Transmission oil leak

[CJPayne 2]

I have owned my Mustang for a month and have noticed some transmission oil on the garage floor. I took some pictures. Oil is dripping from the bell housing and looks like the pan may also be leaking. I was looking on the forum last night and read that there is a top cover I need to check? Any ideas would be appreciated. I should note that I am mechanically inclined and I do have the 1969 shop manuals. I have a stock 351w and FMX.

[1969_Mach1 333]

That looks like motor oil.  Check closely the oil pan around the rear main cap area and the rear main seal.

What type of oil are you using?  Some tend to find small leaks more than others.  On my 351W, when I use to run Valvoline Racing oil I always had a very small leak in the rear main seal or back of oil pan area. Not enough to be concerned with.  But always a small drip off the bottom of the bell housing.  When I switched to Lucus Hot Rod and Classic Car oil the leak stopped.

[barnett468 418]

check the shift shaft seal on the trans.

[RPM 1,190]

Spraying foot powder on the engine/ trans can help find the source of the leak.

[newstang 388]

looks like rear main seal to me

 

[CJPayne 2]

Thanks for all the suggestions so far. What is leaking has a red tint. I took a clean pair towel and wiped what had leaked since Saturday and took a picture of it. Does this change any opinions of the leak? 

I will get some foot powder soon. I will clean everything with brake cleaner first.

I will also warm up the ca for 20 minutes and check the transmission for overfill.

 

 

[CJPayne 2]

I will also check the shift shaft seal as barnett468 suggested.

I had the shifter out replacing the bushings that were totally gone. Can you see the top plate with the shifter out?

[barnett468 418]

54 minutes ago, CJPayne said:

I will also check the shift shaft seal as barnett468 suggested.

I had the shifter out replacing the bushings that were totally gone. Can you see the top plate with the shifter out?

You can remove the trans cover on the front of the trans then you may be able to use a small telescoping mirror to see if the rear seal on the engine is leaking. You can use the same mirror to look at the top of the trans. Auto parts stores sell them cheap.

[1969_Mach1 333]

If you look at the original post, the back of the engine oil pan is soaked with oil as well.  If that is trans fluid on the bell housing, there is likely more than one leak?  Maybe it's me, I see motor oil on the paper towel.

[CJPayne 2]

I do think there is also a motor oil leak as well, so I think you may be right 1969_Mach1. So maybe the front seal on the tranny and the rear seal on the engine?

[newstang 388]

42 minutes ago, CJPayne said:

I do think there is also a motor oil leak as well, so I think you may be right 1969_Mach1. So maybe the front seal on the tranny and the rear seal on the engine?

it is unlikely the seal on the trans pump is the culprit. I still say that is an oil leak rear main.

 

[barnett468 418]

2 hours ago, CJPayne said:

I do think there is also a motor oil leak as well, so I think you may be right 1969_Mach1. So maybe the front seal on the tranny and the rear seal on the engine?

Unfortunately, guessing isn't going to help.

[aslanefe 333]

8 hours ago, newstang said:

it is unlikely the seal on the trans pump is the culprit. I still say that is an oil leak rear main.

 

Few months after I started daily driving my 69 Grande that has not been run for a long time, the rear main started leaking. Removed the C4 and replaced rear main seal. About a month later, the pump to convertor seal on the C4 started leaking. Was so glad to have a transmission jack and 2 post lift.

[CJPayne 2]

I left a paper towel under the leak for a few days. I can not find my inspection mirror so I need to go buy one. My plan is to eliminate one leak at a time. I plan to start with the transmission as it is the larger leak. Thanks for all the help so far.

[barnett468 418]

If the shift shaft is leaking, the valve body needs to be removed to change the seal but it's not complicated.

Also, the bolt holes in the pan are sometimes warped from people over tightening them, but they can be straightened, or you can get a new steel or aluminum one.

 

 

[CJPayne 2]

Update: Good call barnett468. Replaced the shift shaft seal and a new pan gasket and the leak is gone. 

To verify the motor oil leak I changed the oil and filter and cleaned up the underside with brake cleaner. Through some reading I learned it may be possible that the PO used synthetic which may worsen a leak so I went with conventional oil. I am monitoring for a leak now. 

 

[RPM 1,190]

Nice fix. 

[Brian Conway 264]

Always great to hear of a successful repair.