700R4 temp monitoring

[LiftedAWDAstro]

I believe that the plug is a tapered fit so don't over tighten and use some thread tape.

Don't use thread sealant or tape as it will not ground the sensor. It must ground itself through the threads.

[oldsmoker]

I really want to do all i can to ensure longevity of this transmission, I want to know whats is going on with it, esp in these hot south Florida summers!!

If i have to I will install a bigger aux cooler, but initially, im gonna experiment with my current set-up of stock rad cooler flowing into aux cooler, and then bypass the rad completely, and see what effect that has.

The bottom line for me, is that I need to find out for myself, and educate myself thru my own experience.

I appreciate the valuable input, gentlemen.

[1Gary]

My opinion is the type of aux I prefer is the tube style over the plate style because it is less likely to clog over time.I'll give up the little difference in cooling between the two for that feature.Most people(myself included)while doing maintenance of a filter change flush the fluid of course,"might" flush the T/C,but rarely back flush the cooler/lines.Although this seems to be a off topic to this thread,I do think it is one part of the big picture behind a temp gauge and I very much support having a temp gauge.There are very good points about where to locate the sensor.For me I think I want to know the temps before the fluid is in the trans on the return line to help me based on that be more proactive to prevent damages.My trans guy told me the single weakest link in the 700R4,and the "E" series trans is they especially in lock up don't flow(volume) the fluid well.

[oldsmoker]

I installed a magnefine filter before my aux cooler, both at the same time....to keep that cooler nice n clean!

thanks you your input!...I love this forum!

[MrJames]

Let me begin by saying knowledge is power and good for you in seeking that.

If your vehicle has almost 300,000 miles on the original transmission and no noticeable issues then my assumption is that all is well especially if it is serviced regularly. Also, you infer that you have an auxiliary fluid cooler which adds another layer of protection. I would retain the radiator cooler in line.

What is the condition of the fluid that is removed when a change is made ?

Do you have a magnetic drain plug ? If so, are there any particles on the plug ?

Are the cooler(s) and lines back flushed when servicing ?

The ambient temperature of the Arctic verses a HOT Summer Florida day has some affect. The major cause of transmission overheating is driving style and tow load.

A tapered thread, by its nature, provides a tighter seal than a non tapered thread and may be more than enough to provide a seal.

LiftedAWDAstro is correct that a single wire sensor grounds itself through the thread. If you use a 100% effective sealant or wrap so much tape around the thread the sensor circuit could or will be broken.

IMHO a single wrap of a tape and not a sealant will allow contact because the crests of the thread will cut away some or all of the tape when tightened and provide the necessary ground. The tape will mostly be left in the thread valleys. To me tape is just a means to insure no leakage at all.


Transmission temperatures can change quickly in high load conditions. As I mentioned before, there are a couple of schools of thought as to sensor location.

Some say to put it anywhere in the pan so that it measures the temperature of the fluid that the transmission is sucking up. This location would be the average temperature being monitored.

Others say that the true measurement is in line on the output line to the cooler because this is just after the converter and will show the peak fluid temperature. Any problem will be seen immediately there.

A few say put the sensor on the return line from the cooler(s). This location would be the lowest temperature being monitored.

I have recommended the pressure test port for ease of installation with the caveat that you follow up by measuring the other locations to determine if or how much of a variance you record. If you are not satisfied with the port location then you can continue on to the second part of your project with little loss of effort.

Remember that a high quality gauge system is more reliable and accurate and in the long run costs less the replacing or repairing the transmission.

Happy Motoring !!!

[oldsmoker]

What is the condition of the fluid that is removed when a change is made ?

6 months ago, the tranny was slipping and doing other weird stuff (this is my 1st vehicle with auto trans) I did a pan drop service, new trans filter, replaced fluid with Valvoline Fully synth, 2 bottles of Lubeguard red, added a tru-cool 4454 aux cooler and the magnefine filter... steadily it seemed to fix itself and is now good.

2 months ago, I had an issue with the gear selector, it was stuck in Park, during this simple fix, it had another fluid (pan drop) service. since then, no issues. i do not drive the vehicle hard.

Do you have a magnetic drain plug ? If so, are there any particles on the plug ?

No drain plug at all. when I did the pan drop, the magnet inside was completely covered :/

Are the cooler(s) and lines back flushed when servicing ?

not by me, yet.

The ambient temperature of the Arctic verses a HOT Summer Florida day has some affect. The major cause of transmission overheating is driving style and tow load.

I never tow and dont drive it hard.

A tapered thread, by its nature, provides a tighter seal than a non tapered thread and may be more than enough to provide a seal.

Agreed.

LiftedAWDAstro is correct that a single wire sensor grounds itself through the thread. If you use a 100% effective sealant or wrap so much tape around the thread the sensor circuit could or will be broken.

IMHO a single wrap of a tape and not a sealant will allow contact because the crests of the thread will cut away some or all of the tape when tightened and provide the necessary ground. The tape will mostly be left in the thread valleys. To me tape is just a means to insure no leakage at all.


Transmission temperatures can change quickly in high load conditions. As I mentioned before, there are a couple of schools of thought as to sensor location.

Some say to put it anywhere in the pan so that it measures the temperature of the fluid that the transmission is sucking up. This location would be the average temperature being monitored.

Others say that the true measurement is in line on the output line to the cooler because this is just after the converter and will show the peak fluid temperature. Any problem will be seen immediately there.

A few say put the sensor on the return line from the cooler(s). This location would be the lowest temperature being monitored.

I have recommended the pressure test port for ease of installation with the caveat that you follow up by measuring the other locations to determine if or how much of a variance you record. If you are not satisfied with the port location then you can continue on to the second part of your project with little loss of effort.

Remember that a high quality gauge system is more reliable and accurate and in the long run costs less the replacing or repairing the transmission.

Do you think i made a good gauge choice?

Happy Motoring !!!

[MrJames]

The plot thickens with the previous issues that you have had outlined. The motivation is more than just an educational thing.

Last thing first. I have no idea as to the quality of that particular gauge. My comment was more like penny wise pound foolish.

I hope that someone else here can answer your questions.

[oldsmoker]

the first time I dropped the pan, the fluid was pretty dark, burnt looking.

You are right, I am trying to extend longevity, it may cool better if i dont have the Engine coolant heating the fluid up before it hits the aux cooler?....hence the gauge so that i can find out.

Fortunately, I do have a friend sitting on a known good 700R4 that has done few miles after full rebuild by a very competent chap. He doesnt want big $ for it either.

[MountainManJoe]

it may cool better if i dont have the Engine coolant heating the fluid up before it hits the aux cooler?

Of course the radiator cools the ATF down. You plumb the aux cooler downstream for additional cooling.

im gonna experiment with my current set-up of stock rad cooler flowing into aux cooler, and then bypass the rad completely, and see what effect that has.

Please do post your data!

[1Gary]

Let me begin by saying knowledge is power and good for you in seeking that.

If your vehicle has almost 300,000 miles on the original transmission and no noticeable issues then my assumption is that all is well especially if it is serviced regularly. Also, you infer that you have an auxiliary fluid cooler which adds another layer of protection. I would retain the radiator cooler in line.

What is the condition of the fluid that is removed when a change is made ?

Do you have a magnetic drain plug ? If so, are there any particles on the plug ?

Are the cooler(s) and lines back flushed when servicing ?

The ambient temperature of the Arctic verses a HOT Summer Florida day has some affect. The major cause of transmission overheating is driving style and tow load.

A tapered thread, by its nature, provides a tighter seal than a non tapered thread and may be more than enough to provide a seal.

LiftedAWDAstro is correct that a single wire sensor grounds itself through the thread. If you use a 100% effective sealant or wrap so much tape around the thread the sensor circuit could or will be broken.

IMHO a single wrap of a tape and not a sealant will allow contact because the crests of the thread will cut away some or all of the tape when tightened and provide the necessary ground. The tape will mostly be left in the thread valleys. To me tape is just a means to insure no leakage at all.


Transmission temperatures can change quickly in high load conditions. As I mentioned before, there are a couple of schools of thought as to sensor location.

Some say to put it anywhere in the pan so that it measures the temperature of the fluid that the transmission is sucking up. This location would be the average temperature being monitored.

Others say that the true measurement is in line on the" output line" to the cooler because this is just after the converter and will show the peak fluid temperature. Any problem will be seen immediately there.

A few say put the sensor on the return line from the cooler(s). This location would be the lowest temperature being monitored.

I have recommended the pressure test port for ease of installation with the caveat that you follow up by measuring the other locations to determine if or how much of a variance you record. If you are not satisfied with the port location then you can continue on to the second part of your project with little loss of effort.

Remember that a high quality gauge system is more reliable and accurate and in the long run costs less the replacing or repairing the transmission.
Happy Motoring !!!

I meant to say the output line.Sorry for the error.Consider what your seeing in the fluid changes.Those partials are parts that are wearing out.I do think you can prolong the life of your trans,but temper that knowing nothing last forever.

[MrJames]

I have a few more questions that may help others to assist you better.

Are you the original owner of the van ? If not then do you know the van's history as to number of owners and previous use ?

Does it have a hitch and did someone else tow with the van before you ?

Is it a FL vehicle with a non rusty body and frame ? Is the interior in good shape ?

How much is the van worth to you ? Is it enough to spend money on that other transmission you mentioned ? How long will that other 700R4 be available to you ?

I believe what Gary indicated was that after more than a quarter million miles it may have out performed beyond normal expectations. Given the signs of wear particles and burnt fluid you have to ask "How much longer is it going to serve you".

Food for thought.

[1Gary]

For me in terms of my project I want to know what the details are in a rebuilt trans.My starting core is a 91 V8 truck 700R4 for the 383 I am building for Ole Yellar.It will get oversized TCI servos,constant pressure TCI valve body,heavy duty sun gear and all the dressings not for the hot rod side of things,but for long term durability.

I am going to send it out for the rebuild to a long term friend's shop,but supply what parts are used for the rebuild.I suggest to be told it is a rebuilt trans isn't enough.Ask questions and post that here where we can help more.

Here the standards for a rebuild was a Trans-To-Go valve body rebuild kit,Vett servo's,and a .5 boost valve.

[brokenwrench]

I believe that the plug is a tapered fit so don't over tighten and use some thread tape.

This is not a mechanical gauge that you provided the link to. Single wire electrical gauges rely on electrical resistance varying due to changes in ground conduction. If you teflon the threads, you may interrupt the ground and the gauge may not work or it may be inaccurate.


The ideal transmission setup for longevity is to put on the biggest pan you can get, Derail makes a pan that is huge, I buy them for $35.00 and the extension is about $25, (I make my own). They have an integral drain plug. If you want through a bar magnet in the pan or get a magnetic drain plug $5.00. Factory filters only filter to about 80 micron, bore wear occurs from particles in the 20 to 30 micron size. You need an aftermarket inline filter. I buy the bases from the local hydraulic supplier, but after market ones are cheap, the ultimate setup is a dual filter remote like those used for remote oil filters. This also adds capacity. If you look through the Fram online site you can see which filters work for hydraulic oil and what size of filtering they do. Many people use PH8 filters, same as for oil. The dream auxillary cooler is thermostat controlled with a bimetallic controller, (no wiring to controller), this triggers the fan to turn on and all that I have seen are set for 175 degrees. This is ideal. The correct place for a temperature sending unit is on the return line to the transmission.You want to know how effective your cooler is, the temperature will always be hotter on the way out. If you put the remote filter on the return line you can either drill and tap for the sender unit or just plump it in with pipe fittings on the return side of the filter assembly. If you put the filters on the inlet side of the cooler your cooler will stay eternally clean inside, but you should not put the heat sender unit on this side. If you put the sending unit into the case, you will only be sampling a port used for sampling pressure, it in no way represents how much heat your transmission is making and the temperature may not be representative of what is going on inside at large. Bypassing the transmission is the correct thing to do if you have a 190 degree thermostat in the engine and a good sized cooler. The radiator integral transmission fluid cooler is to keep the transmission temperature form getting too hot, which you can do towing with a factory transmission cooler. Best thing is a big ass fan style cooler with the radiator bypassed.

[oldsmoker]

Im not the orig owner, have had the van 2 years now. no hitch.

previous use and # of owners is vague, think it had 1 owner before me for a long period of time, used as a locksmith van.

the body has a little rust, minimal for its age, the underside is very clean for i ts age, think its been an FL all its life.

was an old Zimmer conv van, i took the orig seats out, they were shot. the rest of the int is ok i guess.

The guy that gave it to me said the the trans had been rebuilt, no specific details as to when or at what mileage.

the other trans is avail for $2-300, will prob have to make a decision on it within the next 2 months or loose it....the guy has a rebuilt 4.3 too, form the same van. Hes a smart guy, used to be a mechanic with his own shop, ive seen him work/seen his work, a sound, trustworthy guy, i regard him as a very good mechanic. he rebuilt the engine himself and had a friend of his who used to have a trans shop do the trans. My understanding is that the trans will have been rebuilt to a standard spec, i will check though.

what is the van worth to me?....I had a guy offer me $900 for it a few days ago??? im kinda attached to it, have done a lot of work on it, the engine is tired, lots of fuel dilution goin on, i think in its locksmith days, it sat idling a lot, there was an inverter in it when i got it, under the pass side valve cover was a mess of flaky black carbon build up....she still runs!

[MrJames]

My 1989, purchased new, cargo van was worth more than $1,000,000. Problem was that is what I alone thought. It was a northern vehicle with 130,000 miles that rusted out from under me. I kept sinking money in it to keep it alive. I had to say goodbye to it one year ago with much heartbreak.

One day, six months ago, I felt the need to be in another Astro. I found, near Tampa, a one owner 2002 FL only Astro that was in very good shape for less than $6,000 including tax and title at a dealership. I love the improvements and extras in the LT. I believe that I will spend less in the long run to keep me motoring in more style now for the next two or three decades.

If my experience is of any value then I recommend that you stop putting money in such an old van and use your time looking for another one. I know that you could purchase another problem but you could also get more for less.