4L70E - How to tell if pump or torque converter broke?
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Joined: Aug 2010
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From: Ann Arbor, MI
That indicates plenty of fluid in the trans.
After any trans work, with the engine off I suggest filling the trans until the dipstick is about 1" above HOT as a safe starting point. With the engine running it will drop about 2".
After any trans work, with the engine off I suggest filling the trans until the dipstick is about 1" above HOT as a safe starting point. With the engine running it will drop about 2".
Can't go out and try it since it's snowing and my wide ran the battery down with the hazards and listening to the radio while waiting.
When I looked at the fluid the next day, the level was just by the "C" in "CHECK", so above the "HOT" range, like in the photo below (not my dipstick, closest example I could find):
I will charge up the battery and see if the level drops with the engine running once the weather improves.
When I looked at the fluid the next day, the level was just by the "C" in "CHECK", so above the "HOT" range, like in the photo below (not my dipstick, closest example I could find):
I will charge up the battery and see if the level drops with the engine running once the weather improves.
TECH Junkie
Joined: May 2012
Posts: 3,042
Likes: 713
From: Poplarville, MS
Can't go out and try it since it's snowing and my wide ran the battery down with the hazards and listening to the radio while waiting.
When I looked at the fluid the next day, the level was just by the "C" in "CHECK", so above the "HOT" range, like in the photo below (not my dipstick, closest example I could find):
I will charge up the battery and see if the level drops with the engine running once the weather improves.
When I looked at the fluid the next day, the level was just by the "C" in "CHECK", so above the "HOT" range, like in the photo below (not my dipstick, closest example I could find):
I will charge up the battery and see if the level drops with the engine running once the weather improves.
TECH Junkie
Joined: May 2012
Posts: 3,042
Likes: 713
From: Poplarville, MS
He also said that he checked the fluid the next day. Just wanted to verify. That what I thought, but when you start assuming things on forums you will be wrong about as many times as right. lol
I checked the fluid the next day with the engine cold, that is when the level was at the "C". I was not able to start the vehicle as the battery was too low, then this weekend we got snowed in, so it will be later on in the week when I get a change to charge the battery and see if the level goes down or stays the same.
If it stays the same I'll start looking for a replacement pump as most likely the rotor breaking would have cause scarring. What would be a good source?
Also, would my application, 2006 Trailblazer SS with the 4L70E need a pump with the short or the long stator? I know it has to be the one with the ISS.
If it stays the same I'll start looking for a replacement pump as most likely the rotor breaking would have cause scarring. What would be a good source?
Also, would my application, 2006 Trailblazer SS with the 4L70E need a pump with the short or the long stator? I know it has to be the one with the ISS.
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From: BERWICK PA
If your level cold not running is at the C mark you are actually way low and probably did shatter the pump due to cavation and slide vibration . I have seen many times on dyno what a low fiuid condition looks like presure wise and the sound. It jumps all over the place and slide bounces due to presure spike and drops.
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Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
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Joined: Aug 2010
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From: Ann Arbor, MI
Frank, perhaps you missed a few posts, but this is the "C" which is a good 1-1/2" above the FULL/HOT mark which IMHO is perfect for a cold trans with engine off.
Last edited by mrvedit; Feb 21, 2026 at 02:18 PM. Reason: typo
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From: BERWICK PA
I may have, I thought he meant the C down there at COLD actually my dip does not say cold and hot but just C and H but yes I see what you mean now .
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Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
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Small update.
Charged the battery and started the vehicle. Fluid looked like it sucked down and was at the normal level for cold. Put the car in drive and it moved forward. Put the car back in park, checked the level again and it went up. Got back in the car and tried all gears, but no movement in any gear or any direction. The transmission is going to come out regardless, but why did it have one brief moment of wanting to work? I have a theory and will share after some input, don't want to skew any ideas.
Charged the battery and started the vehicle. Fluid looked like it sucked down and was at the normal level for cold. Put the car in drive and it moved forward. Put the car back in park, checked the level again and it went up. Got back in the car and tried all gears, but no movement in any gear or any direction. The transmission is going to come out regardless, but why did it have one brief moment of wanting to work? I have a theory and will share after some input, don't want to skew any ideas.
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From: BERWICK PA
My guess would be the coverter clutch came apart and is stopping up the filter .
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Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
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