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Username Post: Leaking a thick oil, where from?        (Topic#362582)
tkruger 
Newbie
Posts: 30

Reg: 07-19-18
09-15-20 08:53 AM - Post#2803508    

I have a 1941 Master Deluxe with the original drive train.

After running it (idle in place) the last time a thick oil seems to have leaked from somewhere around the transmission. I could see a small drop on the drain plug but that is tight and seems to be a low spot.

Is there a common spot for these to leak from? Could it just be that I have a gasket that dried out? I am looking for a starting spot to go from. My kids and I are learning this as we go.

Little history:

Car was last known to be on the road in 1969.
My sons and I have been bringing it back to life over the last two years. All fluids have been replaced. After replacing the water pump, all the belts, hoses, plugs etc. it idles perfectly. Needs other work before going on the road and has not been run other than in neutral and in place (other than a 1 mile trip two years ago to make sure the tranny shifted properly, it did). Holds temperature perfectly and last was run for 20 minutes straight.



 


pauldian 
Contributor
Posts: 337
pauldian
Loc: seligman,arizona
Reg: 05-14-09
09-15-20 02:57 PM - Post#2803528    
    In response to tkruger

Sounds to me like it might be the rear engine
main seal that's leaking ? Just my opinion !



 
2blu52 
"19th Year" Silver Supporting Member
Posts: 19475
2blu52
Age: 87
Loc: Montana
Reg: 03-12-02
09-15-20 03:40 PM - Post#2803533    
    In response to tkruger

Transmission oil has a specific smell if that is not obvious then it is probably engine oil leaking from the rear seal. Pull the clutch housing cover, if it is wet with oil inside then the source would be the rear main seal. Over time it will ruin the clutch disc.

"PEACE IS THAT GLORIOUS MOMENT IN HISTORY WHEN EVERY ONE STANDS AROUND RELOADING"

THOMAS JEFFERSON


 
1971BB427 
Contributor
Posts: 430

Loc: Portland,Or
Reg: 12-06-09
09-16-20 07:41 AM - Post#2803570    
    In response to 2blu52

If it's gear oil from the transmission, there are a couple places it can leak from. My first guess would be the front seal, as wear over the years, or sitting and drying out can cause them to leak when you start driving again after a long rest.
The other less likely place is the gasket that seals the shifter plate. But that's not very common, even after sitting.


1969 Suburban 2wd 350
1939 Chevy pass. coupe 350/700R4
1937 Austin gasser 327/TH350


 
tkruger 
Newbie
Posts: 30

Reg: 07-19-18
09-17-20 07:17 AM - Post#2803643    
    In response to 1971BB427

What is leaking is far thicker than oil. The oil level also has not changed in all the time it has been leaking. I did notice a smell that I could not place in my garage, not a strong one but it is well ventilated too. When we are working the doors are all open. What is the smell like? What does the oil in the transmission look like? How thick is it? This is thick like syrup, does not flow well.



 
1971BB427 
Contributor
Posts: 430

Loc: Portland,Or
Reg: 12-06-09
09-17-20 08:21 AM - Post#2803650    
    In response to tkruger

Best way to describe gear lube smell is it stinks. Unlike any other lubricant in any other part of a car. You could easily pull a plug on the transmission and put a fingertip in it and then sniff it to compare the smell to what's dripping. There'd be no doubt at that point what it was.


1969 Suburban 2wd 350
1939 Chevy pass. coupe 350/700R4
1937 Austin gasser 327/TH350


 
tkruger 
Newbie
Posts: 30

Reg: 07-19-18
09-17-20 12:21 PM - Post#2803667    
    In response to 1971BB427

  • 1971BB427 Said:
Best way to describe gear lube smell is it stinks. Unlike any other lubricant in any other part of a car. You could easily pull a plug on the transmission and put a fingertip in it and then sniff it to compare the smell to what's dripping. There'd be no doubt at that point what it was.



No the question of what should be in the transmission? I am yet to open it up and change the fluids there. I am wondering is it may have been filled with 100+w gear oil or something and that is what is on my floor. It is thick like that. The oil I put in the engine (30w) flows far easier, hence the reason I suspect that it is not oil (but I have not pulled the cover to prove it). Joy of old cars that you do not know all of the history of.



 
1971BB427 
Contributor
Posts: 430

Loc: Portland,Or
Reg: 12-06-09
09-17-20 06:37 PM - Post#2803697    
    In response to tkruger

Might easily be 90 wt. gear oil in those old transmissions, but if you haven't changed it, then it might be too low to put a finger in and check the smell. But if it's thick, and gooey it's likely gear oil from the trans.
If the trans has to be removed to reseal it, it's not going to be a simple job. The enclosed driveline requires the rear axle to be unbolted and slid back before the trans can be removed for new seals. If it goes that far, then the trans should be closely inspected, and at the very least all new seals put in, even if the trans looks great inside.


1969 Suburban 2wd 350
1939 Chevy pass. coupe 350/700R4
1937 Austin gasser 327/TH350


 
tkruger 
Newbie
Posts: 30

Reg: 07-19-18
10-15-20 01:01 PM - Post#2805531    
    In response to 1971BB427

Took the cover off the floor and had a good look from the top and the bottom. Also took the little inspection cover off on top of the bell looking at the clutch. Clutch area is dry. It is slightly moist around the upper rear of the side cover where the linkage goes in. The speedometer cable is moist but not wet. The bottom of the torque tube is moist.

The car only leaks when it is running and warm for 20+ minutes. Note that I have not moved it so is it really possible to have it leaking from heating up?

Where do you fill this from? The speedometer cable? Also does the torque tube take any fluid?



 
2blu52 
"19th Year" Silver Supporting Member
Posts: 19475
2blu52
Age: 87
Loc: Montana
Reg: 03-12-02
10-15-20 04:10 PM - Post#2805545    
    In response to tkruger

On the passenger side pf the transmission there a square headed nut, remove that and stick your finger in the hole bend it down and if it touches oil you are okay, if no you need to fill it. The torque tube does not need oil. But you should check the differential by removing the square headed plug located about center of the rear cover. Use the finger trick again.90W gear oil is what the manual calls for in both cases.

"PEACE IS THAT GLORIOUS MOMENT IN HISTORY WHEN EVERY ONE STANDS AROUND RELOADING"

THOMAS JEFFERSON


 
1971BB427 
Contributor
Posts: 430

Loc: Portland,Or
Reg: 12-06-09
10-16-20 07:10 AM - Post#2805575    
    In response to tkruger

There's a seal at the transmission end of the driveline tube that fits closely to the pivot "ball" on that end of the tube. It's there to keep gear oil inside the tube, and might be dried out. It could be dried out, or cracked, and may need replacing. The cover is a two piece bolt together flanged unit, but once split it will require the driveline to be split to allow the new O ring seal to be installed. That's a bit of a task, as it takes a fair amount of labor to split the driveline to get the seal into the housing.


1969 Suburban 2wd 350
1939 Chevy pass. coupe 350/700R4
1937 Austin gasser 327/TH350


 
2blu52 
"19th Year" Silver Supporting Member
Posts: 19475
2blu52
Age: 87
Loc: Montana
Reg: 03-12-02
10-16-20 05:44 PM - Post#2805621    
    In response to 1971BB427

I did my Oakie bushing in about 3 hours start to finish.

"PEACE IS THAT GLORIOUS MOMENT IN HISTORY WHEN EVERY ONE STANDS AROUND RELOADING"

THOMAS JEFFERSON


 
Mel Foye 
*VIP* Original Founding Member Group
Posts: 4982
Mel Foye
Reg: 09-29-00
10-26-20 04:05 PM - Post#2806276    
    In response to tkruger

1) Thick oil leaks === someone added to steering box, manual trans or rear end.
2) Running car for short periods really builds up condensation in engine and exhaust. Try to keep to a minimum. Mel



 


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