190 Too Hot?
Thread Starter
Racer
Joined: May 2006
Posts: 423
Likes: 3
From: New Port Richey, FL
190 Too Hot?
I was sitting on this patch of high way about a mile long and had to sit at 3 traffic lights about 5 minutes each. After the last one I noticed that my trans pan oil temp was at 190 degrees. Is this too hot? I bypassed the radiator, and mounted the trans cooler under the gas tank with a pusher fan on it. I never noticed it to go any higher than 160 before but like I said, these were really long lights I had to stop and wait for
Team Owner
Joined: Jan 2006
Posts: 37,637
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From: Crossville TN
190*F is about normal for an auto tranny. Final testing temps are usually at 180*F, although some more modern systems use lower temp fluids with the same viscosity as 180*F transmission oil. Trans oil doesn't start getting damaged until 250*F or so. If you are concerned about it, start using synthetic oil in the transmission. That's safe to over 300*F.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
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From: Hermosa
I can’t imagine that 190 is too hot as far as the fluid is concerned.
when the cooler is routed through the radiator the coolant can easily exceed 190 on a stock config which would allow the trans fluid to also exceed 190.
when the cooler is routed through the radiator the coolant can easily exceed 190 on a stock config which would allow the trans fluid to also exceed 190.
Racer
Joined: May 2018
Posts: 297
Likes: 43
trans oil is cooled by the radiator. sitting in traffic your relying on the fan and electric fan for airflow which will be less then highway, I wouldn't be concerned if the engine coolant is 200 ish and tranny is 190 ish, its working properly.
I re read the post and you stated you relocated the trans cooler, all I can say to that is good luck, without airflow I cant imagine how you can get stable temps.
under the gas tank.. heat rises, hot gasoline expands and provides less hp.. why do this?
I re read the post and you stated you relocated the trans cooler, all I can say to that is good luck, without airflow I cant imagine how you can get stable temps.
under the gas tank.. heat rises, hot gasoline expands and provides less hp.. why do this?
Last edited by sambrand; Aug 19, 2018 at 12:12 AM.
Thread Starter
Racer
Joined: May 2006
Posts: 423
Likes: 3
From: New Port Richey, FL
trans oil is cooled by the radiator. sitting in traffic your relying on the fan and electric fan for airflow which will be less then highway, I wouldn't be concerned if the engine coolant is 200 ish and tranny is 190 ish, its working properly.
I re read the post and you stated you relocated the trans cooler, all I can say to that is good luck, without airflow I cant imagine how you can get stable temps.
under the gas tank.. heat rises, hot gasoline expands and provides less hp.. why do this?
I re read the post and you stated you relocated the trans cooler, all I can say to that is good luck, without airflow I cant imagine how you can get stable temps.
under the gas tank.. heat rises, hot gasoline expands and provides less hp.. why do this?
Race Director
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Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
seems like above 200 is not advisable
http://www.txchange.com/heatchrt.htm
http://www.txchange.com/heatchrt.htm
I would assume that it would be conventional and if the fluid were not changed that the mileage shown would represent the failure of the transmission due to the failure of the fluid.
What is interesting to me is that these engines ran 200+ in stock config with the cooling of the transmission dependent on the radiator cooling tubes. So the fluid would regularly exceed 200* in normal operation, even 225*, so what gives on the stock config?
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
If putting the trans cooler in the radiator was a bad idea, why would nearly all auto manufacturers do it? I know...they want to guarantee high warranty costs so they can go broke!
Sounds like a theory that the aux trans cooler manufacturers dreamed up to get you to buy their product.
The cooling system designs take into account the heat from the engine AND transmission, so they are well capable of handling both in nearly all situations. Pulling a 2 ton trailer up a mountain with your Toyota Camry?? Probably not within its design parameters....
Sounds like a theory that the aux trans cooler manufacturers dreamed up to get you to buy their product.
The cooling system designs take into account the heat from the engine AND transmission, so they are well capable of handling both in nearly all situations. Pulling a 2 ton trailer up a mountain with your Toyota Camry?? Probably not within its design parameters....
Last edited by 7T1vette; Aug 21, 2018 at 07:17 AM.
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Le Mans Master
Joined: Aug 2017
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From: Cool Northern Michigan
I did this because I've read that having a ATF running through the radiator itself is a bad idea since the engine coolant gets a lot hotter than the trans fluid should be. There is about a 4" gap between the gas tank and the cooler as the pusher fan is mounted in between the two
As a side note, modern transmissions by-pass the auxiliary cooler out front until a certain temp is reached. H-m-m-m-m-m-m-m-
Le Mans Master
Joined: Apr 2011
Posts: 6,284
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From: Hermosa
Sounds like a theory that the aux trans cooler manufacturers dreamed up to get you to buy their product.
Obviously there would need to be far more details to determine if you even need an additional cooler for your transmission.
The radiator warms the tranny fluid when its cold. Which is good. But the rad is also a cooler reducing heat before it goes to a remote tranny cooler out in front if you installed one. Its a win-win running those two "coolers" in series.
Last edited by REELAV8R; Aug 21, 2018 at 11:01 AM.
Team Owner
Joined: Apr 1999
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Don't let the nay sayers get you down. Bypassing the engine radiator keeps both the engine and tranny temps down. 190 is getting up there. Coolers are rated in GVW or Gross vehicle Weight or even BTU's. Your cooler might be of a marginal size for your application. I used the biggest B&M cooler with 1/2 inch SS braided lines from the tranny to the cooler. My 700R4 had brass reducers to 3/8th coming out of the case. I removed the reducers and ran the full 1/2 inch.
My engine temps were generally about 200. I always use a 195 T-stat. My tranny gauge rarely exceeded 160.
You could try shifting into "N" on long stops. You might also have an inefficient TC that is causing the heat. My 700R4 had a non working lockup 3800 stall and I drove it around for years without lockup
My engine temps were generally about 200. I always use a 195 T-stat. My tranny gauge rarely exceeded 160.
You could try shifting into "N" on long stops. You might also have an inefficient TC that is causing the heat. My 700R4 had a non working lockup 3800 stall and I drove it around for years without lockup
Last edited by gkull; Aug 22, 2018 at 09:08 AM.
Burning Brakes
Joined: Apr 2013
Posts: 1,072
Likes: 61
From: Saint clair shores Michigan
Mine with a separate trans cooler will run at 210° if I'm running the heck out of it. I've got a separate switch mounted below the steering column so that I can turn it on. But until I lay off the petal, it runs at 210°. Mines mounted in front of the radiator.
Thread Starter
Racer
Joined: May 2006
Posts: 423
Likes: 3
From: New Port Richey, FL
Don't let the nay sayers get you down. Bypassing the engine radiator keeps both the engine and tranny temps down. 190 is getting up there. Coolers are rated in GVW or Gross vehicle Weight or even BTU's. You cooler might be of a marginal size for your application. I used the biggest B&M cooler with 1/2 inch SS braided lines from the tranny to the cooler. My 700R4 had brass reducers to 3/8th coming out of the case. I removed the reducers and ran the full 1/2 inch.
My engine temps were generally about 200. I always use a 195 T-stat. My tranny gauge rarely exceeded 160.
You try shifting into "N" on long stops. You might also have an inefficient TC that is causing the heat. My 700R4 had a non working lockup 3800 stall and I drive it around for years.
My engine temps were generally about 200. I always use a 195 T-stat. My tranny gauge rarely exceeded 160.
You try shifting into "N" on long stops. You might also have an inefficient TC that is causing the heat. My 700R4 had a non working lockup 3800 stall and I drive it around for years.
Thread Starter
Racer
Joined: May 2006
Posts: 423
Likes: 3
From: New Port Richey, FL
I have a 200R4. I wonder if my trans has reducers also. If so I'll go 1/2" coz I know my cooler is that. In the meantime I'll try shifting to N at a stop. I also have a 3800 convertor, but it is lockup. Either way my radiator is for a manual trans (no ATF reservoir), and I'm not about to change that
Team Owner
Joined: Apr 1999
Posts: 21,953
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Are you saying that you have some sort of tranny cooler t stat. If you do take it out
I also used an extra 4 quart deep pan. My temp sender was on the pan. It made the pan hang down about 2 more inches, but not as far down as my headers
the big B&M cooler came with 1/2 inch in and out. So I had a local business make my ss braided lines with correct ends.
what is the name of your TC?
I also used an extra 4 quart deep pan. My temp sender was on the pan. It made the pan hang down about 2 more inches, but not as far down as my headers
the big B&M cooler came with 1/2 inch in and out. So I had a local business make my ss braided lines with correct ends.
what is the name of your TC?
Thread Starter
Racer
Joined: May 2006
Posts: 423
Likes: 3
From: New Port Richey, FL
Are you saying that you have some sort of tranny cooler t stat. If you do take it out
I also used an extra 4 quart deep pan. My temp sender was on the pan. It made the pan hang down about 2 more inches, but not as far down as my headers
the big B&M cooler came with 1/2 inch in and out. So I had a local business make my ss braided lines with correct ends.
what is the name of your TC?
I also used an extra 4 quart deep pan. My temp sender was on the pan. It made the pan hang down about 2 more inches, but not as far down as my headers
the big B&M cooler came with 1/2 inch in and out. So I had a local business make my ss braided lines with correct ends.
what is the name of your TC?
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
I can't remember.who made my convertor. It was a guy who has a shop in Kansas, and it was 10 years ago. I paid about $800 for it then. I done a lot of research when I found him. He makes them one at a time, and talking to him he wanted to know everything about my car. I'll pull the inline stat out but that means the fan will run all of the time when the key is on (switched).
Thread Starter
Racer
Joined: May 2006
Posts: 423
Likes: 3
From: New Port Richey, FL
The instructions say that it's an IN-LINE THERMOSTAT SWITCH. I quote,"The in-line thermostat switch is designed to thermostatically control the electric fan on a remote mounted transmission cooler". So I'm guessing that it doesn't restrict flow, it just waits until the fluid reaches 180 degrees, and then turns the fan on
Le Mans Master
Joined: May 2006
Posts: 9,993
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From: League City Tx
For auto trannies, 190* is a good temp...maybe a bit on the warm side but normal. You really don't want to be over 210* constantly on trans temps though....Heat is the leading cause of death in auto transmissions. Contrary to 60's beliefs, there is no such thing as "too cool of auto trans fluid".... (within reason)..... This is why new Corvettes/Camaros have separate coolers that bypass the radiator and normally run in the 120-130* range in the Summer. I regularly see my trans temp at 115-120* on my C7Z during the summer when cruising normally. If you want them to last, keep them cool.
All that said, a T400 is tough as nails and you would have to run it really hot for a long time to kill it.
All that said, a T400 is tough as nails and you would have to run it really hot for a long time to kill it.