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sprinkles08
sprinkles08, ASE Certified Technician
Category: UK Car
Satisfied Customers: 21596
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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I just need your expert opinion. I have a 2005 SAAB

Customer Question

Hello, I just need your expert opinion. I have a 2005 SAAB 93, which occassionally surges/lurches when driving. No other known problem with car. After garage repairs, car crawls like snail after stopping at lights/junctions for about 10 seconds, before suddenly moving off . Mechanic says his repair has improved engine power, and this engine power improvement has highlighted a previous fault in the gearbox. This now means the gearbox does not have the capacity to keep up with the improved engine's pace. How could this statement be?
Is it possible for a car to have a gearbox problem and for a mechanic not to notice it at diagnosis stage prior to starting work on the car?
I will appreciate it if you can throw more light on this for me please.
Submitted: 1 year ago.
Category: UK Car
Expert:  sprinkles08 replied 1 year ago.
Hello and welcome to JustAnswer!
It sounds as if the transmission may be in limp in. If the trans controller sees an issue that can cause potential damage or it thinks it doesn't have complete control then it can lock you in a single, higher gear. This could be the TCM itself, an internal trans issue, solenoids, speed sensors, wiring issues, etc.
Not to say the shop caused this issue, but with the information I have I don't really believe that repairing an engine power issue allowed you to notice the transmission issue. If the engine had been producing low power before then it would have exaggerated a transmission issue, not the other way around. I would expect they would have noted the transmission problem at the same time the engine was being worked on also.
Customer: replied 1 year ago.
Apologies if I am asking too many questions, I am not a very techie person. I,ve just got some more questions, and I will appreciate your honest and objective opinion.1. If the engine had been producing low engine power before, then it would have exaggerated a transmission issue. I assume that this exaggerated transmission/gearbox issue would not have gone un-noticed at diagnosis, especially when the car was test-driven, right?
2. Also, if i get you correctly, are you saying the improvement in engine power should not have suddenly exaggerated an underlying transmission issue? Rather it should have been the other way round?
3. According to the garage, the gearbox was jumping in and out of gear, due to the valve body being worn out. If this was the case, in your experience, is this something a mechanic is expected to have picked up on when conducting a comprehensive health diagnosis of the car? Especially if the car was road-tested for about 3-5 miles before commencing work?
4. If there was indeed a worn valve body, do you think such car is drive-able for over 38 miles?
5. If the car had a worn valve body issue, what sort of problems should i have noticed while driving the car for about 40 minutes in different road conditions?
6. These valve bodies, do they usually get worn out easily? Would you say they need replacement often in diesel cars of 166600 miles?
7. When there is a worn valve body, is getting another used/reconditioned gearbox the only option? Are there usually cheaper alternatives?
Expert:  sprinkles08 replied 1 year ago.
1. I don't believe a transmission issue would not have been noticed if the problem was present when it was worked on.
2. Increasing engine power shouldn't have caused a trans issue to be more noticeable.
3. If the problem was present during their work I expect they wuld have noticed it.
4. Depending on what is actually wrong and what it's doing it could be possible to drive it indefinitely, although not shifting correctly.
5. That depends on what the actual problem is. It may be slipping, not shifting or shifting at incorrect times.
6. Valve bodies don't often need to be replaced but it isn't unheard of for valves to wear into the soft aluminum bores. Automatic transmissions have a finite life and getting 166,000 miles out of one before having issue's isn't bad at all.
7. The valve body can usually be replaced on it's own.
Customer: replied 1 year ago.
As an additional information, the garage's diagnosis is "The gearbox was jumping in and out of gear due to the valve body being worn out, so that when it gets to a certain temperature while driving the car, the gearbox looses pressure around the valve that controls the forward clutch.
Would you say that based on the garage's explanations above, if indeed the car had a worn valve body, and regardless of whether the car's engine was underpowered or not, one should have noticed while driving the car for as long as 40 minutes; this issue of the car crawling like snail after stopping at lights/junctions for about 10 seconds, before suddenly moving off ?
Expert:  sprinkles08 replied 1 year ago.
It sounds as if the trans may be disengaging or slipping due to a loss of line pressure. If the problem was present when they drove it then they couldn't have not noticed.
Customer: replied 1 year ago.
Lastly, please compare the garage's diagnosis and the resulting fault below-
Diagnosis -"The gearbox was jumping in and out of gear due to the valve body being worn out, so that when it gets to a certain temperature while driving the car, the gearbox looses pressure around the valve that controls the forward clutch.Resulting fault- Car crawling like snail after stopping at lights/junctions for about 10 seconds, before suddenly moving off ?My question is - Would you say I should normally experience the resulting fault above while driving the car for about 40 minutes, if the diagnosis/statement above was true?I know the cost of valve bodies will vary, depending on what make of car. Are they usually expensive? Can you give me a range of prices.....£100....£250...£1000?
Expert:  sprinkles08 replied 1 year ago.
The problem could happen after driving 40 minutes, a longer or shorter time. I've seen slippage happen after a minute of run time or less.
I'm showing a new replacement valve body runs $1,843.10.
Customer: replied 1 year ago.
Could I ask what your qualifications/credentials are, and how many years of experience you have please?
Customer: replied 1 year ago.
Also, what is your name and the name of your garage?
Expert:  sprinkles08 replied 1 year ago.
I have almost fifteen years of dealership experience, nearly the entire time being the sole individual doing automatic transmission work.
I'm not at liberty to publicly give my name or place of employment.