I generally use Aeroquip "socketless" hose (it's rated to 300psi.),along with tube nuts/sleeves. They require a 37° flaring tool though. I've used the compression style before on both oil,and trans lines without any issues at all...

 

I've seen your hose/cooler setups and they look good. However, I'm committed to using Red/Blue ends along with SS hose since that's what I used on the Oil Cooler lines and I want it to match. I'm keeping most of the factory parts/hookups and just improving them. I really like the look and security of braided, but it sure gets expensive when you start adding up all the hose and fittings. But its nice to not worry about it leaking and it looks great.

Looking at a few fitting options to mate the SS hose to the hard lines. I'm pretty familiar with the Tube nut/sleeve and whats required there and also the Compression fittings (CF). The CF would be the easiest option since I dont have a 37* flaring tool for 3/8" line and the one I was going to borrow only went as small as 1/2" line...just my luck.

Still want to see if I can get an idea of PSI on these hoses. I'm pretty sure its no where near the internal line pressure of the tranny, but just want to see if someone knows what the PSI is at the external cooler connections. It does look like it fluctuates with the throttle as I see the hoses move when I give it some gas. But it cant be too hight since the one hose connection is just a hose barb with a worm clamp on it. I've also had this setup for quite a while and never had leaks.

I'm also looking at the total cost to run the entire length braided compared to keeping the Hard Line and using fittings. BustaBill has a nice writeup here with part numbers, just going to require more SS hose but no HL adapters.

http://www.impalassforum.com/vBulletin/showthread.php?t=231055&highlight=trans+cooler+lines


Pretty sure the Hard Line adapters (compression fittings) from Earls or Russell will work fine for this application. I would just feel better if I could get an idea of what the PSI is on these lines. So anyone know what the PSI is on the cooler lines?

Thanks

 

from ClassicCars.com:
"..a transmission cooler line holds about 20 to 50 PSI of pressure at idle, but this can increase to over 100 psi during operation."
That at least gives you a ballpark figure.

 

from ClassicCars.com:
"..a transmission cooler line holds about 20 to 50 PSI of pressure at idle, but this can increase to over 100 psi during operation."
That at least gives you a ballpark figure.

Thank You both - I was doing some Googleing last night and did find numerous posts on other sites pretty much all saying that these lines are more about Volume than they are Pressure. But still nothing really definte but the general concensus was its low PSI. The PSI ranges were similar to what you mentined in that 20-50 range but no where near what the Internal trans pressures are which are much higher.

At this point, I've pretty much talked myself out of using a 50 PSI compression fitting. It may be fine, but I dont want to risk it blowing off and possibly worse. If I'm gonna do this, may as well do it right. Depending on fittings needed and cost of either package, I will either replace the entire Hard Line and run full braided from the Trans to the Coolers or just get a Flaring tool and use the Tube Nut/Sleeve approach. Once everything is purchased and installed, I add some info to the Braided Cooler Hose thread.

If you're no longer using the cooler built into the radiator,then consider running the lines on top of the passenger side frame rail. I found the original line routing to be in the way of practically anything,and everything I ever tried to work on in that area.

I'm pretty much running a stock setp on the car. So my Trans cooler is both the in-Rad cooler and External Cooler (which I did add since the old L99 never had it) in series with each other. I dont quite have as much custom work done and prefer to keep a lot of the factory items and their Factory fit/location.

On bypassing the in-tank trans cooler, I dont have a link but there was a good discussion on this and why you really "shouldn't" remove it. I know on your car you mentioned that your trans temps are very low, but not everyone bypassing the in-tank cooler would take the additional steps you have to assure temps are down. Still something to consider if someone has concerns with the trans cooler in the radiator.

 

Trans line woes...

If you're no longer using the cooler built into the radiator,then consider running the lines on top of the passenger side frame rail. I found the original line routing to be in the way of practically anything,and everything I ever tried to work on in that area.

The lines run up alongside the line to the steering box from the P/S pump. It's so much easier getting to stuff now.

Here's what the lines look like as they they travel up the frame rail to the cooler,etc,etc...

 

To me the major drawback to the in-radiator cooler is risk...If it would ever begin to leak (even slightly) the trans fluid would quickly become contaminated with coolant. Due to the cooling system remaining under pressure when the car's motor is turned off,and the pressure inside the trans lines goes to zero. Does this happen a lot? No,but it has happened usually resulting in a totally destroyed transmission as all the friction material is broken down by exposure to coolant. Instead,I'll run P/S fluid through it. Though it's mostly just sat there unused up until now...

 

The pressure in the radiator trany cooler lines is very small. the reason is the line just dumps the cooled fluid into the tranny sump / pan . since the only restriction would be the tubing resistance to the , flow the pressure is quite small. placing a T fitting on the line would confirm this with a gauge to see what pressures are created. when the fluid is very cold the pressure would be higher than hot .

 

If you can, avoid Russell and Earl's [R/E] braided hose fittings.

Aeroquip are by far superior to those above.

Compare the thread 'lengths' of the inner fitting. On R/E fittings, as you tighten them, they run out of thread before fully tightened. Aeroquip are fully threaded, and the collar doesn't run out of thread when butted up against the inner fitting.

The above stated, R/E fittings work okay with 1/4" dia. hose, but anything larger I'd go Aeroquip.

 

Confirmed and Shocked

Even though I was commited to either the Flare and Tube Nut/Sleeve approach OR braided the entire length. I was still curious what the true PSI is out to the Coolers. So I picked up some fittings and a gauge from our shop to splice into the Line that goes to the bottom Rad fitting. I believe this is the input to the coolers where the pressure would be the highest.

Made up this part.....

As Gomer Pyle would say...."Surprise, Surprise", I was shocked to see how high the pressure actually is. If you look closely at the pic you will see its between 110 and 120 PSI at idle and remains pretty constant as you rev the throttle.

So the moral to the story, DONT Trust Compression fittings that are rated at 50 PSI. The Brass Compression Fittings on there now are ones that I picked up at Home Depot's plumbing section years ago.

Never a problem with them but they may be rated higher, I dunno? In any case, I will be looking at the cost of a flare tool and all of the fittings to keep the metal lines vs. just replacing the entire cooler lines with braided and fittings. Will report back with what I come up with in the Oil Cooler thread.

 

Hmm... Ahh....

Nice 'observation' as I've been curious for years about this pressure too.

Could you go one step further?

Plumb that gauge into the return line; with all things at same temp and flow - to see what the pressure drop is across the cooler... pressure in vice pressure out.

Tip o'da hat if you can; otherwise thanks for the above! You've educated many readers - myself included.

doug wood/stock ga

 

Nice 'observation' as I've been curious for years about this pressure too.

Could you go one step further?

Plumb that gauge into the return line; with all things at same temp and flow - to see what the pressure drop is across the cooler... pressure in vice pressure out.

Tip o'da hat if you can; otherwise thanks for the above! You've educated many readers - myself included.

doug wood/stock ga

You were 1 step ahead of me...did that today. Didn't have a coupler or any extra hose to splice in at the time. Cant do braided yet so I just picked up 2' of Power Steering Hose til I do.

At startup and after a good warmup, pressure held pretty steady at 52 PSI on the other side of the coolers going back to the trans. I have both the In Rad and 9C1 external coolers in series.

So thats about a 50% pressure drop on the other side. Was surprised to see that much of a pressure drop.

If you're using black rubber hose, make sure to use transmission cooler rated hose.
I just picked up some gates hose just the other day. Comes in 3 foot packs.

Looked last night at pressure rating. It's rated to 400 psi. Makes sense seeing idle has 100 psi. Good job on actually measuring!

Good point on the TYPE of hose to choose. I once used left over Blue Coolant hose from the GoodYear Hi-Miler kit and it quickly Ballooned up and got very spongy. Just found out the current Fuel Pressure hose I had on there was only rated at 50 PSI (probably not enough pressure rating) but held up and wasn't too soft or anything when I removed it.

Went to Advance and told the Girl that happened to be next to help, I needed just 2 feet of "Transmission Cooler Hose" and she looked it up on the computer. Went to the section where the "Cut to Foot" stuff is and it took her 10 minutes to find the correct hose....or so "we" thought. It seemed to me it was soft of a hose but I trusted she got the right stuff until I got home and googled the SAE number on the hose. You guessed it, back to Advance to get the correct hose.

When I got back there and waited for one of the guys that looked like he knew his stuff. I told him about the hose I just got which was only about $4 and needed to get something with a high pressure rating for hot trans fluid. I asked him if I could walk back trhere and we found a 3/8" Power Steering hose (SAE J2076) that is high pressure and heat rated. I had my phone with me this time and looked up the part number. He felt bad for the extra trip (plus she didn't even charge the correct price for what she sold me.....ditz!) and let me just have the more expensive hose.

 

If you're using black rubber hose, make sure to use transmission cooler rated hose.
I just picked up some gates hose just the other day. Comes in 3 foot packs.

Looked last night at pressure rating. It's rated to 400 psi. Makes sense seeing idle has 100 psi. Good job on actually measuring!

 

The main reason one doesn't use ATF in power steering systems is it's incompatibility with the hoses. I generally use Aeroquip "socketless" hose as it is synthetic,and is safe to use with most fluids (except brake-fluid,and gasoline) stainless braid is similar,with teflon braided stainless the most bullet proof by far.

 

Just looked again. The gates tranny line is J1019 for future reference.

 

Yeah, that was 1 of the "J" numbers i found earlier for Trans Cooler use.

Had another J# for tranny hose I wrote on the receipt when I had to go back but threw it away. We couldn't find either number so I just settled on the PS hose which should hold up til I comvert over to braided.

 

Thank You 4DRSS

Two thumbs and a tip o'da hat for that effort and info.

You've answered a question I have wondered about for years; just never really had the opportunity to 'lets check this out'.

Your stock on this forum just rose a couple points! Well done!

Thanks again,

doug wood/stock ga

[btw - the pressure drop was greater than I thought].

 

I think something is either fundamentally wrong with your gauge or wrong with your transmission. In park at idle, stock line pressure at the tap on the driver's side of the trans should be 65-70psi. Even when cold, my 4L60Es never ran the main line pressure as high as what your gauge is showing. The cooler feed line should at least be lower than main line pressure.

Who built your 4L60E, when, how many miles on it, what brand/type fluid is in it, what mods are in it? How is the garage shift? In P, N, D, or OD at idle while warmed up and stopped, are the pressures all the same?

 

I agree with your comments on the pressures he got. I also feel something is wrong on the 120 psi. this is the normal pressure you would get in idle at the tranny pressure test port . I have never measured the return line pressures with a T port gauge installed but many times I have removed these lines at the cooler to do the tranny fluid exchange method. never was there any indication of high pressures. fluid would just flow very slowly out the hose into my marked container .

any lines or the cooler restricted would cause these higher pressures.

 

A garage shift means the car is stopped with your foot firmly on the brake, no throttle applied, and you shift from P or N into any gear. Is it smooth like stock or does the car try to leap or jerk when it goes into any gear?

I don't have the ability to do any testing at the moment, but those readings you show indicate to me that something else is wrong. I would not post up about this if I didn't feel strongly about it. I agree with j_cat; GM puts a measly spring clamp on the stock trans cooler lines even on 9C1s, and I've NEVER had it blow off even after multiple fluid flushes. There's no way they'd do that with pressures as high as you are showing.

Do you have the ability to datalog or at least monitor the force motor current or commanded line pressure and see if the tune is bumping base line pressure? You should be seeing 1.0 to 1.1 amp at idle with no throttle in P, N or OD/D. It's also possible that somebody cranked the set screw in the force motor inside the trans to get the pressures up that high.

Do you have a stock torque converter? Looser aftermarket torque converters can mask harsh garage and part-throttle shifts.

If you have the ability to put a stock tune back in it, that would eliminate the tune as a variable. That's pretty easy to try - save the tune you've got, upload a stock tune, check pressures and drivability around the block, then put your aftermarket tune back in.

 

A garage shift means the car is stopped with your foot firmly on the brake, no throttle applied, and you shift from P or N into any gear. Is it smooth like stock or does the car try to leap or jerk when it goes into any gear?

she seems to shift fine into gear without any major jerking. While driving shifts are very smooth with no lag when easy on the throttle. With "spirited driving" the shifts are very firm and she sometimes will chirp 2nd gear and has a consistent shift through all the gears with all types of driving.

I don't have the ability to do any testing at the moment, but those readings you show indicate to me that something else is wrong. I would not post up about this if I didn't feel strongly about it. I agree with j_cat; GM puts a measly spring clamp on the stock trans cooler lines even on 9C1s, and I've NEVER had it blow off even after multiple fluid flushes. There's no way they'd do that with pressures as high as you are showing.

the hose clamp was one reason I assumed pressures were low, along with what I found on the web. However, if you are familiar with the GM lines you will see that the high pressure side does not use clamps, it's a crimp fitting there. The return side which comes out of the 2nd cooler and lower pressure does use the clamp there with a bulb fitting on the metal line.

Do you have the ability to datalog or at least monitor the force motor current or commanded line pressure and see if the tune is bumping base line pressure? You should be seeing 1.0 to 1.1 amp at idle with no throttle in P, N or OD/D. It's also possible that somebody cranked the set screw in the force motor inside the trans to get the pressures up that high.

no I don't have the ability/tools/knowledge to do that.

Do you have a stock torque converter? Looser aftermarket torque converters can mask harsh garage and part-throttle shifts.

no, it appears to be the stock convertor.

If you have the ability to put a stock tune back in it, that would eliminate the tune as a variable. That's pretty easy to try - save the tune you've got, upload a stock tune, check pressures and drivability around the block, then put your aftermarket tune back in.

The car runs great and shifts fine and I have no desire to swap out the ECM to find out or familiar with uploading a tune. This was a test that I did just to gauge what the pressures may be here.

I can't explain why you think the numbers may be too high. I have not seen any other evidence to prove that these numbers are incorrect or a problem since its been untouched for a few years with this drivetrain and drives, shifts, runs great. To me, it is obvious that there is a significant pressure drop across the coolers regardless if the gauge is faulty (too high) or not. That alone (just a thought) would indicate to me that the incoming pressure needs to stay fairly high to compensate for that. The only thing I can offer to do is to re-test with 2 seperato gauges when the time comes to replace the lines. I will commit to do this when I can cut the rubber lines again, but that may not be for a while. I plan on flushing the Trans the next time the lines are disconnected.

 

I commend you for carefully thinking through all of this - most folks don't go this far. It sounds like your car is operating normally despite cooler line pressures that don't seem right. Like I said, a standard 4L60E running in a near factory configuration should have around 65-70psi in the trans at idle, and there's no way a pump putting out that pressure would end up with the converter output 40psi higher - it would feed right back through the pump!

My main concern here is that folks see your photos above and assume that their cooler lines are all operating at these pressures. I wish I had the ability to run some testing of my own but I don't at the moment.

 

with the in line pressure gauge showing 120 psi . I would guess that the return line to the tranny sump has a restriction. this would create a high pressure. With the line removed at the cooler output port and doing the fluid exchange procedure ,if the pressure was 120 PSI ,that fluid would be uncontrollable... 120 psi out of a 3/8 line would shoot pretty far..

 

I would strongly recommend spending the $45 or so to buy a 0-300psi transmission pressure gauge off of Ebay. That has been invaluable to understanding how a 4L60E works and responds.

 

UPDATE - New Readings

Before flushing the fluid and converting to Braided I wanted to confirm the numbers I originally posted. It does appear the initial numbers were incorrect based on what I'm seeing now. However, my shop guy did have a Fluke Tester for checking the Gauge I had and it tested fine, so not sure what happened before.

So, I went ahead and borrowed 2 more gauges and used the same Tee setup as before. In all new tests the car was cold and just run for a few minutes. On the Input side to the coolers, I was getting 40 PSI at idle and would max out at 110-ish PSI (still too high to trust Compressioin fittings - IMHO) when revving the engine. Here are some pics....

At idle....

Revving engine....

On the output side, I saw similar pressure drop across the coolers. At idle it was only 20 PSI but would increase to approx. 60 PSI when I revved the engine.

At idle.....

Here's a video......

http://s1256.photobucket.com/user/4...a/MVI_1095_zpsdxwdvjo2.mp4.html?sort=3&o=0&_suid=141972816891202055235108818818

 

You're worrying too much, people have been using compression fittings to repair steel trans lines for years without any issues. In fact my trans guy had to use one on my car when he did the trans as the line would not come out of the fitting on the trans so he cut the line near the trans and when he reinstalled it he just used a compression fitting and it's been like that for just over a year now and no leaks or issues.

 

For me it was more just curiosity as I was converting to AN fittings anyway and already committed to using Tube Nuts/sleeves and flaring the metal lines. The most difficult part of this is investing the money for a good 37* flaring tool (about $100) or finding one to borrow. I lucked out and found the Parker Tool tool to borrow....excellentt tool for this application.

As was mentioned in the first post of this thread, I've had Brass Compression Fittings on there for many years without an issue, check the pics. However, household plumbing can see pressures upwards of 100 PSI or greater, so maybe Brass is higher pressure rating than aluminum fittings.

The aluminum compression fittings offered by Earls are only rated to 55 PSI. I'm sure they could most likely see greater than that and not fail. No one knew the exact pressures so I just decided to post up some numbers for others since I was cutting the lines and had easy access to all the parts to test.

At least we all have some numbers to go by now based on my current application. Others may see similar numbers and I would be curious to see if there are any differences. There is no reason to test further as I have all I needed for my conversion and was just sharing what I found.

 

Guess I'm not seeing their advantage since installing a tube nut/sleeve is not that difficult. I have used compression fittings on oil-cooler lines,but mostly due not having good access to them.