Transmission service?

2008 PONTIAC GRAND PRIX
78,000 MILES
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TRIPLERUSH
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i was told the trans fluid looked pretty dirty. After about 2000 or 2500 miles i noticed what I would describe as a hesitation at 50 mph, I would actually watch my rpm's jump around +/- 200 or 300 rpm. it was really only when I would maintain that speed or let up slightly, and only at 50. If I would give it a little gas it would be fine and also at any other speed. I put fuel system cleaner and engine cleaner in after an oil change, it was called Z max. I had 3/4 of a tank of gas I went through most of that and have noticed no change. oh and I think it only does it after 10 or 15 minutes of driving. After adding Zmax now i have noticed a wine coming from the engine sounding kind of like you get from the power steering but its all th time. Also when the car is cold there is a hesitation now in 1st gear or low rpm ( i only noticed this to happen once or twice in the last couple days) When I drive the car every thing seems to be ok when i give it a little gas it shifts fine and downshifts fine so im wondering where i should start? maybe the fuel system, tune up, ???? Thank You
Nov 12, 2012 at 2:30 AM
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ASEMASTER6371
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Hello,

I would try a transmission fluid and filter change to see if that helps, here is a guide to help walk you through the steps with instructions in the diagrams below to show you how on your car.

https://www.2carpros.com/articles/how-to-service-an-automatic-transmission

Fluid Types


AUTOMATIC TRANSMISSION FLUID

DEXRON-VI Automatic Transmission Fluid.

Capacities


AUTOMATIC TRANSAXLE

Bottom Pan Removal .................... 7.4 quarts (7.0 liters)

Complete Overhaul .................... 10.0 quarts (9.5 liters)

Dry .................... 13.4 quarts (12.7 liters)

NOTE: All capacities are approximate. When adding, be sure to fill to the approximate level. Recheck fluid level after filling.


Check out the diagrams (Below). Please let us know what happens.
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Nov 12, 2012 at 2:34 AM
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TEMBODY
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Which is better, Transmission flushing or pulling the pan and replace the filter and fluid ?
Apr 9, 2020 at 11:45 AM (Merged)
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MMPRINCE4000
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I prefer to change the filter and fluid change vs. a flush.

Keep the parts clean, because any small particles can block passages in valve body and cause many problems.

A flushing may be needed if fluid is discolored or has a burnt smell.
Apr 9, 2020 at 11:45 AM (Merged)
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GRANDPRIXOWNER2006
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I have a 06 Grand Prix GT and I was curious as to a clunking/clanking noise I hear from the front of the car that only happens during acceleration at a slow/ moderate speed. I didnt think too much of it till I noticed it was occuring as I would brake as well. I'll get anywhere from 1 clunk to about 4 maybe 5 before driving sounds normal again. The noise was occuring after my last one. Car is about to 50,000 miles. Any help would be appreciated as I've tried checking out as much as I could online and from friends that have more knowledge then me about cars. Could it have anything to do with the steering system? Because I also notice a a vibrating whining ONLY during left turns. like I said any help would be appreciated.
Apr 9, 2020 at 11:46 AM (Merged)
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MMPRINCE4000
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Raise car, put on stands. Grasp tire and push/pull both horizontally and vertically, if any movement then possible wheel bearing, ball joint, tie rod, control arm bushing.

Check CV boots for any signs of leakage or cuts/rips in rubber boot.
Apr 9, 2020 at 11:46 AM (Merged)
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NANAKIM
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I own a Pontiac Grand Prix 2005, with 174,000km. Was thinking about a transmission flush, but was told not to, as this would be the first time and could cause issues. Was told to just have the fluid changed. What do you recommend???? Confused...and concerned.....

Kim..
Apr 9, 2020 at 11:46 AM (Merged)
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DOCFIXIT
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Well jury still out on flush vs. drain and refill. If trans operating good and this is maintence issue I would drain , filter and refill
Apr 9, 2020 at 11:46 AM (Merged)
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DENISEHUNT
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i have a 04 grand prix and i drive about 150 miles a day. my problem is that sometimes when i stop at a light or a stop sign the cars fine, but when i get ready to accelerate it jerks like almost if someone hit me from behind. It doesnt happen all the time just once in awhile. I took it in and they can't duplicate the problem, but they flushed the transmission fluid and it still doing it. We have only had it for 5 months.
Apr 9, 2020 at 11:46 AM (Merged)
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RHALL77
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do you do alot of highway driving? does it do it when you come off the highway after a long drive? I need a little more info.
Apr 9, 2020 at 11:46 AM (Merged)
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DENISEHUNT
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well yes I do alot of highway driving. however I serviced the transmission and the car seems much better, thanks for you help on this.
Apr 9, 2020 at 11:46 AM (Merged)
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DENNYP
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Nice work, we are here to help, please use 2CarPros anytime.
Apr 9, 2020 at 11:46 AM (Merged)
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ERICKNOTTS
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transmission shifts hard and slips after car warms just had transmission serviced
Apr 9, 2020 at 11:46 AM (Merged)
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MMPRINCE4000
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Hard shifts are a sign of excessive hydraulic pressure, or a restriction in valve body.

The slipping is never a good sign. Have shop that serviced it fix the slip, or you will be replacing trans.
Apr 9, 2020 at 11:46 AM (Merged)
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ETHANLJ14
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Hi, over the past 3 months the transmission in my grand prix has started to act really weird. If im on the street for longer than 20 mins the engine service light comes on and the whenever the transmission switches a gear the whole car shakes really violently. Ive read that this happens to a lot of grand prixs in my model year. So i was wondering whats the cheapest way to fix it.
Apr 9, 2020 at 11:46 AM (Merged)
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JASONRAY
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Sounds like the transmission is 'shuddering' when it shifts. This could be caused by a faulty pump or by some other internal hydraulic problem. Your best bet will be to take it to a transmission shop. It will, more than likely, need to be replaced. The damage is probably already done. A good transmission shop will offer advice on the cheapest route to take. They can also check the pressures that the pump is producing and determine a possible cause of your problem.
Apr 9, 2020 at 11:46 AM (Merged)