1995-1999 W Transmission Auxiliary Oil Cooler (KD1)
This document is a compilation of information collected from various sources regarding transmission fluid flow and installation of GM's auxiliary oil cooler for GM W-body vehicles. This document makes references to the 1997 - 2000 Pontiac Grand Prix. Sources include Steve Calbert, Frank Gore, Paul Jerkatis, John (UdoyupGTP), Mike Levy, and the GM service manual.
Understanding Fluid Flow
(Document ID # 598363)
Transmission Oil Cooler Description
"The transmission oil cooler is located inside the right side end tank of the radiator. Two quick-connect fittings on the outside of the outlet tank are connected to a transmission oil cooler located inside the outlet tank. Two transmission oil cooler lines are connected from the transmission to quick-connect fittings. A/T fluid is pumped by the transmission through a transmission oil cooler feed line to the transmission oil cooler lower inlet quick-connect fitting. The A/T fluid temperature is regulated by the temperature of the engine coolant that surrounds the transmission oil cooler as the A/T fluid passes up through the transmission oil cooler. The A/T fluid leaves the transmission oil cooler through the upper transmission oil cooler outlet quick-connect fitting and returns back to the transmission through the transmission oil cooler return line."
(Select to enlarge)
(Select to enlarge)
Steve Calbert's web page confirms the pipe/hose identification on the transaxle. The fluid feed line pipe has a U-bend, the fluid return line pipe does not.
Deciding Where to Connect the Auxiliary Oil Cooler
Consider the following before deciding where to connect the auxiliary cooler to the existing transmission oil cooler in the radiator to best suit your application:
- The auxiliary cooler is intended to be used in conjunction with the existing transmission cooler in the radiator, not instead of it
- Consider your engine coolant thermostat (stock is 195F, after market are 180F, 160F, etc.)
- Fluid should be forced up, against gravity, whenever possible, to minimize or eliminate foam or trapped air during fluid freefall
- If the auxiliary cooler is placed before the existing transmission cooler, the transmission fluid will be cooled to no lower than your engine coolant temp (195F stock); this may be desirable for those operating their vehicle in prolonged cold temperatures
- If the auxiliary cooler is placed after the existing cooler, the transmission fluid could be cooled to lower than the engine coolant temp (195F stock); this may be desirable for those operating their vehicle in prolonged hot temperatures or for frequent idling/slow speed operation; during colder weather, the transaxle may require a longer warm-up period before allowing upshift to D or OD
John (UdoyupGTP) posted a 1999 W-Body (Monte Carlo/Z34) transmission auxiliary cooler call-out diagram and part manifest at ClubGP on January 2, 2001. The call-out diagram shows that the auxiliary cooler connects to radiator transmission cooler lower inlet (feed line), which would imply that the auxiliary cooler is installed before the radiator cooler. (Transmission fluid cooled to no lower than engine coolant temperature.)
(Select to enlarge)
(Select to enlarge)
The GM service manual shows the following connection diagram, in which the auxiliary cooler connects to the radiator transmission cooler upper outlet (return line), which would imply that the auxiliary cooler is installed after the radiator cooler. (Transmission fluid could be cooled to lower than engine coolant temperature).
For the purpose of this document, the following are objectives:
- achieve maximum transmission fluid cooling (auxiliary cooler installed after radiator transmission cooler)
- use GM fitment recommendations
- do not use higher-cost AN connectors
Ordering the Auxiliary Oil Cooler Kit
Auxiliary cooler fitment:
Auxiliary cooler hose assembly:
Auxiliary cooler connection to return line
For a 2000 GTP, I ordered and received the following items for the 1999 W-body KD1 option (as researched by John "UdoyupGTP" and Mike Levy):
| Call | Part # | Description | Usage | Year | Qty | Total Cost US$ |
|---|
| 009 | 10416317 | HOSE, TRANS FLUID CLR LINE(W/PIPE TO AUX COOLER) | W(KD1) | 95-99 | 01 | 7.66 |
| 010 | 12337828 | SCREW,HEX W/FLAT WA(TRANS FLUID CLR PIPE CLIP) | | 95-99 | 02 | 0.70 |
| 011 | 10227107 | BRACKET,TRANS FLUID CLR PIPE | W(KD1) | 96-99 | 01 | 2.30 |
| 012 | 10254586 | PIPE,TRANS FLUID AUX CLR(UPR FROM AUX COOLER) | W(KD1) | 96-99 | 01 | 2.89 |
| 013 | 11517293 | NUT,HEX W/CON WA 6X1X5.5 OD ZP 9 (TRANS FLUID CLR) | | 95-99 | 02 | 0.58 |
| 014 | 10275682 | COOLER,TRANS FLUID AUX(AC-DELCO #10275682) | W(KD1) | 96-99 | 01 | 28.51 |
| 015 | 11513894 | BOLT,HEX W/FL WA,TAP,M8X1.25X20,6202M,POR,14.2 THD,TR FT,24 OD(TRANS FLUID CLR) | | 95-99 | 02 | 4.60 |
1999 W Transmission Auxiliary Oil Cooler Kit (picture by Mike Levy):
(Select for a larger view)
Installing the Auxiliary Oil Cooler
Auxiliary cooler fitment:
Auxiliary cooler hose assembly:
Auxiliary cooler connection to return line
Transmission fluid flow:
- transaxle feed to radiator lower
- radiator upper to auxiliary cooler lower
- auxiliary cooler upper to transaxle return
(to be completed)
Last Revision: Wed Feb 21 2001
