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My Tranny is Hot..

 
Old 06-10-2019, 02:00 PM
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AgentEran
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Default My Tranny is Hot..

I recently rebuild and modified my 4L60e I have in my LT1 car. The build went really well, outside of the brake switch that wasnt allowing TC lockup. Now that that is fixed I have been enjoying driving the car and learning its new shifting habits. I also added a B&M TC w 2000 rpm stall. Overall im really really satisfied with the mods I made and the performance that i gained.

This past weekend I drove this car. It was pretty hot, ~90 degrees or so. This particular car I have not managed to change the fan strategy so the fans are on the stock 228* setting

So, when I am sitting in traffic the coolant temp starts to rise. It goes up to 230, the fan kicks in and temp reduces to ~200 - 195*. Well I noticed that when the coolant temp reaches 230* it takes the transmission oil temp with it. But the trans temp does not reduce like the coolant does. It will stay about 220 - 215* after the coolant cools to under 190 and even 180.

So I need to add a new oil cooler for the tranny. Trying to decide whether to add a cooler in series with the radiator oil cooler in the front of the a/c condenser, or to eliminate the radiator cooler and add a big cooler with a fan in the spare tire area.

What I am confused about is, we all know C4s have a stupid stock fan strategies and many change this setup either by adding larger radiators, wiring in fan switches, adding new fan relays, etc etc. But what about the owners who dont do this? Do they actually drive around with tranny temps above 220*?? This seems improbable but I have had 3 c4s and ALL of them ran hot (200+ deg) until I made mitigating modifications. This is my first A4 vette so this tranny temp issue is foreign to me. So unless mods are made, your tranny will run 200+ degrees??

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Old 06-10-2019, 02:13 PM
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383vett
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Just put a tranny cooler in front of the condenser and you'll be fine. I bypassed the radiator and use a B+M stacked cooler for my 4l60e.
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Old 06-10-2019, 03:14 PM
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Originally Posted by 383vett View Post
Just put a tranny cooler in front of the condenser and you'll be fine. I bypassed the radiator and use a B+M stacked cooler for my 4l60e.
okok. Do you mind letting me know which one you are using?

I have both of these in my Summit shopping cart, trying to figure out which one will be sufficient:

This one with 48 rows:

https://www.summitracing.com/parts/bmm-70274/overview/



of this one with 36 rows:

https://www.summitracing.com/parts/bmm-70266?rrec=true

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Old 06-10-2019, 03:24 PM
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Terrible thread title
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Old 06-10-2019, 03:27 PM
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Originally Posted by Pete919 View Post
Terrible thread title
It got you here.. lol
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Old 06-10-2019, 04:15 PM
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Originally Posted by AgentEran View Post
okok. Do you mind letting me know which one you are using?

I have both of these in my Summit shopping cart, trying to figure out which one will be sufficient:

This one with 48 rows:

https://www.summitracing.com/parts/bmm-70274/overview/



of this one with 36 rows:

https://www.summitracing.com/parts/bmm-70266?rrec=true


I'm using the smaller of the two.
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Old 06-10-2019, 04:27 PM
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I went with the B&M 70264 on mine. It's small, but gets the job done. Keep in mind I'm not drag racing the car, so I don't need as much cooling. I also need to balance out cold morning temps with hot afternoons. I plumbed it inline with the stock cooler. I kept getting high temps(230+) when going uphill on my commute, and now even on a hot day, it rarely goes over 200. It cools down much quicker too, once I've crested the hill and back on somewhat level road. I haven't tested it over 90 degrees yet, but I will soon. The real test is going uphill on a mountain road on a hot day, stuck behind a line of ****** tourists that peak at 25mph, and slow down to 15 for most corners.

And yes, even after a new t-stat and complete coolant flush, the tranny was always hitting 220+. Going up hill it would get as high as 260! Would take forever too drop too. That was making me cringe hard watching it hit those temps, lol.

Last edited by novaks47; 06-10-2019 at 04:29 PM.
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Old 06-10-2019, 05:04 PM
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Originally Posted by novaks47 View Post
And yes, even after a new t-stat and complete coolant flush, the tranny was always hitting 220+. Going up hill it would get as high as 260! Would take forever too drop too. That was making me cringe hard watching it hit those temps, lol.
Everything I read online suggests that at 250+ degrees you are causing damage to the tranny. More specifically, varnish forms, then seals next. So I am certainly in the same boat as you, looking at these temps and fretting big time. Which brings me back to my original quandary, that Chevy sold these cars knowing the tranny temps could be 250+ during normal non-racing usage?? Something seems wrong about that.

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Old 06-10-2019, 05:12 PM
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"that Chevy sold these cars knowing the tranny temps could be 250+ during normal non-racing usage??"

I forgot to mention that I changed the fluid to dex 6 as well, which helped a lot. I think so many C4's end up with overheating trannys is due to really old fluid that's never been changed, not due to Chevy dropping the ball. I'm sure when these cars were new, they never ran that hot. But after 20+ years, and lots of miles, that fluid is done for. Fresh fluid, plus better fluid = lower temps. I've never bought a used car that didn't have old and worn out tranny fluid. Almost nobody changes that, regardless of what the manual states or how many miles they rack up.

I also got a pan with a drain plug, so I can at least drain and fill the fluid in between filter changes.

Last edited by novaks47; 06-10-2019 at 05:13 PM.
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Old 06-10-2019, 06:17 PM
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Change it's name from Bruce to Kaitlyn it'll cool off real fast
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Old 06-10-2019, 06:41 PM
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Originally Posted by Pwnage1337 View Post
Change it's name from Bruce to Kaitlyn it'll cool off real fast
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Old 06-11-2019, 12:26 AM
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Originally Posted by novaks47 View Post
"that Chevy sold these cars knowing the tranny temps could be 250+ during normal non-racing usage??"

I forgot to mention that I changed the fluid to dex 6 as well, which helped a lot. I think so many C4's end up with overheating trannys is due to really old fluid that's never been changed, not due to Chevy dropping the ball. I'm sure when these cars were new, they never ran that hot. But after 20+ years, and lots of miles, that fluid is done for. Fresh fluid, plus better fluid = lower temps. I've never bought a used car that didn't have old and worn out tranny fluid. Almost nobody changes that, regardless of what the manual states or how many miles they rack up.

I also got a pan with a drain plug, so I can at least drain and fill the fluid in between filter changes.

Please elaborate on how you can tell when the fluid is "worn out"?? I am curious.
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