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2009 Pontiac G6 base sedan 144000 miles Automatic. I was on my way to work and had to hit brakes pretty hard since some people on the highway cut off the car in front of me. Came to a complete stop and then when I tried to move the car again it wouldn't budge. The engine was reving but it wouldnt move. I was stuck like that for around 10 seconds probably before the car started moving again.

When I got out of the highway I came to a slow complete stop but I felt a small bump right at the end and the car was stuck again. The engine would rev but not move forward. I shifted to reverse and the car went back a little and would shift to drive again but it would not budge again. This also lasted about 10 seconds before the car moved.

A few red lights and stop signs to work with no issues and in the parking lot I tried braking hard and soft to see if it happened again to get out and see if the brakes were locked but it did not happen again. Hopefully the drive back home goes fine but I will go slow.

I had this happen a couple times last year but only for a second or two and the mechanic told me it was probably just because I was late on my oil change. Again now my oil life meter is pretty low. I also had my front brake pada change a month or so ago.

So any ideas and what I should ask to mechanic to look at more in detail since this seems to be getting worse with time?

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  • I assume it's an automatic right? I did check if this car comes with a manual tranny, which it apparently does.
    – Paramone
    Commented Apr 6, 2018 at 14:23
  • Does the car come to a stop on it's own like the brakes are sticking?
    – JPhi1618
    Commented Apr 6, 2018 at 14:29
  • Have you checked the fluid level? Have you ever serviced the transmission filter?
    – Moab
    Commented Apr 6, 2018 at 22:57
  • It's possible the brakes are sticking. You should be able to feel the heat coming off one the brake drums/ rotors after you've driven a while. Might be VERY hot, smelly too.
    – mike65535
    Commented Jul 6, 2018 at 0:23
  • 1
    My first car was a 95 mercury Tracer, and I knew absolutely nothing about cars so I did nothing to maintain the car, it's funny but it's not. Well one day I was turning a corner and I was driving really slow, but rrruumm I was pushing the gas, then jerk jerk, stop, rummmm, nothing. I was out of transmission fluid. I never changed it, so a few days later it just stopped running, odd right lol
    – user38183
    Commented Oct 4, 2018 at 10:00

2 Answers 2

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If the problem is repeatable, and it sounds as though it is, you may not have to ask your mechanic to look at anything specific. If he test drives the vehicle and it locks the brakes as you've described, he'll have a few ideas where to begin. That covers the question you've posted.

The curious part of your trouble is that you can drive after ten seconds. What is there in the braking system that could be varying in a ten second period?

I'd wonder if you have a stuck master cylinder that slowly releases itself, or possibly something related to the vacuum booster.

I had to perform a panic stop, many years ago and the forces applied caused the seals on the slave cylinder of one wheel to fracture and blow out, leaking all the brake fluid. I had only one of two circuits of brakes working until I rebuilt it. I don't think you have a problem in the seals of your calipers, but it isn't completely out of the question.

A late oil change on the engine will not affect the braking. I would not expect a failing ABS (anti-lock braking system) to fail in such a way as to lock the wheels for ten seconds.

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This is knowledge from my mechanic (he is good but not working anymore). Post: An automatic transmission has disk plates that rotate synchronizing the speed. or you can read here

Problem: sudden braking of the car with automatic transmission.

  • I assume this is over-limit from safe speed? (eg:<60kmh).

From your post is stated you can rev but didn't move, the engine is not dead correct? or the engine is not rattled like too much weight on it correct?

The main culprit is your transmission disk is slipped because the engine is not dead. Probably because when you hard braking, the engine is still on high RPM, which in your transmission revving on high speed but you try to stop the output of the transmission so quick the disk is melted in such a way (because hot from one disk is rotating and one disk is not)and ultimately making your disk cannot grip another disk because it's faded.

The disk is like a clutch disk that has a bulge or strip to grip another disk, so if there is no strip or clean straight like a plate it will not gripping anything/slipping away.

If your engine is hard to running like moving a ton of brick it's probably your brake is sticking. This you could check if your rim is hot or not.

If your mechanic says it just needs an oil change, you need to change your mechanic right away, because it just a lazy reason to avoid checking further.

How to check: drip out your oil transmission, get it on a bowl or so, see if any rubbish like dirt or sand-like (but it's not metal), if you found that with a good amount, your disk needs to change to avoid slipping in next running.

'or use higher SAE rating or thicker oil :) it's the cheapest way to avoid slipping.

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