widetrak60

what is opperating temp for a 518a and when is it hot. my son has a temp gauge but we dont know when to be concerned or get out of od when pulling a load.

DBF

That depends on where you mount the sensor to measure the fluid temperature.

Where is his mounted?

Very generally speaking, trans fluid starts to deteriorate above 200*.

Regards, DBF (regretting that we won't get to Alaska this year)

Boatnik

If you mounted the sensing bulb in the same line as the factory sensor. The fluid will get to 280-285 before the overdrive will lock out. I believe this is the line from the tranny to the coolers. In my opinion that is too hot. I keep mine below 260 if at all possible.

DBF

I have three temp sensors on two gages. If the one at the output of the trans gets much above 210*, I get out of OD.

I have two in-line coolers with fans under the bed which help control temps which then allows longer times between fluid changes.

Another sensor is in the pan of the trans, so it reads what is going *into* the trans internals. If this temp starts rising, everything else is going to rise until I slow down, get out of OD, or go to 3rd (direct). I like it when the pan temp is around 170.

Everybody has their own way of doing things, mine won't be correct for anyone else. Just passing on information.

Regards, DBF

Boatnik

Chief, That is a very good and conservative approach. I have the the same or similar torque converter and valve body mods. Towing on those hot Fla days, how hard is it to keep it below 210? The reason I ask is because we get some of those hot days in VA and I don't have aftermarket coolers. With the old T/C I would hit 260 on 95 degree days towing 7200 pounds of fiberglass and Tee top at 55 mph.

DBF

The worst part is towing thru a city in stop-and-go traffic at 90*+ with the A/C on. Pure murder, fans on all the time and all you can do is keep the RPMs up, using second if needed. Even so, I've seen 250*+. I jot down a note to change the oil a little earlier next round and go on.

On the flats at 90* with the A/C on, I can keep the fluid under 190* towing a 7500# 5er, if I keep the speed down (55-60) and stay out of OD (the 3200 spring helps a lot). A moderate hill will send the temps up again but not usually over 210*.

If it's 75* outside, I can do a lot better. Cruise at 65 in OD, only coming out for hills.

Regards, DBF

THE 0NE

i have a aftermarket tran and when i put my foot in it it goes all the way up to 250 is that normal? i have a aftermaret tranny cooler with fan and it still gets that high?

DBF

Where's the sensor - if its in the trans output, you can see that high on a hot day with your foot in it, easily. With that, the fluid is deteriorating.

See this site:
http://www.txchange.com/heatchrt.htm

I don't vouch for their figures, but the idea is correct.

Regards, DBF

Boatnik

I've noticed the tighter DTT torque convert heats up the fluid at a stop light much faster than the stock one did. I have started putting her in nuetral if it looks like I am going to be sitting more than a couple of minutes. I am going to Amsoil at the next fluid change. It will handle heat a lot better than regular ATF. I have run it in other vehicles and am very pleased with the results.

DBF

Good idea - I'll have to do more of that.

Regards, DBF

THE 0NE

The sensor is right in the side of the pan. i am buying a aftermarket pan soon so i hope that helps some.

DBF

Wow. 250* in the pan is way high. You say it gets up there when you have your foot in it and you have a cooler with fan installed.

I'd have to have my foot in it for a long time on a hot day to get that high.

Are you sure the cooler's fan is operating?

What is the size of the tubes in the cooler (1/4", 3/8", 1/2"?).

Is the small fluid cooler on top of the radiator still installed?

Fluid level correct?

Is the engine getting hot as well?

Regards, DBF

THE 0NE

1/2 inch lines, the cooler is under the truck by the trans i was worried about air flow. eng temp stays normal, fan is on, the cooler is like 12x12. and dip stick reads normal.

dpuckett

Make sure you're in neutral and not Park to check tranny fluid.

Also, what is your EGT doing? That can also effect tranny temp, as fluid flows right under the hot exhaust manifold. No personal experience, just thinking out loud.

DP

DBF

You haven't filled in your "signature", so I don't know anything about the truck you're driving, other than it runs hot and has an auto with cooler/fan.

I'm puzzled. That cooler/fan, combined with the little cooler above the radiator, combined with the engine/trans heat exchanger, ought to keep that thing cool at any temp/speed. Unless you're talking about it getting hot when you're towing something and haven't mentioned that.

Could you run through the details and the timing of starting to the time the pan temp is up at 250*?

Tx, DBF