transmission leak

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  #1  
Old 06-19-15, 04:48 AM
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transmission leak

My wife has an 03 merc sable with 183k that has had a mystery transmission leak for about 5 yrs Until recently it only needed about a half a quart per year but in the last 6 months it's jumped to a quart a month

The crazy part is crawling under the car reveals no sign of any major/fresh leak. There are never any fluid drops under her car when it's at home. We just got back from vacation [900 miles] and the fluid level is still full BUT sometimes when she goes to work the fluid will run out from underneath her car. She does have a lead foot but at work [different jobs over the yrs] is the only place she's seen it leak. If it wasn't for me having to add fluid I'd think she's crazy but the fluid is definitely leaking out somewhere and a bunch all at once.

Any ideas as to where it's leaking or why it's so hard to find?
 
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  #2  
Old 06-19-15, 05:34 AM
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If there is an inspection pan between the transmission & the engine, remove it & see if it's wet inside. If it's leaking there, it's the "front seal". It sounds like where she parks at work is on an incline & the home driveway is level. That's why you see it at work & not at home. Lucas might have a sealer for transmissions. Take a look at Walmart or an auto parts store.

Years ago there were vacuum modulator valves. If the went bad, the vacuum would suck the fluid out of the transmission & the engine would burn it. You would see white smoke. I don't think that applies, in your case but look at the exhaust anyway.
 
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Old 06-19-15, 05:46 AM
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She parks in a garage at work so it's mostly level, same as on top of the hill where we live. She's fixin to leave for work in a few minutes but I'll check out that inspection pan when she comes home next week.
 
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Old 06-21-15, 06:55 AM
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Vacuum modulator would be a prime suspect if they were still around as Pulpo mentions. Been quite a few years since cars had them, tho. My '64 Buick Special blew a modulator once and I thought I had an engine problem from the smoke.
 
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Old 06-21-15, 07:04 AM
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There isn't any smoke and the only place it appears to leak is on her patient's garage floor If it wasn't for having to add fluid I would think she's mistaken as it's never left a stain at the house and I've never noticed any fluid at any parking lot that I could attribute to her car. I was a little leery about taking her car on vacation and checked the fluid at every stop going to the beach and a couple of times on the return trip but the fluid level was always full.

I'll crawl back under it tomorrow, hopefully I'll get it figured out.
 
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Old 06-21-15, 07:14 AM
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Don't forget to try one of the Lucas products. I'm sure that they make a sealer for transmissions.
 
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Old 06-21-15, 07:16 AM
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I assume it leaks a whole lot at the time the circumstances are right so I doubt a sealer would work. You'd think there would be evidence under/on the transmission of a big leak but so far I've not found it.
 
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Old 06-21-15, 07:36 AM
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https://www.youtube.com/watch?v=YK9AN5Qr7YU

I did a little more research. That ^^ video explains that when you have transmission fluid leaking out of nowhere, it could be the "transmission breather valve". It's a dealer item. In other words, it's not available from a parts store. It costs about $27 plus tax. Apparently, when the breather valve is restricted, it forces the fluid to exit through the dip stick. That's why it's very hard to find the leak.
 
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Old 06-21-15, 12:08 PM
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Thanks Pulpo! definitely something to check into.
 
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Old 06-21-15, 11:55 PM
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I've replaced leaking O rings on the dipstick tube where it goes into the transmission on several Ford products. Usually with this problem you will see fluid on the pan and the trans leaks heavily when parked on a downward slope.
 
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Old 06-22-15, 05:06 AM
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Picking up my truck this morning where I left it with tranny guy during my vacation and I'll ask if there are any other possibles.
 
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Old 06-22-15, 12:29 PM
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I only had a few minutes to spend on her car this morning but it does look like it could be the vent valve as there is more evidence of a fluid leak on/around the dipstick than elsewhere. Also I had the dipstick out when I shut the motor off and you could hear it gurgling thru the dipstick tube, something I've never noticed before.

She went to the grocery store this morning and I had some work to do for one of the kids and planned to dig deeper into this afternoon ....... but she loaned her car to one of sons, said "oh you can fix it another time" Just like a woman, wants stuff done but don't want to give you the time to do it
 
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Old 06-22-15, 02:46 PM
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At least you have a better idea as to what the solution is. While you are waiting for the time to fix it, call the dealer to see if they have the part in stock. It might have to be ordered.
 
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Old 06-22-15, 02:55 PM
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Wouldn't be a bad idea although I was planning on cleaning the old valve and reinstalling it unless I change my mind after looking at it.
 
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Old 06-22-15, 03:05 PM
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If you're really low on cash, then take the chance. The guy in the video that I posted said that his wasn't clogged but he replaced it anyway. You don't want to do the job twice especially since your wife is very busy.
 
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Old 06-29-15, 02:29 PM
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Finally got a chance to remove/inspect the valve - I don't believe it's the culprit. The valve was clean/open and the 'port' that it inserts into also looked nice and clean. I don't believe there is any obstruction there. After inspecting the part I don't know why the guy in the video replaced his, had it been plugged it would have been a simple matter to clean it.
I guess the next step will be to take it to a transmission shop maybe next week. Funny thing is it hasn't used any transmission fluid at all since a week before we went to the beach - almost 3 weeks.
 
  #17  
Old 06-29-15, 03:28 PM
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The guy in the video replaced his even though it wasn't clogged probably because he already had it apart. I've done things like that too. In your case, it's still cheaper to replace the valve than it is to bring it to a transmission shop. Stay away from transmission shops.

Since you noticed that the dipstick had more evidence of a leak than anywhere else, I would still keep my focus there. Try to determine the highest wet point. In other words, what is the highest spot where you see transmission fluid? Is the top of the fill tube? If not, where?

Finally, if staying at the beach stops leak, that's the way to go.
 
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