Transmission cooler system for all seasons
 

Hi everyone!
You know, i live in a city with different weather during the year, its 27...2F in winter and 86F and more in summer, so its reasonable to hold ATF in work temperature in winter and cool it as soon as it warming up above normal, especially in summer, thats why i use oil thermostat in this system. Here we go:

1. Set:
Hayden OC-1405 transmission cooler kit
MOCAL oil thermostat 3/8'' Push on 80C
ATF hose 1m
Clamps (x8)
ATF

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2. Preparing:
-Drain coolant
-Remove upper radiator hose
-Unplug fans, remove right radiator fan
-Remove from radiator both ATF hoses (dont care about little amount of ATF)
-Remove lower radiator hose
-Remove radiator with left fan then remove fan

3. Installation:
-Install cooler to radiator (use 4 thermo spacers and 4 strainers, included in cooler kit)
-Install cooler hoses (i`ve cut 50/50 1m hose)
-Check how it all together fits to the radiator panel
-Pick up thermostat and measure hoses length, paint cut lines
-If ok, remove this sandwich again, tighten up strainers, cut tails of strainers, put both fans to the radiator and check how they spin - they must dont touch strainers, cut hoses

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After that, install thermostat (dont forget to install clamps - 4 pieces at this stage). I used 1st fitting variant in instruction.

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Then bolt up all fans, install radiator, install upper and lower hoses, fix all, plug fans.
Jack left side
Install inlet stock ATF hose (left if watching towards in front of engine) to the radiator, better install new clamp.
Remove outlet stock ATF hose
Measure, cut and install 2 hoses (dont forget to install last clamps):
-from radiator to thermostat
-from thermostat to transmission
Install rubber between cooler hoses and radiator, if hoses touch it (the best way - cut 2sm of hose, slit it and embrace of hose in place where it touch radiator)

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4. Finally:
-Refill coolant
-Run engine, check ATF leaks, touch 2 hoses (cooler-thermostat lines) - they must be cold, touch 2 hoses (radiator-thermostat, thermostat-transmission) - they must be hot
-Drive several miles till ATF become hot, check cooler-thermostat hoses - they must be hot - it means that thermostat and system in general works.
-Refill ATF

5. How it works:
When engine starts, ATF flow only through radiator, stock system. At this time, ATF warming up to the work temperature 92...112F.
When ATF warms up to 107F, thermostat starts to open and open fully at 112F - at this time ATF flow through radiator and only THEN through cooler. When temperature drop to 107F, thermostat will close. So, dont worry about overheating or driving with cold ATF - all the time ATF temperature will be near 110F

Re: Transmission cooler system for all seasons
 

If I get this right, it sounds like the stock cooler and external cooler will be in series when the tstat opens up. The setup sounds great from a temperature standpoint. But flow resistance will be even higher than stock at operating temperature. That could be compounding what some believe to be the real issue. However, others say that flow through the cooler is irrelevant to line pressure. I guess I still don't know who to believe. Does low pressure cause damage which causes overheating or does overheating cause the atf to degrade which leads to damage?

If the stock cooler's screen was the main issue the question is, did it cause low pressure when blocked or did it cause poor cooling when blocked? If it was low pressure, I would think running an additional cooler in series with the already highly restrictive stock cooler would be counterproductive. A second thought is with regards to location. Since your setup solves the problem of heating up the atf in cold temperatures to enable lockup, why not locate the extra cooler in the fender with a fan attached? Then you would not be restricting airflow through the radiator by putting that cooler in front of it. Since your tstat solves the heating up problem, you don't need to put the cooler in contact with the radiator to get some heat exchange while heaing up.

Re: Transmission cooler system for all seasons
 

Paint diagrams)

Tstat closed:
http://s2.ipicture.ru/uploads/20120517/3e2owwIv.jpg

Tstat opened:
http://s2.ipicture.ru/uploads/20120517/ReDvX0yX.jpg

1. I think oil flow is not a problem, there are no 90 degrees corners in line, the flow is the same with No-tstat-setup. Anyway, much better than with external oil filter in line, so never doubt about it. Moreover, MOCAL is a world famous brand for cooling systems, including race systems.

2. I think stock cooler is a good system, enough for normal pressure. And it can be a good system for cooling, if it were not so weak tranny for this engine. This is the reason why i`ve supplemented stock system with additional cooler. Not replace.

3. I thought about in-fender-location, but realize that it will be a torture for me to clean it of mud, snow etc every day when the weather is sucks. Moreover, that is a complicated setup (fan, wiring, gauges)
I`ve installed my setup month ago and i noticed that engine temperature everytime is ok, in traffic jams and on highway, no matter.
And thermo spacers prevent heating from radiator.

I think its the best setup for SVX`s live in different weather seasons

Re: Transmission cooler system for all seasons
 

Very good idea and very well done. Only one thing that I think should included if you can - the part number of the t-stat. It's almost visible in the picture with the packaging, but the pictures won't stay up forever.

Beautiful job, man. We here at the internet thank you.

Re: Transmission cooler system for all seasons
 

That is a serious trans cooler.

Great work, I had wanted to do something like this with my car. I started noticing that when driving in very cold temperatures the torque converter would unlock for a minute or so every little bit on the highway and concluded the same thing, the trans fluid was being cooled excessively.

However, since I no longer have ATF to cool, it's not really an issue any more. :D

Re: Transmission cooler system for all seasons
 

You`re welcome;) Thanks for rate;)

I am not sure what exactly part number of tstat (maybe it is "OT/1"), i think MOCAL havent part numbers, i bought it online here:

http://thinkauto.com/acatalog/On_lin...lstats_30.html

OT/1 Small body thermostat with push-on tails
3/8'' 80oC

Re: Transmission cooler system for all seasons
 

There are also Permacool and Derale thermostat units available from Jeg's or Summit Racing.

I am in the process of doing up a cooler for my car but will take advantage of the natural airflow over the car to circulate the air. All it takes is a little negative pressure.

-Mike O

Re: Transmission cooler system for all seasons
 

.

Another configuration which has been used in the past is the counter-flow of the ATF. This involves the external cooler, in series with the stock ATF cooler, and a manually-operated diverter valve (a ball cock configuration).

http://www.subaru-svx.net/forum/atta...1&d=1351626143


http://www.subaru-svx.net/forum/atta...1&d=1351626181

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Re: Transmission cooler system for all seasons
 

But that still puts the stock cooler in series with the external cooler. As Tom has mentioned, the stock cooler has very high flow resistance. IF flow is an issue then you wouldn't want to do that. I think what we would want is coolers in parallel until the ATF is up to temperature and then just the external cooler at temperatures above that. Then you could have the benefit of a low resistance, high efficiency, external cooler and the benefit of heating the ATF at low temperature.

Alternatively, you could have the stock cooler in line until the ATF comes up to temperature and then have the external cooler in line. You still would have more flow restriction but only until the fluid is up to temperature.

The TStat that has been discussed above is nice in that it actually provides some flow in both directions, most of it bypassed, until the fluid is up to temperature and then only straight through flow when it is up to temperature. In that way, it sort of does put the coolers in parallel when the ATF is cold and then only uses the external cooler when hot. The diagram is attached.

http://www.subaru-svx.net/forum/atta...1&d=1351692836

Re: Transmission cooler system for all seasons
 

Simpler plumbing:

http://www.subaru-svx.net/forum/atta...2&d=1351693592

Re: Transmission cooler system for all seasons
 

If getting the trans up to operating temp and keeping it within best-case limits without sacrificing flow is the goal then several things can be done. Simpler is better because bends and adapters all create restrictions in flow.

Another thought is that the best the embedded cooler can do in ideal conditions is match the engine coolant temp. Since conditions are not ideal (thermal gradient of the tubes, coolant temp variation, etc) it seems best to eliminate the embedded cooler and go with a high capacity unit that is closer to ambient temps then couple it with a quality thermostat if using a tube/fin cooler (or skip the tstat if using a plate cooler) to manage the ideal ATF temp and stay close to it.

Here is what I am doing to my car:

For quick warm-up an oil-oil heat exchanger. This little gem goes on the oil filter mount. It has passages for the engine oil and a mount for the filter to retain the spin-on. As the engine warms (faster than the trans) the trans fluid loops through the oil-oil exchanger and is warmed by the engine. This will warm the trans much faster than the embedded exchanger which relies on the engine warming a much larger volume of fluid (coolant). This also will allow me to cap the exchanger in the radiator and quit using it.

From there the ATF goes to a stacked plate cooler (Derale, Hayden, Earls', and B&M all make them). This type of cooler does the job with no thermostat because it relies on the dynamic behavior of the ATF at a given temp to govern the flow of the fluid.

When cold the fluid bypasses the plates and flows through the large passages (tanks/bypass on some models) on the cooler very effectively bypassing the plates. As the ATF warms more flows through the plates (path of least resistance and all that). This provides dissipation in direct relation to the temp of the ATF. On a tankless type a similar action occurs but happens in the tubes because this type is full flow like a tube/fin cooler. Either can still work with a thermostat if you like.

Simple fluid dynamics. No voodoo. No thermostat.

So what you end up with is a stable ATF temp based on the average of engine oil and gearbox load then dissipated by an air-oil exchanger of adequate capacity.

The radiator now only has one job; cool the coolant.

The external trans cooler has one job; cool the ATF.

The oil-oil exchanger has one job; warm the ATF with engine oil eliminating the variability of the radiator embedded exchanger.

Fewer connections. Less turbulence. Proportional cooling. Rapid warm-up.

Seems like a winning combo to me :)

I'll post install/fitment seperately.

-Mike O

Re: Transmission cooler system for all seasons
 

So the oil-oil exchanger is in series with the ATF cooler? Is the path, Tranny Out-to-exchanger-to-cooler-to-tranny in?

Re: Transmission cooler system for all seasons
 

Yes.

AT Out -> O2O -> Plate Cooler -> AT In

If the plate cooler is full flow (no bypass) like the Derale and some Hayden units then it behaves like a tube/fin cooler and it is still necessary to add a tstat. Then it would be plumbed like your simplified drawing substituting the O2O for the radiator embedded unit.

A tstat could be used in either case.

-Mike O

Re: Transmission cooler system for all seasons
 

I kinda like it. The only concern I would have is that the oil is much hotter than coolant. The ATF could get quite warm before hitting the cooler. I guess the unknown is how much heat hot ATF would extract from the oil through the exchanger. If the cooler is really effective I suppose it could drop the ATF temperature enough that the tranny followed by the exchanger wouldn't overheat the ATF but that would need to be proven.

An added benefit is better engine cooling. The radiator would be slightly more efficient at cooling the coolant and the ATF cooler would also be removing some engine heat acquired through the exchanger.

Re: Transmission cooler system for all seasons
 

Agreed. The oil does run hotter but a filter base O2O exchanger is small (only slightly larger than the filter diameter). The amount of heat transferred is limited but effective.

-Mike O