TH 350 Tranny Temp Question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**PbFut** · 03-09-2025, 03:41 PM

I have little experience with TH350 transmissions. Using a Autometer electric temp gauge with the sensor inline on the OEM cooler line at the exit of the tranny, I am getting what to me seems rather high temps. In the 210 to 230 range. A check of the pan temp with a Temp gun it is at 175 to 180. Does this seem normal, or do I need to investigate further? Checking calibration of the Autometer sensor with a temp gun and the temp of the sensor seems to match the Autometer Gauge. The good news is that it shows the coolers doing their job. But 230 out of the case is a bit scarry to me. Air temp is 70, hate to think what 95 brings.

**PbFut** · 03-10-2025, 08:59 PM

No ideas?

**leddzepp** · 03-10-2025, 09:04 PM

If the transmission is functioning properly and your fluid isn’t burnt I’d just keep on rollin’.

**Rust_never_sleeps** · 03-10-2025, 09:41 PM

pan temp seems OK, outlet temp sounds high, but tbh, I never checked

**PbFut** · 03-10-2025, 09:42 PM

The rebuild has all of 2 hours on it. If it's not right I'd rather address things now before I start burning other parts.

**Steeveedee** · 03-10-2025, 09:51 PM

Not sure where the trans oil temp is taken on my truck, but pulling a 6k pound trailer up hills, engine coolant and trans oil gauges were riding on 260F. I have since gotten the cooling system under control, but I now have a newish motorhome and am not towing that trailer, anymore. The truck's trans fluid doesn't look burnt. Does yours look or smell burnt?

KQQL IT · 03-10-2025, 11:45 PM

4l80 guys say 100+ of ambient is fine

72c20customcamper · Yesterday, 08:42 AM

My trucks trans runs about 150 unless I’m towing then it clumps to 210-220 never got any hotter than that ,the water temp in the head around 190 again it will climb when towing

**PbFut** · Yesterday, 09:52 AM

Quote:

Originally Posted by 72c20customcamper

My trucks trans runs about 150 unless I’m towing then it clumps to 210-220 never got any hotter than that ,the water temp in the head around 190 again it will climb when towing

Where is your sensor? In the pan or the cooler line? If in the line, before or after the cooler(s).

72c20customcamper · Yesterday, 10:07 AM

Quote:

Originally Posted by PbFut

Where is your sensor? In the pan or the cooler line? If in the line, before or after the cooler(s).

Out line of the trans just before it goes into the factory cooler in the radiator . It also has a cooler mounted in front of the radiator . It’s mounted on the inner wheel house I’ll try to dig up a picture

Found it

72c20customcamper · Yesterday, 10:17 AM

From what I have researched you have problems when the temps go over 250 for a sustained length of time .

**PbFut** · Yesterday, 12:38 PM

Thanks Mark. I think the rebuild is running too hot. It's only inch the high 60s low 70s and not correctly maintained tranny temp. And it seems the engine comes up about 10 degrees when tranny is pushing out 230. So i think this trans is on edge of overwhelming things. I'll need to further investigate. Your data was very helpful. Thank you

03-09-2025, 03:41 PM	#1
PbFut Senior Member Join Date: Feb 2022 Location: Ca Posts: 713	TH 350 Tranny Temp Question I have little experience with TH350 transmissions. Using a Autometer electric temp gauge with the sensor inline on the OEM cooler line at the exit of the tranny, I am getting what to me seems rather high temps. In the 210 to 230 range. A check of the pan temp with a Temp gun it is at 175 to 180. Does this seem normal, or do I need to investigate further? Checking calibration of the Autometer sensor with a temp gun and the temp of the sensor seems to match the Autometer Gauge. The good news is that it shows the coolers doing their job. But 230 out of the case is a bit scarry to me. Air temp is 70, hate to think what 95 brings.

03-10-2025, 08:59 PM	#2
PbFut Senior Member Join Date: Feb 2022 Location: Ca Posts: 713	Re: TH 350 Tranny Temp Question No ideas?

03-10-2025, 09:04 PM	#3
leddzepp Moderator Join Date: May 2007 Location: Southern Cal Posts: 20,115	Re: TH 350 Tranny Temp Question If the transmission is functioning properly and your fluid isn’t burnt I’d just keep on rollin’. __________________ 1972 C/10 Cheyenne Super SWB. Restored, loaded, slammed. 1968 C/10 50th Anniversary LWB. Unrestored, stock, daily driver/work truck. RIP ElJay RIP 67ChevyRedneck RIP Grumpy Old Man RIP FleetsidePaul

03-10-2025, 09:41 PM	#4
Rust_never_sleeps Senior Member Join Date: Jun 2022 Location: San Ramon,CA Posts: 695	Re: TH 350 Tranny Temp Question pan temp seems OK, outlet temp sounds high, but tbh, I never checked __________________ 1970 C10 Custom longbed 350/350 Code: __ ______\|__]\____ ....\|___(o)_____(o)_]

03-10-2025, 09:42 PM	#5
PbFut Senior Member Join Date: Feb 2022 Location: Ca Posts: 713	Re: TH 350 Tranny Temp Question The rebuild has all of 2 hours on it. If it's not right I'd rather address things now before I start burning other parts.

03-10-2025, 09:51 PM	#6
Steeveedee Who Changed This? Join Date: Jan 2013 Location: Simi Valley, CA Posts: 10,932	Re: TH 350 Tranny Temp Question Not sure where the trans oil temp is taken on my truck, but pulling a 6k pound trailer up hills, engine coolant and trans oil gauges were riding on 260F. I have since gotten the cooling system under control, but I now have a newish motorhome and am not towing that trailer, anymore. The truck's trans fluid doesn't look burnt. Does yours look or smell burnt? __________________ ~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA

03-10-2025, 11:45 PM	#7
KQQL IT At the body shop. Join Date: Aug 2009 Location: Land of fruits and nuts. Posts: 5,316	Re: TH 350 Tranny Temp Question 4l80 guys say 100+ of ambient is fine __________________ " That didnt make it any newer " " Dont antique the equipment "

Yesterday, 08:42 AM	#8
72c20customcamper Registered User Join Date: Jul 2018 Location: Catskill Mountains,NY Posts: 8,915	Re: TH 350 Tranny Temp Question My trucks trans runs about 150 unless I’m towing then it clumps to 210-220 never got any hotter than that ,the water temp in the head around 190 again it will climb when towing Attached Images __________________ Mark 72 c20 custom camper Husky edition, 66 SS396 Chevelle 1964 Hawk, 63 Avanti,62 lark 1969 AMX , 1968 c20 stepside ,85 K20 1977 Suburban sold 68 anniversary.

Yesterday, 10:17 AM	#11
72c20customcamper Registered User Join Date: Jul 2018 Location: Catskill Mountains,NY Posts: 8,915	Re: TH 350 Tranny Temp Question From what I have researched you have problems when the temps go over 250 for a sustained length of time . __________________ Mark 72 c20 custom camper Husky edition, 66 SS396 Chevelle 1964 Hawk, 63 Avanti,62 lark 1969 AMX , 1968 c20 stepside ,85 K20 1977 Suburban sold 68 anniversary.

Yesterday, 12:38 PM	#12
PbFut Senior Member Join Date: Feb 2022 Location: Ca Posts: 713	Re: TH 350 Tranny Temp Question Thanks Mark. I think the rebuild is running too hot. It's only inch the high 60s low 70s and not correctly maintained tranny temp. And it seems the engine comes up about 10 degrees when tranny is pushing out 230. So i think this trans is on edge of overwhelming things. I'll need to further investigate. Your data was very helpful. Thank you



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.