Need advice please!
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Teching In
Joined: Oct 2014
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From: CO
Need advice please! I'll try to keep this short and sweet. I was pulling into my neighborhood the other night and transmission wouldn't shift into second gear... I immediately pull over and put it into neutral then to reverse and it operates normally. I then shift back into drive and it engaged extremely hard. I proceed to roll forward give it some gas and yet again it's not shifting. I'm far from an expert but I'm just wondering if this sounds like a serious trans issue or if it can be something else I'm unaware of. Also It was like 95 degrees out and I had been driving it for about an hour so I'm just curious if it may have been overly hot but I'm almost afraid to shift it into drive again. Thanks in advance for any advice!
Last edited by GMsfinest; Jul 29, 2016 at 01:57 AM.
Thread Starter
Teching In
Joined: Oct 2014
Posts: 35
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From: CO
Thread Starter
Teching In
Joined: Oct 2014
Posts: 35
Likes: 0
From: CO
Moderator
Joined: Aug 2010
Posts: 7,323
Likes: 529
From: Ann Arbor, MI
A missing or harsh 1-2 shift could be as simple as a broken piston in the 1-2 accumulator. (A harsh shift could be a broken spring there.)
This is easy to check and correct after dropping the pan - the accumulator is dome shaped and held with 3 bolts. It contains a rod, a piston and one or two springs. GM used a plastic piston in some years which is prone to break; whether broken or not it should always be replaced with a GM aluminum piston or the Sonnax pinless piston.
I'm not guaranteeing this is the problem; the probability might only be 25%, but it is the first thing I would check.
If not that, I would put on a pressure gauge; perhaps your line pressure is all over the place, e.g. due to a sticking PCS. That is likely even a lower probability, but I would check lower probability things that are easy and cheap to fix before pulling the trans for a rebuild.
This is easy to check and correct after dropping the pan - the accumulator is dome shaped and held with 3 bolts. It contains a rod, a piston and one or two springs. GM used a plastic piston in some years which is prone to break; whether broken or not it should always be replaced with a GM aluminum piston or the Sonnax pinless piston.
I'm not guaranteeing this is the problem; the probability might only be 25%, but it is the first thing I would check.
If not that, I would put on a pressure gauge; perhaps your line pressure is all over the place, e.g. due to a sticking PCS. That is likely even a lower probability, but I would check lower probability things that are easy and cheap to fix before pulling the trans for a rebuild.
Last edited by mrvedit; Jul 29, 2016 at 08:53 AM.
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Thread Starter
Teching In
Joined: Oct 2014
Posts: 35
Likes: 0
From: CO
A missing or harsh 1-2 shift could be as simple as a broken piston in the 1-2 accumulator. (A harsh shift could be a broken spring there.)
This is easy to check and correct after dropping the pan - the accumulator is dome shaped and held with 3 bolts. It contains a rod, a piston and one or two springs. GM used a plastic piston in some years which is prone to break; whether broken or not it should always be replaced with a GM aluminum piston or the Sonnax pinless piston.
I'm not guaranteeing this is the problem; the probability might only be 25%, but it is the first thing I would check.
If not that, I would put on a pressure gauge; perhaps your line pressure is all over the place, e.g. due to a sticking PCS. That is likely even a lower probability, but I would check lower probability things that are easy and cheap to fix before pulling the trans for a rebuild.
This is easy to check and correct after dropping the pan - the accumulator is dome shaped and held with 3 bolts. It contains a rod, a piston and one or two springs. GM used a plastic piston in some years which is prone to break; whether broken or not it should always be replaced with a GM aluminum piston or the Sonnax pinless piston.
I'm not guaranteeing this is the problem; the probability might only be 25%, but it is the first thing I would check.
If not that, I would put on a pressure gauge; perhaps your line pressure is all over the place, e.g. due to a sticking PCS. That is likely even a lower probability, but I would check lower probability things that are easy and cheap to fix before pulling the trans for a rebuild.
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Teching In
Joined: Oct 2014
Posts: 35
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From: CO
Update... So I grew a set of ***** overnight and said F it I'm going to go try to shift it. I back it up put it in drive and it engages normally. I roll forward and it shifts smoothly. I proceed to take it around my neighborhood and it shifts up and down completely fine I even go from neutral to drive a couple times and it doesn't duplicate the violent occurrence from before. Only thing that happened is my fuel gauge isn't working anymore and I turned it to off and on to accessory about 5-6 times. It moves but then goes back down to E. (I know I'm full I took it to the gas station to make sure that someone didn't just steal my gas) I have an appointment with a reputable family owned shop near by this week but I know there are a lot of very knowledgeable and experienced people here. Thanks again to all!
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Joined: Aug 2010
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From: Ann Arbor, MI
Sounding more like a stuck PCS (Pressure Control Solenoid) which is relatively simple to replace:
1. Drop the pan (perhaps after pumping ATF out through the dipstick).
2. Remove the 1-2 Accumulator housing - good time to check the piston and springs
3. Unclip the wiring to the PCS.
4. Remove the single 8mm bolt which holds it.
1. Drop the pan (perhaps after pumping ATF out through the dipstick).
2. Remove the 1-2 Accumulator housing - good time to check the piston and springs
3. Unclip the wiring to the PCS.
4. Remove the single 8mm bolt which holds it.