Kerouac

Hello Everyone:

I recently posted a picture of a pool of fluid under my car (1965 Coupe, 327/365 L76 w/ 4-speed Muncie).



I thought it was oil, and several of you gave me some good suggestions on what to check and tighten, etc. Everything seemed to check out, and also my oil level (on the dipstick) remained full. Tonight, while climbing under there, I noticed what appears to be a crack in my transmission housing. See below:



Now I'm wondering if maybe that fluid is transmission fluid. So what do you think? Can a cast housing have a surface crack and still be fine? Or am I looking at a complete replacement? Tranny seems to work fine, although from time to time I hear a grinding noise as I try to put it in reverse.
As always, I appreciate the help, guys.

anyChevy

It sure looks like a crack. See if you can feel it with your fingernail, then wipe it clean, let it idle and see it weeps.
Also gear oil has a distinct smell and is usually thicker than engine oil.

Kerouac

Thanks. I'll wipe it down tomorrow and see. This fluid has no smell and seems pretty thin.





Thanks again. I'm hoping this isn't a cracked tranny.

66jack

Check the fluid level in trans...when you pull the plug it should be right at the top almost running out of the hole when you pull the plug....

Check it cold...

Use your little finger and reach in a little at a time checking each time until you feel the oil...that will let you know about how much its low...

tuxnharley

The distinct odor and heavy viscosity would be true if it was filled with the old trans oil, like 90 weight.

Many rebuilt trans have been using the newer lighter weight synthetic fluids for easier shifting, especially when cold.

Sounds like maybe that could be the case with yours. How long have you had the car? What do you know about the history of the trans?

Kerouac

pm sent.

Kerouac

Thanks for weighing in, tuxnharley. Bought the car in May. Don't know much about the history of the transmission, but the car had a frame-off restoration about 8 years ago. After I bought it I had Corvette Specialists in San Dimas, CA, do a lot of work for me -- new wiring, correct radiator, etc. They did a pretty comprehensive check of the car and there was no red flags regarding the transmission. It shifts great, although I occasionally get a grinding sound when I'm trying to get into reverse. Thanks again.

Dave Tracy

The grinding when you put it in reverse is because the reverse gear does not have synchro rings. Many times it happens when you have the transmission in neutral, clutch out, and want to put it into reverse. To stop it, put the transmission into any forward gear first then into reverse.

Kerouac

Man, I love tips like that! Thanks, Dave.

Boyan

Pull the dipstick. Take it to the oil puddle. Smell both . If they smell the same its engine oil, if the puddle one smell is much stronger , its trans fluid.

DansYellow66

I have never seen a picture of a Muncie cracked like that. But I've been very lucky over the years in avoiding engine and transmission carnage so doesn't mean much. They do make a reproduction Muncie housing now that is superior to the original so if it is cracked (and it sure looks like it) a rebuilder can swap your other parts into a new case and rebuild as necessary. Probably some good original cases around also. The tip on shifting to 1rst or 2nd before slipping it into reverse works really well.

Roger Walling

It seems to me that if you had a crack that big, oil would be seeping out so bad that the whole underside of the car would be covered with it and the case would be flexing so much that it would be very noticable as a crack.

Kerouac

Very smart. Will do that today. Thanks.

Kerouac

That's what I think, too. I need to get it up on a lift and have a really good look around.

Easy Rhino

The M20 tranny fluid capacity is only 2 1/2 pints when full, so there is another indicator for you. If I had your indications, I would check tranny fluid level first, but I would also take 1/2 pint of similar viscosity oil and pour it on your garage floor (to match the surface finish which affects the spread of fluids on your floor). If 1/2 pint looks like 1/5 of you puddle, you have about 2 1/2 pints on your floor - matching the tranny capacity. Also, if you have 2 pints on the floor puddle, that's one quart and may be all the tranny had in it if it is a leak, plus one quart engine oil leak loss should be visible on your engine oil dipstick.

Also, while you're at it, dip a corner of one paper towel in the puddle, another corner of a paper towel in your crankcase oil (drop it off your dipstick, and one corner of a paper towel in your tranny oil (while you've got the plug out checking the level). Then compare the engine oil and tranny oil with the oil from the floor.

Besides the smell and absence of indications of engine oil level dropping, you can use every indicator to narrow the choices.

I'm assuming that you have eliminated any other possibilities, such as power steering? Not that many places it could come from.

That does look like a nasty crack; however, it may not be a complete through-crack, but it could be through in a small area, which would somewhat limit the leak rate.

I hope it's not that your tranny case is cracked.

I agree that the reverse grinding is not indicative of a cracked case. As long as the front and rear faces of the tranny case remain parallel, a longitudinal crack would not result in grinding (but if it is a crack, it will tend to grow). If it is a crack, your choices are not as good, and you should not drive it and risk the tranny grinding, resulting in more damage beyond the tranny itself..

Good luck.

426 Hemi

I've had good luck tracing down oil leaks using powder type aerosol deodorant: http://www.motorcyclecruiser.com/no-...nes-and-drives

Might be worth cleaning off the side of the trans and shooting some on there.

jimgessner

I see a lot of oil on the bell housing in the second photo. If this car just went thru a large service, the leaks should have been recognized. The ''crack'' is not a normal one, and I have broken a few Muncie transmissions racing, and they never cracked the case, just the gears inside.

You need to get this to a transmission shop ASAP.

Kerouac

Hey Guys: Got a lot going on with the holiday and family and barbecues, so I haven't responded to everyone individually. But I am grateful for people like anyChevy, 66jack, tuxnharley, Dave Tracy, Boyan, DansYellow66, Roger Walling, Easy Rhino, 426 Hemi, and jimgessner.

As to the pool of liquid on my garage floor -- it looks, smells, and feels like oil. I cleaned up the whole area today and also wiped down the transmission main case and the oil pan. I put down some paper so that I'll be able to identify the source of any new drips. I'll keep you informed. But again, thank you one and all.

Boyan

The pan looks like its recently been replaced. Maybe the shop needs to take a look at it to make sure it didnt split upon installation. Also, keep an eye on the engine oil level anytime you drive it.
Boyan

macdabs

Go to your local Napa and purchase some oil/ trans dye . Start with the transmission first . Go for a 5 mile ride after adding the dye and stop at the local craft store or Lowes. Purchase a 60 watt black light bulb.
Install the bulb in a drop light when home and the dye will glow green/yellow in the crack if the trans is leaking. Do the same with the engine oil with the other half of the bottle if the trans comes back with no glow.
You can PM me if you need any more details.