QuestionQUESTION: Having changed gearboxes and torque convertors in my Hyundai lantra 1997 1.6lsi automatic I have hit a problem.
Though reverse gear works fine, (and as it should) D and forward select gears will not 'engage' immediately and only do so when the revs are built up, often to 2000 / 3000 rpm, it will then engage on what I can only describe as "grab and go". It then drives fine through the gears though appears to be 'slipping' as even at 30 / 40 mph the rev counter shows 3000 rpm too often, a 70mph reading ordinarily.
The selector has been set.
The transmission fluid levels are exact and the oil is new.
The gearbox and torque convertor are both from the same car I owned and so worked fine before being switched to this car.
I have had help on this topic but as yet cannot remedy the problem.
Some things I have been told...
Torque convertor not working!! Would the vehicle engage any gear if this were so?
Pump faulty.
Gearbox needs taking back off and cleaning! Using airline to blow channels where oil travels to clear blockages??
Filter.
I would be grateful for all and any help you would afford me..
Thank you. Ian
ANSWER: This isn't an issue with the torque converter or pump. If it were, the problem would be present in more gear selector positions than "D".
Unless there was a serious problem with the fluid in the transmission, it shouldn't need to be cleaned. I'd have hoped you would have changed the filter when installing a transmission from another vehicle, but even so, unless the fluid were obviously in poor condition, I cannot imagine there would be any negative symptoms that could be resolved by replacing the filter.
In my experience, the symptoms you list point mostly toward the an item in the transmission which would require an overhaul or replacement.
What year and model car did the replacement transmission come from? What was the engine size of this car? There may be differences between the transmissions that are causing the issue.
You might also replace the transmission control module with the one from the other car (if you have it). I doubt this is the issue-- I've never seen these symptoms caused by the control module-- but it cannot hurt to try replacing the module if you have one sitting around.
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QUESTION: Thank you for your input..In answer to your query, the vehicle that the gearbox and convertor were taken from is also an Hyundai Lantra 1.6, only it is a glsi and is a 1996 model (N). I did ask Hyundai tech support and they stated the gearbox is exactly the same and so I proceeded with the change...
I was doubtful the convertor would be faulty and as the replacement fluid is new doubt too the pump would be faulty but did neglect changing the filter though again, figured this would not matter.
I do still have the old gearbox and car and will look at changing the module and having supplied the other car details hopefully you may be able to supply more accurate help now you know.
Thank you again for your time and help.
ANSWER: You're welcome, Ian. My knowledge of this vehicle is limited to what we have here in the U.S. If Hyundai tech support is telling you they are the same transmission, I have no reason to doubt that.
Potentially, there could be an issue with the friction elements becoming dry in the installed transmission. The friction material is made to function properly when soaked in transmission fluid. For a number of reasons, most components are not totally immersed, meaning that if the transmission is allowed to sit unused for a long period of time, the friction capabilities of the friction materials may be compromised. I think this is a more likely scenario than the TCM being defective.
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QUESTION: Once more I thank you for the time you have given me in trying to assist.
Whilst your knowledge may be limited your help is invaluable.
Your last paragraph is now looking like the most likely scenario as I can confirm the gearbox was removed and left standing 'off' any vehicle for about 2 weeks. I believe also, (as I employed a third party to take it out) that it was also left uncovered and exposed to the weather for a day or two and so may very well have become dry...The torque convertor was removed at a later date and though stored within the boot also was not re-fitted for a few days and so too may have dried out so the whole gearbox was off the vehicle for maybe 6 weeks before being fitted. Do you feel this to be a significantly long enough period without oils to cause the issue you suggest?
As this is now looking like the most significant issue what would you suggest?
If I were to remove the gearbox and torque convertor again how would I be able to check they were still suitable for re-use and lubricate them for a second fit? And would this be prudent or of no consequence?
Upon your response I feel I may then have exhausted every avenue open to me but again wish to express my gratitude for your time and help.
Have a fantastic weekend ahead.
AnswerSix weeks isn't a terribly long period of time in our context. But I'm not referring simply to the amount of time it was out of the other vehicle. We need to add to this six weeks the amount of time it's been since the vehicle from which the transmission was removed has been driven.
Additionally, if the transmission was left out without being sealed, I'd have some concern that water may have entered the transmission. This can cause serious problems.
