Vehicles equipped with the Allison 1000/2000-series transmission may exhibit a complaint of transmission fluid overheating or no engagement before or after overhaul. The customer may complain of a trans-temp light being illuminated or the trans-temp gauge reading near 300° F.
The cause may be a restricted transmission cooler and/or an incorrectly positioned stator shaft, or “ground sleeve” as it is named by Allison. To verify, check cooler flow on the ports shown in Figure 1. If the ports are reversed, with the “from cooler” fitting pumping oil to the cooler, you will need to remove the transmission and check the alignment of the stator shaft.
Check the cooler, and if there is a restriction replace or repair as necessary. If the cooler is free and there is no cooler pressure or the ports are reversed, remove the transmission and pump assembly and refer to Figure 2 to check the alignment of the stator shaft in the pump cover. Figure 2 shows the two holes visible in the passage identified as converter in.
Figure 3 shows the stator shaft removed from the pump cover. Notice that there are no splines in the cover, as the stator shaft is pressed into the cover; if the shaft turned once it will turn again. DO NOT REUSE.
Figure 4 shows passage identification for the pump cover. Notice that the converter in, converter out and from cooler/lube passages are right next to each other. This area is where the connection is made when the stator shaft rotates. It is also possible for the stator shaft to rotate and close off the passages altogether, causing no engagement.
A Ford truck equipped with a 5R110W transmission may come into the shop storing codes P2700, P2701, P2702, P2703 and/or P2704, indicating that one or more of the shift friction-apply elements are taking too long to apply to zero clearance. In this instance code P2702 was stored with a scan-tool definition of “Transmission Friction Element C Apply Time Range/Performance.”
The vehicle also exhibited complaints of a delay into drive and a flared 1-2 shift; the transmission was in limp mode and the Tow/Haul lamp was flashing.
The intermediate-clutch solenoid was mechanically faulty, resulting in the TCM not seeing the correct second-gear ratio when second gear was commanded.
Replace the intermediate-clutch solenoid.
It should become standard rebuild procedure to check for fit and tightness of the solenoid stem in the body, because the stem is just crimped into the solenoid body (Figure 5). The solenoid may look good, but separating the stem from the body may require little pulling effort.
Figure 6 shows solenoid identification.
If this fault should happen to the line-pressure-control solenoid, slipping and gear-ratio codes may be stored. If this should happen to the TCC solenoid, converter-clutch slippage may occur and code P1744 or P0741 may be stored.
- Line-pressure-control solenoid. . . . . . . . . . 4C3Z-7G383-AA
- Direct/coast-clutch solenoids . . . . . . . . . . . 3C3Z-7J136-AA
- L/R, intermediate, overdrive & TCC solenoids . . . . . . 3C3Z-7J136-BA
After installation of an auxiliary transmission filter, the truck returns to the shop with the rear planets destroyed by lack of lubrication.
An incorrect filter application was installed.
When flow was checked from the transmission to the auxiliary filter, flow was very good, but from the filter assembly to the radiator there was none. With no cooler flow TO the transmission, no rear lube will be delivered to the gear train.
This auxiliary-filter assembly is not installed at the factory. It is a dealer-installed option (Figure 7). This filter is available only from an Isuzu medium-duty-truck dealer. If you try to buy one from an aftermarket source, what you will receive is an engine-oil filter with a one-way checkvalve. This filter flows in the opposite direction.
To make this after-market filter work you need to switch the cooler lines at the auxiliary-cooler manifold (Figure 8). The alternative is to use the OE filter from Isuzu.
Verify proper cooler flow after repairs!
- 1988-1998 Isuzu N-series diesel auxiliary filter. . . . . . . 97182282
After replacement of the transmission spin-on filter, the transmission now overheats after a short time. Solenoid performance or gear-ratio codes may be stored as well.
A poor-quality spin-on filter was installed, allowing the filter magnet to restrict cooler flow because it has a smaller feed-hole radius (Figure 9). A quality filter will not allow the filter magnet to restrict cooler flow because it has a larger feed-hole radius that the magnet cannot cover.
The solenoid-performance or gear-ratio codes can be stored as a result of the created restriction causing a drop in line pressure. Figure 10 identifies passages in the cooler manifold to which the filter attaches.
Figure 11 shows the spin-on filter and its related parts.
When replacing the spin-on filter, be sure to use one that has a large feed-hole radius.
- Original equipment spin-on filter . . .29539579
- Filtran spin-on filter . . . . . . . . . .F-349
February 2013 Issue
Volume 30, No. 2
- Allison 1000/2000: Transmission fluid overheating or no engagements
- Ford 5R110W: Solenoid failure
- JR403E, 1988-98 Isuzu N-series trucks: Rear-lube failure
- LCT1000/2000: Transmission overheats
