Stock vs. External Tranny Cooler
 

I understand that the efficiency of the stock cooler is higher because of the liquid-to-liquid interface. However, the temperature of the coolant in the radiator must be far higher than ambient air.

Given the higher coolant temperature (I'm guessing 150 - 180 degrees F) in the radiator, and the lower ambient air temp (Santa Fe seldom gets up to 100 deg F), is the actual cooling effect (as opposed to cooling efficiency) of an external cooler higher than the stock cooler?

what a good question. I have no idea and have to think for a while and would have to investigate heat echangers.

one thing to keep in mind is I "believe" (those who read the alignment thread know what my thoughts are worth - not much) that the ideal operating temp is somewhere around 150F. Just high enough to get the TC to lock up, but not so much as to markedly degrade the life expectancy of the ATF.

I think the radiator and a 1/4 size (of orginal radiator) add should be in series, add on after the radiator.

A very large AFT (3/4 size) cooler is needed if the radiator is by passed.

I still do not know the answer to how hot the radiator fluid gets. If the fluid never goes over 180F the setting for the T-stat then the radiator should be included in teh cooling path with the add on.

The question is: How hot does the radiator coolant get after a repeated romping around on the gas pedal?

Re: Stock vs. External Tranny Cooler
 

That's a very good question Dick.

[This is what people generally say when they don't know the answer:) ]

The stock liquid/liquid cooler is more efficient as you say, which means it is better at taking away heat than a liquid/air model. If the coolant liquid was as cool as ambient air, it would be a no contest, stock would win over the additional cooler.

The stock cooler has one big advantage over the add-on model, it can heat up the tranny oil in the morning to the optimum viscosity, and maintain it within the desired range, usually.

I have the extra cooler on mine, and the high viscosity of the cold ATF causes clunky shifts in the mornings.

What the extra cooler does in warmer situations, heavy traffic and hillclimbs, it will keep the temp from going too high, i.e. prevents heat spikes beyond the normal range. This stops the ATF from breaking down and saves our trannies.

In colder climes, the extra cooler may be overkill. Remember, the ATF has to be above a certain temperature range [150ish I think??] before the lockup clutch will operate in 4. Oil being too viscous is also sure to affect fuel consumption.

Joe:)

Re: Re: Stock vs. External Tranny Cooler
 

I can drive for 15 mins in 40 degree weather and only then would the TC finally lock up.

Re: Re: Re: Stock vs. External Tranny Cooler
 

I can well believe this David. This will be costing you a little in the consumption stakes, and we all know the SVX is not exactly a paragon of virtue in this department.

A good fix is fit a valve that will deny oil to the extra cooler in cold winter weather, and work as it is supposed to using the stock one.

A cheaper solution, and just as effective, is to fit a piece of card or light aluminium across the front surface of the extra cooler, again, only in cold weather. Be aware if it is big and fitted in the usual place out front or in the sandwich position, you will also be denying cooling air to the rad and/or the aircon condenser. This would not be good or clever. If you hear the fans coming on a lot, working overtime, compromise and only block half the surface of the extra cooler.

The divert valve is the better solution. In either case, when the weather warms up, don't forget to open the valve or remove the card as the case may be.

Joe:)

PS Enjoy Reading!

I would not worry much on this score. The radiator for the coolant and the fans working it are very effective at keeping the temp even.

My dashboard temp gauge never goes beyond half way, in any hot weather, in heavy traffic, or when thrashing it speed-wise. Good cooling system IMO.

Harvey mentioned in a thread elsewhere that the tray beneath the rads acts in a way to duct extra air through for better cooling at high speeds. Don't know how this works, but I believe it. My temp needle never stirs for any kind of provocation.

Joe

hehe, guess what...I don't have a separate cooler. :p

FYI: The engine temp sensor does not give any indication of the tranny temp. There is simply too much heat mass and too little transfer area in the engine cooling system for the tranny fluid to significantly alter the thremal content. If you install a tranny temp sensor, you'll be able to see that the tranny temp can be significantly higher, in the area of 220+, and yet the engine temp needle will remain steady. The fans will just cycle more often and stay on longer to keep the cooling system at optimal temperature.

KuoH

Thanks Kuoh.

I didn't suggest the engine temp gauge relayed any indication of tranny temp. I was answering his query on whether the coolant temp went up when thrashing the car.

Must admit, if I was going to put in extra equipment, a tranny oil temp gauge is at the top of that list.

Joe

Oops, sorry. I see where you were going with that now.

KuoH

No probs man. Actually your point about the relevant sizes of the heat mass does answer why the lockup does not occur for 15 minutes, even without an extra cooler.

Touche.

Joe:D