rear main leak

[rocket1]

I installed the short block from the rebuilder a couple of weeks ago,the rear main drips oil constantly as the motor is running,I figure the drain hole or tube might be blocked,I plan on pulling the pan to check on this,any other suggestions?

[Will N]

Call the rebuilder.

[Afordman31]

Originally Posted by rocket1

I installed the short block from the rebuilder a couple of weeks ago,the rear main drips oil constantly as the motor is running,I figure the drain hole or tube might be blocked,I plan on pulling the pan to check on this,any other suggestions?

I have a motor that was doing the same thing, leaking from the rear main (so I thought.) I removed the flywheel and found that the gasket that seals the rear of the cam bearing wasn't sealing. I put a new gasket on with sealer and this cured my so called rear main leak. Hope this helps. Afordman31

[V4F]

Call the rebuilder. !!!!!!!!!!

[Purdy Swoft]

Did the rebuilder install the drain tube ? If the drain tube is screwed in even a little bit too far, it will cause rear main leaks . Parking the car with the front higher than the rear will allow oil to flow past the rear slinger .

[Mitch//pa]

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call before you do any work

[Marshall V. Daut]

Wipe off the flywheel housing on the front and underneath to remove any oil that leaked out. Start the engine and lie underneath the car to see where the oil drips out. If it drips down the front of the flywheel housing past the flywheel inspection plate (the half-moon shaped metal one), then it's either a missing gasket between the engine block and flywheel housing, as already suggested, or the rear cork gasket on the pan was not installed properly. If, however, the oil drips through the small hole at the bottom of the flywheel housing where the cotter pin arms hang out, then it is most likely a rear main bearing leak. Rear mains generally don't leak down the front of the flywheel housing; they usually drip out of the bottom. Once you determine where the oil is coming from, you'll know what to do to fix the leak. Unfortunately, if someone forgot to install the gasket between the block and the flywheel housing, the engine has to come out. All that work to install a 75 cent gasket!
Marshall

[rocket1]

I removed the flywheel inspection plate oil drips out of rear main into flywheel housing,rebuilder is 10 hrs. away,he would only say bring it back,not practical, I will drop the pan and check the passage in bearing cap and make sure tube is open and not threaded to bottom of hole.

[Benson]

Does it still leak if you run the engine with the breather cap removed?

[Purdy Swoft]

Another thing to check is the rear main bolts. Sometimes a loose fit of the bolts, inside the rear main cap can cause leaks . I used the modern style main bearing bolts that use sealed washers and use no cotter pins. These bolts are easier to work with. I used the modern bolts on my last two engines and neither one leaks a drop. The only thing is you would have to either remove the engine or the transmission and flywheel to install them now.

[James Rogers]

Modern rear seal?

[Lowell Fast]

Who Is the "Rebuilder" and where is the rebuilder located.? We need to point out these guys to each other. The rebuider should be responsible for having it shipped back to his site.
This is a major *&^*^*&^ to correct if the gasket is leaking or missing. You will never be happy with this engine.nor will anyone where you stop or park.

[James Rogers]

I and some other rebuilders I know, have stopped using the modern seals because of failures. I tried to install all the modern types and never had but one that sealed right and, I tried everything to get them to work. I have even begun replacing the slinger on the crank so the original system can be used. If you have a crank that the slinger has been cut off, I can replace it so you can run the original system. If replacing the slinger does not cure your leaking problems, the leak is from bad clearances or incorrectly done babbitt.

[colin1928]

1 of the things that cause a leak is bad thrust clearance
a quick test is to push the front pulley back with a tyre lever and have someone push the clutch pedal down if you see the crank move you have your problem
this only takes 1 minute without dismantling anything
for single plate clutches only

[Purdy Swoft]

From my experience, I wouldn't push on the crankshaft pulley at all. The cast iron pulleys are very easily broken. Yes, I've have broke crankshaft pulleys and it doesn't take much pressure to do it.

[rocket1]

Originally Posted by rocket1

I installed the short block from the rebuilder a couple of weeks ago,the rear main drips oil constantly as the motor is running,I figure the drain hole or tube might be blocked,I plan on pulling the pan to check on this,any other suggestions?

I pulled the pan,the rebuilder had installed a homemade drain pipe in rear main,about 4 inches long and loosely threaded into cap,not sitting into pan oil.I installed the proper pipe,also the recess where the front pan seal sits had a wide crack,I took picture and I will contact him,bye the way leak stopped after my repair.

[BlueSunoco]

Thanks for posting an update. I learn lots reading them!

[Bruskie]

You need to post the rebuilder so everyone knows who to stay away from

[Tom Endy]

Remove the cap from the end of the breather tube (where you put oil in the engine) and examine the tube or the cap for any blockage. Drive the car a bit with the cap off and see if the problem goes away.

We had a fellow who bought a car from one of our club members. The car was in excellent condition with a newly rebuilt engine. The new owner knew nothing about Model A's. The first thing he did was to go to the local Model A store and load the car up with every glitter accessory he could find. One of the accessories he bought was a highly chromed breather cap. Unfortunately the cap was not a breather cap, it was a solid plug; apparently for a street rod that used an engine with some other type of venting system.

The new owner brought the car back to us because it was pouring oil out the rear main like someone had turned a spigot on.

We felt some obligation to the new owner so we dropped the pan and pulled the rear main cap expecting to find the drain pipe plugged or fallen out. The other possibilities were the thrust washer broke off or the Babbitt fell out of the rear main.

Everything was perfect just like Henry ordered. We had no other option than to put the engine back together. I went to put new oil in the engine and when I tried to pull the chrome cap off the whole tube came off the block. That is when we discovered the cap was not a vent.

We quizzed the owner and he told us he had just installed the cap that day and until then there had not been an oil leak. Lucky for him he noticed the massive leak or he could have destroyed a perfectly good engine.

We found an original vent cap and installed it and the leak was gone. I was astounded by how massive a leak can occur by blocking the vent tube off.

This was a lesson learned for me and it should be a lesson learned for those that stuff Brillo pads in the vent cap to filter the air.

Tom Endy