2014 GMC Sierra 1500 4.3L Trans temp question (6L80)

Ubiquity · April 10, 2023

2 minutes ago, mikeyk101 said:

In my experience, it's the trans fluid temp indicator on the dash gauge screen is usually pretty close and actively monitors the trans fluid temp. It's the analog gauges that aren't accurate and can be off quite a bit.

Thank makes sense to me. But I still love gauges. Too bad their shielded from me directly tapping on them. That's part of their appeal. And yes, I know the thought of doing that makes some people cringe.

mikeyk101 · April 10, 2023

I kind of lied, I do pay attention to the fuel gauge, LOL. And I'm hopelessly addicted to the current mpg screen. But like I mentioned earlier on the coolant temp gauge, it can be off as much as 15⁰ up or down before it moves off the 210⁰. When towing, by the time it starts moving up, it's already headed the wrong direction and the start of a problem. By monitoring with the Torque app, I can keep a closer eye on the current temps and know instantly where I stand.

Willard Norris · April 10, 2023

I should also mention that the trans fluid has turned orange (see pic), and that’s with only 2,000 or so miles since the trans rebuild. It was nice and red after the rebuild. This discoloration seems to have occurred with my recent long drive in March with trans temps around 220°. Outside temperatures were less than 70° during the drive

Willard Norris · April 10, 2023

These are the pics I made during my last long trip in March. 221° was when I came off the freeway to get gas. It rose pretty quickly to that temp. The 214° was a few days later at 70 mph after about 90 minutes of driving though Alabama….not too many hills.

Grumpy Bear · April 10, 2023

23 hours ago, 2015regcablongbed said:

Good to know about the radiator temps. Do you have a recollection on the TFT versus the gauge?

I do. Hand in glove. They read within 1 degree of each other.

Edited April 11, 2023 by Grumpy Bear

Grumpy Bear · April 10, 2023

1 hour ago, Willard Norris said:

I should also mention that the trans fluid has turned orange (see pic), and that’s with only 2,000 or so miles since the trans rebuild. It was nice and red after the rebuild. This discoloration seems to have occurred with my recent long drive in March with trans temps around 220°. Outside temperatures were less than 70° during the drive

That is the fluid thermally oxidizing. This heat thing needs a solution sooner than later. Get those lines and cooler flushed and make sure the TBV is right.

Willard Norris · April 10, 2023

Grumpy Bear (not sure how to flag your name)

So based on the information I’ve given, you believe there’s likely some type of restriction in the lines or cooler, or the TBV is problematic, correct?

I should be able to check the TBV this evening, and will contact the transmission shop tomorrow.

Thank you.

Edited April 10, 2023 by Willard Norris

Grumpy Bear · April 10, 2023

2 hours ago, Willard Norris said:

Grumpy Bear (not sure how to flag your name)

So based on the information I’ve given, you believe there’s likely some type of restriction in the lines or cooler, or the TBV is problematic, correct?

I should be able to check the TBV this evening, and will contact the transmission shop tomorrow.

Thank you.

Type @ and then start the name. A list should appear where you can select.

I'm saying this temperature is unnatural with the modifications you've mentioned and needs to be investigated further. Cooler, lines and TBV are logical choices.

Willard Norris · April 11, 2023

@Grumpy Bear I checked the TBV this morning, and the Superior delete is installed correctly. Next I’ll contact the transmission shop and ask about flushing the lines and cooler.

Also gonna get the Mishimoto VET-180 cooling thermostat as well to see if that provides any relief. There’s a Summit Racing place about 30 miles from here.

Thx again. I’ll follow up with any updates.

Grumpy Bear · April 12, 2023

@Willard Norris

How the Hot Flush Machine Works (hotflusher.com)

If I couldn't find a shop with this equipment, I'd just replace the radiator. Opinion may vary on that and such an opinion from someone like @newdude or @swathdiver would carry some weight that shouldn't be ignored.

swathdiver · April 12, 2023

5 hours ago, Grumpy Bear said:

@Willard Norris

How the Hot Flush Machine Works (hotflusher.com)

If I couldn't find a shop with this equipment, I'd just replace the radiator. Opinion may vary on that and such an opinion from someone like @newdude or @swathdiver would carry some weight that shouldn't be ignored.

GM dealerships use a machine called the TransFlow which is used to do fluid exchanges and to measure the flow rate of the transmission cooler and lines to see if they are still within specifications. Clogged coolers and lines are responsible for many dead transmissions.

Willard Norris · April 13, 2023

@Grumpy Bear @swathdiver

Update for 12 Apr:

-I installed the Mishimoto 180 thermostat in the morning.
-drove 98 miles up to north Georgia with outside air temp ~80°.

-Engine temp stayed around 197 mark on analog gauge the entire time

-Tranny temp hovered around 172 cruising 65-70 mph (see pic)

-Tranny temp got to 183 in some city driving

-conditions were the same for the drive home

-Range AFM delete was not installed

-Other than looking orange, tranny fluid has no metallic shavings that I can detect using a magnifying glass. Of course, that doesn’t preclude debris from being lodged inside the cooler/radiator

So based on that limited information, do y’all still recommend that I

1. Try to find a shop with a hot flush machine

2. Install a new radiator if unable to find hot flush machine

or

3. Drive as-is and monitor and just get fluid changed

As y’all can tell, I’m mot a mechanic, but don’t mind trying to fix my own stuff if able, and I’d like to keep this truck for a while longer if I can get this figured out.

Thx!!

Ubiquity · April 13, 2023

@Willard Norris

Hello: It is not my intention to complicate your situation. It's just that I have a keen interest in your case as I had recently installed the shur cool transmission bypass valve (TBV) as well as did a filter change along with a 6 quart fluid change. I'm about to order the 180 thermostat as well.

I'm getting ahead of my situation, but I would like to question the experienced folks of the efficacy of bypassing the internal transmission radiator cooler and going with an aftermarket external one at some point? This is not a priority for me yet, and may never be as I have yet to fully wring out the recent changes to the system. I don't have any reason to believe it's clogged; I'm just slightly put off by the stock system going forward.

Perhaps tomorrow I'll have a chance to run the vehicle for a good test run. The Outside air is supposed to be near mid to high 80's today and tomorrow here in the northeast.

Grumpy Bear · April 13, 2023

1 hour ago, Willard Norris said:

@Grumpy Bear @swathdiver

Update for 12 Apr:

-I installed the Mishimoto 180 thermostat in the morning.
-drove 98 miles up to north Georgia with outside air temp ~80°.

-Engine temp stayed around 197 mark on analog gauge the entire time

-Tranny temp hovered around 172 cruising 65-70 mph (see pic)

-Tranny temp got to 183 in some city driving

-conditions were the same for the drive home

-Range AFM delete was not installed

-Other than looking orange, tranny fluid has no metallic shavings that I can detect using a magnifying glass. Of course, that doesn’t preclude debris from being lodged inside the cooler/radiator

So based on that limited information, do y’all still recommend that I

1. Try to find a shop with a hot flush machine

2. Install a new radiator if unable to find hot flush machine

or

3. Drive as-is and monitor and just get fluid changed

As y’all can tell, I’m mot a mechanic, but don’t mind trying to fix my own stuff if able, and I’d like to keep this truck for a while longer if I can get this figured out.

Thx!!

I'm going to let @swathdiver take a shot at this first about what to do about flushing or radiator replacement. His hands on and in the shop experience, driving style and conditions more closely mimic yours.

While we have the same set up, you drive faster than I do by about 10-15 mph. That also raises temperature. Peak cooling happens in a radiator at 25 meters/second (56 mph)

I will say it responded directionally as it should have. your dash gauge is where I would expect it to be. I'll also say that getting warmer in the city or any stop and go will have it reaching higher temperatures. No moving air, no cooling. And that, again, is a fan programing issue. After swathdriver weighs in I'd still change that fluid AGAIN. When depends on his advice.

I've posted this graph of mine dozens of times now. The blue line would be relevant to your situation at a steady 55 mph. You could use this as a touchstone. If you can find a place in Georga to drive that slow and yet steady for say 50 miles. :crackup:

Grumpy Bear · April 13, 2023

42 minutes ago, 2015regcablongbed said:

I'm getting ahead of my situation, but I would like to question the experienced folks of the efficacy of bypassing the internal transmission radiator cooler and going with an aftermarket external one at some point? This is not a priority for me yet, and may never be as I have yet to fully wring out the recent changes to the system. I don't have any reason to believe it's clogged; I'm just slightly put off by the stock system going forward.

Perhaps tomorrow I'll have a chance to run the vehicle for a good test run. The Outside air is supposed to be near mid to high 80's today and tomorrow here in the northeast.

If it were me and I had your truck...wait...I do have your truck! (Humor intended). AND I wanted some more cooling capacity I would add a secondary air/air cooler with a switchable fan in series with and downstream of the current cooler AND install the 70C TBV. You need the reasoning, right?

Study the graph I put up for Willard. Note that the transmission warms WITH the TBV to a higher temperature than with the pill flip? That is up to the trigger point. After it is open there is only a degree or three difference with the TBV being a bit higher. Anything that throttles restrict flow a bit, so this is quite normal in a PROPERLY sized system.

This happens because it is WORK put into the fluid that heats it. Look at 10 F points for but the orange (pill flip) and blue (70 TBV). From start up, first thing in the morning the AFT heats FASTER to 110 F as the hot fluid warms it quicker than the cold air. However it will get no warmer. With the TBV it will continue to rise as the AFT is not being cooled by the radiator until it does. The temperature it reaches is warmer and more efficient and yet well below the throttling point.

Now imagine this in the winter. And air only exchanger without a TBV. Allot of engineering goes into properly sizing a cooler and when we do that without that advantage....well.....it may never warm up if the cooler is too large or it may never cool down if too small. I'm saying that if you add a cooler or entirely replace it with a larger air cooler you may wish to add back the 70 TBV.

Now all that said what is too cold? Well, it needs to get warm enough to satisfy all the TCM low temp trigger points, so something consistently north of say 110 F. Last tip is at 104F to lean the fuel map and allow TC lock up. What is too hot?

I can give MY preference. I like the lid on at 160/170 F. Some will argue higher. 160F is the onset temperature for oxidization and it's plenty warm enough for proper operation. That temp keeps the fluid happy. Below 170 F clutches, seals etc. last the longest. I don't panic if it gets warmer in stop and go and if I ran fast, and it got consistently over say 180 F I add cooler and/or change fluid more often.