Transmission Fluid

Kisner · 10-14-2003, 10:15 AM

How can I tell if I have too much transmission fluid in my 68 coupe (302, w/C4 auto transmission) without relying on the dipstick? The reason I ask such a stupid question is I have a repro dipstick which I don't think is the correct length. It's leaking around the pan and now a few other places which I'm guessing may be forcing its way out due to being overfilled. For example, when the transmission is cold, should the fluid be above where the pan meets the valve body? I know the fluid expands when hot. When I've changed gasket and filter in the past only about 1/16 of the dipstick sticks out of the valve body into the pan. I'm thinking it might should be longer and therefore I've got too much fluid in it.

nielsmobers · 10-14-2003, 02:04 PM

If try to find out what the original length of the dipstick should be, than you know if you have the right dipstick. I think a mustang garage should be able to tell you this... maybe this is the most easy way??

Rev · 10-14-2003, 07:58 PM

Mine is the original dip stick and it's just like yours. It should have two marks, one for cold and another for hot. I think the marks actually say "full" and "low". It should read "full" when the tranny is hot. If the trans is over-filled, foaming might occur that leads to low line pressure which I think can allow slippage of clutches etc. and harm the tranny. Look at the dip stick when warmed up after a little hard driving and check for high fluid level and evidence of foamed trans fluid.

Rev

Kisner · 10-14-2003, 08:54 PM

The last time I checked it, it was just a little low after the fluid warmed up. I then added about 2 ounces and then it showed way overfull. I let the engine run about 10 minutes before I checked it. Did I not let it warm up enough? Also, when I checked it, it appeared to have bubbles in it. I do remember the shop manual saying this was an indication it was overfilled. When cold and the engine is off it shows way, way overfilled. I assumed this was normal since the fluid hadn't been picked up by the pick-up tube? Other than having a hard time figuring out how much fluid is in the tranny, it runs and shifts like a champ.

Kisner · 10-15-2003, 02:27 PM

I think at this point the simplest way for me to determine if I have too much transmission fluid in the tranny is to find out where should the fluid be on the dipstick with the engine off and the fluid cold? Should it be way above full, at full, at add, or some other point?

Rev · 10-17-2003, 02:59 PM

Check with the engine running in park and thoroughly warmed up. Yes the dip stick on these cars is extremely sensitive at the full level. A little extra will show up big time on the dip stick.

With the engine off, the level will show extremely high. This often causes leaks when the car is parked. These leaks often occur from the filler tube O-ring, the speedometer cable O-ring, and sometimes from the servos. Mine always seems to leak from somewhere when parked.

Rev

Kisner · 10-18-2003, 10:42 AM

Thanks for all your help. Was able to determine my repro dipstick is a perfect repro of the original, i.e., marks, punch-outs, verbiage, and length. The fluid's about 2 inches too high on the dipstick so will attempt to siphon out a little from the tube today. Out of curiosity, does anyone know how much transmission fluid actually expands when hot, i.e., 5%, 10%, or greater?

Kisner · 10-21-2003, 11:34 AM

Well after all was said and done, I had about 2 quarts too much transmission fluid in the tranny. Siphoned that much out yesterday. What really confuses me though is the shop manual specifically states after you change the filter and gasket to add 3 quarts of fluid and then adjust from there. That's exactly what I did and the last time I changed it I also changed out my cheap chrome pan with a new aluminum deep dish one that held an extra quart. So, I added 4 quarts. The only thing I didn't do was change the filter since it had been changed out only a month earlier when I changed gaskets. By not changing the filter did it somehow trap a couple extra quarts up there somehow? Can't figure out how it ended up with 2 quarts too much when I only added 4?

10-14-2003, 10:15 AM	#1
Kisner Registered Member Join Date: Nov 2000 Posts: 290	Transmission Fluid How can I tell if I have too much transmission fluid in my 68 coupe (302, w/C4 auto transmission) without relying on the dipstick? The reason I ask such a stupid question is I have a repro dipstick which I don't think is the correct length. It's leaking around the pan and now a few other places which I'm guessing may be forcing its way out due to being overfilled. For example, when the transmission is cold, should the fluid be above where the pan meets the valve body? I know the fluid expands when hot. When I've changed gasket and filter in the past only about 1/16 of the dipstick sticks out of the valve body into the pan. I'm thinking it might should be longer and therefore I've got too much fluid in it.

10-14-2003, 02:04 PM	#2
nielsmobers Registered Member Join Date: Jul 2002 Location: Holland Posts: 28	maybe this helps !?! If try to find out what the original length of the dipstick should be, than you know if you have the right dipstick. I think a mustang garage should be able to tell you this... maybe this is the most easy way??

10-14-2003, 07:58 PM	#3
Rev Registered Member Join Date: Nov 1998 Location: Houston, Tx. Posts: 3,887	dip stick Mine is the original dip stick and it's just like yours. It should have two marks, one for cold and another for hot. I think the marks actually say "full" and "low". It should read "full" when the tranny is hot. If the trans is over-filled, foaming might occur that leads to low line pressure which I think can allow slippage of clutches etc. and harm the tranny. Look at the dip stick when warmed up after a little hard driving and check for high fluid level and evidence of foamed trans fluid. Rev __________________ '66 Coupe, 306, 350-375 HP, C-4, 13.07 e.t., 104.8 mph, 1/4 mi. O.B.C. #2 '66 coupe

10-17-2003, 02:59 PM	#6
Rev Registered Member Join Date: Nov 1998 Location: Houston, Tx. Posts: 3,887	Check engine runnig........ Check with the engine running in park and thoroughly warmed up. Yes the dip stick on these cars is extremely sensitive at the full level. A little extra will show up big time on the dip stick. With the engine off, the level will show extremely high. This often causes leaks when the car is parked. These leaks often occur from the filler tube O-ring, the speedometer cable O-ring, and sometimes from the servos. Mine always seems to leak from somewhere when parked. Rev __________________ '66 Coupe, 306, 350-375 HP, C-4, 13.07 e.t., 104.8 mph, 1/4 mi. O.B.C. #2 '66 coupe

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10-14-2003, 08:54 PM	#4
Kisner Registered Member Join Date: Nov 2000 Posts: 290	The last time I checked it, it was just a little low after the fluid warmed up. I then added about 2 ounces and then it showed way overfull. I let the engine run about 10 minutes before I checked it. Did I not let it warm up enough? Also, when I checked it, it appeared to have bubbles in it. I do remember the shop manual saying this was an indication it was overfilled. When cold and the engine is off it shows way, way overfilled. I assumed this was normal since the fluid hadn't been picked up by the pick-up tube? Other than having a hard time figuring out how much fluid is in the tranny, it runs and shifts like a champ.

10-15-2003, 02:27 PM	#5
Kisner Registered Member Join Date: Nov 2000 Posts: 290	I think at this point the simplest way for me to determine if I have too much transmission fluid in the tranny is to find out where should the fluid be on the dipstick with the engine off and the fluid cold? Should it be way above full, at full, at add, or some other point?

10-18-2003, 10:42 AM	#7
Kisner Registered Member Join Date: Nov 2000 Posts: 290	Thanks for all your help. Was able to determine my repro dipstick is a perfect repro of the original, i.e., marks, punch-outs, verbiage, and length. The fluid's about 2 inches too high on the dipstick so will attempt to siphon out a little from the tube today. Out of curiosity, does anyone know how much transmission fluid actually expands when hot, i.e., 5%, 10%, or greater?

10-21-2003, 11:34 AM	#8
Kisner Registered Member Join Date: Nov 2000 Posts: 290	Well after all was said and done, I had about 2 quarts too much transmission fluid in the tranny. Siphoned that much out yesterday. What really confuses me though is the shop manual specifically states after you change the filter and gasket to add 3 quarts of fluid and then adjust from there. That's exactly what I did and the last time I changed it I also changed out my cheap chrome pan with a new aluminum deep dish one that held an extra quart. So, I added 4 quarts. The only thing I didn't do was change the filter since it had been changed out only a month earlier when I changed gaskets. By not changing the filter did it somehow trap a couple extra quarts up there somehow? Can't figure out how it ended up with 2 quarts too much when I only added 4?