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The torque converter will only lock-up when cold.

Tiny
CORSICA95
  • MEMBER
  • 1985 CHEVROLET CHEVETTE
  • 35,000 MILES
Hello. I've had the car for a while now and I noticed that the torque converter actually locks-up when cold, but not when hot. After driving a few minutes, it will stop locking up. Where should I start looking?

Thanks :)
Wednesday, June 20th, 2012 AT 2:34 PM

24 Replies

Tiny
RACEFAN966
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How do you know it is locking up? Does the car stall at stop signs? Get back to me and we will see where to go from here ok.
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Wednesday, June 20th, 2012 AT 2:46 PM
Tiny
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When I reach, and cruise, at about 40mph (when the car is cold) I feel like an "extra gear" engage. Once the car is hot, it won't do it anymore. Thanks for the answer
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Wednesday, June 20th, 2012 AT 2:48 PM
Tiny
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So it sounds like the lock up is working correcty when cold not when hot. Do you have a tach to watch the RPM? What I would like you to is get to place where you can do 45mph and then with out letting up on throttle ever so lightly touch the brake with the left foot. Just enough to turn on the brake lights but not enough to actually brake. Do this when it is hot and cold let me know if the RPM changes and about how much if you could. THanks
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Wednesday, June 20th, 2012 AT 2:53 PM
Tiny
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I "test drove" it this morning, so the car is still warm. I have no tach, but I'd say there's maybe a 100-300 rpm drop when it engages (I may be wrong) and if I step on the brake pedal a little while still pressing on the gas, I feel it disengage and the RPMs go up a little. When the car is warm nothing happends when I do that.
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Wednesday, June 20th, 2012 AT 2:55 PM
Tiny
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Okay, so I checked my Ported Vacuum Switch since I've had small problems with my EGR valve, timing and etc. Since I got the car, and it seems to be a 4 ports (arranged in a square) switch. On the internet, I can only find some 5 port switches and some 2-3 port switches. Is it possible that someone changed the whole switch/vacuums with the wrong ones?
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Wednesday, June 20th, 2012 AT 4:22 PM
Tiny
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Good the lock up is working. From what I can see the 4 port is a vacuum delay valve not a thermal vacuum switch, napa part number 2-927 or 2-29206. Check those numbers out on napaonline. Com and see if they look like what your seeing.
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Thursday, June 21st, 2012 AT 1:32 AM
Tiny
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The one on my car, next to the thermostat.

But I can't seem to find any for the Chevette. They all have 2-3 or 5 ports :S
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Thursday, June 21st, 2012 AT 4:33 AM
Tiny
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You will have to include the pic as the address you posted don't work for me. Thanks
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Thursday, June 21st, 2012 AT 3:44 PM
Tiny
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Here you go :)
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Friday, June 22nd, 2012 AT 12:00 PM
Tiny
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That is a thermal ported vacuum switch. Napa part number 229046.
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Sunday, June 24th, 2012 AT 3:15 AM
Tiny
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So is it possible that someone put that thing in my car even though it's for much bigger GM cars? I guess I would have to go to a scrap yard and find a Chevette and take all the vacuums and the switch to put them in my car?
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Monday, June 25th, 2012 AT 2:27 PM
Tiny
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Ok I can get you a copy of the vacuum diagram for your car but I need to know does it have a/c, power steering and manual or a/t transmission.
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Monday, June 25th, 2012 AT 4:09 PM
Tiny
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Thanks! :)

The car is automatic, no a/c, no power steering.
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Thursday, June 28th, 2012 AT 12:18 PM
Tiny
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Here is the vacuum diagram for that.
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Thursday, June 28th, 2012 AT 2:44 PM
Tiny
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Thanks a lot for the diagram! I have one question though. Is the thing on the right an A/C compressor? (My car doesn't have A/C) :S
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Friday, June 29th, 2012 AT 2:55 AM
Tiny
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I don't get that either as the diagram is suppose to be auto trans with no ac and no power steering. Strange.
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Friday, June 29th, 2012 AT 2:47 PM
Tiny
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Gosh! I forgot to mention that my car is a Canadian car! I guess that's why I kept on finding the 2-3 or 5 ports TVS! I checked on a vacuum diagram website and for Canadian vehicules, the TVS has 4 ports! Now the trick is to find one somewhere.
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Saturday, June 30th, 2012 AT 3:08 AM
Tiny
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Yes true.
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Saturday, June 30th, 2012 AT 1:56 PM
Tiny
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So. I've changed my switch and the idle smoothed itself a bit (?) Except for the egr valve sticking once in a while, but the torque converter still wont lock-up when the car is warmed up.
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Saturday, June 30th, 2012 AT 7:53 PM
Tiny
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It probably the lock up solenoid.
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Sunday, July 1st, 2012 AT 1:22 AM

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