Vacuum Leak

['71 Dart Custom]

Hey Everyone,

I'm sure if I searched long enough I would find the answer to my problem in an old thread, but I'm way past my bedtime and really need to get my car back on the road ASAP.

As my user name implies, I have a '71 Dart Custom, 225 /6. The other day, I noticed that it was shifting hard when going from 1st to 2nd gear. Never did that before in the 5 years I've owned the car. It only did it when the car was cold. Once it warmed up it seemed to shift pretty much like normal.

A few days later, I drove the car again to a friend's house and it did the same thing, shifted hard into second. On the way home that night the car wouldn't shift into 3rd at all. I limped it home in 2nd and parked it.

Next morning, I cranked it and thought, "Maybe I'll let it warm up a few minutes before I take off." so I went back in the house for 10 minutes or so to give the car time to warm up. When I came back outside, the engine was dead. I tried to crank it and noticed it had a BAD vacuum leak. Hard to crank and keep running, but I managed to get it going and took it down the road. It's still not shifting normally, but it did go into 3rd. I mentioned the problem to my dad and he reminded me that those old transmissions know when to shift due to the amount of vacuum. If that's the case, what should I do? Replace the modulator valve?

I'm a decent shade tree mechanic, but I confess I know very little about transmissions. I appreciate any advice y'all might have in this matter.

 

[TrailBeast]

No vacuum involved in these Mopar transmissions.
More likely an out of adjustment TP rod from the carb to the trans.(or possibly the return spring came off)
You can google 904 TP adjustment and find what you need.
Have you checked the fluid running in neutral and see if it smells burned or is dark?

What is it that leads you to believe there is a bad vac leak?

 

['71 Dart Custom]

I've had vacuum leaks in the recent past and the motor spit and sputtered just like it is now. I don't know for sure that that's the problem, but it just acted like a vacuum leak.

Now that the weather has improved, I'll get out and do some investigating today, see if I can find more clues as to what's wrong.

Google 904 TP adjustment? I'll do that and also look for any undone springs.

Thanks!

 

['71 Dart Custom]

Well, I was right about the vacuum leak, but that apparently was a coincidence and totally unrelated to the transmission issue. I found a cap that had come off a vacuum port on the intake. Replaced the cap and the car runs fine.

I took it down the road and it acted like it didn't want to shift into 2nd at first, but then it did and then it went on into 3rd. I think I'll go buy some fluid and a new filter and see if that makes a difference. It's been a couple of yrs since I replaced the transmission filter. Also, the other day when I checked the fluid it was a quart low. I added fluid, but then the vacuum problem happened so I wasn't able to test it out. I think I might have a fluid leak somewhere. It's never lost much fluid over the 5 yrs I've been driving it. I used to check it on a regular basis, but admit I've become neglectful recently since it had never been a problem.

Thanks for the help. I hope I haven't burned up my tranny due to my neglect. It's still shifting at the moment, so hopefully not.

 

[TrailBeast]

A quart low is quite a bit for a TF trans, and it may very well be the shifting problem.

 

[krazykuda]

Here's a link to where you can download the 70 service manual. It should be the same as 71 for your application. They only have the 71 body service manual which odesn't cover mechanicals. they also have a copy of the 71 plymouth service manual and you can look up valiant/scamp for your applications.

http://www.mymopar.com/index.php?pid=109


Transmission is section 21 and they will tell you how do adjust the transmission kickdown and other adjustments for the trans.

Good Luck, We're all counting on you....

[ame="http://www.youtube.com/watch?v=aB2yqeD0Nus"]Good luck, we're all counting on you - Airplane - YouTube[/ame]

 

['71 Dart Custom]

Good Luck, We're all counting on you....

No pressure though, right? lol

I love Airplane! If Blockbuster hadn't closed down I'd go rent it and the sequel tonight. Over Macho Grande? No, I don't think I'll ever be over Macho Grande.....

I feel so stupid letting the Dart run so low on tranny fluid like that. I went and bought a filter and fluid today but it was too late (and cold) to change it. I'll get it done tomorrow and file a status report. Thanks for the info. It might very well come in handy.

 

[fishy68]

If you do a fluid and filter change I highly suggest adjusting the bands too. Bands wear and need periodic adjustment for proper operation.

 

['71 Dart Custom]

If you do a fluid and filter change I highly suggest adjusting the bands too. Bands wear and need periodic adjustment for proper operation.

Adjust the bands? How do I go about doing that? Not to show my ignorance, but I've been changing transmission filters for years and nobody's ever told me I needed to adjust the bands. I'm not questioning you're advice, just asking if you can elaborate. Would band wear account for the fact that after changing the filter the tranny is still reluctant to shift into second?

I found a few pieces of shrapnel in the pan when I dropped it. Nothing big, but still more metal than I've ever seen in the fluid. I've always heard that when a transmission starts to go out, there's no easy fix. I hope that's not true 'cause I can't afford to have it rebuilt at the moment or in the foreseeable future.

 

[67Dart273]

Somebody already told you to download the service manual. It's all right in there.

More stuff in this thread

http://www.forabodiesonly.com/mopar/showthread.php?p=1970088617

and lots of MoparInfo on this site. Some of the stuff posted that did NOT come from Chrysler has mistakes, but there is a lot of original Mopar stuff

http://www.mymopar.com/index.php?pid=31

On the same site above is a wealth of factory service bulletins. Go down this list and notice both videos and pdf's on transmissions

http://www.mymopar.com/index.php?pid=451

If you play with those links you can "get to" the native video at Youtube. If you use, say, Firefox, there are a couple of browser add-ons which let you save YouTube vids to your hd

 

[fishy68]

Adjust the bands? How do I go about doing that? Not to show my ignorance, but I've been changing transmission filters for years and nobody's ever told me I needed to adjust the bands. I'm not questioning you're advice, just asking if you can elaborate. Would band wear account for the fact that after changing the filter the tranny is still reluctant to shift into second?

I found a few pieces of shrapnel in the pan when I dropped it. Nothing big, but still more metal than I've ever seen in the fluid. I've always heard that when a transmission starts to go out, there's no easy fix. I hope that's not true 'cause I can't afford to have it rebuilt at the moment or in the foreseeable future.

Like 67Dart said download the manual and it's all in there on how to adjust the bands or you can search YouTube and find several video's on it. sometimes seeing it done makes it easier to grasp than just reading it in a manual. A lot of times the band adjustment gets ignored but it's vital to the proper operation of a torqueflite. The front band is solely responsible for 2nd gear. If it's not adjusted right it can definitely affect how it ***** into 2nd. Can you post a picture of what you found in the pan? May or may not be enough to worry about.

 

['71 Dart Custom]

I wish I had taken a picture of what I found in the pan, but I dropped the pan at a friend's house and didn't have a camera handy. I'm sitting here trying to think of something to compare the pieces to. I know that every time I've ever changed a filter there is a bit of ground up metal to be found in the fluid, but in addition to that there were two or three slivers about as big around as a grain of salt and about 4 times that long. Maybe a little bigger than that, but not much. More metal than I'm used to seeing in a pan, but it may not be that big of a deal after all.

Anyway, I'll download the manual and also look for some videos. I agree that it's easier to understand if I see it done rather than just read about it. That's one reason I didn't download the manual the other day. Sorry.