tranny leak at the dipstick tube

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trudysduster

trudysduster

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I put the car back together after the resto and decided to go to the local car show and enter it. did great except for this vibration I mentioned.took a trophy. came home parked it in the garage and got up the next morning and went out to get something and about had a heart attack. There was tranny fluid all over the floor. cleaned up the mess. filled it up and checked it. no leaks. ran it, got it hot no leaks. Put a pan under it and let it set and as it cooled off, saw it starting to drip. It was coming from around the dipstick tube. It is a 727. It seems to only leak when it cools down. I am almost sure I put a new o-ring on there when I put it back in. Is there a vent on the tranny somewhere that is building pressure that is causing it to blow out of the tube. I noticed when I took the tranny out that someone had put silicone around the dipstick hole before. I thought that was odd but maybe not. The tranny did not leak before I did the resto. Any thoughts on this. thanks,Bill
 
I dont think the vent is the problem. The fluid should climb the tube without leaking. Maybe the tube itself is damaged. Do you have a strap or anything holding the tube in place ?
 
Either they had the same problem you do or there is something not right with the dipstick tube hole. I bet it is cracked or scratched or scored. Probably why the PO had silicone on it.
 
We used to ALWAYS put just a thin film of silicone inside the tube hole on the trans before we put the tube in.
If you put it inside the dipstick tube hole instead of on the tube itself, you will never see it from the outside.
The vent is at the top of the pump behind the converter but that's not the problem if it only leaks after cooling down and sitting.
I could be that the tube has a crack in it as mentioned, because when it is parked a lot of the fluid runs back into the pan when parked and fills the pan with more fluid than when it's running.
Sitting lets the fluid in the converter drain back into the trans kinda (overfilling it) till the next startup and the trans pump fills the converter again.
 
thanks guys, I will order a new set up from Mancini Racing and it will have a new o-ring on it and I will silicone it before I put it in. It does bolt to the bell housing. I just wasnt aware it all drained back. That explains why the abundance of fluid on the floor. It seeped out of the tube hole. Thanks again,Bill
 
6pakattack said:
I second this emotion !! Had the same problem on my 340/727 in my Dart !Also the dipstick tube should bolt to the bellhousing anyway !!
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Thats why I asked. Most models have a strap spopt welded to the tube.
If that strap is distorted it will draw the tube up and/or sideways which will cause the O ring leak. The trick is to get the tube straight in the trans hole then hold it there while bending the strap as required to support the tube in the correct position.
 
If you silicone the hole make sure you put a small amount on your finger and spread it in the hole wall no more than a 1/16 thick or less.Too much and the tube will push the extra down into the trans and could stop something up.I would check the o-ring and tube for cracks or if its out of round first then silicone if that doesnt fix it.If you silicone the tube you can put it on your finger and run it around the tube much like caulking in a house and it won't be noticeable.
 
mopar410 said:
If you silicone the hole make sure you put a small amount on your finger and spread it in the hole wall no more than a 1/16 thick or less.Too much and the tube will push the extra down into the trans and could stop something up.I would check the o-ring and tube for cracks or if its out of round first then silicone if that doesnt fix it.If you silicone the tube you can put it on your finger and run it around the tube much like caulking in a house and it won't be noticeable.
Click to expand...

If put on the inside of the hole in the trans just a light coat works best.
Just enough to build up around the Oring as it goes in is perfect.

Also it's really easy to fix the tube if that's what it is.
Any welder can braze that right up and then you just paint it.
Probably save you some money, and still look good at the same time.
 
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