Auxillary autobox oil cooler.

[Bat21]

Following on from this thread, I have acquired a very nice slim 7 row oil cooler... I'll tell you more about it later

Will there be any issues mounting this cooler higher up than the one that is already in the rad?

My plan is to mount it on the ARB winch bumper (it will be protected), will there be any issues due to the fact it is about 10" higher than the standard cooler that 'feeds' it?

Also, I plan on using 10mm micro bore copper tube for the plumbing, this will have a couple of 90 degree elbows soldered along the route. Am I right in thinking the ATF doesn't get hot enough to melt the solder? Apologies if this is a dumb question

 

[adrianr]

Re: Axillary autobox oil cooler.

HI Paul

Am no expert on this but from reading various threads I recall (and I might be inaccurate) "hot oil" appears to be around 120 degrees or so.

 

[Crispin]

Re: Axillary autobox oil cooler.

Solder melts, depending on the type, anywhere from 90-450. Even if the hot oil does not melt it but softens it slightly, the pressure could blow the joint apart. I would opt for compression fittings on the pipes.

Not sure if the coppy would be a problem in ann way?

 

[Clive]

Re: Axillary autobox oil cooler.

Instead of soldering bends on why not buy a hand bender for 6/8/10mm pipe and put bends in.

 

[Gav Peter]

Re: Axillary autobox oil cooler.

This sort of thing?

http://www.screwfix.com/prods/17898/Hand-Tools/Plumbing-Tools/Pipe-Bending/Mini-Tube-Bender

 

[Paul]

Re: Axillary autobox oil cooler.

Proper hydraulic pipes are not too dear to have made up. Considering the pressure are not that high there are also some good kits you can buy and trim the pipe, get them in nice colours too

 

[Andy]

Re: Axillary autobox oil cooler.

Copper 'work hardens' & may become brittle (joints cracking) after a long time vibrating etc , not sure how long this would take though.

There shouldnt be any problem with solder melting.

i'd go for flexi hydraulic pipes, not sure where the kits are from.............Paul???

 

[Jon Wildsmith]

Re: Axillary autobox oil cooler.

The Kenlowe coolers come with normal flixible hose (looks like normal double wall fuel type pipe) and barbed pipe fittings that you jubilee clip together. That's been reliable AFAIK for quite a few people so I'd copy that method. You need to leave the OEM in radiator cooler in the circuit BTW.

 

[Andrew Prince]

Re: Axillary autobox oil cooler.

Next question - will you put the aux cooler in the cooling circuit before or after the radiator cooler?

 

[Bat21]

Re: Axillary autobox oil cooler.

Thanks guys, I think I am going to go with braided hoses for the job as that seems a lot simpler to do.

This one will be plumbed in 'down stream' from the one in the rad, I think I'm right in saying the 'output' from the rad oil cooler is on the passenger side of the radiator... is that right?

 

[Andrew Prince]

Re: Axillary autobox oil cooler.

This one will be plumbed in 'down stream' from the one in the rad

Hi Paul,
That seems to be the convention as per Rodney and others. As an engineer (bear with me ) I can't help thinking that the ideal location would be upstream of the radiator cooler (i.e. not as you're proposing). My logic is that your aux cooler cools the hot ATF first and thus reduces the cooling load on the rad cooler. The advantage of this is that when it's cold outside or before the ATF has warmed up, you still have the heating effect of the rad cooler to keep the ATF at its ideal operating temp - cold ATF apparently causes as much wear on the 'box as excessively hot ATF.

Of course, the downside of my theory is if your rad is too hot, then the ATF gets reheated there after being cooled by the aux cooler. But if your rad is too hot, then you have more serious problems. The rad coolant temp should never be higher than the normal operating range of the ATF in any case.

The main negative of plumbing the aux cooler after the rad cooler (i.e. on the return line to the transmission) as I see it is that you have no temperature control - yes, you have cooling but no way of regulating it unless you put in a by-pass and some kind of thermostat or temp regulator. In the set-up I'm suggesting, the rad itself regulates the temp. Simpler might be better

Let us know how you go - this is just me theorising!

I think I'm right in saying the 'output' from the rad oil cooler is on the passenger side of the radiator... is that right?

Yes, I think so - I recall Julian V mentioning the same.

 

[Ian Rubie]

Re: Axillary autobox oil cooler.

If everything is running hot, slow churning through soft sand in high ambient temps for example, the main radiator will be very hot. At least the trans fluid will have the chance to cool a little through the aux cooler before going back to the box.

The other way round, the aux cooler would cool the fluid and it then would then be heated again by the main rad before going back to the box.

Just my take on it.

Ian

 

[Andrew Prince]

Re: Axillary autobox oil cooler.

If everything is running hot, slow churning through soft sand in high ambient temps for example, the main radiator will be very hot. At least the trans fluid will have the chance to cool a little through the aux cooler before going back to the box.

Agreed, Ian but in cold climates there would be excessive cooling of the ATF, which can be equally harmful to the box.

The other way round, the aux cooler would cool the fluid and it then would then be heated again by the main rad before going back to the box.

Yes, but my point is that the rad, even when very hot, is still well within the operating range of the ATF (which has already been cooled by the aux cooler in "my" configuration).
The overheating with the OEM set-up happens because the rad cooler simply can't cool the ATF (fast) enough - it is not a case of the rad running so hot that it overheats the ATF or anything. The ATF can run hotter in its normal operating range than the rad can AFAIK. The (rad) temp gauge apparently maxes out in the red at 125 deg C, whereas the ATF can operate at 120-130 deg C fairly happily, especially if a synthetic is used.

Basically it boils down (no pun intended ) to cooling duty - there is an amount of heat that needs to be removed from the ATF. The radiator cooler can remove a certain amount of heat, which is determined by the design (decided by Mr T and is fixed) and the ambient air conditions (variable - air speed and air temp). In the desert in soft sand, you have low air speed and high air temp, so the cooling duty provided by the rad cooler is relatively low. There is also the ATF which is hot because of the work that the box is doing, and has almost nothing to do with ambient air conditions - i.e. the ATF would get just as hot in winter in the Sahara. If the cooling duty provided by the rad cooler is less than the cooling needed by the ATF, then the ATF (return line) temp continues to rise. Other than stopping, the only way to reduce the ATF temp is to provide additional cooling duty, hence the aux cooler.

In terms of providing cooling duty, it does not matter where the aux cooler is placed - before or after the rad cooler (again the cooling duty of the aux cooler is dependent on the same variables as the rad cooler. And yes, the limits of cooling are determined by the approach temps of ATF and ambient air, i.e. you cannot cool the ATF to within maybe 5 or 10 degrees of ambient temp unless you have an unrealistically big radiator).

So there's no debate that the aux cooler is needed if the rad cooler can't rein in the ATF temps. The real question is what constraints are there in the 2 configurations. I agree that with the aux cooler after rad cooler, the ATF return temp will be lower in hot conditions but what happens in cold conditions to the ATF temp? If the lowest possible ATF temp was the goal, then the aux cooler after rad cooler is the best configuration.

I believe that if the aux cooler removes some/much of the ATF excess heat prior to the rad cooler, then the rad cooler can remove a bit more excess ATF heat (if ATF is hotter than rad coolant) or if the ATF is cooler than the rad, it will help lower the rad coolant a little (probably insignificant) but the ATF will be in spec temperature-wise, because Mr. T designed the gearbox & cooling system to have ATF running at a similar temp to the rad coolant. After all, if Toyota wanted the ATF temp to always be cooler than the rad temp, then they would not have designed a combined rad/oil cooler

This is an interesting debate - no doubt someone will chime in with some experience, rather than theory

Cheers,

 

[Jon Wildsmith]

I don't know what the ideal operating temperature ranges of typical synthetic ATF are Andrew but the temp warning light on an A442F comes on at 150c and goes off again at 120c and I can tell you that up around 160c you can hear the ATF boiling On my 80 I aimed to operate between 80c & 110c and if I was climbing dunes for short periods I might have tolerated 120c but above that and I think you're well into the danger zone for sustained usage and long term damage to the box. I was measuring the temperature at the output union on the side of the box courtesy of Rodney's kit so it's a good indication of the working temp of the ATF.

What would we expect the temperature drop across a good aux cooler to be in this situation? Is it sufficient to mean ATF passing through the aux cooler would be below engine coolant temp in the bottom of the radiator? If it is then you're going to pick up heat instead of dumping it. Excess heat is a much harder problem to solve than not enough of it

Even with an aux cooler the A442F cooling is a bit marginal IMO and you should keep an eye on the ATF temperature. The real fix is a package of aux cooler, extreme vb for increased flow through the cooler plus manual lockup, temp gauge to see what's happening and finaly a driver who makes intelligent use of the gears and manual lock up when the going gets really tough.

 

[Bat21]

Phew..... an excellent debate. I think I'm going to have to wait until this evening, I'm sure all this will sink in better once I have had a glass or two or Red wine

 

[Mal Eade]

I would mount it on the sideboard.

Sound so good it would make a nice ornament bit of basso and bobs your uncle.

When my ATF light came on in 53c of heat I just pulled over opened the fridge and pulled out a cold beer or two. Two beer just seemed enough to let it cool down.


Malcolm (hic hic)

 

[Bat21]

I would mount it on the sideboard.

Sound so good it would make a nice ornament bit of basso and bobs your uncle.

Well I did say it was aesthetically pleasing

Can anyone tell what it is/where it's from? Mal (SilverLady) don't answer that as you have an unfair advantage.

I have been thinking about the mounting fore or aft debate. Although I can see arguments for both cases, I am probably going to fit it BEFORE the main rad mounted cooler. My theory being if the ATF temperature is excessive, then this auxiliary cooler will remove the excess heat before entering the standard cooler. The standard cooler then has a better chance of 'supplying' the ATF back to the box at the required temperature.... of course my theory could be totally wrong

 

[Mal Eade]

I think it would look well on an American hot rod.
Its sort of retro in design.

The I think the mantle shelf is the best place or a towel rail in the bathroom.


Any other ideas ?????


Speak up

 

[Jon Wildsmith]

It looks a bit too shiney for a cruiser looks like a mini radiator ?

 

[Bat21]

..... looks like a mini radiator ?

Nope, it's early 90's and Japanese.