VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc 1932 rear main leak

I have searched for an hour and can not find the post about grooving the rear main bearing. Any help or info appreciated as I am in the process of removing the pan and rear main . After running for only five minutes I had a 6" puddle after shutting it off. If the ball is stuck is it wise to just remove it?

In my opinion I would not remove the ball, but do make sure is is free and the passage is open. The amount of oil you are seeing leads me to believe that there is another problem such as bearing fit too loose, too much crankshaft end play or?

To grove the bearing according to Doug Bell's book "The Cast Iron Wonder" they used to place two hack saw blades side by side and make a grove in the babbirr from the center oil grove to the front of the bearing. This relieves pressure to the rear of the bearing. When I did this on my '39, and it worked I went to off center of the botom of the bearing where the insert is not getting a load. The '39 was driven at high speeds for many thousands of miles after that with no problem.

When the ball check gets stuck in the up (back) position of the main bearing cap a massive oil leak will occur about the size you are describing because the oil can't return to the oil pan. When you get into the rear main bearing if you determine that the ball check is actually stuck in the up (back) position, remove it. I have talked to a lot of fellows over the years that have removed the ball check with great success on eliminating massive oil leaks due restrictions caused by the ball check.

All my '31 and '32 engines still have their rear main cap balls. I obviously didn't and still don't know a valid reason to remove it. The free area in the cap with the ball against the pin is larger than the hole at the bearing which therefore does not impede oil flow. Only reason that I can think of to have the ball impede the flow is if there is crud in the passage. That is a condition that I would like to know about. A large unusual leak might just do that.

Thanks Gene and JYD. Before I pull it apart perhaps a little history would help. To get the rear drums off I tried applying the brakes with the car raised off the ground but was unsuccessful. Next I started the car and moved it outside to try and loosen the rear drums with the nut backed off and went back and forth applying the brakes. When I put the car up on stands I noticed the fresh oil spillage. I am wondering if the torqueing of the crank by applying the brakes might have caused the leakage. I did have to use to use a puller and just took it for a ride and at least the brakes are smooth and quiet thanks to the Kimball/Midwest brake finishing treatment. It is now back in the garage with two new pig mats under it and after 15 minutes there is only one drop of oil. It has eighteen years of usage since hitting the road so I am not alarmed by the buildup of grime and it sure could use a good cleaning. That said I don't want to take it apart at this time with the Six Cyl tour only two weeks away . I am hoping it was a one time occurrance .

I am ruling out the crud buildup scenario at this time as the engine has been completely disassembled twice and only gets about 500 miles of usage between oil changes with 10-30 detergent oil. This is the first time I have had a leak of this size. ( And I am crossing my fingers that it's the last).

I would like to add some times they will leak more with cold oil. The pressure is higher and return in the passage slower due to the cold heavy oil. Take it for a 10 mile ride and check again.
Note that the 1932 engine has full oil pressure to the rear main, first year for that improvement.

Gene beat me to it. I had a bad leak problem but I was only starting it up and moving it around the shop. When I let it warm up it hardly leaks at all. My ball was gone when I checked and I did channel the bearing as Gene describes.

Dave

Just read you post Gene and with cold oil my oil pressure burys the needle. With warm oil it will idle with 7-9 lbs and at 35 MPH has 20 lbs. Did do the ride-see my post above . The oil was cold when I was revving it up and trying to dislodge the rear drums . I kept a copy of the bearing fix so if I do take it apart I will groove the bearing as you described. Thanks for the quick reply.

A '32 engine is not designed to hold 30+psig oil pressure or even 20 psig when hot. It is not surprising to have a leak when you have that high oil pressure.

I am fully aware that the majority of advise is to have higher oil pressure but it is not beneficial in these older engines.

I have been running '32 Chevrolet engines for nearly 50 years and have no desire to have more oil pressure than the engines were designed to have.

I don't know why the pressure is that high but it has been that way since it's first rebuild 18 years ago. This is the first time since that it "spit out" any oil.It was rebabbited and line bored but I do not know which oil pump was used.

I had a '28 engine that had been sitting a long time. When I put oil in and started it the pressure gauge pegged past 30 psig. I immediately shut it down. Found hard black tar like pieces in the oil supply tubes. Removed them by taking the tubes out and rodding/blowing them out. Started it again and normal 10-15 psig oil pressure for a minute or two then pegged the gauge again. Removed engine a second time, removed oil tubes and found each of the ends of the tubes to the main bearing wells had a small piece of that stuff plugging it. Once that was removed the pressure was back to normal: 10-15 psig on startup, ~8 psig at speed (hot) and 1-2 psig idle. It and I were both happy.

Aside: I got really good at removing and installing '28 engines w/transmissions attached.

I'll bet

I have been through the issue of the rear main leak on my '37.

I did remove and reinstall the check ball. I did that so I could thoroughly clean the ball itself. It had what appeared to be a coating of dried oil.

I also removed the same type of coating from the drain passage and the area where the ball seats in the rear main cap.

My efforts did reduce the oil loss. I still have some leakage but I now wonder if the problem is a leaking plug in the block at the rear of the cam shaft. I will probably wait until this winter to pull everything to get to that area. For now I just keep an eye on the oil level and a drip pan under the car.

Just a thought -- These engines are notorious for having the valve cover gasket leak at the rear edge with the oil running down the back of the head and the block and coming out as if it were a rear main leak. You might want to pull the valve cover and look at the gasket and the seating pattern before you go much further, just to be sure.

All the Best, Chip

Hi Chip,

Not sure but perhaps you were responding to my post. Thanks for the reminder about the rear of the valve cover.

Yes, it was leaking there. I made sure the valve cover flanges were at 90 degrees and flat. I installed it with a new 1/4" gasket. Best I can see it is not leaking from that area now.

Got a '32 with most of the symptoms mentioned in this post. Oil pressure at 30 cold and leaking badly at the back of the block. Body is off so I can see its obviously not valve cover gasket. Bellhousing and flywheel not removed yet so can't see exactly what is leaking. Oil level just below full on dipstick. Engine just back from rebuilder. Called him and he mentioned that this engine does not have rear seals, and a gasket is required between the bellhousing and the block at camshaft. Is this accurate?

Your leak is probably due to the ball check being stuck in the up position in the rear main cap or the oil clearance on the rear oil slinger is not correct.

Thanks JD. Will check it out.

It is correct that the engine does not have a rear crankshaft seal, only a slinger ring. There is no gasket between the clutch housing and the block at the camshaft. There is in fact a "freeze plug" in the rear opening of the rear camshaft bearing to prevent oil leakage there. It's part number 836574. But that is unlikely to be the problem.


I agree with JYD about the source of the leak -- either a stuck check ball in the rear main bearing cap or an improperly adjusted rear main bearing. There are tons of discussions of this problem here on the forum. Just search for "rear main leak" and you should find them. Good luck with it.....

All the Best, Chip

Talked with engine shop guy. It's possible they didn't install the camshaft rear bearing hole plug. (They thought there was a gasket to be installed between block and bellhousing) Part #836974. Found it in my parts book but it does not give size. Anybody know diameter and thickness? Or is there a common freeze plug that works?

I checked a couple of books with no luck but did find the number in my 32 book is 836574.I have one more place to check. Found it 836574 is 1-5/8". Good luck.

It's a standard thickness 1-5/8" freeze plug. NAPA or any standard car parts place can get them for you. I usually coat the edges with copper-coat sealer before seating the freeze plug, and if possible (i.e. if the engine is out of the car), it's best to install the cam and shim the plug out about .020" from the end of the camshaft before seating it. Then you can pull the cam back out and remove the shim. That way the camshaft isn't rubbing against the freeze plug when you make the final assembly.

But I'd still bet that the problem is down in the main bearing cap rather than the unsealed camshaft hole, because I believe the bell housing covers that completely and even without a gasket, leakage would be minimal.

Hope you're able to sort it out without too much trouble.

All the Best, Chip

Removed bellhousing (again). No plug at end of cam shaft. The bellhousing actually does not completely cover the hole (only about half) so this looks to be the source of the leak. Questioned the shop guy about the main bearing cap and ball check etc.and he said it was all good. Hopefully installing the plug solves our problem. Only question left is why didn't they notice the leak when they spun the engine at their shop?
Thanks for all the good advice and info on this. Much appreciated.

Missing a "freeze" plug is a pure indication that the machine shop is just not up to date on vintage engines. They may do good work on the modern stuff, but take your vintage engine elsewhere.