No. That is different. I should have specified. They look like this and mounted in front of the radiator (or got zip tied any number of places in the front...)
The "switch pitch" creates more heat with the converter, especially in heavy stop and go traffic or a car that sees "spirited driving" with an engine that is putting out more power than stock. So, a good cooler is imperative to have. (You can use both and external and the one in the radiator connected in series) Heat and/or low fluid pressure will kill an auto transmission very quickly. The result is clutches fail to apply quickly or maintain apply and slip, burning the plates and glazing the friction discs, and once that occurs, it just becomes exponential in damage. If it is caught early, it is mostly "consumable" (parts in most rebuild kits) that are lost, and if it goes on too long, "hard parts" planet, sun, ring gears, pump gear and housings start failing and those can be expensive as well as hard to find. Your transmission guy should see evidence when he drops the pan. But if you get a good unit that operates correctly, you will be very happy with it.
Lots of good information in this thread, https://www.v8buick.com/index.php?threads/transmission-cooler-recommendation.299758/ As far as the stock radiator cooler, see JW's post #57 in page 3 of the above linked thread, https://www.v8buick.com/index.php?threads/transmission-cooler-recommendation.299758/page-3
It's in the shop now. He was able to get it up to temp and felt the slip. The plan now is to eliminate the stock cooler in the radiator and install a high quality fan cooled external cooler.
After replacing the clutch packs right? They're likely fried, the frictions can't tolerate that kind of slippage. Absolutely no reason to leave everything alone and rely on an external cooler at this point, damage has already been done. The question is "why"? Buick put thousands of these things on the road without an external cooler. The answer is most likely that something went wrong with your rebuild. Devon
There is nothing wrong with the built in cooler as designed. A more relevant question is Is the trans builder standing behind his work? The cooler in the radiator is weak, but adequate for stock configured cars. It's also EXTREMELY unlikely to fail in my experience. The person who worked on your transmission failed at their job and should do it over for free. If this is the same person selling you an external cooler, expect more pain.
Those transmissions lasted well over 100,000 miles with a factory transmission cooler... switch pitch or not.
The VP converter is not that loose even in high stall mode. It definitely would not get hot enough to ruin a transmission in a few thousand miles. the other thing to keep in mind is the transmission cooler is located on the side of the radiator that has cooled water. So this means it's probably 130° water and not engine temperature water
Slip is not cured with a bigger cooler. I would check if the pressure (that engages the clutches) is too low, could be a broken spring in the pressure regulator. Bruce Roe
Heat and low pressure/volume. (and filth/trash sticking valves/cutting seals) Will kill an auto, 2 or all, will do it faster. The shop screwed up somewhere.
The leak was found. It's the front pump seal. Also the pump was making quite abit of noise as if the bearing is dry. I think it is quite possible that the trans will end up getting pulled.
