how to add trans cooler pipes to manual rad?

[dlb]

i need to replace the radiator in the project terc. i have two good spare rads but they are both from manual trans tercs and do not have the inlet/outlet pipes for the auto trans oil cooler. they have threaded ports on the bottom in the same spots that the auto trans has the pipes so i assume you can add the pipes to them, but how? the pipes on the rotten rad are welded in place and appear to be stock so i can't swap them.

also, there must be some cap or block in the ports on the spare rads that prevents them from leaking when not in use in an auto terc. how do i remove those caps? i didn't get to spend too much time on this today so it might be obvious when i take a look again tomorrow but if anyone can set me in the right direction now, that would be great.

lastly, are rads interchangeable between the same year of hatchbacks? there are a few of those at my local wrecker.

[Petros]

the trans cooler is a separate chamber the oil passes through in the lower header tank, no coolant should come out of these tubes, if the cooler is not used they can stay open. You have to keep the trans fluid separate from the coolant, you would not want the coolent going into the trans would you?

I think the version of rad you have requires threaded nipples, they should be standard pipe thread you can get at any auto parts store. they are usually brass, get the ones with the male ends with the barbs to hold the oil line, use hose clamps not the spring clips. I have some kicking around my garage you can have if you are coming down this way some time, I took them off a new radiator since I have no auto trans Tercel. likely cheapest just for you to buy them locally.

[dlb]

the trans cooler is a separate chamber the oil passes through in the lower header tank

how does the ATF get cooled in this lower chamber? is the ATF only warm enough that passing through a thinly-walled chamber that sits in the vehicle's airflow is enough to keep it cool? or does it circulate into any of its own fins on the rad?

I think the version of rad you have requires threaded nipples, they should be standard pipe thread you can get at any auto parts store.

i'm really hoping that they're not more british standard pipe thread, like the OPS. fingers crossed. i'll take a look and if it turns into a nightmare i'll take you up on the ones you have, peter. thanks.

[Petros]

how does the ATF get cooled in this lower chamber? is the ATF only warm enough that passing through a thinly-walled chamber that sits in the vehicle's airflow is enough to keep it cool? or does it circulate into any of its own fins on the rad?

it has a fluid to fluid heat exchanger, the lower header tank of the rad is full of circulating coolant of course, the AFT is pumped through a chamber within the lower header tank and there is a direct transfer of heat by conduction through the walls of the inner AFT chamber to the coolant in the radiator. when you cool the AFT in the radiator, it puts the heat into the coolant of the radiator, which than dissipates through the cooling fins of the radiator. this means the radiator has to have excess capacity, and it is the cheapest way to cool the AFT. It is a rather simple system, not complicated at all.

many people elect to add a separate AFT trans cooler (Looks like a small radiator, auto parts stores sell them-they do not cost much) to improve cooling to the trans (makes it last longer) and to reduce the cooling load on the radiator. this is often done are larger vehicles that are intended to be used for towing. Years ago when we owned the first generation Dodge Caravan (first US made minivan), the POS trans failed at only 44k miles, although the rebuild was covered under warranty I wanted to up grade it to make it more durable, put in a shift kit that reduced slippage between shifts and added a large separate trans oil cooler and we doubled the life of the POS Chrysler trans so the rebuild lasted 88k miles. The rest of the van had similar issues, keep redesigning all the parts that kept breaking, but because of that Caravan, I will NEVER own another Chrysler product again, even if now made by Fiat (as if that is going to be an improvement!).

Our Mazda MPV which came with the optional towing package already had an auxillary external trans cooler (and the auto trans in the MPV held up for over 200k miles before replacement), and I have added an external oil trans cooler to my daughter's Suzuki Esteem as well.

[dlb]

it has a fluid to fluid heat exchanger, the lower header tank of the rad is full of circulating coolant of course, the AFT is pumped through a chamber within the lower header tank and there is a direct transfer of heat by conduction through the walls of the inner AFT chamber to the coolant in the radiator. when you cool the AFT in the radiator, it puts the heat into the coolant of the radiator, which than dissipates through the cooling fins of the radiator. this means the radiator has to have excess capacity, and it is the cheapest way to cool the AFT. It is a rather simple system, not complicated at all.

great info, thanks peter. next question: since a double row rad has increased cooling capacity, would using one be a suitable way to improve cooling of the ATF and reduce cooling load on the rad? obv a separate trans oil cooler would be superior but this seems like an easier and cheaper route. the old rad i'm replacing is a single row and both of my spares are double row.

[Petros]

It would increase cooling capacity to the engine (which I have not found to be an issue, even crossing Texas desert in summer at wide open throttle when 104 deg F), but not likely it will cool ATF any better since the auto trans oil cooler in the lower header tank is not likely any larger.

The aux coolers typically are only $60 to 80, it seems a cheap way to get extra cooling capacity. Or you can find one at a wrecking yard, my ford E350 van came stock with one, so did our MPV with the towing package, the All-trac and GTS corolla and celica have external oil coolers too (for the engine oil but they will work for the trans as well) and as stated above, many just add them to their cars to make the trans last longer. All of the japanese oil coolers I have seen on import cars are of very high quality and efficient design, there is one type of after market cooler that is made of folded flat plates, these are not as effective (not as much cooling fin area).