GE cycle times and multiple rinses
GEs always had a strange timing sequence, even in the 70s which I will get to. The multiple water change outs were for three reasons imo: carry over water, no filter and temperature. GE machines always had the highest carry over water for vintage machines and still do to this day for modern ones. The carry over lowers water temperature and brings over extra soil/detergent residue to the new fill, so extra water is required to compensate. Over the years GE reduced the size of the sump inlet (plastisol machines had massive sunken inlets), smaller sump boots and smaller pump bodies in an effort to lower the total water usage.
Heres where it gets strange. First, GE has always stated the extra open detergent cup was for a Pre-wash, however GE machines in most cases had a very short first prewashes with the following ones actually being much longer. For example, mid 80s porcelain Hotpoints had a 1 1/2 minute prewash (end of fill to pull in of drain solenoid), while the second prewash was 3 1/2 minutes long. The 3rd before the main wash was 1 1/2 minutes long. It always boggled my mind why the mid prewash was the longest.
Early to mid 80s BOL Perma-Tufs had 3 equal 2 minute prewashes before the main wash. However in the late 80s the sequence was tweaked. GE made the first prewash 3 1/2 minutes long, the second one 1 1/2 minutes with a reduced fill. So far so good and it makes sense. However, get this, the 3rd prewash is 4 1/2 minutes long... By then most of the detergent has been flushed out, so why make this the longest prewash? Why not have the 4 1/2 minute prewash at the start? Better yet why not have the first prewash at 5 1/2 minutes and then have the other two 1 1/2 minutes just to flush everything out while bring the machine up to temp?
Also interesting is the rinse paradox which I guess was a failed attempt at water conservation. In the 70s GE machines had 7 water change outs in normal cycle with each fill around 2.5 gallons. Then starting with their porcelain Hotpoints it went down to 6 water change outs and each fill was reduced to about 1.9 gallons for a total water usage around 11.4 gallons per cycle. This then carried on to their first model C Perma-Tufs. In the late 80s GE made a change. First, their Perma-Tufs added an third partial post main wash rinse. I say partial, because it was only a 45 second fill rather then the typical 64-66 second fill with a rapid pump out after. If anything it was simply like a purge. They then took 2 seconds away from each fill, and made the second prewash fill 56 minutes. IMO this was to shift water consumption to the added rinse. 5 fills were shortened by 2 seconds giving a total bought time of 10 seconds; the 2nd prewash from 66 to 56 giving 10 seconds so in total 20 seconds of fill time removed from all 6 fills. 15 seconds were added to those 20 seconds to give a 45 second post main wash rinse (purge). Assuming a fill rate of about 0.0287 gallons per second, 15 seconds adds an extra 0.43 gallons of water. This brought the total water usage from 11.4 gallons to 12.1 gallons on the late 80s Perma-Tufs. For the porcelain Hotpoints they simply shifted one prewash to the post main wash rinse give a sequence of W-R-MW-R-R-R at 11 gallons of water, latter shortened a bit to 10.7 gallons in the earlly 90s before finally being discontinued.
In order to compensate for the extra rinse and extended prewash times on the Perma-Tufs, they took 5 minutes away from the dry time. In fact, normally the heater contact opens during the pump out, but they omitted that so drying can take a head start. The motor on earlly Perma-tufs shut off at about 51 minutes and then 57 minutes on the latter versions. Those extra 5 minutes of drying really made the difference. I guess GE then had complaints about drying as there late 90s models all got their 35 minute dry time back.
Anyway, to support everything I said here are the cycle sequences to a GSD500D, GSD500G, and a 1985 BOL porcelain Hotpoint.
