Irish69427

My muncie trans has gone crazy. It is blowing gear oil out of all the seals and the front when running. It acts like it is pressurizing some how. I have never seen anything like it. Neither have any of my mechanics. To my knowledge there is no real vent on a muncie. Just a hole at the bottom of the front bearing retainer. What could cause this?

Zoix

Drain it and fill it with GM syncromesh or equivalent so the oil just starts to come out the fill hole. If it still leaks you probably need to rebuild it. The case could be worn in the area where the counter gear shaft is located (front) thus leaking. Good luck.

AzMotorhead

Sounds like your gear oil is foaming. Drain it and refill with proper fluid to proper level

Irish69427

It is not a gear oil issue. The gear oil was never touched or changed. Simply pulled the trans and put it back in as I replaced the shortblock. Same gear oil as before. But you run the engine about 5 minutes and the oil starts pouring out the front of the trans. Swapped it for another unit I have that is freshly rebuilt. DID THE SAME THING. What could be causing this. As the only thing that changed was the engine block could the input shaft be binding to one side or something so that the front bearing retainer is not pushing the oil back as is should. Have talked to at least 5 mechanics and NONE have a clue and have never seen this happen.

calif phil

Sure sounds like engine oil to me. You sure the rear main seal or intake manifold end seal is not leaking.

Les

That's the only thing that makes sense. What are the odds of 2 different transmissions puking oil? One would be strange enough.

Irish69427

It is not engine oil, this bellhousing has a removable cover plate on the bottom. You can stand there and shine it up on the trans input shaft and bearing retainer and watch it come pouring out. The pan and rear main are dry as a bone. Not to mention I know what gear oil smells like and its viscosity compared to engine oil. After you run it 5 minutes the trans is half empty. It is the trans, period.

AzMotorhead

Always heard no question is a dumb one, so.......
How full is the trans when you start?
Normal full level is 3/4 inch below the fill hole

Les

I wish I could help you but I've never heard of anything like this. Please post the answer when you get it figured out because I think we, including your mechanics, can all learn something here. Good luck.

mikejpss

Since you have the same issue with 2 different tranny's, it MUST be in the motor. You mentioned a new short block. IMHO, your problem lies there as you also mentioned (above). Occam's Razor rule applies here in my opinion. If you look hard enough, your answer will be in the new short block- rear main bearings,etc....unless of course, your newly rebuilt tranns was not properly rebuilt .. are you convinced it was done correctly also?
In ANY case, I am hoping you will post the answer to this riddle when you find it. Good luck.

Garys 68

Any chance the front bearing retainer was taken off?
If it's clocked wrong it wont drain back.

MelWff

found this on another site which may pertain to the second rebuilt transmission

My bet is that the retaining nut is installed backwards... About 25 % of the muncies i take apart that were rebuilt before have the nut on backwards.... The nut is actually a oil slinger arrangement that is designed to vent the transmission and keep the oil from running out the bearing retainer...

sly vette

Just an interested spectator but these 2 posts make the most sense so far!

JOEY CARTEE

After 20 years building and playing with muncies, this will be a good one!!!! Please let us know as im dumber than dumber????

Rockn-Roll

This might be a dumb question, but have you installed the drive shaft and speedometer cable? If not, then that's where it's coming from. Gear oil will get slung onto the top of the tranny and then run down to the back and out the tail shaft through the speedometer cable hole or output shaft.

68L79

Will ask my mechanic friend tomorrow...he will know if anyone in America knows what is wrong...he has shelves that have muncie parts and gears that are piled 4 ft high and they are at least 25 ft long...he has built more/fixed more muncies than chevy has. He was the corvette specialist for years before moving to his own shop at his house. The dealership begged him to let them bring the troubled cars that no one else could fix to his house...he declined as he had a hell of a reputation all over this town and everyone wanted him to fix their cars...me included...the book calls for 8 hours to pull a vette rear end (68) or so...it takes him 45 min with a friend helping.

We were just talking yesterday about venting auto trans and engines and rear ends....

Jimmy in NC

Irish69427

It may have something to do with the motor but it is not the motor. Keep in mind guys we are talking about alot of oil coming out and the trans oil level gos down very quickly. NOT the engine oil. It is not engine oil, trust me. My only theory so far is that the dowel pins on the back of the block are off and the trans is input shaft is being pushed to one side on install. This might jam the input shaft to one side while spining instead of freewheeling in the center of the pilot bushing as normal. This then might alow the oil to come out the other side as it isn't being pushed back into the trans correctly. This is backed up by the fact that two trans missions have the exact same problem - one newly rebuilt and the other was already in the car and worked fine without problems. But I REPEAT it IS NOT ENGINE OIL or coming out the back of the engine.

Irish69427

It has a gear vendors overdrive on the back of the trans. So the tail shaft section is gone and replaced by the gear vendors. The two do not interchange lubricant.

Irish69427

I have also tried venting the trans through various means including taking out the side plug and putting in a piece of fuel line to let it vent. MADE NO DIFFERENCE.

Les

Very strange. So, awhile back you were having problems with your 496 but seemed to have it figured out if I remember correctly. My question probably has nothing to do with your current situation but I'm curious anyway- did you end up replacing that 496 for some reason?