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Welcome to FordPinto.com, The home of the PCCA => General Help- Ask the Experts... => Topic started by: r4pinto on September 27, 2017, 07:05:06 AM

Title: Mysterious transmission fluid leak
Post by: r4pinto on September 27, 2017, 07:05:06 AM
Hey guys,

Got my 1980 Pinto, 2.3 C4 automatic that seems to lose transmission fluid but slight issue. I don't know where it's going. I noticed this morning it was not staying in first too well until it was warmed up. When I got to work I checked the fluid and it was barely on the dipstick! I am at a complete loss since I had recently installed a new transmission filter, gasket, dipstick seal, and chrome transmission pan. By recently I mean approximately 1500 miles ago. (Before I went to Geneva on the Lakes Pinto VS Maverick Show). Over a week ago I noticed it was acting up & was half pint low, so I topped it off & was fine. Well it started again. Any suggestions what to check?

I park in various spots at work, and in my driveway or garage and there is never any signs of leakage, other than a few drops of engine oil here & there.... To answer the question many may have I know it was oil since it was brown/amber in color and smells like engine oil, as opposed to the distinct scent that is ATF.

I also plan to jack up the car and pull off the vacuum line at the vacuum modulator to see if the diaphragm is bad, since I know if bad it will pull fluid back in to the intake and burn it. An additional repair I made was to replace the old worn out tailshaft seal, and new O-ring at the speedometer cable when I replaced the old cable. I know there is that "weep hole" in the inspection cover at the bell housing, and no oil and/or transmission fluid dripping from that notch/hole in the cover so pretty sure the front seal is OK. Additionally when I had the starter out to be replaced the snout of the starter was clean and dry.

I appreciate any suggestions on what to check, as I don't want to have to buy transmission fluid by the case for this thing.

On the bright side, it's not a grenade like the C3 was in my old 77.
Title: Re: Mysterious transmission fluid leak
Post by: Pintosopher on September 27, 2017, 07:12:37 AM
I'm pretty sure that ATF will mess up the Octane of the Fuel. No telling what it will do to the Burn ratio of the fuel and the HC & CO in a smog check. You may have nailed it with that vacuum modulator, Imagine the air leak between doses of ATF to the intake :o
 Pintosopher, the world is connected with actions and consequences.. .
 Be careful what you eat for Lunch :D
Title: Re: Mysterious transmission fluid leak
Post by: r4pinto on September 27, 2017, 07:20:42 AM
Hmmmm. Which could cause the engine drivability issue. One causes the other. Makes sense. On the other hand that motor would be clean inside. Losing that much fluid though I’m sure I’d see some type of leak. Rockauto has them cheap so will get one through them and replace it


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Title: Re: Mysterious transmission fluid leak
Post by: r4pinto on September 27, 2017, 08:20:28 AM
Took a chance. Only saw one vacuum line going down to the transmission so ordered the one with the single line. A whopping $6.10 shipped from Rockauto


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Title: Re: Mysterious transmission fluid leak
Post by: dick1172762 on September 27, 2017, 08:57:38 AM
If the vacuum modulator is bad here is an easy check. Place the shifter in low and drive the car. If the vacuum modulator is bad the tranie will not shift out of low with out moving the shifter. The tranie is made to shift out of low automaticly at a certain rpm to prevent you driving all the way to work in low gear. On my last drag Mustang I used this trick to remain in low to 6000 rpm before shifting to second. Makes no difference in second gear as you can't lock second gear like you did in low. Second gear will shift into high regardless of what you do. I did this until I got a manual valve body for my Mustang.
Title: Re: Mysterious transmission fluid leak
Post by: r4pinto on September 27, 2017, 09:05:11 AM
If the vacuum modulator is bad here is an easy check. Place the shifter in low and drive the car. If the vacuum modulator is bad the tranie will not shift out of low with out moving the shifter. The tranie is made to shift out of low automaticly at a certain rpm to prevent you driving all the way to work in low gear. On my last drag Mustang I used this trick to remain in low to 6000 rpm before shifting to second. Makes no difference in second gear as you can't lock second gear like you did in low. Second gear will shift into high regardless of what you do. I did this until I got a manual valve body for my Mustang.
Doesn’t do that but ordered a new one and will install it anyway. The car sat for who knows how long, and the transmission fluid is going somewhere. If it ain’t leaking it’s gotta be burning. Very odd to be that low and a bone dry pan. We’re talking not a drop of fluid on the ground anywhere that resembles transmission fluid in scent or appearance. At $6 it’s worth a try. I normally don’t throw parts at a car but make exceptions when it is zero cost or close to zero.


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Title: Re: Mysterious transmission fluid leak
Post by: r4pinto on September 27, 2017, 03:16:03 PM
The mystery has been solved. The car is smoking like a freight train, and when you pull the lien off it is saturated with fluid. Car is now being parked until I can get a new one from rock auto which was ordered. That transmission is too valuable to chance burning it up. Thanks for the suggestions


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