For years now we have seen manufacturers produce transmissions without a conventional fill pipe and check level stick, which we know as the dipstick. Still to this day it becomes a conversation on the technical help line and seminars with mixed opinions regarding the subject. Some find it to be a nuisance, while others like it as not every car owner will be inclined to change the transmission fluid on their own. The question asked more often than not is why manufacturers have gone this route. I have heard many theories about it. One was that the transmissions were shipped to the assembly line prefilled. This improved assembly line procedure both in time and fluid fill accuracy. Another was a cost-saving factor of not having to produce these parts. Another was related to “Lifetime Transmission Fluids” eliminating the need for it. Yet another was to prevent pollution from spills. And finally, another was that owners neglect checking fluids so they do not need them. Perhaps there are other possibilities that I have not listed, which you may have heard. But for whatever the reason, the reality is that with each passing year there are an increased number of transmissions without dipsticks. Some manufacturers are providing a fluid level sensor to present a digital display of the fluid level. This has yet to catch on with most manufacturers and certainly does not bring back the dipstick. But at least one would know in time if a small leak had developed.
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Knowing the return of the dipstick is only a pipe dream, it becomes necessary to learn how to fill a transmission to its proper level. There are similar procedures among the manufacturers so when you get the gist of it, you can just about figure out what needs to be done. This does not eliminate the need to track down specific fill procedures, as there are nuances (or nuisances) to be aware of. Some of these nuances relate to a complete dry fill of the transmission to a simple fluid and filter change.
Generally speaking, you begin with an initial fill. Once the transmission is close to being full, most systems will require specific fluid temperatures to be reached to fine tune the level. Sometimes this may also require engagements into gear before the level is checked. The locations for draining, fluid fill and level check is where the variety of differences primarily arises, ultimately influencing the procedures involved.
Using a Nissan CVT7 transmission as an example, located on the bottom pan is a 19mm drain plug. But when it is removed, located inside the threaded area, an internal tube with a hex head bolt will be seen (Figure 1). This is the check-level or “overflow” pipe (Figure 2). This check-level pipe can be removed (Figure 3), allowing the location to double as a drain plug.
The manufacturer’s procedure begins with the disclaimer to use Genuine Nissan CVT Fluid NS-3. The specification for a complete fill is 6.9L (7 ¼ quarts). The procedure to fill and check the transmission is quite extensive and requires a special tool called the charging pipe, part number KV311039S0 (Figure 4). The charging pipe screws into the check-level overflow pipe area. This will require the ability to pump fluid up into the transmission from this location.
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