Transmission Temp Gauge Mounting PITA

[sdstriper]

I have my gauge mounted in the hot out line under the trans. where the line straightens out and goes towards the passenger side to the heat exchanger. I used a Tee union with compression fittings on each side for the hard line, these have been leakers and I have had it with them. PITA...



I am interested in what others have done with their gauge mounting. Where, with what etc.

 

["Mad Max"]

ideally, pull the transmission pan and have a weldable steel bung welded in place. Doesn't take long at all - maybe a little messy, but if all the labor is ready to go it's a pretty quick job. There are also compression bungs that screw in place verses welding.

Originally I spliced into the hot out line, and while it didn't leak it was a bit tricky to do. My readers rigs has pics of that. Here's a pic of the transmission pan on my rig now - it's a MHT pan - has the port tapped and ready to go - pretty sweet and super simple.



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- M2

 

[PToombs]

Ross, check this out; DieselManor - Autometer Products

I thought of using this, then decided to go for the pan. Genos sells a thing that clamps to the line and holds the sensor. Heard a couple guys on here say it works.

 

[KOG]

I used a trick tht I picked up from a post here. Got a brass Tee big enough to drill to fit the OD of the hot line. Sawed it in half so that it could be clamped to the line using a gear clamp on each side. Tapped the ID of the branch to fit the sending unit, using a reducer. works like a charm, no cutting of fluid line, thus no possibility of leak.

 

[sdstriper]

I used a trick tht I picked up from a post here. Got a brass Tee big enough to drill to fit the OD of the hot line. Sawed it in half so that it could be clamped to the line using a gear clamp on each side. Tapped the ID of the branch to fit the sending unit, using a reducer. works like a charm, no cutting of fluid line, thus no possibility of leak.

Do you have any pics? I'm cheap and that sounds like my style! I would have to replace the out cooler line at this point.



PToombs, That's basically what I have now using hardware store parts. Much cheaper than that thing. Those compression fittings may be better quality from the looks of it, even so I have assembled carefully,taken out and bench fit them, reassembled and still drips/leaks.



"Mad Max", I want the actual hot out temps. especially since this is the 727 and I tow. There is a lot of fluid in your pan, 1 gallon more than stock. That fluid being cooled will have a different temp. reading for sure. Do you have any comparison of hot out line readings to in the pan now that you have it in there? Wouldn't really compare to my application though, you have the benefit of OD...

 

[KOG]

I can get pics by Saturday or so. I'm about 200 miles from the truck at the moment.

 

["Mad Max"]

Do you have any comparison of hot out line readings to in the pan now that you have it in there? Wouldn't really compare to my application though, you have the benefit of OD...

It seems to be very close to the same temps as I had before when I was tapped into the output line. Once the transmission is heat soaked the fluid inside the case/pan should be nearly the same as the output line, and so far this rig appears to have the same temps as my last one - transmission seems to run about 10* cooler than the engine.



As I understand while the extra fluid does help in longevity it doesn't necessarily make the transmission run cooler. The difference is the fluid lasts longer because there's more to use and it doesn't break down as fast. I also tow big, but once it's hot, it's hot.



- M2

 

[Greenleaf]

I installed one in the pan via a weld-in pipe fitting. I installed another one in the line where the transmission OEM sensor is located. I used a street T on that application. I was told that is no good becasue the fluid flows past the street T and said sensor will not pick-up the true temp. Therefore, I do not know how a clamp on sensor like Geno's Garage sells could possibly work. Or any clamp on sensor for that metter.



Maybe somebody was just feeding me a line... ... ... I never see the gauge move off 140°F, untill I do a quick/short burn-out then it jumps up to 160° pretty quick. It must function.



I was also told that in the pan sensor location is no good either cuz the fluid is not **INSIDE** the transmission and it's already been cooled... ... ... . I cannot win. :{



There are ice burgs in the Gulf of Mexico too.....

 

[sdstriper]

I'll try the "Bite-Seal" compression tube adapters, hopefully a better piece of hardware will do the trick. The leakers were Watts brand brass compression fittings from Lowes, I don't recommend them for the application.



I am sticking with the sensor in the hot out line. Towing into high winds with heavy loads at 75+ mph the 727 with OEM converter would heat up the engine coolant to the point where I had to slow down or pull over to let it cool off last summer. Recent converter upgrade will improve it a bit but I want to know how hot that oil coming right out of the converter is and the pressure line is the best place to get the reading. I have a couple of the sensors, I think I'll put one in the pan eventually too, toggle switch them.

 

[ScottLewis]

I wrote the TDR article and post about using a brass Tee that I adapted to hold the sensor against the cooling line. I now have a few thousand more miles on it and it continues to perform great. The advantage of having the sender on the output line is that you can back off when the temp starts to climb, before the case and pan get heated up. The metal line quickly transfers heat to the sender without being submerged in the oil. There is no chance of leaks or contamination of fluid because of opening the line. I'll try to add a picture.

 

[cerberusiam]

It seems to be very close to the same temps as I had before when I was tapped into the output line. Once the transmission is heat soaked the fluid inside the case/pan should be nearly the same as the output line, and so far this rig appears to have the same temps as my last one - transmission seems to run about 10* cooler than the engine.



As I understand while the extra fluid does help in longevity it doesn't necessarily make the transmission run cooler. The difference is the fluid lasts longer because there's more to use and it doesn't break down as fast. I also tow big, but once it's hot, it's hot.



- M2

Hmmmm... that doesn't sound quite right. I, and others, have seen upwards of 100 degrees difference between pan and output line when under a hard pull. Eventually the pan will climb within 20-30 degrees of the output line but thats the difference between cooking the fluid and being in a relative safe temp zone.



Unfortunately once you cook the fluid past a certain point for a cetain time span it doesn't seem to make much difference if its 5 qts or 5 gallons, the addtives boil out and are gone. More fluid is definitely going to help with overall temp but if you are consistently hitting 280 on the output line you are just going to change more fluid sooner.

 

[y-knot]

You guys kill me on this site, If you would go to any reputable transmission shop or performance shop and they install something as stupid as that, you would have a fit. Good graces, if you don't or can not do the project right then leave it alone or take it to someone who can. The automatic is already suspect in these trucks at stock HP levels, and this jury rigging is only going to make it worse.

 

[sdstriper]

y-knot, You think buying a pan is the solution then huh? Your dead wrong buddy. I suggest you go straight to DTT's forum and read up what Bill Kondolay has to say about the sensor in the pan. My complaint has nothing to do with a half assed installation that is for damn sure. In fact I took extra special care to install the hardware I have now, I used a high pressure tee union and the only NPT pipe to tube compression fittings I could find at the time with the exception of the compression fittings not being that high of quality and certainly not meant for the vibrations etc of use on a vehicle. (Not SAE rated) I did not want to run a fitting right off the case of the trans. There is linkage clearance etc, not to mention the chance of a cracked case.



I don't appreciate your reply. Your poor advice of buying a pan isn't even a good idea and in fact is a bad idea and waste of money. The pan that is on the truck would suffice if you wanted to measure the temperatures of cooled fluid. $8-16 bucks will buy you a drain plug with a sensor provision.



I have a deep aluminum pan on the truck, holds a gallon more than stock, a better investment would have been another transmission cooler. I may add an additional sensor in there as I said, and I'll be sure to point out to you how much more accurate the pressure out line reading is when I get it done.

 

[DBF]

I have my gauge mounted in the hot out line under the trans. where the line straightens out and goes towards the passenger side to the heat exchanger. I used a Tee union with compression fittings on each side for the hard line, these have been leakers and I have had it with them. PITA...



I am interested in what others have done with their gauge mounting. Where, with what etc.

I just stuck one temp sensor into the hole where the 92 has a temp switch, a few inches outside the trans on the output line (I don't know if your 89 has one or not). No sweat, no problem whatever. The switch is tied up out of the way.



I installed another sensor, feeding a second gage, in the pan. Easy enough to drill a hole & tap it for the sensor.



Now I can watch both temps. There's a reason for that. If the temp in the pan rises, the temp out of the trans has to rise. You can track it as the fluid warms up.



I must point out that I have no heat exchanger on the passenger side of the engine - it leaked & I removed it. So my coolant and trans fluid loops are completely independent of each other.



As I'm towing my fiver, I watch both trans fluid temps. Little excursions in the output don't raise/lower the pan temp much. But a long uphill will, if the coolers can't adequately cool the fluid. Then the pan temp gets hotter and so on.



If the pan temps start up from the normal 160/170 I usually see on an 80-90* day down here (FL), I start getting off the narrow pedal. If output temp is higher than I like, I start getting off the narrow pedal.



Getting back to the normal configuration, with heat exchanger, some folks say you don't need the sensor in the pan - just the one on the output, since the pan ought to be stable. I think you should still have one in the pan. Why?



The coolant temps are connected with the fluid temps. If you're running a long uphill pull with an inefficient radiator or lazy fan clutch, the engine temp goes up and may actually cause the trans fluid temp to go up faster than the cooler can handle. But you'll know what temp the fluid in the pan is at, and if it's higher than you like, you can take action before the output temp goes through the roof.



I hope I haven't given you more information than you want. My bottom line is that gages are cheap and transmissions are expensive.



Regards, DBF

 

[KOG]

My sensor is on the output line exactly like danavilla's. Works like a charm. I did use a small amount of JB Weld when mounting to ensure a good thermal connection to the one. I've not seen over 140 in normal highway use with light (4K) towing, but it'll heat up very rapidly if manuvering trailer at crawling speed or shaking dirt from the dump with full throttle from stop. That indicates to me that the sensor is working correctly and accurately.

 

[sdstriper]

Here is another difference in the early 1st Gen's then. The cooler out line doesn't have the temp sensor port in it, and it doesn't have that short section of hyd. hose at the heat exchanger either. And that non-sensor port cooler out line is more expensive to replace too. I would go with the newer 94'-up steel tubing with sensor port and short section of hyd. hose if I replace it, on Rockauto.com it is cheaper, don't know about other places.



Thanks DBF, again! I like the way you think, and that is helpful positive information.



The title of the thread was a sort of rant obviously, cheerful rant though. I just completed R&R of the transmission etc. I don't want leaks again! I am trying to become a "former member of the external lubrication club"...



IMO the downflow radiators are inadequate, PO had just replaced this one so it's a no brainer, I'm not replacing it until it's shot or I trip on one for cheap in great shape. And towing with the three speed transmission at interstate traffic speeds will heat up the engine coolant and the transmission fluid both. IMO because of the radiator and the lack of OD, operating at higher than optimal rpm's etc. It is a fact. I like what DBF says about the cost of sensors and transmissions and I agree that it's cheaper to monitor than replace.

 

[DBF]

Yup, I was afraid of that. Too bad.

I'm in the process of learning how to bend 1/2" tubing. Doesn't seem too hard to do. With some luck and a few goofs, I'll straighten out that rat's nest I have around the trans output you could see in my old pictures.

On another note, I've always loved the three-letter airline designation for the Sioux Falls airport.....

Regards, DBF

 

[cerberusiam]

The coolant temps are connected with the fluid temps. If you're running a long uphill pull with an inefficient radiator or lazy fan clutch, the engine temp goes up and may actually cause the trans fluid temp to go up faster than the cooler can handle. But you'll know what temp the fluid in the pan is at, and if it's higher than you like, you can take action before the output temp goes through the roof.

If that scenario ever happens its a pretty good indication there is a transmission problem or blockage somewhere that is causing it. Trans fluid temps are almost never going to be much higher and for the most are lower than coolant temps if the stock fluid-to-fluid cooler is in place and functioning correctly. The extra cooler in front is not worth a lot if you push it but in most cases it is enough to keep the temps 20-30 degrees under coolant temps on the return side.



If your coolant temps ever start pushing the trans fluid temps over 220 degrees there is a MAJOR problem somewhere. These trucks just don't normally run that kind of heat in the coolant and the stock fuid-to-fluid cooler is pretty efficient at its job. Where problems start is when the stock systems are replaced with an aftermarket setup that is not sized correctly. Generally too large of lines are used and flow is too fast to provide adequate time in the air-to-fluid cooler to extract the heat.

 

["Mad Max"]

Worst I ever saw in my last truck was when I was pulling 18,000 lbs gross up a grade for almost an hour. maintaining 60 mph in od the engine got to an all-time high of 225*, transmission got to it's all-time high of 235*. Maintained that for a while, never went higher. Pyro was at 1200* steady. Aux bed cooler was howling the whole time. Once I got to the top it all came back down to under 200*. Granted the engine/transmission had 245,000 miles on them and the engine was making 253 hp, but I thought that was pretty good considering. That was the 'worst'/'hottest' it ever got, and was my self-inflicted 'test' for the trucks systems. That was when I was wishing I had both a NV4500 and a water/meth kit with a 5-gallon reservior :-laf . transmission temp sender was mounted in-line with the output line, not the pan. Wish I had a sensor in the pan too - that would have been a great comparison test!

- M2

 

[BGolden]

o.k., I am going to take a swing.

Far from an expert myself, My Isspro gauge came with weld-on nut to accommodate thier sending unit in pan. Our local trans hot-shot put mine there, at the same time he changed fluid and installed a "R. V. shift kit". Fluid change was do, and I was also installing performance parts, and wanted transmission to be able to handle more power, and shift kit was his reccommendation.

As far as Bill Kondolay's remarks, 1 quart per 20 seconds (or whatever the flow rate was)coming out of cooler, so outline from cooler is the only reliable place to measure temp. Wouldn't same rate be moving throughout trans-to accomodate that which is flowing in from cooler? I do agree that the(photo) inline "T" hose clamped on looks somewhat unfinished or out of place. No offense to anyone here, just hoping Isspro and my local trans. guy knew what they were doing on my install.