Weird Transmission Issue
June 3rd, 2019, 3:26 PM
#1
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Weird Transmission Issue
Hi all. Wanted to see if you can help me diagnose the issue I am having.
I have a 2002 Tahoe LS V8 FFV 5.3 Liter.
I noticed the a month or so ago, after getting off the interstate, that the transmission was starting to hard shift as I began to accelerate after stops. Then as I paid closer attention to it, if I stayed on side roads and not go up above like 55mph, It never had an issue with shifting and ran like a top.
I got off the interstate over the weekend and it started to hard shift again. So, at the light I turned off engine and turned it back on and when I accelerated it, it shifted normally.
As I ran errands this weekend, I kept checking different driving routes and turning the engine off and on after interstate rides.
Its quite bizarre.
Anyone have any clue as to the problem? The check engine light is on but the code is reading hard shift only.
I have a 2002 Tahoe LS V8 FFV 5.3 Liter.
I noticed the a month or so ago, after getting off the interstate, that the transmission was starting to hard shift as I began to accelerate after stops. Then as I paid closer attention to it, if I stayed on side roads and not go up above like 55mph, It never had an issue with shifting and ran like a top.
I got off the interstate over the weekend and it started to hard shift again. So, at the light I turned off engine and turned it back on and when I accelerated it, it shifted normally.
As I ran errands this weekend, I kept checking different driving routes and turning the engine off and on after interstate rides.
Its quite bizarre.
Anyone have any clue as to the problem? The check engine light is on but the code is reading hard shift only.
June 3rd, 2019, 6:45 PM
#2
How many miles?
Has it ever been rebuilt?
How often do you flush the transmission fluid?
If the transmission fluid level correct?
Do you have a trans temp gauge on the console? If so, what does it show when this happens?
Has it ever been rebuilt?
How often do you flush the transmission fluid?
If the transmission fluid level correct?
Do you have a trans temp gauge on the console? If so, what does it show when this happens?
June 4th, 2019, 6:48 AM
#3
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Mileage is 248,000
All original
I have barely had the truck 2 years. (less than 12,000 miles I have put on it) I have never flushed the fluid since I have owned it.
I check all levels and they are normal
No trans temp gauge, just the one for the engine.
Apart from all of that, I have talked with a few mechanics and I see, to get the same response. Its too old for them to maintenance. The liability of it not working after wards due to the high mileage is something that they don't want to touch.
I was also told that I could change the fluid and that could be the only thing keeping it working as is right now. So, that might be a wrong move.
But I was also told that if I change it, it may work and the issue may go away. Kind of one of those double edged swords it seems like.
All original
I have barely had the truck 2 years. (less than 12,000 miles I have put on it) I have never flushed the fluid since I have owned it.
I check all levels and they are normal
No trans temp gauge, just the one for the engine.
Apart from all of that, I have talked with a few mechanics and I see, to get the same response. Its too old for them to maintenance. The liability of it not working after wards due to the high mileage is something that they don't want to touch.
I was also told that I could change the fluid and that could be the only thing keeping it working as is right now. So, that might be a wrong move.
But I was also told that if I change it, it may work and the issue may go away. Kind of one of those double edged swords it seems like.
June 4th, 2019, 10:15 AM
#4
You checked the fluid while the vehicle is running, correct?
This could be the throttle position sensor on the throttle body.
It could just be running hot due to the age of the fluid and all the contaminants in it.
It's believed by many that flushing the trans fluid in a high mileage transmission that has never been serviced will damage it due to the "sludge" and materials in the fluid keeping it operating. I believe this to be a myth. Usually what happens is someone is having transmission problems in their never maintained high mileage transmission so the first thing they do it flush it. A week or month later, the transmission dies. If they didn't flush is, it most likely would have still died in the same time frame if not sooner.
It could be caused by buildup of material in the valve body and a faulty manifold pressure switch.
If it was me, I'd drain the fluid in the pan and pull the pan. Examine what's in the pan. The magnet will have quite a bit of very fine metal material which is normal. If there are chunks of material in there or thick layer of friction material on the bottom of the pan, you probably have significantly worn clutches. Since it sounds like it's operating fine but with harsh shifts occasionally, I'm guessing the clutches are fine. I'd then pull the valve body, disassemble and examine if for wear. If all looks good, clean and reassemble. Replace the pressure switch manifold. While you're in there, Replacing the solenoids might be advisable as well. New filter also. At most, you'll have to replace about 6 quarts of transmission by dropping the pan. I believe the capacity is 13 quarts total so you'll be replacing almost half of what's actually in the trans, torque converter and cooling lines.
Of course, you're taking a risk no matter what you do to a high mileage trans with unknown maintenance. You could continue driving it as is but if something is wrong inside, It could go out on you eventually. You could try doing a complete fluid flush but if there is something wrong inside, it could still eventually go out on you.
This could be the throttle position sensor on the throttle body.
It could just be running hot due to the age of the fluid and all the contaminants in it.
It's believed by many that flushing the trans fluid in a high mileage transmission that has never been serviced will damage it due to the "sludge" and materials in the fluid keeping it operating. I believe this to be a myth. Usually what happens is someone is having transmission problems in their never maintained high mileage transmission so the first thing they do it flush it. A week or month later, the transmission dies. If they didn't flush is, it most likely would have still died in the same time frame if not sooner.
It could be caused by buildup of material in the valve body and a faulty manifold pressure switch.
If it was me, I'd drain the fluid in the pan and pull the pan. Examine what's in the pan. The magnet will have quite a bit of very fine metal material which is normal. If there are chunks of material in there or thick layer of friction material on the bottom of the pan, you probably have significantly worn clutches. Since it sounds like it's operating fine but with harsh shifts occasionally, I'm guessing the clutches are fine. I'd then pull the valve body, disassemble and examine if for wear. If all looks good, clean and reassemble. Replace the pressure switch manifold. While you're in there, Replacing the solenoids might be advisable as well. New filter also. At most, you'll have to replace about 6 quarts of transmission by dropping the pan. I believe the capacity is 13 quarts total so you'll be replacing almost half of what's actually in the trans, torque converter and cooling lines.
Of course, you're taking a risk no matter what you do to a high mileage trans with unknown maintenance. You could continue driving it as is but if something is wrong inside, It could go out on you eventually. You could try doing a complete fluid flush but if there is something wrong inside, it could still eventually go out on you.
Last edited by KChevy75; June 4th, 2019 at 8:43 PM.
June 4th, 2019, 7:37 PM
#5
CF Active Member
If you go to the trouble of changing the fluid I'd consider putting in a quart of Lucas with the rest of the new fluid. The Lucas will help swell up the seals - it's possible the seals have hardened with age. As suggested, I would not do a flush, but drop the pan and see what material is in the pan. Fine metal particles on the magnet is normal, but if any chunks of metal are in the pan it's not a good sign.
Good luck!
Good luck!
June 5th, 2019, 12:56 PM
#6
You don't say where you are located but search bgfindashop.com put in your zip code to find the nearest shop and have them to the complete flush probably after they do first scan and road test. You may be able to save it. Let us know how it goes. *BW*