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Misdiagnoses of Transmission Failure
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Js101
Novice
Jun 1, 2013, 9:35 AM
Post #1 of 18
(1865 views)
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Misdiagnoses of Transmission Failure
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Recently, I was driving out of town and had a vehicle breakdown. I ended up having the vehicle towed to a transmission shop and they replaced the transmission.
2005 Mercury Mariner
157,000 Miles
4 Cylinder 2.3 Liter
3 Speed Automatic w/ Overdrive
The vehicle got to a point where it would drive for a few thousand feet, then disengage completely. It would only shift up to 2nd gear before doing this. Turning off the engine and letting it cool would allow me to drive a few thousand feet again. Prior to that, there had been some stalling problems when the vehicle was stopped after long periods of travel. Additionally, the vehicle had been lacking power at start-up, which I suspected was due to the transmission failing to shift down to first gear at start-up.
Now that the vehicle has a rebuilt transmission, the vehicle drives without slipping into neutral, as it did before, but it is still lacking power, as it did before the repair. Very little start-up power, and sputtering at 3800-4000 RPM.
I am wondering if it is possible that the "transmission failure" was actually due to the engine issue.
Obviously, the vehicle drives now that it has a rebuilt transmission, but could the more worn, old transmission have worked for another 10-20K miles if the engine was running normally?
Is there mechanisms in the automatic transmission that dis-engage when it senses a lack of engine horsepower?
(This post was edited by Js101 on Jun 2, 2013, 9:37 PM)
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Discretesignals
Ultimate Carjunky
/ Moderator
Jun 2, 2013, 1:06 PM
Post #2 of 18
(1828 views)
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Re: Misdiagnoses of Transmission Failure
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It is very possible for an engine issue problem to affect the operation and health of the transmission. About a week ago I had a customer complaining of a rough running engine on a 2003 Buick Lesabre. The engine would stall out at times. She had been driving it like that. The problem with it was the MAF sensor was faulty. The MAF on that one is used by the engine computer to determine engine load, but it is also used for line pressure control in the transmission. Since the pressure wasn't being controlled properly by the bad input from the MAF sensor it caused the transmission to slip and fry the clutch material.
The strategy on a GM vehicle, such as that one, is to ramp up line pressure when it sees that timing between shifts are excessive. The adaption was maxed out indicating the transmission was toast. She is still driving it, but it is definitely on borrowed time.
Your problem maybe similar in that the whole cause of the transmission failure was something outside the transmission itself. It is very very important that any drive-ability problems are resolved before condemning or replacing a transmission. They may have repaired the effect, but without determining the cause the repair will eventually fail again.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Jun 2, 2013, 1:12 PM)
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Js101
Novice
Jun 2, 2013, 9:41 PM
Post #3 of 18
(1810 views)
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Re: Misdiagnoses of Transmission Failure
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Thanks for the reply. I have limited knowledge of automatic transmissions.
My question here is whether or not the transmission could have lasted another 10K miles or so. The transmission is now repaired and is driving the vehicle dispute the engine power issues. This at least proves that the transmission was worn. Could it be possible, though, that immediate repair of the transmission was not necessary?
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MarineGrunt
Enthusiast
Jun 2, 2013, 10:03 PM
Post #4 of 18
(1805 views)
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Re: Misdiagnoses of Transmission Failure
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It's possible but there's no way to know for sure without knowing what's wrong with the engine or what kind of shape the old transmission was in. We just don't have enough info about the engine or the transmission to give an accurate answer. Although, from the sound of it your old tranny did need rebuilt.
The main concern right now should be getting the problem with the engine fixed just in case it is causing wear on the tranny. If it is causing excessive wear the old tranny might not have made it another 100 miles. It's possible the new transmission may not even make it to 1,000 miles let alone 10,000 miles. I'd stop driving it until you get it figured out just in case the engine is at fault. As you know, it's too expensive of a repair to take the change.
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Discretesignals
Ultimate Carjunky
/ Moderator
Jun 3, 2013, 4:57 AM
Post #6 of 18
(1792 views)
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Re: Misdiagnoses of Transmission Failure
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and if that giant hole in the roof was caused by a rotting tree who's limb came down, do you repair the roof and leave the tree to drop more limbs?
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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Js101
Novice
Jun 3, 2013, 6:55 AM
Post #7 of 18
(1783 views)
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Re: Misdiagnoses of Transmission Failure
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The reason I had asked if the repairs were necessary was due to the fact that the vehicle is old. If the transmission would have lasted 10K more miles, I would not have wanted to replace the transmission. Basically, I am asking if the transmission diagnosis could have not been necessary. In short: if the engine was working properly, could it have possibly been that the transmission wouldn't have shown the symptoms it did when it did?
(This post was edited by Js101 on Jun 3, 2013, 6:56 AM)
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jun 3, 2013, 7:50 AM
Post #8 of 18
(1780 views)
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Re: Misdiagnoses of Transmission Failure
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Js101 : This has 157K as you said. IMO if a trans issue whether primary or secondary would call for an overhaul. You just asked and did if it could last another 10K.
Unless there's some crystal ball or fortune teller I don't know how to guess at how many miles a trans will last or know anyone who could guess that. They can plain snap from new or last ages. Full of moving parts and wearing parts, sensors, seals and all sorts of things to measure, test see up close that just can't be done without it apart and why would any shop go that far and not redo it with the new parts as seen when in there?
Transmissions are a specialty but techs need to know that inputs from an engine are correct as well. There are some external reasons for things that can go wrong that don't require a tear-down. In short, you can't guess how many miles one will last. Add your personal driving habits/conditions and you seriously don't know,
T
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Js101
Novice
Jun 3, 2013, 8:08 AM
Post #9 of 18
(1775 views)
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Re: Misdiagnoses of Transmission Failure
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I am not asking for someone to predict the life of the transmission. I was just wondering if the diagnoses could possibly have been false. Could it possibly have been that if the engine was running normally, the transmission would have not shown symptoms of failure when it did, or is this impossible?
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jun 3, 2013, 8:23 AM
Post #10 of 18
(1771 views)
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Re: Misdiagnoses of Transmission Failure
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Quote from first post: ">>Obviously, the vehicle drives now that it has a rebuilt transmission, but could the more worn, old transmission have worked for another 10-20K miles if the engine was running normally? <<"
This is a web forum of course. Not the replacement for being there diagnosing things in person. Could something be faked in some circumstances to buy some time - yes. Are some clues obvious that you are in trouble - yes again.
I default to trusting the techs/shops in biz. It sure doesn't bode well for anyone to fail at a repair or misdiagnose a problem that is costly especially.
Not sure why you are asking these things instead of getting a hands on check. Again, unless this was just recently redone the miles alone would cause a shop to suggest an overhaul. If they said it was fine and it failed how would they look?
T
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Js101
Novice
Jun 3, 2013, 12:12 PM
Post #11 of 18
(1761 views)
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Re: Misdiagnoses of Transmission Failure
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My reason to ask here is that I am doubting the original mechanic. It does bode well for a transmission shop to falsely, or by error of omission, diagnose a transmission failure if it is expensive, since transmissions are their only line of business.
I am just trying to find out if it is a possibility that the transmission was not totally shot, as stated by the shop. I don't know everything about automatic transmissions, but I am not buying the shop's defensive suggestion that since the engine ran and the drive-axle was fine, it was for sure the transmission. I know enough to know it is not a simple single chain and sprocket mechanism.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jun 3, 2013, 12:34 PM
Post #12 of 18
(1753 views)
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Re: Misdiagnoses of Transmission Failure
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If you have a problem with the transmission shop bring it up with them with some other shop's opinion if they will blame another at all. You are here dealing with mostly pro techs, retired, owners of shops with tons of experience at hand.
Any trade could make up something to make more money. Don't be so fast to blame one as it seems that part of your trouble is fixed now. It sure doesn't help a tech, shop to get a bad reputation if caught doing something on purpose just to make a fast buck. There's enough legitimate work to keep any good tech/mechanic busy out there.
The other side is there are also customers who think if someone touches anything that everything that ever goes wrong forever is that person's/shop's/or whatever's fault. So yes - customers get the bad name and nobody is going to help you if one of those locally.
If you are looking for a web site to steer you into complaining about work done this case and place isn't going to fly,
T
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Js101
Novice
Jun 3, 2013, 1:48 PM
Post #13 of 18
(1744 views)
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Re: Misdiagnoses of Transmission Failure
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Any experienced shop owner or tech would know there are both good and bad tech's. So far, the shop has been cooperative with my inquiries. I was simply wondering if it was possible, given the circumstances described above, that the transmission could have not needed to have been replaced AT THE TIME IT WAS if the failure with the engine would have been found.
Just wondering if it is possible..
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Hammer Time
Ultimate Carjunky
/ Moderator
Jun 3, 2013, 2:09 PM
Post #14 of 18
(1742 views)
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Re: Misdiagnoses of Transmission Failure
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How is anyone here going to know what condition your transmission was in before you repaired it?
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Hammer Time
Ultimate Carjunky
/ Moderator
Jun 3, 2013, 2:54 PM
Post #16 of 18
(1721 views)
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Re: Misdiagnoses of Transmission Failure
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Apparently you just don't get it. Nobody can have any idea what the situation was with your transmission before you repaired it. Give it up. There is nobody online that can know anything about your car from your vague and useless description of your symptoms.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Js101
Novice
Jun 3, 2013, 3:16 PM
Post #17 of 18
(1715 views)
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Re: Misdiagnoses of Transmission Failure
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I am not an idiot. i am not asking for a online diagnoses. The basic question here is:
Is it possible for a worn, but functional transmission to slip out of gear during driving due to engine failure? And if so, could engine repair fix the problem, thereby increasing the overall transmission life?
It is not a question of the ethics of the shop. It is not a question specific to my transmission or situation. It is simply a question that someone with a thorough understanding of automatic transmissions should be able to answer. I am not asking you to judge the shop. I am not asking you to tell me what the problem is over the internet. I am just wondering if this suspicion of mine is even possible.
(This post was edited by Js101 on Jun 3, 2013, 3:18 PM)
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