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slipping in 4th gear


sevillests

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while driving at around 100 k/m an hour (60m/h) in 4th, my rpm is at 2000 give or take .then it seems to rev to 3000 rpm while doing the same speed! if i let off and coast the rpms drop to 1300, when i give it gas the rpm goes back to 3000 with no feel of power until i hit 3000rpm. if i shift it to 3rd the rpm goes up 200to300 rpm. when i go back to 4th it drops to 2000 again , but within 10 seconds it slips out again.....i noticed to on the first start of the day it gives a strong thump or bong you can feel, at first i thought it was the a/c coming on, but the next time it happend the a/c was off.also when shifting from park and just ideling out the drivway i feel like the clutch lets go . any help would greatly be helpful ....thanks thomas...p.s. no codes came up .

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while driving at around 100 k/m an hour (60m/h) in 4th, my rpm is at 2000 give or take .then it seems to rev to 3000 rpm while doing the same speed! if i let off and coast the rpms drop to 1300, when i give it gas the rpm goes back to 3000 with no feel of power until i hit 3000rpm. if i shift it to 3rd the rpm goes up 200to300 rpm. when i go back to 4th it drops to 2000 again , but within 10 seconds it slips out again.....i noticed to on the first start of the day it gives a strong thump or bong you can feel, at first i thought it was the a/c coming on, but the next time it happend the a/c was off.also when shifting from park and just ideling out the drivway i feel like the clutch lets go . any help would greatly be helpful ....thanks thomas...p.s. no codes came up .

How about codes?

The saddest thing in life is wasted talent

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It almost sounds like a solenoid that has cracked, but not broken off entirely. Check the transmission fluid level first. If the fluid level is OK, then I would check for broken solenoids.

Britt

Britt
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the fluid level is ok, it dosnt smell burt , just well used. its not a good red color nor is it brown. i have never changed it . like i said no codes came up and i did the check a number of times. the car has only 116800 miles on it . i very rarely drive it hard, and it dosnt burn a great amount of oil.

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the fluid level is ok, it dosnt smell burt , just well used. its not a good red color nor is it brown. i have never changed it . like i said no codes came up and i did the check a number of times. the car has only 116800 miles on it . i very rarely drive it hard, and it dosnt burn a great amount of oil.

Did you check VCC engagement? It's an easy test.

The saddest thing in life is wasted talent

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could be a bad solinoid, any way you can drop the pan to check? If not do you know a shop you would trust to check it? (not someone who who would tell you its broke without even checking it!) Doubt its the VCC the RPM's should only go up 50 to 100 rpm's

Good Luck

Joe

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while driving at around 100 k/m an hour (60m/h) in 4th, my rpm is at 2000 give or take .then it seems to rev to 3000 rpm while doing the same speed! if i let off and coast the rpms drop to 1300, when i give it gas the rpm goes back to 3000 with no feel of power until i hit 3000rpm.  if i shift it to 3rd the rpm goes up 200to300 rpm. when i go back to 4th it drops to 2000 again , but within 10 seconds it slips out again.....i noticed to on the first start of the day it gives a strong thump or bong you can feel, at first i thought it was the a/c coming on, but the next time it happend the a/c was off.also when shifting from park and just ideling out the drivway i feel like the clutch lets go . any help would greatly be helpful ....thanks thomas...p.s. no codes came up .

The changes in RPM is too great for a VCC problem to cause. I would check the solenoids as the symptoms seem to point in that direction. The transmission will show different responses depending on which solenoid fails. I have had a solenoid fail and it was limited to 2nd gear. I have read of others that were limited to fourth gear. If the solenoid body is partially broken, it could have symptoms like Sevillests is describing.

Britt

Britt
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If you are losing 4th gear, it will probably be the "A" solenoid. The solenoids come in a kit. The kit has two new style solenoids, a retainer bracket and a bolt for the bracket. If you drop the pan and remover the pickup screens, you should see a wiring harness that comes from the left side toward the center of the valve body. The items that the wiring harness attaches to are the shift solenoids. If one of the solenoids seems loose then it is probably cracked at the base.

This is not an extremely difficult repair. But it does take some patience and expertise. A GM service manual for the particular year is a MUST have.

The valve body must be dropped and partially disassembled to replace these solenoids.

There are EIGHT check balls in the valve body that will drop out. They MUST be reinstalled properly.

I was able to remove the channel plate from the spacer plate/gasket assembly and not disturb the check balls. I did this by being careful NOT to have the assembly upside down when I took it apart. This way the check balls remain in position in the channel plate. Being careful not to invert the channel plate until it is reassembled to the spacer plate/gasket assembly will insure that the check balls are in their proper positions.

The other trick is using a piece of .020 to .030 shim stock to hold the LO/Reverse band in position while reinstalling the valve body. This is explained and a drawing showing how to insert the shim stock is in the manual.

Also, there is a wealth of information on this subject in the archives.

Britt

Britt
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Seville, you won't get a code, at least not on the 'noids, if you don't have the time to drop the pan take it someone you trust. I had the same problem about 2 years ago, would hold 4th for a few seconds then drop to third the shop swore 4 gear was cooked and wanted 2800 to rebuild it, I wound up getting one out of a wreck and had a friend install cost a grand start to finish.

Hope you do better

Joe ;)

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