How much pressure is in the transmission cooler hoses leading to the radiator

The ATF is not under high pressure when it is traveling to the transmission cooler. High pressure lines will not be held in place with a spring clamp and are usually threaded.

The pressure going to the transmission cooler is probably under 20 PSI.

i'm not sure about your car, but a lot of cars can have anywhere in the range of 50-150 psi going through those lines. standard trans hoses and properly fastened clamps will be okay.

But remember that doesn't apply as a blanket rule to all cars, and it's good that you thought to check.

As an example, on some old GM Powerglide transmissions the cooler line pressure is low in Neutral and Drive - but it spikes to around

150-200 PSI when you shift into Reverse, and can blow cooler hoses that aren't made to handle that much pressure.

Even at 150 PSI with 1/4" hose the hose fittings don't have to be too special, besides having a positive retaning bump or 'arrowhead' groove as a retainer, and the hose has to be clamped past the bump with wide worm-drive clamps to make sure it can't come off.

(No 'wire spring' clamps, not enough clamping force.)

But when you get much higher in pressure than that, or larger hoses that will see the effects sooner, you have to go to a mechanically clamped hose fitting system of some sort. Notably the ones using the Aeroquip design (or equivalent) if you want to field assemble the hose and fittings.

They have a threaded mandrel 'nut' that clamps the outer sheath of the hose into the fitting, so it can't pull out short of severe abuse

- things like a motor mount shearing and the hose tries to hold the engine in the car...

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So does anybody know what the pressure is for the 95 Camry?

Mark

Likewise, I'm not sure about the particular car being discussed, but when vibration against one of the clips holding it to the frame ate a pinhole in the metal line of an 80's vintage Ford F-150, and started spewing tranny-juice all over bottom of the driver's side exhaust manifold one evening far from home (I thought the freakin' engine had caught fire, the smoke was so heavy!) I found that 3-4 wraps of typical black electrical tape was an adequate "until the parts places open in the morning and I can get a new piece of line" repair. Ended up not having any option but to drive it for almost 4 days before being able to actually crawl under and fix it proper, and when I did, found that leakage after applying the tape was close enough to zero, and the tape showed no inclination to "blow out". So for that case, the answer is "comparatively low". Mileage is all but certain to vary from one setup to the next, though - I have no doubts that there are vehicles out there running high pressure to the cooler, and that such rides would have popped the tape almost instantly.

I've been using rubber fuel line and hose clamps for years so there can't be much pressure. Cooler kits often come with similar hoses and clamps.

Look above (a little closer) for the answer - I snipped it down to only the relevant bits for ease of reading comprehension. ;-)

Ray was a District Service Manager for Toyota for many years, and went through all the same training as the line technicians...

He can't give you an exact figure, obviously, but "under 20 PSI" for the models of transmissions offered in that vintage Camry is more than "close enough for Gummint Work".

Any purpose-made hose that they shipped with a trans cooler kit, the rubber compounds used can handle the fluid without deteriorating and should be fine, they are usually rated at 100 PSI or better in those small sizes. The hose ratings should be printed on the side of the hose, and on the package.

You do NOT want to use regular "fuel line" or "heater hose" - that is NOT meant for transmission fluid, and will go bad and leak/burst on you much faster than the right hose.

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Actually, "under 20 PSI" is just a guess on my part, I can check a factory service manual when I get home tonight. IIRC, the pressure going to the ATF cooler is much lower than internal line pressures, which is how I came up with 20 PSI.

I have never measured it directly, but I believe the cooler circuit runs about 10 to 30 psi. You should be OK if the clamp is past the tubing flare, but I can't help but wonder how you had any difficulty replacing the hoses. The factory hoses go back on quite easily, and new hose (of the correct ID) fits easily as well.

That said, the cooler circuit can move fluid at a high rate of volume. If the hose pops off it won't take long to drain the sump.

Toyota MDT in MO

How much pressure is in the transmission cooler hoses leading to the radiator? I can answer that very simply: more pressure than what's in the President's Mini-Me when he's "helping out" Laura. [laughter]

Like Sharx, the President is also a Nominal Hetero [chuckle]

You are correct about your pressure guestimate, the cooler circuit pressure is regulated (reduced) in the valve body. I suspect you will not find a spec on cooler pressure, but if you do let me know. The only spec I have ever seen in any model/year Toyota RM is for line pressure under various conditions.

Toyota MDT in MO

I don't recall ever seeing a spec on cooler pressure either, just line pressures.

Where have you been? We can use your help for those few posters who actually have problems!

I typically only reply to rec.auto.tech but sometimes a poster will query multiple groups so my reply and followups go to all groups involved.

The Toyota group has really turned me off for a while now with the OT junk and those few idiot regulars that try to ruin it for everyone. At rec.auto.tech the idiots are easier to shoe away, or so it seems :)

Good to hear from you, Ray.

Toyota MDT in MO

I could also do without all the OT stuff at alt.autos.toyota! I'll have to check out rec.auto.tech.

Thanks,

Simple enough to fix - but first, you'll have to get a real newsreader, as Google Groups doesn't offer any forms of filtering.

Then you warm up the Twit Filter in the offline news reader software, and plonk all the people who are normally way off in left field, and wouldn't know a clue if it walked up with a name tag on and introduced itself.

Set the filter with a 30-60-90 day timeout if you think they may develop a clue in time.

I have 18 entries in my filters for a.a.toyota at the moment (many for one person) and all of the political threads that have turned into inane shoutfests marked "Ignore", and I feel much better.

Doesn't take much to pull the Signal/Noise ratio out of the mud.

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Pardon me. My previous post should have appeared in an Off-Topic thread, not this one.

they were generic hoses for tranny coolers,,, they were snug and I just didn't get them inserted as far over the flare as I would have liked, but they are on far enough that the clamp is fully past the flare so I should be ok, just my usual bit of paranioa after a big job... wondering about what I may have done wrong...

thanks

Mark

thanks guys, I'm sure its fine, just a bit of after job paranoia on my part...

Mark