8a8mfh

iTrader: (3)

I just installed a trans temp gauge and put the sender in the cooler line going out to the cooler. It has a 11x13 cooler that bypasses the radiator.
The temp goes up to 220 at idle, if I start driving it will slowly move down but as soon as it locks up the temp drops down real quick and stays there until it unlocks again. I've seen it drop up to 50 degrees in under a minute.
Is this normal?


It's a 1998 4L80E out of a 3500HD truck. I got the trans at 60,000 and had to put in new bushings, fwd clutch housing, rear band and apply servo with a longer pin, sonnax press limiting boost valve. And I swapped the spring steel cushion plates with the old waved type.

Gilbert@Ace Racing

That is perfectly normal operation of the cooling system. When the converter clutch locks up the converter is not longer stalling. The Turbine is locked to the frt cover therefore there is no fluid sheer, no heat is being generated.

g

8a8mfh

iTrader: (3)

Dang, I had no idea it built that much heat. It will run cool going steady down the highway.

99Hawk262

iTrader: (19)

The temp shouldn't go to 220 at idle? That sounds odd. As for the temp drop, my cooler setup is similar to yours and it'll heat up in town or on WOT runs quickly, then cool down fast once the converter is locked. You can literally watch the needle move on the gauge.

Gilbert@Ace Racing

I agree... 220* at idle seems excessive... but I would think it is not relative to anything but the converter stall and the time at idle. I'll kick it around with John in the morning, but it could be that it is not producing cooler flow during certain events such as idle.

Hawk are you running Vince and Chucks FLT Lvl4 4L60E? The OP is running an 80E. I have never studied the heat generating characteristics of each, but I would be hesitant to compare the two.

Next time you are in a car with a brake and a gauge bring it up on the converter and watch the gauge. On average, when on the trans brake at max throttle the temp will increase 10* per second! So, if the tranny is at operating temp when you get to the line and then you take it up on the brake for say 5 - 7 seconds your are increasing the tranny temp by as little as 50*. It is very relavent to the size of the converter and the rpm the stall was set at... but you get the point.

Spooky huh?

g

performabuilt

iTrader: (25)

Yes the heat generator in a transmission is the converter , When they hit lockup esentially the converter isnt even there. And the heat generated by the incidentail friction in the trans is insignificant, I have seen a bad converter however heat a trans setting still in park to 250 plus degrees in just a very short time.

8a8mfh

iTrader: (3)

I have noticed it idling kind of high lately, since before I put the gauge on.
It idles around 1000 rpm in neutral, IIRC the chip is set for a 650 rpm idle. I can burn chips for this truck and I think thats what I set it at.
Looks like maybe an IAC problem.
It is the stock converter out of the 1998 3500HD.
It's been together for at least 25,000 miles now.
Could the forward clutch clearance being too tight cause high idle temp?
Not sure if it is but I know I have the specs on this written down somewhere. I tend to run tight fwd clutches depending on where the clearance ends up.
EDIT: the forward clutch clearance was .059, with one old style th400 waved plate instead of the blue colored spring steel plate.

performabuilt

iTrader: (25)

That is alotta heat for a stock converter of course you are idling it pretty high so alota stress there, As for the forward clutch clearance I would say no , Because to generate that kinda heat they would have to be cooking and would die really quickly,

FLT

iTrader: (1)

Wow funny to read this thread. I have tested this topic on our Dyno. It is equipped with a temp gauge as well as the other gauges. I have found in doing this test with a 4l60e to do just as 8a8mfh has stated here the first couple times the clutch is cycled. The temp will drop when I release the tcc which I know makes little sense. My procedure is to run the trans through the gears and lock it up. Then let it run for a while allowing the clutches and band to stay applied letting the temperature rise. I believe what happens is there is oil in the converter that really does not circulate. Thus trapping cooler uncirculated oil. I believe that this oil stays cooler and this is why we see the temperature drop. When you apply the tcc you will see cooler pressure and flow increase, obviously something changes as far as the flow of oil in the converter. In 8a8mfh case it is a stock 4l80e converter that is very big. Thus it will hold more oil and I think that is why he is seeing greater numbers. Keep in mind that the Dyno does not have a for say cooler on it. I find that after you cycle the TCC a couple times the temp will stay more stable inside the converter. Now put this whole equation on the street with a large trans cooler and a high stall converter. When the tcc is not locked we all know that the converter is building heat. However when the tcc locks the cooler flow and pressure will increase thus circulating more oil. Also increasing the cooling/lubrication capabilities of the transmission and the cooler of the vehicle. Good topic but very confusing from what I have tested. The first time I saw it for myself I was like that is totally backwards to what should be happening. Maybe one of the converter geniuses will chime in here and take this topic to the next level. Vince

99Hawk262

iTrader: (19)

I understand that there is a difference in the two trannies, but obviously there is a similarity in generating heat while unlocked and then cooling down once locked. The scenario he described his 80 doing is what my 60 does every day.

8a8mfh

iTrader: (3)

Vince, I had the same thoughts on fluid being trapped somewhere. And just dumping out after lock up only because I can't see my cooler cooling fluid that quickly.

Most drop I've seen in the two days I've had the gauge was 220 at idle I got right onto the highway and it might have hit 210, then the TCC applied and it shot down to 160, then it went back up and stayed at 175 or so at cruise. This is with a low 70 degree outside temp.

FWIW I put the sender in the outlet line because I wanted to read the hottest temp, I know most people put it in the pan to get an average reading, but IMO I want to see the max temp.
I also had it in the pressure test port at one time, the readings there were slightly higher but more consistant, I think it was reading case temp.

I also would like to hear from a converter manufacturer.

Gilbert@Ace Racing

Interesting comments regarding the trapped / non circulating fluid. That did not occur to me. Thanks for sharing your experiences Vince.

I think I will take a Laser pointer type thermometer to a converter next time I have one running and see what I can see.

g

01Z0H6

iTrader: (63)

That's crazy hot!! My trans rarely if ever gets hotter than 180*.. typically runs around 160.. I installed my sensor in the side of the tranny core. ( drivers side bung).

8a8mfh

iTrader: (3)

What would go bad in a converter to make it build heat at idle?
It seems to work ok, the TCC apply is as firm as the gear shifts.
Is there any hydraulic problems that would let it work normal but stay partially applied? like a cross leak in the pump. I wet air checked the pump when installing the sonnax boost valve and it wasn't as tight as I would have liked to see it.

Ragtop 99

iTrader: (7)

That was the first question I had - Where was the temp being measured? If it is being measured at output it makes sense that as soon as it locks it drops down to around 160* which is the average for the fluid assuming a big cooler. It takes a lot of calories to heat the fluid 10* when measured in the pan. Think about how driving it takes before engaging lock-up in this weather.