Normal operating temp for 4L80E in a plow truck?

[upper_tanker]

I'm on mobile so it's a PITA to quote messages so I'll try to reply to Schurkey and Stutaeng at the end.

I stopped by the trans shop today and talked to them. He said the reverse band is probably starting to go. He said reverse is all mechanical so it's just probably that. He told me it would be around $2500 for a rebuild to beef it up like it belongs in a plow truck. I think I said it earlier, but these guys have done a ton of 80E rebuilds for my dad and we haven't had an issue with any of them, so I trust them. I also told him about the temp and he said it's not uncommon for a stock trans in a plow truck to see those temps occasionally on a 35-40 degree night. He said he would not recommend another cooler as long as it doesn't get above 225 or stay at 220+ for extended periods of time. He did say the reverse issue may be causing the heat issue as well.

I do not see metal flakes in my trans fluid, and if there are, then they're not on the dipstick. Also, the fluid does not smell burned. It actually still looks pretty red and clean.

It doesn't feel like reverse is "slipping." When I think of slipping, I think of somebody driving a manual who has little or no experience. I do not have to get the motor screaming to get it to move in reverse, it just kind of chugs along in reverse until a certain speed, and THEN it goes. Again, this is only when I give it light gas.

I'm still going to try to make it 1-2 more plows with it. I've already put 20 hours behind it so far this year plowing, and the severity of it hasn't changed. I will, however, plan on a rebuild eventually. I'd just rather pay for it with plow money vs out of my pocket if I can help it.

 

[upper_tanker]

Schurkey, I don't know why, but the last part of your message didn't load when I wrote my last response. Now that I've seen it....

When you say a delayed reverse, do you mean a delay in the time it takes to actually engage into reverse and gently jerk the truck back when you move the shifter to reverse?

 

[stutaeng]

Here's a good article on how to check the "lost reverse" issue on 4L80e. It's a bit older article, but seems like a good starting point.

Looks like you need a line pressure gauge. I read and understand the first 2 steps, but not the 3rd step...

https://www.sonnax.com/tech_resources/88-diagnosing-the-elusive-no-reverse-with-the-4l80-e

 

[Supercharged111]

The trans in my dually has this weird sort of delay I've never been able to put my finger on. Sometimes when you leave a stop sign it feels like it doesn't quite respond as expected, then there's a small bump, then everything goes back to normal. Almost like there's insufficient flow at idle. Doesn't do it all the time and I did a full flush this spring. I haven't noticed it in reverse either so not sure of your issue is similar to mine. Mine hasn't gotten worse and I haul heavy with the dually. The torque converters on both trucks drain overnight and don't like to move move if you fire them up stone cold and immediately throw them into gear. I hardly notice it because my driveway has such an incline. By the time I roll back into the street and put it in drive it's ready to rock.

 

[Schurkey]

Schurkey, I don't know why, but the last part of your message didn't load when I wrote my last response. Now that I've seen it....

When you say a delayed reverse, do you mean a delay in the time it takes to actually engage into reverse and gently jerk the truck back when you move the shifter to reverse?

When cold, I'd move the shifter to "R", and get NOTHING. It's like the trans was in neutral. Ten, twenty seconds. When really cold out, maybe a minute of "false neutral".

Eventually, it'd engage reverse. From then on, for the rest of the drive the trans would be fine. But that first engagement of the morning took a long time.

MY solution was to park the vehicle facing outward. Get in, throw it in "Drive" and go. No reverse needed. However, SWMBO didn't see the humor in that.

I"m still surprised that my Reverse delay was apparently caused by a faulty or plugged filter.

 

[Supercharged111]

When cold, I'd move the shifter to "R", and get NOTHING. It's like the trans was in neutral. Ten, twenty seconds. When really cold out, maybe a minute of "false neutral".

Eventually, it'd engage reverse. From then on, for the rest of the drive the trans would be fine. But that first engagement of the morning took a long time.

MY solution was to park the vehicle facing outward. Get in, throw it in "Drive" and go. No reverse needed. However, SWMBO didn't see the humor in that.

I"m still surprised that my Reverse delay was apparently caused by a faulty or plugged filter.

Maybe it was misplaced schmoo that the new fluid was able to purge?

 

[Pinger]

In a perfect world 180 all the time. In the real world 160 to 200 is fine. Every 20 degrees above 200 cuts the trans life in half. This is per TCI and I trust them. I have been selling their stuff over 25 years.

Yes, I remember the old deal about trans life being cut in half for every twenty degree rise in temp. When I first heard that, dinosaurs still roamed the Earth, and the lower temp started at 170 degrees. Now, I guess, the story is starting at 200. It's like every other "rule of thumb"...wildly inaccurate, and perhaps deliberately so. Your trans is not constantly at 220, it's seeing occasional 220.

Could this be a case of a story growing arms and legs?
Pretty much accepted that each 20 degree increase halves the oil's life. Not quite the same as saying what the oil is in's life will be halved - though the tendency is in that direction.

The truck has a trans cooler with a fan on it. I have no clue if it's stock or aftermarket, but it looks stock the fan IS working.
.

I could be way out.... but is it not the case that an external cooler when supplied from the factory it is unconnected until the owner plumbs it in? Worth checking?

As an aside... on my C2500 with a 4L80E and external cooler (but no saddle cooler) I fitted a thermostat. In light running in cold conditions I've been checking (by hand, feeling the lines the other side of the thermostat) and the thermostat has remained closed. After a very long steepish climb (my ears popped at the top) in 4th OD with the TC unlocked (should I have downshifted to 3rd?) on a pretty cold day I had reason to stop a fair way down the other side of the hill and when I checked, the thermostat had opened (later confirmed by a slight drop in fluid level as the cooler was now filled).
My point is that it is possible to have an external cooler and have it operate only when required.
(The saddle cooler is a cooler until the rad it's in sees hot coolant from the engine - and that isn't until the engine thermostat has opened).

 

[thegawd]

just throwing this out there, since the problem seems to be related to how far the throttle is open, have you verified that the throttle position sensor is in 100% working order? I can test the tps with my cheap obd2 scanner in graph form. it should rise smoothly as the throttle opens. any missing data or jumps and it is no good. a new TPS, replacing a tired one can wake your truck up. I did a burn out in my burb immediately following a tps replacement.

you could have a problem with the tps that's simply not noticed when moving forward because you probably have it opened passed that point. a tps wont set a code if its still sending data, the data is just wrong.

Al

 

[Pinger]

just throwing this out there, since the problem seems to be related to how far the throttle is open, have you verified that the throttle position sensor is in 100% working order? I can test the tps with my cheap obd2 scanner in graph form. it should rise smoothly as the throttle opens. any missing data or jumps and it is no good. a new TPS, replacing a tired one can wake your truck up. I did a burn out in my burb immediately following a tps replacement.

you could have a problem with the tps that's simply not noticed when moving forward because you probably have it opened passed that point. a tps wont set a code if its still sending data, the data is just wrong.

Al

Crossed my mind that the hesitation could be from the engine.
Good call on the last paragraph as to how it could go unnoticed driving forwards.

 

[thegawd]

well, it's a $30 part and free to test. but it is so damn important in providing data for engine managment. I think it gets overlooked all the time. I know I didnt consider it for years.

Al