pose some problems at the main cap. The side seals and pan can be a little challenging on an engine stand. It gets a little more interesting in the vehicle. All the oldies start leaking when there is pressure! They just need a little TLC. No do not put in any "magic poop".

Here is more info: https://willysjeepforum.kaiserwillys...-Main-Oil-Seal