Transmission leak

[Bradley D.]

67 327/350 wMuncie 4-speed.

I've noticed after a long drive (more than 10) I get transmission fluid drip. Sometimes quite sizable.
It is bothersome. Since it is now on a hoist awaiting parts(trailing arms), I've taken a closer look and have determended that it is transmission fluid coming from the front of the transmission.

I've read a few older posts about this issue and have no clear cause/fix. As I understand there is no seal on the input shaft, only a 'oil slinger' (whatever that is) to prevent the fluid from leaking. Another idea is that the fluid is over filled.
Should be 1/2 inch below the fill hole. The service manual says to fill to the fill hole.

My thought is to put gasket sealer around the outside along the seam between the trans and the engine.

I could not find any real solution, just how it works. Am I off base here?

Another unrelated question. I have trouble doing a search and getting back totally unrelated posts. If you do a search on 'transmission' you get stuff on wiper transmission, or radio transmission. How do you/can you be more selective. I've tried using 'text' but that doesn't work either.

[Paul J.]

Re: Transmission leak

Brad, the transmission fluid is coming from inside the transmission (I know that you know that), but the fluid/oil is running down the outside of the front, so by blocking it you can make a bigger problem. Unfortunately, I don't know of an easy fix.

As far as the search engine, this happens to me too. If it could accept phrases it would help, but if you're patient you can usually find what you want.

Paul

[Jim T.]

Re: Transmission leak

Bradley many years ago (1966) I had a 58 Impala with 348. I put a Muncie 4-speed out of a 1964 El Camino in my 58. Problem occurred after many miles, the front retainer that bolts to the Muncie broke, leaked transmission fluid and was replaced. The end of a round shaft that can be seen on the front of the transmission can also leak transmission fluid.

[Mike M.]

Re: Transmission leak

cluster gear shaft, as it inserts into the front of the case, is almost certainly the source. remove tranny and have it repaired. good luck, mike

[Joe L.]

Re: Transmission leak

67 327/350 wMuncie 4-speed.

I've noticed after a long drive (more than 10) I get transmission fluid drip. Sometimes quite sizable.
It is bothersome. Since it is now on a hoist awaiting parts(trailing arms), I've taken a closer look and have determended that it is transmission fluid coming from the front of the transmission.

I've read a few older posts about this issue and have no clear cause/fix. As I understand there is no seal on the input shaft, only a 'oil slinger' (whatever that is) to prevent the fluid from leaking. Another idea is that the fluid is over filled.
Should be 1/2 inch below the fill hole. The service manual says to fill to the fill hole.

My thought is to put gasket sealer around the outside along the seam between the trans and the engine.

I could not find any real solution, just how it works. Am I off base here?

Another unrelated question. I have trouble doing a search and getting back totally unrelated posts. If you do a search on 'transmission' you get stuff on wiper transmission, or radio transmission. How do you/can you be more selective. I've tried using 'text' but that doesn't work either.

Brad------

By far, the biggest culprits behind this problem are as follows:


1) Worn countergear shaft orifice in the main case.

2) Worn front retainer bolt tappings in the main case.

Either requires removal of the transmission and dis-assembly for proper repair.

[Don H.]

Re: Transmission leak

67 327/350 wMuncie 4-speed.
I have trouble doing a search and getting back totally unrelated posts. If you do a search on 'transmission' you get stuff on wiper transmission, or radio transmission.
How do you/can you be more selective. I've tried using 'text' but that doesn't work either.

Brad- click below to go to recent thread in Discussion Board Help forum on Searching tips.
https://www.forums.ncrs.org/showthre...earch-Function

[Bradley D.]

Re: Transmission leak

Brad- click below to go to recent thread in Discussion Board Help forum on Searching tips.
https://www.forums.ncrs.org/showthre...earch-Function

Thanks Don that should help.

[Domenic T.]

Re: Transmission leak

Brad,
The most common leak is caused by overfilling the trans and your discription seems to confirm what I think it might be ( to much oil).

The old books said to fill (COLD) 1/2" below the filler plug because the oil rises when hot and leaks out around the input shaft.

It has been said to fill lower than 1/2 " by many rebuilders and thats what we do.

The newer muncies have a seal on the input shaft.

There is a possibility that it is leaking in the front of the trans where the cluster shaft exits the case and that can be sealed with the trans moved back about 1/2 " .
You spray carb or brake cleaned on the shaft, blow it dry, and seal it with a sealer like RTV. The cluster shaft is not sealed and usually leakes when the trans gets old. The trans has to be tightened to the bellhousing before the sealer dries so also clesn the bellhousing.

I use a sealer and then put a very a thin piece of plastic wrap about 2" round on the trans over the sealer I put on to insure a good seal when the trans is pulled against the bellhousing.


DOM

[John D.]

Re: Transmission leak

Brad
I would suggest you install the trailing arms and drive the car all summer and worry about the trans drip some other time...these things have a habit of taking a long time.

[Tom P.]

Re: Transmission leak

cluster gear shaft, as it inserts into the front of the case, is almost certainly the source. remove tranny and have it repaired. good luck, mike

Mike has pointed out the MOST LIKELY cause.
Yes, there are other causes (as already mentioned), but unless something is broken (front bearing retainer, stripped threads for the bearing retainer, etc), then it is probably the hole for the cluster gear shaft (lots of people INSIST on the correct term, counter gear, us old guys still call it a cluster gear). In time, with lots of miles/use/abuse, the steel shaft in the alum hole applies enough stress/pressure that the hole becomes enlarged. The shaft is a press fit in that hole and once it loosens, you have a leak. There are multiple temporary fixes, such as pulling the tranny, cleaning the oill off of the front of the tranny, applying a copius amount of sealant around the hole and bolting it back up to the bell housing--------------------THAT DOES NOT FIX THE CAUSE OF THE LEAK---------------it's only a "bandaid" fix!
I've been building 4spds (mostly Muncies) for 45+yrs, and 95% of the front oil leaks that I've seen are from a loose hole for the cluster shaft.
There is only one fix. Either requires TOTAL disassembly of the tranny. Then, either have the hole reduced in size by swedging, OR, send the case to an EXPERIENCED person to have the hole bushed. If it has a matching number case (VIN stamped on the case), then it may be worth the expense of having the case fixed. Otherwise, locate a case with a super tight hole-----------------OR, buy a new Autogear Muncie.
Oh ya, the proper oil level is up to the bottom of the filler hole. Fill it until the oil begins to run out of the hole, screw in the plug real quick and wipe off the oil that runs down the side of the case.
And there is not, and never has been, an oil seal at the front of a Muncie. That's an old wives tail from people who know nothing about a Muncie.

[Domenic T.]

Re: Transmission leak

Tom,
strangly enough I have done 2 later muncies that had the seal in the front bearing retainer.
Now as I see it that's the only place for the trans to breath ( the hole at the bottom of the retainer) and in my old manuals (1960's) it said not to fill to level
but 1/2 " down.
If you checked a hot trans that was filled to the hole then you got a cup of hot oil running down the side, and I had that happen many times doing a grease job that required all fluid levels to be checked.

There' a gear place ( I think in Michigan) that agrees and says to fill about 1" (below) as the gears will sling oil every where.
I think the book was at the chevy dealership that specified the 1/2" below, COLD in the tranny back in the 60's.

Now in the 50+ Ive been doing them I only found 2 with seals and they were on models near the end of production.
They may have been added by another rebuilder but for the sake of knowing maybe someone could look it up in a parts book.

DOM

DOM

[Dick W.]

Re: Transmission leak

If you can reach the transmission oil with your finger, it has enough in it. Plenty of leaks are the result of overfilling.

[Bradley D.]

Re: Transmission leak

Brad
I would suggest you install the trailing arms and drive the car all summer and worry about the trans drip some other time...these things have a habit of taking a long time.

Yeah, this is what really going to happen, I need to drive it this summer. I will reduce the fluid a bit see what gives. Then decide.
Parts for trailing arm are due any day.

[Joe L.]

Re: Transmission leak

Tom,
strangly enough I have done 2 later muncies that had the seal in the front bearing retainer.
Now as I see it that's the only place for the trans to breath ( the hole at the bottom of the retainer) and in my old manuals (1960's) it said not to fill to level
but 1/2 " down.
If you checked a hot trans that was filled to the hole then you got a cup of hot oil running down the side, and I had that happen many times doing a grease job that required all fluid levels to be checked.

There' a gear place ( I think in Michigan) that agrees and says to fill about 1" (below) as the gears will sling oil every where.
I think the book was at the chevy dealership that specified the 1/2" below, COLD in the tranny back in the 60's.

Now in the 50+ Ive been doing them I only found 2 with seals and they were on models near the end of production.
They may have been added by another rebuilder but for the sake of knowing maybe someone could look it up in a parts book.

DOM

DOM

Dom-----


I don't know of any seal used on the front of any 63-74 Muncie, either. In addition, I just checked the parts catalogs and I can't find any reference to a seal.

[Bradley D.]

Re: Transmission leak

Thanks to all that responded. I have replaced both trailing arms (left was the source of the noise) as both were in need of repair.
Things are much better now.

The trans leak will be tested using a lower fluid level( removed some when on hoist) and will await results to see it it a next years project.

Until then I'm back to driving it and will have it judged this fall.

:-)