The radiator infront of my radiator

[DirtScaresMe]

So I swapped out the radiator. It seems like the engine coolant and transmission fluid both use the fancy radiator I put in, and the air conditioner uses the half-sized one right behind the grill.

So what's up with the metal-finned-radiator thing between the real radiator and the ac unit?

 

[Landseer]

Transmission cooler is the smallest cooler (roughly 1 foot by 1 foot) and is in front, then AC condenser in the middle and Radiator in the back. Transmission fluid flows from the tranny to the transmission cooler then to a heat exchanger in the bottom of the radiator then back to the tranny.

 

[DirtScaresMe]

Transmission cooler is the smallest cooler (roughly 1 foot by 1 foot) and is in front, then AC condenser in the middle and Radiator in the back. Transmission fluid flows from the tranny to the transmission cooler then to the bottom of the radiator then back to the tranny.

I plugged two hoses to the bottom of my new radiator that looked mighty like atf fluid. The fsm I think even noted it as such. I think.

 

[DirtScaresMe]

So the atf went from the 1x1 back into the bottom of the big radiator?

 

[Landseer]

Yup. The transmission cooler (small front one) cools the ATF then the heat exchanger in the bottom of the radiator further cools or heats the ATF, on a cold day with light engine loads the transmission cooler could actually cool the ATF below operating temps so running through a heat exchanger in the radiator helps keep the temp in range.

The transmission cooler was actually an option, probably called a "tow package", but was installed on essentially every 80 sold in The States, some 80's sold overseas don't come with a separate transmission cooler.

 

[Formulaonehd]

This thread was very helpful. I just had my tranny serviced and solenoids changed and I noticed my main radiator levels were very low the next day it took over 1L of fluid to top it back up .
The mechanic told me to check fluid but I assumed he meant tranny fluid levels , did he mean check radiator levels ?

 

[Kaninja]

Seems messed up to me going from tranny cooler back to heat exchanger in radiator then back to transmission. Everything I've ever read says going from heat exchanger in rad to tranny cooler then back transmission is the best way to keep temps down. However I have over 400k km's on my transmission.....guess it works.

 

[Formulaonehd]

God knows you can't kill an 80 except by your own hand (wrecking for parts) in which case it's spirit lives on in other 80s

 

[Landseer]

Seems messed up to me going from tranny cooler back to heat exchanger in radiator then back to transmission. Everything I've ever read says going from heat exchanger in rad to tranny cooler then back transmission is the best way to keep temps down. However I have over 400k km's on my transmission.....guess it works.

Routing the ATF from the radiator to the trans cooler then back to the trans is the best way to keep temps down, however this can push the ATF temp down too far. The transmission functions best within a certain temp range, on a cold day the trans cooler can cool the ATF below that optimum range causing problems for the trans (I believe 4th gear and torque converter lockup are unavailable until the trans reaches proper temp on the 80 series automatics). Routing the ATF from the trans cooler to the radiator allows the radiator to warm up the ATF a bit.

For racing applications, where everything is going to constantly be very hot, routing ATF from the radiator to the trans cooler then back to the trans would provide optimum cooling. However for a vehicle designed to reliably work in conditions ranging from -40F to 120F the routing from the trans cooler back to the radiator is superior.

 

[Landseer]

This thread was very helpful. I just had my tranny serviced and solenoids changed and I noticed my main radiator levels were very low the next day it took over 1L of fluid to top it back up .
The mechanic told me to check fluid but I assumed he meant tranny fluid levels , did he mean check radiator levels ?

He probably meant trans fluid (ATF) but you'd have to ask him. To accurately measure the ATF level the transmission has to be warm (drive at least 10 minutes) and the engine has to be running when the measurement is taken.

 

[Formulaonehd]

He probably meant trans fluid (ATF) but you'd have to ask him. To accurately measure the ATF level the transmission has to be warm (drive at least 10 minutes) and the engine has to be running when the measurement is taken.

Bummer looks like the rad might be blocked then it's drinking coolant at the moment

 

[bloc]

Transmission fluid flows from the tranny to the transmission cooler then to a heat exchanger in the bottom of the radiator then back to the tranny.

Have any documents to back this up? It is contrary to pretty much every ATF cooler flow diagram I can find. I'm digging through the FZJ80 FSM at the moment and not able to find anything specific to this chassis.. but plenty of examples of the opposite (rad first, then air/fluid heat exchanger) on non-racing vehicles in google searches online.

I ask because I have the cooler lines for my swap set up rad first, but if the FZJ80 was different I'll switch them.

 

[Landseer]

Have any documents to back this up? It is contrary to pretty much every ATF cooler flow diagram I can find. I'm digging through the FZJ80 FSM at the moment and not able to find anything specific to this chassis.. but plenty of examples of the opposite (rad first, then air/fluid heat exchanger) on non-racing vehicles in google searches online.

After browsing Google I tend to agree with you that most setups are radiator first then trans cooler (although several site do mention that this can cause problems at temps below 0F). My 94 is currently set up trans cooler first then radiator, I'd like to think thats the factory set up but who knows whats been done to it in the last 20 years. I looked through the FSM and A442F manual and I don't see anything on the ATF line routings.

 

[inkpot]

Bummer looks like the rad might be blocked then it's drinking coolant at the moment

A blocked radiator will not cause coolant to disappear, but it would more likely cause overheating. Coolant being lost would be an external leak that should be visable or an internal leak that would go into the oil bath or out the exhaust. Internal may indicate headgasket issues.

 

[flintknapper]

Routing the ATF from the radiator to the trans cooler then back to the trans is the best way to keep temps down, however this can push the ATF temp down too far. The transmission functions best within a certain temp range, on a cold day the trans cooler can cool the ATF below that optimum range causing problems for the trans (I believe 4th gear and torque converter lockup are unavailable until the trans reaches proper temp on the 80 series automatics). Routing the ATF from the trans cooler to the radiator allows the radiator to warm up the ATF a bit.

Typical Transmission fluid routing (With Aux cooler) is: Transmission to Radiator, Radiator to Aux Cooler then back to Transmission.

This gives the fluid the best chance to cool IF your engine is overheating (which also heats the trans fluid as it goes through the exchange cycle in the radiator).

As you alluded to...the transmission is designed to work (best) in a certain temperature range. Torque converter lockup (4th gear- Overdrive) will not occur until the coolant temp (not trans temp IIRC) reaches approximately 130° F. Since the Trans fluid runs through the bottom of the radiator there is an exchange of heat. So in essence...the radiator both 'Cools' and 'Heats' the transmission fluid depending upon circumstance.

IF/WHEN someone bypasses the radiator cooler in favor of the Aux Cooler, then yes...cold temperatures can present a problem (at least temporarily).

But if the factory set up is left in place, it would have to get mighty darn cold for the transmission fluid to not become suitably heated by the radiator (provided there is a properly working thermostat in the cooling system). The Aux Cooler further cools the fluid before returning to the transmission but its a pretty short trip, it shouldn't be cooled so much as to cause problems under all but the most extreme conditions.

 

[slow95z]

i have 3 spare trans coolers. wonder if i should rig up 2 and then bypass the rad for my v8 swap. might help me get away with electric fans and make things easier...

 

[flintknapper]

i have 3 spare trans coolers. wonder if i should rig up 2 and then bypass the rad for my v8 swap. might help me get away with electric fans and make things easier...

If your purpose was to achieve the best cooling (but only cooling)...then yes. BUT if you live/drive where wintertime temps get below freezing, you would be relying strictly on the transmission (primarily an unlocked Torque Converter) to heat the transmission fluid..

Remember...in certain circumstances (cold weather) the heat exchange from the radiator actually warms the transmission fluid. Only when the Trans fluid is hotter than the radiator fluid (coolant) does the exchanger help to cool the trans fluid.

 

[slow95z]

I live in a climate that sees 100+ in the summer and maybe 40s for the high in the winter. Cooling systems here are strained in the summer.

 

[bloc]

Personally I'd see what the trans and coolant temps run before messing with it. May not be necessary at all.

Also keep in mind that adding more heat exchangers in front of the radiator will reduce ambient airflow through the core.

 

[flintknapper]

I live in a climate that sees 100+ in the summer and maybe 40s for the high in the winter. Cooling systems here are strained in the summer.

Sounds to me like you have a need for both heating and cooling then. Perhaps a 'diverter' system would be best for you. In the summer you could bypass the radiator, in the winter...switch it back to stock configuration...with just the turn of a valve.