Transmission fluid leak

Tiny
BUICK_DUDE
  • MEMBER
  • 1987 BUICK LESABRE
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 150,000 MILES
Need help to determine if a transmission fluid leak is the pan or internal. The transmission cooler lines are good.
Monday, April 6th, 2020 AT 9:41 AM

11 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
I am not sure I understand the question. Are you seeing a loss of transmission fluid and trying to find out if it is an external leak or not? Do you see fluid on the outside of the pan?

Or are you seeing a performance issue and trying to figure out where the pressure loss may be, pan or internal to the unit?

Just let us know a little more detail about what is happening and we can go from there. Thanks
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Monday, April 6th, 2020 AT 9:45 AM
Tiny
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I'm losing fluid. Found out it was missing a pan bolt and replaced it, but it continues to leave fluid leak on cardboard.
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Monday, April 6th, 2020 AT 9:50 AM
Tiny
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The pan is covered in fresh fluid. Every time I drive it leaves a small smear of transmission fluid in the parking spot.
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Monday, April 6th, 2020 AT 9:51 AM
Tiny
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Also, does the pan gasket need a bead of sealent or do I just remove and replace gasket?
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Monday, April 6th, 2020 AT 10:24 AM
Tiny
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If when you pull down the pan, it has a gasket then you don't need sealant. It is leaking because it basically has a failed seal so no matter how tight you make, it still have the path. If there is no gasket then you use a sealant silicone rated for transmission fluid.

Sounds like you just need to pull it down and reseal it. I attached the process which does not have a lot detail but it does give the steps.
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Monday, April 6th, 2020 AT 2:53 PM
Tiny
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It was missing a bolt so maybe that caused the gasket to fail prematurely. I was able to order the gasket so I assume it needs and has one, but I will find out soon if thats the case. I have never replaced it. Ill update. Will be working on it on Saturday.
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Monday, April 6th, 2020 AT 5:03 PM
Tiny
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Sounds great. Normally they do have a gasket so I am sure you are good to go. If you want to use a couple dots of silicone to hold it in place while installing it you can do that but I normally just stick two bolts through the pan and the gasket then those bolts hold the gasket in alignment when putting the pan up. Finger tighten those two bolts then start the rest.

I will wait to hear back from you if you have issues. Thanks
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Monday, April 6th, 2020 AT 5:14 PM
Tiny
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Thanks, I will update when I get part. Will snap some pics to upload. Be well.
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Tuesday, April 7th, 2020 AT 3:00 PM
Tiny
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Thank you for the update. That sounds like a good plan. Appreciate the update.
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Tuesday, April 7th, 2020 AT 7:37 PM
Tiny
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Got it jacked up an hour ago and saw there was a scrape in the transmission pan were fluid would tear up after cleaning it. Cleaned and added some quicksteel epoxy and letting it cure.
Things look pretty nasty down there hahaha. Attached is a video.
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Monday, April 13th, 2020 AT 2:47 PM
Tiny
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Yeah. That is the issue. I attached the still shot of it. That pan clearly hit something like a speed bump and put a hole in the pan. All that grime is from fluid coating everything and then dirt sticking to it.

Hopefully the repair holds and you are good to go. Some engine cleaner from a parts store will clean all that up if you want to.

Good video. Thanks for the update.
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Monday, April 13th, 2020 AT 7:31 PM

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