What type of pressures leave the transmission to the cooler? I see talks of 225-245PSI in the trans but can we agree it's impossible the line pressures travel to the cooler, right? I see the newest aluminum plate coolers rated at 150PSI burst pressure. These should blow apart if they see line pressures. Tell me if you think otherwise... or tell me what pressures reach a trans cooler.

I am thinking of going with a new bypass style cooler that bypasses the cooler or rows of it until the ATF is warm enough to need it. (I'll be using the vehicle for every purpose necessary, and I'm in the Northeast.) These coolers don't need inline bypass switches/diverters which are extra cost and may fail. If you have any experience with these coolers please comment here.

 

under the right circumstances (or wrong circumstances, however you want to look at it) yes, cooler line pressure most definitely can match line pressure.

 

The couple of thermostats I'm familiar with, when you look at how they are made will bypass under pressure,
its a relatively light spring that pushes the thermostat valve shut and open.
Finger compressible. wild guess I'd be surprised if they would hold 100 psi.
That being said the average cooler is as strong as the piece of aluminum tube in the radiator that the stock setup is using.

 

Wouldn't that cause stock radiators w/built-in coolers to blow up? And for aftermarket coolers--Have you seen ANY coolers with burst psi anywhere near high line pressure? (225+psi) Have you replaced any/many from pressure failure, not leaky fittings?

I think where you measure psi would make a difference too--the port is what size? I'm no engineer but have designed fuel systems for supercharged cars and a larger hose or tube diameter will have more volume but less pressure. Let's assume the cooler line tubing and/or hoses are 3/8". The psi should be lower if you tapped a 3/8" gauge takeoff or T or Y at a 3/8" hose or tubing at the cooler that was fed that size line from the trans all the way to it than a smaller fitting on the case? I'm not even talking fitting loss, just cross-sectional capacity/differences in psi... no? Yes.

 

How many of you have actually seen Converter-Charge and/ or Cooler-Pressure readings for...
Stock and Modified THM400 and 4L80E Transmissions?

 

I dont think the cooler pressures will match line pressure (Stock and in Neutral) at least.
I always disconnect the cooler line and run the truck to drain the pan of the tranny. The drain pressure is not even close to 50 psi or higher.

I never flare the cooler line once i install an aftermarket hayden. The 3/8 rubber hose goes preety freely on stock 3/8 pipe and i clamp it. If it had even 50 psi, it would explode and squirt ATF all over the cars behind me

06:33 here

 

All I was getting at is NO...we can not agree on this.
It's not impossible at all and it happens more frequently than anyone would think...especially on modified transmissions.

hose barbs with a flare and a hose clamp on the hayden, with properly sized hose and clamp tightened properly, can take well over 120psi

stock coolers in stock radiators are just a tube looped in the end tank of the rad...no it is not gonna blow.
The factory aux coolers are plate and fin coolers that are good quality. Typically the fittings are the same quick connect you'll find right at the trans. So those aren't going to pop either.

Without knowing any of the specifics of your setup, it's nearly impossible to give you any advice here...but if you're asking about possible and not possible...200psi in a cooler line is possible and I've seen it more times than I'd like to count. not in every trans in all circumstances. But that's not what you asked.

 

I replaced my filter today and decided to test this.
i confrm that when i asked my friend to help me and run the truck and put the tranny to R when i hold the hose from the cooler to empty the pan, the fluid shooot so strong, i was super surprised. My hose jumped off of the line and the fluid squirted literally everywhere. Never thought there is such pressures in the cooler lines.

So yeah. I didnt measure it but im 99.9% sure that LP = CP.

 

Thanks for your detailed reply!

I don't doubt anybody's personal experiences here... let me say that right off the bat. My automotive career is in the rear view mirror.

I just would like to know how transmissions that reach 245psi, or higher, don't blow coolers rated at 150psi burst pressures, unless they aren't reaching the same pressures, which is why I'd like to see a gauge installed at the cooler outlet. I'm assuming you are saying it's possible to combine those trans pressures with those much lower cooler ratings, yes?

Are burst PSI instantaneous happenings or #s that must be continuously reached or surpassed for damage to happen?

Does everybody with an optional or aftermarket cooler have a horseshoe up their *** or Lady Luck in the passenger seat? (Sorry, very old sayings, maybe before your time...)

Thanks.

 

It seems that many people who do not work on this stuff regularly... don't quite know what is going on.

Some Converter Charge pressure is necessary for the TC to operate as we want it to.
Too much pressure is not a good thing here.

Altering this is how were alter the TC behavior with a Dump-Valve.

Anytime we examine the fluid dynamic properties...
There is always going to be a trade off between Fluid Flow and Fluid Pressure.
Most often, One will affect the other in the opposite direction.

When we have enough pressure for the Circuit to operate properly...
We want to have enough flow, or increased flow, for an increase in Cooling Performance.
Pressure increasing higher, will most often reduce Flow and Cooling Performance.

 

I started watching this video but started wandering--is there a reason they have different rated fittings for line (300psi) and cooler (200psi)? See:

 

mater you still haven't told us your setup.

for a couple examples here:
a 4l60e with modified TCC Reg valve will allow converter pressure (and cooler pressure) equal line pressure. Now, usually line pressure when cruising during lockup isn't 150+ but with the right converter and with some pressure modification and/or tuning...150+ can often be seen
The same holds true for a 4l80e. 80e in stock form, converter pressure approaches line.
TH400 with fixed line pressure can be 120 just at idle in the cooler and that can go up with load/throttle
th350 that has been modified for "line to lube" using a kit like transgo or b&m etc will feed line pressure into the converter/cooler circuit. depending on orifice sizing this can mean the 2 systems match pressure

Now if we add to the mix any aftermarket shafts, stator tubes, bushing setups, etc and you can very quickly get a mis match of parts that results in cooler matching line pressure

Compound all of these with the fact that a converter is a pump of sorts. So, even if you only feed the converter with 80psi of oil, given the right circumstances, the converter will actually increase the pressure via the pumping action inside the converter and you'll see 120+ on a gauge at the cooler line.

There is ALOT going on with converter/cooler circuits that is often not very well understood

p.s. the reason burst pressure says 150 and they all live longer than that is factor of safety.
It's the same reason a bridge is rated for 20ton but won't collapse until 50 ton.

 

Maroon, thanks for all your contributions here, you and vortec are teaching at least 1 old dog new tricks!

I'm building a 2007 4l60e core for a 5300lb vehicle because a rusty cooler line blew on the interstate while I was, ironically, meeting at the Dept. of Motor Vehicles the wife of a guy that bought my ZR2 X-cab, which... wait for it... lost 3-4 when I went to pick up a pizza around Christmas 2019. I spent 8 months online looking for a replacement for the ZR2 and fell in love with a GMC that is somewhat rare, made only for about 18 months with reportedly about 10% equipped with the 5.3 aluminum block LM4 LS motor.

It's what you may call a Chevy Avalanche in GMC SUV clothing. It has a power rear roof that moves forward and a tailgate that folds down or swings out. It's loaded to the gills, right down to the GM Navigation System, XM Radio, power heated leather seats, Bose sound system, electric sunroof... electric pedals... about every option except Rain Sensing wipers. It has around 77K miles on it, 1 owner, and had it shipped from VT. I only put on like 281 miles. What also attracted me was how complete the Carfax was--there was so much replaced on it, and I didn't know if this made it a lemon, or a well maintained dealer-serviced vehicle.

It also has a "mid-gate", that's where the Avalanche comes in. The mid-gate is behind the 2nd row seats and has a power window completely isolating the cargo area from the cabin, if wanted, or it can be powered & folded down and act like a pickup and haul 4x8 sheets with the tailgate down... OR... with the roof powered forward, you can haul things that are tall, like ...armoires... refrigerators... or... trees! Wanna get a load of topsoil or manure? When you're done, you can just hose the back out--it has special, hidden floor drains in the cargo area. Even the Air Level Control suspension (G67) still works. It's a 2004 model; in 2005 they made the V8 with the cylinder deactivation so I avoided that combo, but I'd assume it's even more rare.

As for the replacement trans, I had already bought some TransGo & Sonnax parts and I haven't rebuilt a trans since the '90's and I thought was done with automotive mods but when prices for a 4l60e for the ZR2 where coming in around $2000+, I:

a) didn't know if a trans shop would give me what I want, and

b) didn't know if a trans shop would give me what they say...

So I decided to tackle the rebuild myself, which is no small task because I'm handicapped and can't really walk, and have no running/driving 2nd vehicle, not to mention I got rid of my tools around the turn of the century. ALL the trans tools I'm buying as needed when I can afford. I originally intended this to be a basement build but figured I wouldn't be able to get it back out after assembly; I saw pics of somebody rebuilding their trans on a white living room carpet and figured if they could do it, I could too--and I have no woman bitching at me about it... besides my carpet's brown, not white. This did start as a yard build on a WEN $100 cart though.

The fly in the ointment was this core has a "ISS-ready" pump which took a while to figure, with the stator plug, no ISS reluctor, but I already ordered lots of Sonnax parts for early design 4l60e's, so it was a whole fiasco getting the right pump to match the Sonnax shaft/Smart Tech drum. I'm using a billet 10-vane from Jake's. I sent back the 2.84 set upon vortec's recommendations and I used that Trump money & got Chris's output shaft. Oh I didn't mention, it's switchable between 2WD, A4WD, and 4HI/LO, it just doesn't have the ZR2's ground clearance.

We have a local 1/8th mile track, and a 1/4 track is within 2 hrs away. I'm 10 minutes from Canada too. This job dwindled my bank account and I didn't even start thinking about motor mods, turbos, a Vortech, etc. I may even consider the Cadillac huffer--supposedly there are adapters to use on LS motors. Since I can't do the trans R&R myself, and don't have anybody to do the job yet, the motor must wait and the trans job really needs to be done ONCE... so I must overbuild it, as a 4l80 in that body with 4WD/AWD is much more difficult than a C/K or even F...

To get it up & running, I'm buying an 1800-2200rpm Trailblazer converter. This vehicle came standard with 3.73's but somebody (customer or dealership) ordered it with 3.42's. It has G80. I'll look for a Trailblazer SS for F&R diffs as they come with 4.10's I think. I'm thinking of using the cooler at the top of this thread too, unless anybody had problems with it. My other hurdle is another "already bought it", pinless accumulator pistons. I plugged 4th but must figure how to use 1-2, since the stock one is a dense plastic piston. The Forward had no problems. I'm using nine GPZ frictions and eight .077" Kolene steels scuffed with a green pad.

Any other questions just ask me. Thanks for listening.

 

Back to that Youtube video with the Nova racecar, he was saying you might get 45-100 at the cooler and 200+ psi at the trans? Did I hear that right? Is a Glide much more different with pressures? Here's about where he said it, I tried to cue it up closely:

 

Merry Christmas everyone!

 

Yes, you too vortec! Merry Christmas EVERYBODY!!!