1970 Muncie 4-speed fluid question
Thread Starter
Pro
Joined: May 2006
Posts: 573
Likes: 5
From: Georgetown Township MI
1970 Muncie 4-speed fluid question
Hello,
I have what appears to be a transmission fluid leak, covering the underside of my car.
I changed it a couple of years ago. I think I may have put too much in. I can't
remember if I had the car in the air on floor ramps or jack stands.
So hear is a dumb question:
Can it be siphoned out if elevated on ramps in front?
I read an article recently that said the gear lube may have additives in it that may be
affecting my seals and recommended siphoning out all of the fluid and replace it with
only 1 quart of straight 50 motor oil.
The only kind of 50 weight oil I found was
Valvoline VR1 Racing Oil SAE 50. Could this work?
Thanks.
Joe
I have what appears to be a transmission fluid leak, covering the underside of my car.
I changed it a couple of years ago. I think I may have put too much in. I can't
remember if I had the car in the air on floor ramps or jack stands.
So hear is a dumb question:
Can it be siphoned out if elevated on ramps in front?
I read an article recently that said the gear lube may have additives in it that may be
affecting my seals and recommended siphoning out all of the fluid and replace it with
only 1 quart of straight 50 motor oil.
The only kind of 50 weight oil I found was
Valvoline VR1 Racing Oil SAE 50. Could this work?
Thanks.
Joe
Last edited by Rudy's Stingray; Aug 5, 2011 at 06:41 PM.
Drifting
Joined: Mar 2006
Posts: 1,526
Likes: 2
From: Oak Ridge NC
If you can get it level on jack stands or a lift, then remove the fill plug and let the excess drain. When it stops draining, then it's filled properly.
Many conversations over the years on which oil. I use 75/90 gear oil. You think that going to 50w will stop the leaks? And only 1 qt?
Many conversations over the years on which oil. I use 75/90 gear oil. You think that going to 50w will stop the leaks? And only 1 qt?
Thread Starter
Pro
Joined: May 2006
Posts: 573
Likes: 5
From: Georgetown Township MI
I went to the local GM dealer 3 years ago where they looked it up and
recommended GM SAE 80W90 Axle Lubricant. Since then, it has leaked.
I filled it to the bottom of the fill plug. Like I said in my original post, the drain
and refill with the 1 quart straight 50 motor oil was what I read. I'm just repeating
what I read and thus asking the question, have you ever heard of this?
recommended GM SAE 80W90 Axle Lubricant. Since then, it has leaked.
I filled it to the bottom of the fill plug. Like I said in my original post, the drain
and refill with the 1 quart straight 50 motor oil was what I read. I'm just repeating
what I read and thus asking the question, have you ever heard of this?
Pro
Joined: May 2011
Posts: 581
Likes: 5
From: BC
I went to the local GM dealer 3 years ago where they looked it up and
recommended GM SAE 80W90 Axle Lubricant. Since then, it has leaked.
I filled it to the bottom of the fill plug. Like I said in my original post, the drain
and refill with the 1 quart straight 50 motor oil was what I read. I'm just repeating
what I read and thus asking the question, have you ever heard of this?
recommended GM SAE 80W90 Axle Lubricant. Since then, it has leaked.
I filled it to the bottom of the fill plug. Like I said in my original post, the drain
and refill with the 1 quart straight 50 motor oil was what I read. I'm just repeating
what I read and thus asking the question, have you ever heard of this?
I stress "immediately" because what often happens is that several weeks or even months go by after the change and the leak appears. It may have absolutely nothing to do with the fluid change.
Wash it down and look carefully for your leak. There is no front seal used on that trans. It has a "thread" cut into the input shaft that spins the oil back into the case when it reaches the input shaft. So the leak is going to be externally visible. There's a reasonable chance it's a simple fix, seal on the slip yoke, loose bolts on the side cover, speedo gear retainer etc. I can't remember for certain, but I think there are o-rings on the shift shafts. You can remove the side cover to replace the ones in the 1-2 and 2-3 shift shafts, but the reverse requires disassembly of the trans.
Steve g
Thread Starter
Pro
Joined: May 2006
Posts: 573
Likes: 5
From: Georgetown Township MI
I've never heard of it and I wouldn't do it. A lot of research goes into determining the correct oil, and gear oil has been it forever. If you filled it to the bottom of the fill plug and it started leaking immediately afterwards I would suspect that someone had previously filled it with an oil thickner like STP or that Lucas crap to stop the leaks. Or the old oil had started to thicken on it's own if it had been in there a long time.
I stress "immediately" because what often happens is that several weeks or even months go by after the change and the leak appears. It may have absolutely nothing to do with the fluid change.
Wash it down and look carefully for your leak. There is no front seal used on that trans. It has a "thread" cut into the input shaft that spins the oil back into the case when it reaches the input shaft. So the leak is going to be externally visible. There's a reasonable chance it's a simple fix, seal on the slip yoke, loose bolts on the side cover, speedo gear retainer etc. I can't remember for certain, but I think there are o-rings on the shift shafts. You can remove the side cover to replace the ones in the 1-2 and 2-3 shift shafts, but the reverse requires disassembly of the trans.
Steve g
I stress "immediately" because what often happens is that several weeks or even months go by after the change and the leak appears. It may have absolutely nothing to do with the fluid change.
Wash it down and look carefully for your leak. There is no front seal used on that trans. It has a "thread" cut into the input shaft that spins the oil back into the case when it reaches the input shaft. So the leak is going to be externally visible. There's a reasonable chance it's a simple fix, seal on the slip yoke, loose bolts on the side cover, speedo gear retainer etc. I can't remember for certain, but I think there are o-rings on the shift shafts. You can remove the side cover to replace the ones in the 1-2 and 2-3 shift shafts, but the reverse requires disassembly of the trans.
Steve g
Thanks so much for your reply. My biggest problem, no lift.
I got the car in the air using my ramps. From what I can see,
the leak is coming from where the motor and transmission come together.
The transmission fill plug had a light amount of fluid under it so I barely
tightened it. I can put up with a few drips here and there and will just check
fluid levels periodically until I have to get it repaired.
Melting Slicks
Joined: Aug 2008
Posts: 2,200
Likes: 3
From: Lehigh county Pennsylvania
And NO, I have not heard of filling a Muncie with 50wt engine oil.
Drifting
Joined: Oct 2010
Posts: 1,873
Likes: 134
From: Bushkill Twp. PA
St. Jude Donor '17
Make sure you use GL4 gear oil, most of whats in auto parts stores is GL5. GL5 is not good for our old syncros. I got mine from amsoil. It took about 1.5 bottles, a bottle pump is also handy to get it in the fill hole.
http://www.amsoil.com/storefront/mtg.aspx
Synthetic Manual Transmission and Transaxle
Gear Lube 75W-90 API GL-4 (MTG)
http://www.amsoil.com/storefront/mtg.aspx
Synthetic Manual Transmission and Transaxle
Gear Lube 75W-90 API GL-4 (MTG)
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Advanced
Joined: Jul 2007
Posts: 99
Likes: 1
From: Iowa Park TX
I was preparing to put Royal Purple mine, but just read the previous post that said use GL4, but not GL5. does anyone know off of the top of their head which one the RP is? If it's a 4, I'll use it; if it's a 5 I'll go with the Amsoil....
Burning Brakes
Joined: Mar 2011
Posts: 969
Likes: 1
From: NJ
Drifting
Joined: Oct 2010
Posts: 1,873
Likes: 134
From: Bushkill Twp. PA
St. Jude Donor '17
I can get you the part # if you'd like from the bottles that I put in my car.
Burning Brakes
Joined: Mar 2011
Posts: 969
Likes: 1
From: NJ
I read some people say their manual specifies GL4, other say to use GL5. Just looked in my manual and all it says is to use SAE 80 or SAE 80-90 Multi-purpose gear lubricant MI-L-2105B.
Where did the GL4 / GL5 specs come from?
Where did the GL4 / GL5 specs come from?
Burning Brakes
Joined: Mar 2011
Posts: 969
Likes: 1
From: NJ
Do you personally use the STA brand from Napa? I stopped by my Napa and that was THE ONLY GL4 they had. Not a popular brand and not looking as flashy as other bigger brands ... is the quality as good? Anybody using the STA gear lube?
Melting Slicks
Joined: Aug 2008
Posts: 2,200
Likes: 3
From: Lehigh county Pennsylvania
I drained the Richmond GL6 gear lube that I had in since last year, (my Muncie has a drain plug)
and poured in the StaLube GL4 about 300 miles ago. Not a long enough time to fully judge it qualities. But it has not seized up the gears yet.
Yes, GL4 is hard to find these days. Not unlike most things needed for antique performance cars. I was happy somebody still made it. CRC in Warminster, PA., not some inferior CHINA knockoff.
and poured in the StaLube GL4 about 300 miles ago. Not a long enough time to fully judge it qualities. But it has not seized up the gears yet.
Yes, GL4 is hard to find these days. Not unlike most things needed for antique performance cars. I was happy somebody still made it. CRC in Warminster, PA., not some inferior CHINA knockoff.
Instructor
Joined: Jul 2008
Posts: 105
Likes: 1
From: germantown tn
HAVE ALWAYS USED stalube gl4 , i have a drain plug change it every 2 years or there about, make sure to drain add a pint or so roll it a few times and redrain , make sure it is level and fill till it runs out, when the garage gets real cold mine may drop a dime size drop from the drivers side , thats nothing . i had to go check for some reason i thought i had used swepco lube before
Last edited by KHW34; Oct 14, 2011 at 12:21 AM.