thud when starting up the engine and switching to Drive

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Old 06 Apr 2009, 05:17 pm   #1 (permalink)
mrdarrett@gmail.com
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Default thud when starting up the engine and switching to Drive

The situation: at a red light, especially a left-turn one, I shut off
the engine, placing the trans in neutral. Suddenly the light turns
green. I turn on the engine. I'm near the front, and in a bit of a
hurry. I slip the gear into Drive, then press on the accelerator. I
feel a noticeable "thud" as the car shifts into drive.

What is this thud, exactly?

Is it bad for the longevity of the trans?

Thanks,

Michael
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Old 07 Apr 2009, 02:35 am   #2 (permalink)
johngdole@hotmail.com
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Default Re: thud when starting up the engine and switching to Drive

When you're not in a hurry to accelerate. For example, start the
engine (the engine speed stabilizes to normal idle), and then shift.
Do you still feel the thud?

Typical questions: How's the condition of the ATF (pink/red, grey,
brown, black)? Strainer (not blocked I'm sure but with/without tiny
particles visible)? Last service (month, years, never)?

If you take it easy and there isn't a thud, then there is a bit of
delay in going into gear. My guess is slow ATF pressure rise. For
example, the older v6 tranny (the budget 540 series) was notorious for
sluggish pressure rise (therefore accelerated clutch friction wear,
and the downward spiral continues), and IIRC a steel valve sleeve was
made to delay the wear in later years.



On Apr 6, 3:17*pm, mrdarr...@gmail.com wrote:
> The situation: *at a red light, especially a left-turn one, I shut off
> the engine, placing the trans in neutral. *Suddenly the light turns
> green. *I turn on the engine. *I'm near the front, and in a bit of a
> hurry. *I slip the gear into Drive, then press on the accelerator. *I
> feel a noticeable "thud" as the car shifts into drive.
>
> What is this thud, exactly?
>
> Is it bad for the longevity of the trans?
>
> Thanks,
>
> Michael


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Old 07 Apr 2009, 02:37 am   #3 (permalink)
johngdole@hotmail.com
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Default Re: thud when starting up the engine and switching to Drive

Now suppose you just step on the gas from a stop. Say at a left turn,
do you feel the thud?

Another possibility: inner CV joint. I'll try to find some articles on
this.


On Apr 6, 3:17*pm, mrdarr...@gmail.com wrote:
> The situation: *at a red light, especially a left-turn one, I shut off
> the engine, placing the trans in neutral. *Suddenly the light turns
> green. *I turn on the engine. *I'm near the front, and in a bit of a
> hurry. *I slip the gear into Drive, then press on the accelerator. *I
> feel a noticeable "thud" as the car shifts into drive.
>
> What is this thud, exactly?
>
> Is it bad for the longevity of the trans?
>
> Thanks,
>
> Michael


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Old 07 Apr 2009, 10:37 am   #4 (permalink)
mrdarrett@gmail.com
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Default Re: thud when starting up the engine and switching to Drive

On Apr 7, 12:35*am, johngd...@hotmail.com wrote:
> When you're not in a hurry to accelerate. For example, start the
> engine (the engine speed stabilizes to normal idle), and then shift.
> Do you still feel the thud?
>
> Typical questions: How's the condition of the ATF (pink/red, grey,
> brown, black)? Strainer (not blocked I'm sure but with/without tiny
> particles visible)? Last service (month, years, never)?
>
> If you take it easy and there isn't a thud, then there is a bit of
> delay in going into gear. My guess is slow ATF pressure rise. For
> example, the older v6 tranny (the budget 540 series) was notorious for
> sluggish pressure rise (therefore accelerated clutch friction wear,
> and the downward spiral continues), and IIRC a steel valve sleeve was
> made to delay the wear in later years.
>
> On Apr 6, 3:17*pm, mrdarr...@gmail.com wrote:
>
> > The situation: *at a red light, especially a left-turn one, I shut off
> > the engine, placing the trans in neutral. *Suddenly the light turns
> > green. *I turn on the engine. *I'm near the front, and in a bit of a
> > hurry. *I slip the gear into Drive, then press on the accelerator. *I
> > feel a noticeable "thud" as the car shifts into drive.

>
> > What is this thud, exactly?

>
> > Is it bad for the longevity of the trans?

>
> > Thanks,

>
> > Michael




Oh the trans is fine otherwise. I drained and filled numerous times
chasing another problem (eventually solved it), even changed the
strainer once.

Slow ATF pressure rise sounds reasonable. Wears out the clutch, eh?

Thanks,

Michael
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Old 07 Apr 2009, 12:39 pm   #5 (permalink)
Leftie
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Default Re: thud when starting up the engine and switching to Drive

mrdarrett@gmail.com wrote:
> The situation: at a red light, especially a left-turn one, I shut off
> the engine, placing the trans in neutral. Suddenly the light turns
> green. I turn on the engine. I'm near the front, and in a bit of a
> hurry. I slip the gear into Drive, then press on the accelerator. I
> feel a noticeable "thud" as the car shifts into drive.
>
> What is this thud, exactly?
>
> Is it bad for the longevity of the trans?
>
> Thanks,
>
> Michael



It's probably the delayed or slow shifting that John mentions.
Equally important, though, is that you shouldn't be doing that -
shutting the engine off at red lights. I know hybrids do it, but they
are designed for it, and your car isn't. If you are saving any gas at
all, it's being more than made up for by accelerated wear in the starter
and transmission. If you're doing it because of the notorious Camry
'shaking at idle in Drive' then just shift to Neutral, leave the engine
running, and when you see the light go yellow on the other side, shift
back to Drive. Never press the gas pedal before you feel the
transmission engage. We have a '95 wagon that was neglected before we
got it, and the transmission is very slow to shift into Drive or
Reverse; it's taken a conscious effort to remember to wait for it to
engage before stepping on the gas.
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Old 07 Apr 2009, 12:55 pm   #6 (permalink)
mrdarrett@gmail.com
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Default Re: thud when starting up the engine and switching to Drive

On Apr 7, 10:39*am, Leftie <N...@Thanks.net> wrote:
> mrdarr...@gmail.com wrote:
> > The situation: *at a red light, especially a left-turn one, I shut off
> > the engine, placing the trans in neutral. *Suddenly the light turns
> > green. *I turn on the engine. *I'm near the front, and in a bit of a
> > hurry. *I slip the gear into Drive, then press on the accelerator. *I
> > feel a noticeable "thud" as the car shifts into drive.

>
> > What is this thud, exactly?

>
> > Is it bad for the longevity of the trans?

>
> > Thanks,

>
> > Michael

>
> * * It's probably the delayed or slow shifting that John mentions.
> Equally important, though, is that you shouldn't be doing that -
> shutting the engine off at red lights. I know hybrids do it, but they
> are designed for it, and your car isn't. If you are saving any gas at
> all, it's being more than made up for by accelerated wear in the starter
> and transmission. If you're doing it because of the notorious Camry
> 'shaking at idle in Drive' then just shift to Neutral, leave the engine
> running, and when you see the light go yellow on the other side, shift
> back to Drive. Never press the gas pedal before you feel the
> transmission engage. We have a '95 wagon that was neglected before we
> got it, and the transmission is very slow to shift into Drive or
> Reverse; it's taken a conscious effort to remember to wait for it to
> engage before stepping on the gas.



I was doing it to save gas. Heard that the fuel injection system
doesn't use much gas to restart, compared with carbureted engines.
I'll keep in mind the stress on the starter though, thanks.

It's a '96 camry, 164,000 miles, thought I'd try to hypermile a bit.
Saving the car for my brother-in-law, else I'd sell it already.

I had the stalling problem at red lights, and fixed it by replacing
the coolant temperature sensor. (At first I thought it was a stuck
torque lock solenoid, so I changed the coolant every oil change...
turns out that wasn't it.)

Thanks,

Michael
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Old 07 Apr 2009, 12:57 pm   #7 (permalink)
mrdarrett@gmail.com
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Default Re: thud when starting up the engine and switching to Drive

On Apr 7, 10:55*am, mrdarr...@gmail.com wrote:
> On Apr 7, 10:39*am, Leftie <N...@Thanks.net> wrote:
>
>
>
> > mrdarr...@gmail.com wrote:
> > > The situation: *at a red light, especially a left-turn one, I shut off
> > > the engine, placing the trans in neutral. *Suddenly the light turns
> > > green. *I turn on the engine. *I'm near the front, and in a bit of a
> > > hurry. *I slip the gear into Drive, then press on the accelerator. *I
> > > feel a noticeable "thud" as the car shifts into drive.

>
> > > What is this thud, exactly?

>
> > > Is it bad for the longevity of the trans?

>
> > > Thanks,

>
> > > Michael

>
> > * * It's probably the delayed or slow shifting that John mentions.
> > Equally important, though, is that you shouldn't be doing that -
> > shutting the engine off at red lights. I know hybrids do it, but they
> > are designed for it, and your car isn't. If you are saving any gas at
> > all, it's being more than made up for by accelerated wear in the starter
> > and transmission. If you're doing it because of the notorious Camry
> > 'shaking at idle in Drive' then just shift to Neutral, leave the engine
> > running, and when you see the light go yellow on the other side, shift
> > back to Drive. Never press the gas pedal before you feel the
> > transmission engage. We have a '95 wagon that was neglected before we
> > got it, and the transmission is very slow to shift into Drive or
> > Reverse; it's taken a conscious effort to remember to wait for it to
> > engage before stepping on the gas.

>
> I was doing it to save gas. *Heard that the fuel injection system
> doesn't use much gas to restart, compared with carbureted engines.
> I'll keep in mind the stress on the starter though, thanks.
>
> It's a '96 camry, 164,000 miles, thought I'd try to hypermile a bit.
> Saving the car for my brother-in-law, else I'd sell it already.
>
> I had the stalling problem at red lights, and fixed it by replacing
> the coolant temperature sensor. *(At first I thought it was a stuck
> torque lock solenoid, so I changed the coolant every oil change...
> turns out that wasn't it.)
>
> Thanks,
>
> Michael



Whoops, changed TRANS fluid every oil change (not coolant... that
would be silly...)

Thanks,

M
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Old 07 Apr 2009, 11:20 pm   #8 (permalink)
johngdole@hotmail.com
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Default Re: thud when starting up the engine and switching to Drive

I take it that in typical starts this thud doesn't happen? I think
with Aisin transmissions it can take about 0.5-1.2 seconds to shift
into gear. The new transmissions of choice, Borg Warner Direct Shift
Gearbox designs (DSG) would need only about 8 milliseconds.

So try stepping on the gas 0.5-1.2 seconds AFTER shifting. If that
solves the problem all is fine.

Otherwise also check inner CV joint and possible differential (spider
gear) problem. Here is an article on CV joint (inner and outer) noise
diagnosis:

http://www.motor.com/magazine/pdfs/022000_09.pdf




On Apr 7, 10:55*am, mrdarr...@gmail.com wrote:
> I was doing it to save gas. *Heard that the fuel injection system
> doesn't use much gas to restart, compared with carbureted engines.
> I'll keep in mind the stress on the starter though, thanks.
>
> It's a '96 camry, 164,000 miles, thought I'd try to hypermile a bit.
> Saving the car for my brother-in-law, else I'd sell it already.
>
> I had the stalling problem at red lights, and fixed it by replacing
> the coolant temperature sensor. *(At first I thought it was a stuck
> torque lock solenoid, so I changed the coolant every oil change...
> turns out that wasn't it.)
>
> Thanks,
>
> Michael


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Old 07 Apr 2009, 11:23 pm   #9 (permalink)
johngdole@hotmail.com
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Default Re: thud when starting up the engine and switching to Drive

I meant from N into R or D.

On Apr 7, 9:20*pm, johngd...@hotmail.com wrote:
> So try stepping on the gas 0.5-1.2 seconds AFTER shifting. If that
> solves the problem all is fine.

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Old 07 Apr 2009, 11:24 pm   #10 (permalink)
johngdole@hotmail.com
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Default Re: thud when starting up the engine and switching to Drive

So how's the condition of the ATF the last time you changed it?

On Apr 7, 10:57*am, mrdarr...@gmail.com wrote:
> Whoops, changed TRANS fluid every oil change (not coolant... that
> would be silly...)
>
> Thanks,
>
> M


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