Kickdown problem - The 1947 - Present Chevrolet & GMC Truck Message Board Network

skokie · 01-27-2004, 05:33 PM

I have a 350 with a 400 turbo. When I floor it it kicks down to passing gear but it wont come out of passing gear unless I drop gerars from D to L2 and back then it works. Any ideas what could be causing this?

Thanks

Longhorn Man · 01-27-2004, 09:00 PM

A sticking vacume modulator, or a vacume leak feeding that line.

skokie · 01-27-2004, 09:05 PM

Vacumn Modulator? How hard is that to change out?

jhow66 · 01-27-2004, 09:38 PM

On pass side of trans-will have a vacumn line going to it-only 1 bolt to remove-pull out the old push in the new- install bolt and vacumn line-done.

skokie · 01-27-2004, 10:56 PM

Ok sounds easy enuff. Should I expect a flood of tranny fluid?
Thanks

jhow66 · 01-27-2004, 11:45 PM

no-mostly above fluid line.

skokie · 01-28-2004, 01:11 AM

May do this tonight. I got the modulator.
Thanks again.

skokie · 01-28-2004, 02:28 AM

Ok Modulator changed out did notice that the old hose had a crack in it. I have replaced that as well however problem still here. What else should I be checking?
Thanks

Hooter · 01-28-2004, 03:46 AM

um the switch on your gas pedal could be sticking? or is the switch on your carb?

jhow66 · 01-28-2004, 01:42 PM

Does it change into high with regular driving?

skokie · 01-28-2004, 03:37 PM

Switch is on the carb and I checked it. It does not appear to be sticking. It does change into high with regular driving but sometimes when you first start out you can put it in drive and it wont change to 2nd unless you change it manually from D to L2 and back again. After that as long as you dont put it in park it works fine.

zyggy72 · 01-28-2004, 04:05 PM

I wonder if it could be a problem with the fluid flow in tranny that is causing the problem. When was the last time the fluid and filter were changed?

skokie · 01-28-2004, 04:25 PM

Fluid was changed out two weeks ago along with a new filter.

2wdBlazer · 01-28-2004, 04:56 PM

Don't mean to hijack but I wonder if that vacuum modulator would keep the tranny from downshifting into first? Mine never drops down by it's self when I come to a stop. Anyone know?

useRc10 · 01-28-2004, 05:34 PM

i have been having aproblem similar to 2wdblazers on my '85...it seems like it doesnt want to downshift when i slow down...vaccuum modulator?
-Nick

jhow66 · 01-28-2004, 06:05 PM

Next thing to check is the governor-it could be worn or sticking-it is the round bowl like thing on pass side of trans. The cover can be removed by taking the spring clip off. Some fluid will run out-not much. Pull ass. out and check to see it it is sticking or replace with known good one.

skokie · 01-28-2004, 06:11 PM

Is it on the front of the tranny or the back on the passenger side? Where is it in relation to the vac modulator?

Thanks

jhow66 · 01-28-2004, 06:41 PM

here it is

skokie · 01-28-2004, 06:47 PM

In the middle. Got it. Rookier question here but what should I do to test it?

Thanks

jhow66 · 01-28-2004, 06:47 PM

Sorry wrong picture--here is the 400

jhow66 · 01-28-2004, 06:53 PM

The weights should move in and out easy-as the weights spin then move outward causing the shaft to cover or uncover holes to make trans shift. I am not a trans expert either so I do not refund any money on advice. LOL

WRMZ71 · 01-28-2004, 08:03 PM

that still sounds like straight up vaccum problems to me. I'm no tranny expert by any means either though. You've changed the modulator and changed the rubber line but have you changed the whole line to a rubber piece? The line itself should be metal most of the way except for where it plugs in at the tranny and at the manifold. I'd check to make sure you got a good connection at the right spot on the manifold too. I see some people that run all rubber hoses for the vaccum advance on the tranny and the hoses will loose there strength cause of the heat and they will collapse and not get proper vaccum through. thats my 2 cents

skokie · 01-28-2004, 08:23 PM

Its 2-3 inches of rubber line to the manifold, 2-3 inches or rubber to the modulator. The rest is all metal. I am going to remove the metal line tonight and see if anything is stuck in there and give it a good cleaning.

skokie · 01-29-2004, 01:46 AM

Ok here is a pic of the setup behind the carb. Its a 3/8 nipple in the manifold with a 3-4 inch piece of 3/8 tube going into a 3/8 and 1/4 tee. The 1/4 tee is connected to the metal tranny line going to the modulator. Is it ok to tee this off? Not sure why it was done this way.

Thanks

Hooter · 01-29-2004, 02:04 AM

hm is that connected to the back of the carb, Id much prefere to connect it to the nipple on the back of the intake manifold in the same place where the brake boost is connected

01-27-2004, 05:33 PM	#1
skokie Registered User Join Date: Oct 2003 Location: San Jose Ca. Posts: 3,343	Kickdown problem I have a 350 with a 400 turbo. When I floor it it kicks down to passing gear but it wont come out of passing gear unless I drop gerars from D to L2 and back then it works. Any ideas what could be causing this? Thanks Last edited by skokie; 01-27-2004 at 07:52 PM.

01-27-2004, 09:05 PM	#3
skokie Registered User Join Date: Oct 2003 Location: San Jose Ca. Posts: 3,343	Vacumn Modulator? How hard is that to change out? __________________ RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234

01-27-2004, 09:38 PM	#4
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	On pass side of trans-will have a vacumn line going to it-only 1 bolt to remove-pull out the old push in the new- install bolt and vacumn line-done. __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

01-27-2004, 10:56 PM	#5
skokie Registered User Join Date: Oct 2003 Location: San Jose Ca. Posts: 3,343	Ok sounds easy enuff. Should I expect a flood of tranny fluid? Thanks __________________ RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234

01-27-2004, 11:45 PM	#6
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	no-mostly above fluid line. __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

01-27-2004, 09:00 PM	#2
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	A sticking vacume modulator, or a vacume leak feeding that line.

01-28-2004, 01:11 AM	#7
skokie Registered User Join Date: Oct 2003 Location: San Jose Ca. Posts: 3,343	May do this tonight. I got the modulator. Thanks again. __________________ RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234

01-28-2004, 02:28 AM	#8
skokie Registered User Join Date: Oct 2003 Location: San Jose Ca. Posts: 3,343	Ok Modulator changed out did notice that the old hose had a crack in it. I have replaced that as well however problem still here. What else should I be checking? Thanks __________________ RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234

01-28-2004, 03:46 AM	#9
Hooter My other Love Join Date: Aug 2001 Location: Castlegar B.C. Canada Posts: 4,085	um the switch on your gas pedal could be sticking? or is the switch on your carb? __________________ Castlegar B.C.The great white North (Canada Eh!) Hooter_5@hotmail.com First generation Monte Carlo club pictures of my life

01-28-2004, 01:42 PM	#10
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	Does it change into high with regular driving? __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

01-28-2004, 03:37 PM	#11
skokie Registered User Join Date: Oct 2003 Location: San Jose Ca. Posts: 3,343	Switch is on the carb and I checked it. It does not appear to be sticking. It does change into high with regular driving but sometimes when you first start out you can put it in drive and it wont change to 2nd unless you change it manually from D to L2 and back again. After that as long as you dont put it in park it works fine.

01-28-2004, 04:05 PM	#12
zyggy72 Can't kick the addiction! Join Date: Jan 2002 Location: Riverton, CT 06065 Posts: 402	I wonder if it could be a problem with the fluid flow in tranny that is causing the problem. When was the last time the fluid and filter were changed?

01-28-2004, 04:25 PM	#13
skokie Registered User Join Date: Oct 2003 Location: San Jose Ca. Posts: 3,343	Fluid was changed out two weeks ago along with a new filter. __________________ RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234

01-28-2004, 04:56 PM	#14
2wdBlazer The Blazer King Join Date: Sep 2000 Location: Valrico, Fl (Tampa) Posts: 1,213	Don't mean to hijack but I wonder if that vacuum modulator would keep the tranny from downshifting into first? Mine never drops down by it's self when I come to a stop. Anyone know? __________________ 72 2wd Blazer. Its the superbichinest, megacoolinest, superflowinest.

01-28-2004, 05:34 PM	#15
useRc10 Registered User Join Date: Feb 2001 Location: Mechanicsville, VA, 23111 Posts: 1,138	i have been having aproblem similar to 2wdblazers on my '85...it seems like it doesnt want to downshift when i slow down...vaccuum modulator? -Nick __________________ -'02 Chevy Avalanche, 5.3L, 4x4... needing a small lift and bigger tires -'72 Chevy C-10(350, bored 60 over)dual flowmasters, 3 on the tree -'85 K5 Blazer,305 NO MORE...350 is in,2" lift,33" Mickey Thompson Baja Claw Radials -dads '70 burb (red, 5-7 drop, 350...) www.geocities.com/userc10/truckhome.html AIM: Auntjoedadda



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01-28-2004, 06:05 PM	#16
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	Next thing to check is the governor-it could be worn or sticking-it is the round bowl like thing on pass side of trans. The cover can be removed by taking the spring clip off. Some fluid will run out-not much. Pull ass. out and check to see it it is sticking or replace with known good one. __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

01-28-2004, 06:11 PM	#17
skokie Registered User Join Date: Oct 2003 Location: San Jose Ca. Posts: 3,343	Is it on the front of the tranny or the back on the passenger side? Where is it in relation to the vac modulator? Thanks __________________ RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234

01-28-2004, 06:41 PM	#18
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	picture here it is Attached Images __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

01-28-2004, 06:47 PM	#19
skokie Registered User Join Date: Oct 2003 Location: San Jose Ca. Posts: 3,343	In the middle. Got it. Rookier question here but what should I do to test it? Thanks __________________ RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234

01-28-2004, 06:47 PM	#20
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	picture Sorry wrong picture--here is the 400 Attached Images __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

01-28-2004, 06:53 PM	#21
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	The weights should move in and out easy-as the weights spin then move outward causing the shaft to cover or uncover holes to make trans shift. I am not a trans expert either so I do not refund any money on advice. LOL __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

01-28-2004, 08:03 PM	#22
WRMZ71 Cause the Chicks DIG IT!! Join Date: Nov 2003 Location: Beaufort SC Posts: 509	that still sounds like straight up vaccum problems to me. I'm no tranny expert by any means either though. You've changed the modulator and changed the rubber line but have you changed the whole line to a rubber piece? The line itself should be metal most of the way except for where it plugs in at the tranny and at the manifold. I'd check to make sure you got a good connection at the right spot on the manifold too. I see some people that run all rubber hoses for the vaccum advance on the tranny and the hoses will loose there strength cause of the heat and they will collapse and not get proper vaccum through. thats my 2 cents

01-28-2004, 08:23 PM	#23
skokie Registered User Join Date: Oct 2003 Location: San Jose Ca. Posts: 3,343	Its 2-3 inches of rubber line to the manifold, 2-3 inches or rubber to the modulator. The rest is all metal. I am going to remove the metal line tonight and see if anything is stuck in there and give it a good cleaning. __________________ RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234

01-29-2004, 01:46 AM	#24
skokie Registered User Join Date: Oct 2003 Location: San Jose Ca. Posts: 3,343	Ok here is a pic of the setup behind the carb. Its a 3/8 nipple in the manifold with a 3-4 inch piece of 3/8 tube going into a 3/8 and 1/4 tee. The 1/4 tee is connected to the metal tranny line going to the modulator. Is it ok to tee this off? Not sure why it was done this way. Thanks Attached Images

01-29-2004, 02:04 AM	#25
Hooter My other Love Join Date: Aug 2001 Location: Castlegar B.C. Canada Posts: 4,085	hm is that connected to the back of the carb, Id much prefere to connect it to the nipple on the back of the intake manifold in the same place where the brake boost is connected __________________ Castlegar B.C.The great white North (Canada Eh!) Hooter_5@hotmail.com First generation Monte Carlo club pictures of my life

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