Trans over temp issue

[jlee]

My 09 5.3L non-K5L with 161k recently had the following work done at a shop:
New Delco trans cooling lines as old were leaking
Added stock K5L oil cooler as we are planning on getting a boat and I was already changing lines
Delco trans fluid change and delco filter change (no flush) as it was last done around 75k.

My first longer trip on a warm day was my trip back from zoo with the family and trans temps kept climbing on way home. It hit 250 as I rolled into the driveway which I know is way too high. Last 15 minutes of the 45 minute drive was over 220. I checked the added cooler right after we got home and it was cool to touch (same as ambient according to IR gun) along with lines to / from the added cooler suggesting trans fluid wasn't flowing through the radiator / cooler. No leaks anywhere. Checked fluid and it seemed a little over HOT, but it's hard to tell with the clean fluid. Checked fluid level this morning after sitting overnight and it was between the cold and hot range idling, but I didn't shift between gears before checking. Coolant temp never went above the normal 210, so I don't suspect any kind of radiator / fan issues. Before the above work, I usually hit max of 195 or so on a 90+ day like yesterday. Never noticed any odd trans shifts/slips or temp warning from the truck on our trip home.

As I understand it, there's no air purge procedure for the cooling lines / coolers, right? Also, there shouldn't be any check valves in the system that if lines were swapped would block of flow, right? Could high trans fluid level prevent fluid from flowing through radiator / cooler? Once we get it fixed, should I have fluid changed out once again to be safe? Anything else trans related I should have looked at after these temps?

I'm probably taking it back to the shop that did the work on Monday, just looking for some possible explanations to what's going on here and whether or not I should get the fluid changed out again to be safe.

 

[swathdiver]

My 09 5.3L non-K5L with 161k recently had the following work done at a shop:
New Delco trans cooling lines as old were leaking
Added stock K5L oil cooler as we are planning on getting a boat and I was already changing lines
Delco trans fluid change and delco filter change (no flush) as it was last done around 75k.

My first longer trip on a warm day was my trip back from zoo with the family and trans temps kept climbing on way home. It hit 250 as I rolled into the driveway which I know is way too high. Last 15 minutes of the 45 minute drive was over 220. I checked the added cooler right after we got home and it was cool to touch (same as ambient according to IR gun) along with lines to / from the added cooler suggesting trans fluid wasn't flowing through the radiator / cooler. No leaks anywhere. Checked fluid and it seemed a little over HOT, but it's hard to tell with the clean fluid. Checked fluid level this morning after sitting overnight and it was between the cold and hot range idling, but I didn't shift between gears before checking. Coolant temp never went above the normal 210, so I don't suspect any kind of radiator / fan issues. Before the above work, I usually hit max of 195 or so on a 90+ day like yesterday. Never noticed any odd trans shifts/slips or temp warning from the truck on our trip home.

As I understand it, there's no air purge procedure for the cooling lines / coolers, right? Also, there shouldn't be any check valves in the system that if lines were swapped would block of flow, right? Could high trans fluid level prevent fluid from flowing through radiator / cooler? Once we get it fixed, should I have fluid changed out once again to be safe? Anything else trans related I should have looked at after these temps?

I'm probably taking it back to the shop that did the work on Monday, just looking for some possible explanations to what's going on here and whether or not I should get the fluid changed out again to be safe.

Well, you want to make sure they hooked up the lines in the correct order and removed the block off plate gasket and exchanged it for the oil cooler gasket! Then there is pump failure to check for...

 

[jlee]

Well, you want to make sure they hooked up the lines in the correct order and removed the block off plate gasket and exchanged it for the oil cooler gasket! Then there is pump failure to check for...

Sounds like you are thinking about the engine oil cooler, that is still blocked off. I had the transmission cooler lines replaced and added the auxillary trans cooler in front of the radiator that comes with the K5L cooling package.

 

[swathdiver]

Sounds like you are thinking about the engine oil cooler, that is still blocked off. I had the transmission cooler lines replaced and added the auxillary trans cooler in front of the radiator that comes with the K5L cooling package.

Well, I partially confused the two! But maybe they did use the wrong gasket??? Did you use a factory cooler and lines and are they new? Old lines and cooler can become clogged and inhibit flow, which the TransFlow machines the dealers use test for when they do fluid exchanges.

 

[jlee]

Well, I partially confused the two! But maybe they did use the wrong gasket??? Did you use a factory cooler and lines and are they new? Old lines and cooler can become clogged and inhibit flow, which the TransFlow machines the dealers use test for when they do fluid exchanges.

Shop found one of the new lines was collapsing while running. Replaced that line and now temps are good and the cooler is hot to touch as one would expect.

 

[swathdiver]

Shop found one of the new lines was collapsing while running. Replaced that line and now temps are good and the cooler is hot to touch as one would expect.

Good deal Jeremy! If I remember right, yours has 3.08 gears and you were planning to tow with it right?

Here's a few shots of my temps, to give you an idea of what to expect, cruising down and then up the highway with a good sized load in the truck and not towing:

 

[jlee]

Good deal Jeremy! If I remember right, yours has 3.08 gears and you were planning to tow with it right?

Here's a few shots of my temps, to give you an idea of what to expect, cruising down and then up the highway with a good sized load in the truck and not towing:

View attachment 225935 View attachment 225936

I've got 3.42 gears as I searched for at least that when I bought it. As I understand it, I'm engine oil cooler (different radiator) and upgraded cooling fans away from K5L yet. I wanted some extra trans cooling in case I get stuck in stop and go traffic with a boat headed back from the cabin to the Minneapolis suburbs.

 

[mattjones]

Does anyone know what sort of temp range we should expect? My 2011 Z71 Tahoe was over 200° recently and I remember thinking that was a little weird because I didn’t remember my 08 Tahoe ever going above 180 or 190. I assume if it gets too hot it would trip a check engine light or something but I don’t know what that magic too-hot temperature is.

 

[swathdiver]

Does anyone know what sort of temp range we should expect? My 2011 Z71 Tahoe was over 200° recently and I remember thinking that was a little weird because I didn’t remember my 08 Tahoe ever going above 180 or 190. I assume if it gets too hot it would trip a check engine light or something but I don’t know what that magic too-hot temperature is.

What were the conditions when the temperature reached 200? Towing, temp outside?

You can see my normal temps in the photos above. Yesterday it was 96 degrees outside and the transmission and transfer case temps were at 156 while running 73 mph on the highway and 167 in city driving afterwards on the way to grandma's house. Pretty normal for us. Truck weighed about 7,200 pounds on that run.

See post #290 here:

https://www.tahoeyukonforum.com/threads/useless-information.97483/page-29

 

[jlee]

Does anyone know what sort of temp range we should expect? My 2011 Z71 Tahoe was over 200° recently and I remember thinking that was a little weird because I didn’t remember my 08 Tahoe ever going above 180 or 190. I assume if it gets too hot it would trip a check engine light or something but I don’t know what that magic too-hot temperature is.

Before I added the cooler I'd hit 190's on 90+ days if I hit some stop and go traffic without even towing. Never saw over 200 that I recall though.

With the line issue, I hit 250 without towing and no check engine light. Had I not been watching it on the display, I'd probably not have even known. Seems unusual to be this warm and not get a light.

After the line fix (with added k5l trans cooler), I'm now running about 15F to 20F cooler and have barely even seen 170's so far.