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TH350 Temperature at interstate speeds

Joel Wilson

Joel Wilson

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I'm sure this is going to open a can of worms, but this is the first time in a long time of relocating sensors that I actually got real time real temp data.

I drove 18 miles at roughly 60 mph and the temp on the TH350 pan was no more than 150. On the way home at 75 to 80 mph temp was no more than 180 on the interstate. Pulled into Safeway for 15 min and temp dropped to 150. So I am saying to myself, is this that bad?

I am running the normal trans cooler in the radiator cooler plus a pancake cooler on the passenger fender. The pancake cooler is under the engine oil cooler which never got above 150 on the same trip and and has a fan that is thermo controlled at 190. Engine coolant temp never got above 110 coming out of the bottom of the radiator.

I have a 24" single pass tube cooler that I could mount easy enough before it enters the trans pan. I believe that I have lost my 2nd gear or the trans just shifts past 2nd due to too much pressure. Not sure.

Any help is greatly appreciated.

Joel
norcal
 
Temps are good

there’s no reason it should skip 2nd gear though
 
Skipping 2nd isn't due to too much pressure. Something is broken. I lost 2nd in the th350 in my Nova many moons ago. Broke the cast ring in the intermediate clutch pack. Worked like a powerglide from that point forward. First to direct. Found it when I pulled it out and replaced it with one I built for it.
 
ZooMad75 said:
Skipping 2nd isn't due to too much pressure. Something is broken. I lost 2nd in the th350 in my Nova many moons ago. Broke the cast ring in the intermediate clutch pack. Worked like a powerglide from that point forward. First to direct. Found it when I pulled it out and replaced it with one I built for it.
Click to expand...
That's what I was afraid of. Hoping it wasn't but kinda knew it was. I have another short shaft TH350 and if I can find the broken ear for it, will have it rebuilt for over 500hp and just set it off to the side and have it waiting. I'm running enough torque to where it doesn't make that much difference really, I"m just not winning any drag races.

Joel
norcal
 
Some simple things to check:
-Is the vacuum line connected? Any ATF in it?
-Is the kickdown cable connected and properly adjusted?
-Does manually selecting 2nd gear bring it from 3rd to 2nd? Note that running this way may be weaker than it's supposed to be, if the forward sprag is munched.

As for temps, you're fine. The transmission is being warmed by the engine, as it's designed. You didn't mention if the torque converter is lock-up type. Also, where is the temp sensor?
 
Blue85 said:
Some simple things to check:
-Is the vacuum line connected? Any ATF in it?
-Is the kickdown cable connected and properly adjusted?
-Does manually selecting 2nd gear bring it from 3rd to 2nd? Note that running this way may be weaker than it's supposed to be, if the forward sprag is munched.

As for temps, you're fine. The transmission is being warmed by the engine, as it's designed. You didn't mention if the torque converter is lock-up type. Also, where is the temp sensor?
Click to expand...

Torque converter is not a lock up and is supposed to be a 1200 stall. Temp sensor is located on the side of the pan about 1.5 inches from the bottom. Vacuum line going to the modulator was way loose so replaced that. No ATF in there. Kickdown cable not attached and transmisdion was supposed to be rated at 525 to 550hp and has a manual valve body. Trans pan is plus 3 qts capacity. I also took that same trip to Red Bluff and trans got to 205 but I was running close to 85 trying to catch up to that Altima that cut me off. Going from D to 2nd does nothing. Going to 1st just gives me 25mph going back to 2nd still only gives me 25mph. Back to D gives me top end. Thanks for any help. Joel Norcal
 
If you end up doing trans work, I would go 1600 to 1800 rpm on the stall. Maybe go to a 160 degree thermostat for the summer. I run 160 all year now. Your trans once warmed up will never run much cooler than the radiator temp, if you are using the in rad cooler.
 
Wes Harden said:
If you end up doing trans work, I would go 1600 to 1800 rpm on the stall. Maybe go to a 160 degree thermostat for the summer. I run 160 all year now. Your trans once warmed up will never run much cooler than the radiator temp, if you are using the in rad cooler.
Click to expand...
That makes sense especially since I'm running a 180 thermostat now and using the built in radiator cooler. I am also running a second cooler but it is not very big and I have my doubts as to its efficiency. Its just a 10x10 pancake cooler that can be used for power steering or transmission. It is also underneath the engine oil cooler which is under an electric fan on the passenger inner fender.
Joel
Norcal
 
Trans update. I bought another cooler 12x12 ish and moved it from the engine compartment to out in front of the grill just to the side of the winch. It's at a 45 degree angle and so far it has dropped my trans oil temp from 210 at 75 degrees ambient to 190 at 90 degrees ambient. I have a fan mounted to it, but it isn't wired up yet. Between work and my mother in law passing away, I just haven't had time. Trans temp is also a lot slower to get to 190. 210 was making me nervous at 75 degrees ambient.

Joel
norcal
 
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