1999 Toyota 4Runner Bucking when taking off.

AKALAY

MEMBER
1999 TOYOTA 4RUNNER
6 CYL
4WD
AUTOMATIC
146,000 MILES

I will try to be brief. 3 months ago, I was advised my trans return lines into the radiator had allowed anti-freeze into the trans. R&R radiator and flushed trans then drove to florida. No problems. About a month ago, after an hour drive on the NJ Turnpike, I arrived at a light and my trans was acting weird. When I took my foot off the brake pedal, the truck was not moving forward. Then when the gas pedal was hit, it bucked a bit and then it was fine. I get to a parking lot and try to back up and it hesitates and I have to hit the gas pedal harder to get it to move. During normal driving to and from work or any other time on short drives (even at high speed limits), it does not do it, it seems only after about an hour of 65mph++ driving. This has now occurred 4 different times. Took the car to the dealer and they couldnt duplicate. All Fluids are on target. Smelled the trans dip stick for burning, it seemed normal, color normal (slightly dark for being changed 3 months ago)

Any suggestions.

Thanks.

6 Replies

KHLOW2008

MECHANIC
41,815 POSTS

Hi akalay,

Looks like a pressure or fluid problem.

When the problem occured, after taking off, were the gear changes ok, or did slippage occurs during hard acceleration?

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Friday, June 20th, 2008 AT 11:53 AM

AKALAY

MEMBER
3 POSTS

KHLow2008,

thank you for your response. After the intial bucking the gear changes seemed fine at higher speeds but at the next light, the same bucking occured during take off with just feathering the gas pedal. The reverse not working took me by surprise. It felt like a manual with the clutch slipping but with the added hesitation.

But today, all is well, you would not know there is a problem. Only after a consistent 65+ speeds does the issue pop-up.

Thank you for your time on this matter.

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Friday, June 20th, 2008 AT 12:11 PM

KHLOW2008

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Hi akalay,

You are welcomed.

I would suggest changing the fluid again as the last flush done might not have cleared the system 100 %.

Any idea if the fluid used was of correct spec?

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Friday, June 20th, 2008 AT 12:18 PM

AKALAY

MEMBER
3 POSTS

The flush was done at a Toyota Dealership 3 months and 5,000 miles ago. I will find out if the dealer will reflush or I will attempt. I was advised that never to flush a trans when the vehicle reaches high mileage but I had no choice.

Also worth mentioning, when I come to an abrupt stop and the gears are dropping and trying to catch up, there is a big thump in the trans. Or if I take off before it catches up, there is a thump, but again it doesnt happen all the time.

Thank you.

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Friday, June 20th, 2008 AT 12:40 PM

KHLOW2008

MECHANIC
41,815 POSTS

Hi akalay,

The contamination of the trans must have caused the control valves in the trans body to be sticking at times.

In this case I would suggest servicing the trans valve body.