Let's discuss air-cooled fluid (oil, transmission, power steering) coolers

[skrit]

There seems to be a few styles of fluid coolers. I want to discuss the pros and cons of each (not including powered fan units).

I've looked for comparison videos on Ytube on which cools the best relative to pressure drop. This is what is called "efficacious" which means the most effective (not to be confused with efficient). If someone knows of a "Project Farm" style video or test then share and this will be a short discussion.

There are several variables here with the main ones being:

1. Number of passes
2. Mounting location (in front of radiator/frame cross member/other)
3. Physical size/cooling surface area

I see there are these main types (all pics are Derale products which are USA made from what I can tell):

Fin-tube style:

Stacked Plate style:

Aluminum Heat Sink style (dual pass for this discussion):

Which ones have you used that have met or exceeded your expectations on reducing fluid temps?

 

[1969]

Currently I have the fin-tube style on my Gen 1 Raptor power steering system and it’s definitely helped cool it down, how much I can’t say but those trucks are notorious for going through steering racks and mine is pushing 200k on the original.

I have also used an Aluminum Heat Sink style dual pass on a 80 series Land Cruiser power steering system. That system would get so hot the fluid would boil out, and I even had it blow a seal on the gearbox high up in the sierras. Installed the cooler and it solved all of my problems.

I’ll be running the dual pass heat sink style on my Bronco due to mounting space.

 

[Yeller]

Stacked plate is my preference for engine and trans cooling, however my favorite transmission cooler is for ford 6.0 and 7.3 trucks, always does the job, the 7.3 version fits EB’s better. Power steering gets what fits, I typically use a heat sink style but when room is a premium a tube/fin unit gets the nod.

I’ve found the fan wash is enough to keep my power steering in check with a very small tube and fin unit mounted next to the pump. My bronco has a heat sink style mounted next the the spring bucket and it never has an issue either.

 

[Broncobowsher]

There is also the header tank, looks like a radiator.
Another is a tube with little coils on it, sort of like a fin tube but only a single pass.
There are some OEM coolers I really like. Nissan trucks and vans have a double pass stacked plate cooler that has a thermostat built in. Reverse of the cooling system. When cold, open, allows bypass. As it warms up it closes and forces all the fluid through both passes.
And one more cooler that often gets overlooked, bare tubing. Ford has famously used this for decades. My dentside F250 had about a 6-pass serpentine of just bare metal tubing as a power steering cooler. Early 80s, 3 elongated loops on the lower crossmember. Crazy simple.

The fin and tube is low on my like list. I look at it as the first fin gets the most heat, conducts it to the outgoing tube with the coldest fluid. If I could cut half the fins to keep the heat from conducting to the outgoing fluid I would be happier.

Stacked plate is my go to choice. Robust design. Fluid gets flattened out and no channeling of hot fluid through the center while cool oil clings to the walls. No delicate fins.
Fin and tube can have corrosion issues where the heat won't conduct from the tube into the fin. That is where the surface cooling of the stacked plate is preferred by me. The headered tank design is a really good cooler, but more fragile as well.

Heat sink style. This is a flash in the pan choice. Drag race, the shear mass of that much volume takes that slug of heat. But the square inches of surface area and generally poor airflow make this a poor choice for sustained loads. Least cooling for the highest weight.

 

[AZ73]

Interesting topic since I'm in the process of mounting mine now. AGR built my heavy duty steering box and high performance pump. They included a stacked plate with the kit.

 

[DirtDonk]

I’ve always preferred stacked plate style.
Back in the 70s and 80s and 90s I think the magazines had tech articles showing that it was the “best” design. But that was so far in the past I don’t remember what the criteria were.

Tube and fin have been used successfully for half of forever as well. Broncos came stock with a small tube and fin power steering cooler mounted right next to the pump.
But for more critical stuff, seems like the factory is used stacked plate.
From the early 60s the Corvair engine oil coolers GM used were stacked plate.
My 79 F350 has a stacked plate auxiliary transmission cooler (in addition to the one in the radiator) from the factory, and one of those multi loop single tube to the crossmember types that Broncobowsher was talking about.
If you have a place to put it, stacked plate always gets my vote simply because of its strength and resistance to damage. Especially if it’s going to go in the front grille area, or underneath somewhere along the frame.
Too much junk getting thrown up and bounced around for my liking.
Tube and fin might see more damage. At least to the fins…

 

[ntsqd]

There is a missed option out there. Setrab and BAT-Mocal make them. They are a stacked plate design, with a row of fins between each pair of plates. These are my preference in a liquid to air heat exchanger (HE). This is the HE that I'm using on the Wagon for it's aux trans cooler:

This replaced a heat sink cooler that the PO had used as the only cooler for the trans!

It's overkill, but since the Wagon now has Hydro-Boost on it I went with a similar design, though smaller HE for the PS system:

Can see the PS cooler that Broncobowsher mentioned in my pic below. Note the tubing on the front face of the under-engine cross-member. It is not the greatest of pic, but it's the only one that I have of it:

All of the trans cooler and PS return lines on the Wagon are aluminum, specifically because of the cooling effect that it has. One section of the PS system that is too close to an exhaust manifold has some of the Longacre thermally protective orange silicone & glass-wool insulating sleaving on it.

 

[DirtDonk]

Setrab is a name I haven’t heard in a long time. I had a good reputation, and I wouldn’t be a bit surprised if they were an OE supplier.
Looks like the perfect combo you have. Did you bend those lines? Looks pretty trick.

 

[ntsqd]

The stacked plates seem to have a lot more wetted surface than a tube & fin, so that is better at getting the heat out of the fluid and into the metal of the cooler. I feel that the row of fins does a better job of dissipating the heat in the cooler into the air than the small gaps/tunnels between the plates that the pure stacked plate design has. Counter that with I think that the pure stacked plate design is the most robust of all the designs mentioned in this thread. Except for possibly the loops of tubing.

I did bend those tubes, one of my past employers had me bending small tubing as a near daily job function. I've estimated that I've bent at least a mile of SS tubing, 20 feet at a time. I'm not as good at it as I used to be.

Those two coolers in place:

 

[toddz69]

Setrab is a name I haven’t heard in a long time. I had a good reputation, and I wouldn’t be a bit surprised if they were an OE supplier.
Looks like the perfect combo you have. Did you bend those lines? Looks pretty trick.

Setrab is top-notch. I'm not sure if they were ever an OEM supplier or not - I seem to recall that they might have been on Saabs?

In any case, they're now one of the zillion brands owned by Holley.

Todd Z.

 

[bronco italiano]

Using a stacked plate style for my sons Firebird. This fatbody cooler should be good to go

 

[ntsqd]

Setrab is top-notch. I'm not sure if they were ever an OEM supplier or not - I seem to recall that they might have been on Saabs?

In any case, they're now one of the zillion brands owned by Holley.

Todd Z.

Not sure, but I think the cooler that I'm using for the trans came off of a Ford. It had Ford-ish looking OEM bracketry on it when I started and the fluid ports are inverted flare, not NPT.