Installing tranny cooler question

[Ron Mummert]

I bought a B & M cooler #70255 & will have it installed this Wednesday on my '92 with 84K on it. The prior service history is sketchy, but per heresay, a Suby rebuilt tranny was installed at around 65K. Right now, I can detect no problems of any kind, & would like to keep it that way (yeah, right!). The questions - I don't know if it has synthetic fluid in it. Is enough fluid generally lost while installing a cooler, that will require topping off, & if so what should be added, since I don't know what's there now. OR should I go ahead & flush the thing & pray that nothing gets stirred up in the process that will maim the tranny in a week? Should I have the pan pulled & get the magnet de-gooked, & the filter changed too? If you say "flush it" is it OK to now use synthetic fluid? Oy vey, why didn't I just keep my '87 Chrysler that never had fluid change in over 230,000 miles? Oh, now I remember, I wanted "cool" windows.
Thankingly yours, Ron.

I f i were you I would have the filters changed and the fluid replaced with synthetic

Ditto.

You won't lose much fluid in the cooler install and the cooler doesn't really hold much fluid (maybe a 1/2 pint to a pint) but a new filter and fluid can't hurt. I don't have experience with flushing transmissions so I can't give you advice in that area. As for "mixing" fluids I have been told that the newer synthetics are compatible with organic varieties. The transmission can not be completely drained so some of the old fluid will remain. I have been told the stock variety of filter is to be changed every 30,000 miles. That information was from a service writer at a local Subaru dealership so take it for what it is worth. Filters are cheap and easy insurance. I got the whole install kit from Couer D'Alene Subaru in Idaho for $8.25 plus shipping (local dealer wanted $35 just for the filter! Must have been running low on Crack that day and needed to score)

Good luck with the install and let us know how it turns out.

[1994SubaruSVX]

the cooler rated at 19,000 GVW's? that is what i bought and i was able to fit it in front of the radiator and condensor so that it is 100% effective. if you buy the cooler rated at 24,000 GVW it will not fit because it is about a quarter to half an inch too deep. also i went ahead and just plugged my stock cooler so now i am strictly running the b&m cooler. installing the cooler in a series appears pointless to me because what happens if one of the coolers gets clogged? then both are useless...... good luck and i hope this info. helps.

Only when you are moving. Once you are in stop and go traffic the air flow through this cooler is minimal because of the limited abilitiy of the cooling fans to move air over it. Just something to keep in mind.

[htyei]

Are you talkinga bout changing the external ATF filter that we go as part of a recall? (for 1992s) I wanted a replacement filter, but I was told be subaruparts, that I could only get one ifI didnt have the recall, something about checking my vin # etc etc. Also said should never need to be replaced. I was a little dubious so I bought the only thing I could from him without authorization, a legacy atf filter kit.


Does anyone wellinformed know if the svx atf filter kit and the legacy one is the same, or compatible?


Wow i get conflicting advice, (change at 30k miles, or never change)

Henry,

Call Larry at Couer D'Alene Subaru Parts. 1-800-525-2441. Tell him you are looking for the filter installed on SVXs as part of a campaign in 93. If you tell him you are looking on line for the thing he will give you a better price. The kit comes with bracket, hoses, clamps *and* filter for $8.25.

As for the compatibility with a Legacy I couldn't say. As for the 30,000 mile replacement I was told that at the dealer who did my trans replacement. I just had them re-replace the transmission because it failed after 20,000 miles due to a suspected clogged filter. Heck, at $8.25 you could replace the thing monthly if you wanted. I don't know what you'd do with all those brackets though

[Ron Mummert]

Thanks all for your comments so far. The cooler info says 13-16K GVW, 7X11X3/4 inches. I don't know if it will fit in front of the radiator, ideal, I guess, or behind it. Interestingly, the instructions recommend "in series" not parallel connection, but I have to agree, that doesn't make sense. Any other opinions on that point? I found out the tranny was replaced at 71K (July 2000) with one that was out of a totalled SVX, but had been rebuilt, & has the recall filter on it. The mechanic (ex-Subaru) remember it as a "clean" tranny. He used regular Dextron III. That means it's got 13K on it with organic fluid. Still OK to use synthetic? Ah, whatever happened to the "simple" life? I'll let everyone know how everything went. Ron.

I bypassed my stock cooler altogether. I suspected it of being clogged also. The early coolers, 92-93, had a mesh material inside them to cause turbulence in the fluid to help it transfer heat. Unfortunately it acted as a filter and clogged. This caused more heat and then failures. The filters were added as a "recall" measure until the later models were built without the mesh. Other members have replaced their radiators (with trans cooler installed) with units without the mesh from later model years.

The call is yours but deninitely replace the filter.

As for the synthetic fluid I hear it is better for high heat conditions. Dextron should be fine if you change it frequently but the main damage to the trans is attributable to high heat and that, historcally, was caused by clogged coolers.

[svxistentialist]

Originally posted by lightning_8669
I bypassed my stock cooler altogether. I suspected it of being clogged also. The early coolers, 92-93, had a mesh material inside them to cause turbulence in the fluid to help it transfer heat. The call is yours but deninitely replace the filter.

As for the synthetic fluid I hear it is better for high heat conditions. Dextron should be fine if you change it frequently but the main damage to the trans is attributable to high heat and that, historcally, was caused by clogged coolers.

Ron,
I was saying on another post to Chris that I am about to get a cooler installed. Bypassing the rad cooler altogether seems to me to be an un-necessary step, unless you are absolutely sure nothing is passing through. First, and lightning makes the point himself, with an aux cooler only, you are at the mercy of airflow and ambient temperature.

With the stock cooler, the pump is pushing the hot oil through a liquid/liquid heat exchanger, which in theory is a more efficient way to remove heat, and this is why the owner's manual recommends pulling the car over, and revving gently to improve throughput to cool the box if the temperature warning light comes on. This would not work if you solely depended on an aux cooler using air cooling.

Change the filter, put in the extra cooler in parallel, refill the system with synthetic HiTemp. If it is running too cool for your lock-up clutch in cold weather, put a thermostatic valve in the aux circuit to shut off the extra cooler till the temp is up enough. Shouldn't have any trouble with that set-up.

Joe

[1994SubaruSVX]

could not do them parallel. how would you run them parallel? i did not know about the pumping capability. i bypassed my stock cooler too. ron if you have a 16,000 gvw cooler then it will fit in front of the condenser and radiator because i have one rated at 19,000 (b&m) and it is in the front. please give me some instructions on running the cooler parallel because i will have him reconnect the stock cooler.

A short word on flow dynamics and the path of least resistance. In parallel the majority (perhaps all) of flow will be through the cooler with the least resistance. If and when this cooler clogs the flow will then divert to the cooler with greater resistance and back and forth until both are clogged. If no clogging ever occurs (as shouldn't) the cooler with the least resistance will provide all cooling. I know someone out there has the formulas but I'll just apply the logic to it casually if I may. A cooler with less "restriction" will have less time to cool the fluid passing through it because the fluid spends less time in it. However, if the cooler with the lower resistance has greater cooling efficiency then that cooler will provide better cooling.

My question to you is this; Which cooler has the greater resistance and which has the greater efficiency?

Case One: Stock cooler greatest resistance/greatest efficiency.
Result: Majority of flow through cooler with least cooling.

Case Two: Stock cooler least resistance/greatest efficiency.
Result: Cooling adequate with stock cooler no aux. required.

Case Three: Aux. cooler least resistance/greatest efficiency.
Result: No cooling provided by greater resistant stock cooler.

Case Four: Aux. cooler greatest resistance/greatest efficiency.
Result: Majority of flow through cooler with least cooling.

I would guess the efficiency of the aux. cooler to be greater than the stock cooler but can't say which cooler has the greatest resistance. If the aux. cooler has greater resistance, and is mounted in parallel, then it's just money hanging out front of your condensor blocking the wind.

The choice is yours. Me? I decided to bypass the stock cooler in favor of the above logic.

[svxistentialist]

Originally posted by lightning_8669
My question to you is this; Which cooler has the greater resistance and which has the greater efficiency?

Case One: Stock cooler greatest resistance/greatest efficiency.
Result: Majority of flow through cooler with least cooling.

Case Two: Stock cooler least resistance/greatest efficiency.
Result: Cooling adequate with stock cooler no aux. required.

Case Three: Aux. cooler least resistance/greatest efficiency.
Result: No cooling provided by greater resistant stock cooler.

Case Four: Aux. cooler greatest resistance/greatest efficiency.
Result: Majority of flow through cooler with least cooling.

I would guess the efficiency of the aux. cooler to be greater than the stock cooler but can't say which cooler has the greatest resistance. If the aux. cooler has greater resistance, and is mounted in parallel, then it's just money hanging out front of your condensor blocking the wind.

The choice is yours. Me? I decided to bypass the stock cooler in favor of the above logic.

I can't and won't argue with your deductive logic, JP, but one small point undercuts the argument you make for bypassing. Your thesis/scenario implies that very little or no oil will pass through the high resistance channel , be it the most efficient or not.
This is not the case. Oil will flow through both coolers, and the overall cooling achieved will be a function of the percentage throughflow past each multiplied by the efficiency of each. Granted because of laminar flow the expected effficiency in the fast flow channel will be reduced, but it will still be cooling the oil.

Also, a couple of easy adjustments at fitment time would solve the quandary. Measure the pressure required to drive oil through the stock pipes. Measure the pressure needed to drive oil through the additional cooler.
If the pressure is less through the new cooler, put in a blanking washer in the pipe to reduce flow and increase pressure to the same level as stock. That way you have 50-50 flow, both coolers working. With both doing equal work, you are getting the stock cooler to help with its liquid intercooler in stop start traffic.
If the stock cooler clogs, more oil will divert to the aux, you are still ok.

Second adjustment is you can fit a manual shutoff valve to either circuit. I would do it on the new cooler. You could shut it off in winter, and as summer, or heavy traffic, or hill climbing comes in, let oil to the extra cooler. No sweat.

Joe

Joe,

You are correct about some flow going through both coolers. Perhaps I "oversimplified". I'm somewhat familiar with the coolers from B&M Racing and they have between one and two "bypass" channels to allow cold, thicker fluid to bypass the majority of the cooling elements. As the fluid heats it flows to more and more of the channels that perform cooling. To balance the coolers, as you suggest, would require the system to be hot or at operating temp. The balancing could be performed but, as you say, requires a bit of research. If a filter is installed clogging should not become a concern and should eliminate the need for recalibrating the system. I was thinking a way to cal the coolers would be through a gravity measurement. Pour a specified amount of fluid through the cooler and measure the time it takes to drain. However, this would not work the the B&M cooler because of its bypass design.

My thinking is the balancing act may be more effort than some members would be willing to go through. I have bypassed my stock cooler with a B&M 24,000GVW cooler. I have mounted it behind the engine (which allows it to perform at 60% efficiency, 14,400 GVW) cooling fans so when the engine calls for cooling in stop an go traffic the fans also blow across the trans cooler. I have driven the car at temps down to 10 degrees F and the converter lock up occurrs at about the same time it did with the stock cooler. The trans also appears to perform well at temps in the 90s.

Disclaimer: "These results are recorded by untrained, unlicensed test pilot. Your results may vary."

Thanks, by the way, for the enlightening discussion.

[1994SubaruSVX]

basically what i am hearing is that we really dont know which is the best route to take. both of you make a good argument but i think i will stick with my current setup of having the b&m cooler stand alone while bypassing the stock cooler altogether. my logic is that the stock cooler was only rated for a car the size of the SVX. my cooler mounted in front of the condenser and radiator is rated at 19,000 gvw. also in that location it is supposed to be at 100% efficiency. this is just going to have to be a risk that i take. this car is like a crap shoot sometimes, just going with my gut i guess.....thanks for you help guys.