[Slick71ss]

I have an auto meter trans temp gauge that reads up to 250 degrees. After about 10min of driving, the needle is buried past 250!!! This is just regular, cruising in town driving. I suspect that's not the correct temp, but not sure. I have a th400 with a 3600 stall. The temp sending unit is installed on the trans cooling line leading to the cooler in front of the radiator. Here's a pic of it's location...



Any suggestions what may be wrong? I understand that a sender in the trans pan is best, but I still shouldn't get this kind of reading. I'm trying to locate one of those digital temp readers that you just aim. If the gauge is accurate, what do I do to fix the temp problem? If it's not accurate, is the sender bad? Too close to my engine block or headers? I'm puzzled.

 

[Mike Feudo]

That is a lot of convertor. What is your rear axle ratio? I suspect the convertor is loose the whole time you are driving. If that is the case you will need a very large trans cooler.

 

[Slick71ss]

rear ratio is 4:11

I don't like the converter for street driving at all. Like you said, it's very loose. I'm usually around 2000 rpm's while driving in town.

Will a bigger trans cooler actually keep it cool enough if the converter is slipping all the time? My current cooler is 8.5x11 inches, which isn't small. I don't know what brand it is.

How good are the coolers that have an electric fan?

 

[Schurkey]

Since your temp probe is in the cooler tube leading TO the cooler, you're going to be indicating the highest temperature the fluid reaches.

Me, I'd want to know how hot the fluid in the pan is. Or, for that matter, how hot is the fluid coming OUT of the cooler?

 

[Slick71ss]

Since your temp probe is in the cooler tube leading TO the cooler, you're going to be indicating the highest temperature the fluid reaches.

Me, I'd want to know how hot the fluid in the pan is. Or, for that matter, how hot is the fluid coming OUT of the cooler?

The highest temp shouldn't be over 250 though. Right? For all I know the temp could be reaching 300!

 

[Schurkey]

So far as I know, you want 170--190 in the pan. It'll be a lot hotter coming out of the converter, and if you have a sloppy converter, it'll be even worse.

First guess: For that car, 250+ on the trans cooler supply tube is perfectly normal.

This is why I asked what the temp was in the pan and in the cooler return tube.

 

[Slick71ss]

I didn't know 250 might be ok leading to the cooler. Thanks for clearing that up. Guess I'll have to get a pan with a sensor in it. If it turns out it's too hot in the pan as well, I just might have to bite the bullet and purchase a better converter sooner than I thought.

 

[Schurkey]

Big difference between "OK" and "Normal".

I have no doubt that you're shortening the life of the fluid with the 250+. But if it's cooled down right away, it doesn't have much time to oxidize. If you had 250+ in the pan, you'd be in real trouble. Not only would the fluid be too hot, but the rubber seals in the hydraulic system would be that hot, too. As is, I suspect the only harm being done is to the fluid itself, and since it doesn't stay that hot very long it may not be anything to get too wiped out about. Change it every year or two.

 

[Slick71ss]

Stupid questions, but I have to ask...

Does the tranny cooler drain through the lines if it's mounted higher than the trans?

How can I tell if my fluid is burnt? My fluid is blue so I can't tell if it's darker. It doesn't smell burnt either.

 

[jcautotech]

250 deg is in the hot side best place for sending unit is the pan type of cooler you using stock or cooler by air this what i do in if was mi case move sending unit to oil pan use two oil coolers one internal cooler in side rad oil flow in / out to external in/out flow back to trans check, oil flow aprox 1 qt in 20 sec ( note ) diff. readings w/ infrared gun at least 10 deg cooler in case you read temp w/ this type of tool

 

[Slick71ss]

I don't have a stock radiator, so I can only use an external cooler. Found out my cooler is a B&M supercooler. I'm going to upgrade that to one with an electric fan. I might be getting a new ATI torque converter as well, so I'll have to see what kind of difference that'll make.

 

[rdj59]

Hi, I've also got a Trans Temp Gauge installed in the line out from the trans and my highest reading i've ever had is 210. That is after doing a very long brake torque. After that it cooled down real quick. Otherwise it stays right around 150-160 while driving around. This is with a 3000 ebay stall convertor (really ~3500), rebuilt th350 with shift kit, 4.10 gears, internal cooler, old (free)14 pass oil cooler, behind a built up 350 buick in a 4200 lb lincoln town car.

Jeramie

 

[Slick71ss]

Put a new aluminum deep pan on and moved the temp sensor to the pan.

Is the trans fluid temp supposed to get hot by just idling the car for 15-20 min? I can't drive the car right now because I have the front end apart. The trans temp got up to 190 from just running the car! I put it in each gear so I could level off the fluid, but nothing else. That's hotter than what the water temp gets up to(180)! :angry:

 

[Schurkey]

Have you dropped the sending unit into a pot of boiling water to see if it reads anywhere close to correct?

20 minutes of idling in gear with the wheels not turning=yeah, it's gonna be hot. 20 minutes of idling in neutral shouldn't generate anywhere near as much heat.

 

[Slick71ss]

It was in park the whole time, besides when I shifted through each gear.

It's a brand new sender and I didn't test it in a pot of boiling water. The trans pan and cooler didn't feel real hot when I laid my hand on them. The pan is cast aluminum so it might not get as hot as a steel pan. When the water temp reads 190 there's no way I can lay my hand on the radiator hose and keep it there. When checking the fluid it didn't seem real hot.

Stupid question, but would 190 degree fluid be hot enough to burn you or at least cause discomfort?

 

[Schurkey]

It's a brand new sender

With the problems you're having, I don't care.

I didn't test it in a pot of boiling water.

Well...get to it.

The trans pan and cooler didn't feel real hot when I laid my hand on them.

Yup, that's why I think you have a defective sender/gauge.

Stupid question, but would 190 degree fluid be hot enough to burn you or at least cause discomfort?

Since the safety nazis want you to turn down your home water heater to 120F, I'd say that you'd be scalded pretty bad at 190. I have a stereo amp that runs at 110--120, and it seems pretty hot to me.

 

[Slick71ss]

I appreciate all the help! Makes me feel a lot better thinking my gauge or sender is bad. It would make sense if the gauge is bad since 2 different senders have been reading too high.

I'll test a sender with hot water as you suggested. Gotta go find or buy a thermometer to compare the gauge reading to. I'll post the results, may not be until tomorrow.

 

[Slick71ss]

Yup, that's why I think you have a defective sender/gauge.

You were right!

At 110 degrees the gauge reads 190.
At 140 degrees the gauge reads 250!

So, once my trans temp gets above 140, my gauge is maxed out over 250. I emailed Auto Meter to make sure I didn't miss checking anything before I buy a replacement gauge. Both senders gave the same results.

Thanks Schurkey!

 

[Schurkey]

s'allright.

 

[Slick71ss]

It turned out to be a bad ground connection on the gauge!!! :clonk: