KitchenAid/Hobart KDP-20 Not Rinsing Well

First thing to check is that the dishwasher is filling to the proper level. This dishwasher is time filled. Buildup occurs on the inlet screens of the water valve overtime causing a restriction, especially under hard water conditions, and the dishwasher will underfill. Water should crest just over the filter once it stops filling. If the water level is below this height, it's underfilling and a new water valve needs to be installed. Water Valve Part# WP4171000.

Speaking of filter, you have cleaned the filter, yes? Most who never read the instruction manual or are not the original owner(s) are unaware that the filter should be cleaned after each load. Check for any calcium buildup.

Remove the upper spray arm water deliver tube in the upper rack and carefully inspect for cracks, signs of deterioration, and a loose fit. Part# 4171544.

Give the lower wash arm a good hefty spin. If it chatters, the wash arm support and/or wash arm bushing are worn. This is common at this age with heavy use and will drastically cause performance issues. Remove the wash arm and inspect the wash arm support bearing. It should be rock solid with no lateral or vertical movement. The newer wash arm supports have been redesigned for better wear characteristics. Wash Arm Support Part# 4162724. Wash Arm Part# 4161484.

The cycles in these dishwashers are FAST. They're designed for HOT water and heavily phosphated detergent that contains chlorine bleach. NO PODS, they will sudslock the machine in under 2 minutes even with rock hard water conditions. No liquids, they will leak out of the dispenser. You may squeak by with liquid in the pre wash cup but the main wash cup will be nearly empty by the time the main wash cycles begins.

The detergent cups in these are designed for powdered detergent ONLY. No enzyme based detergents in these machines, the cycles are far too short for enzymes to do their job. Until recently, Cascade Fryer Boil Out detergent was best option as this was the formula originally designed for these dishwashers using both phosphates and chlorine bleach. This formula has recently been discontinued. You will need to find a powdered detergent with chlorine bleach and add STPP in each cup.


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Post# 1155946 8/4/2022 at 15:21 (628 days old) by Pikespeakdad (Colorado)
Checkrate/Likes We inherited a KDP-20 Patrician model dishwasher with our new house and have noticed that it leaves white specks on all of our glasses to the point where they don't look clean at all. Does anyone have any tips on maximizing it's efficiency? We're using Cascade liquid detergent, could that be the culprit? Thanks from a young guy who loves old machines.

Post# 1155963 , Reply# 1 8/4/2022 at 19:13 (627 days old) by combo52 (50 Year Repair Tech Beltsville,Md)
Checkrate/Likes *White spots and film on dishes* The cascade liquid detergent could definitely be a problem unless you have very soft water. But on a dishwasher this age it�s likely you also are not getting enough water in the machine or it has other problems, try using a premium pod in the second dispenser on the right and see if it improves perform significantly if not read up on some of the forums about this dishwasher for reasons they don�t wash well. John L

Post# 1156038 , Reply# 2 8/5/2022 at 11:30 (627 days old) by Tomturbomatic (Beltsville, MD)
Checkrate/Likes Also check the condition of the vinyl tube that delivers water to the upper wash arm. If it is not in good shape you won't get adequate water to the top rack if the lower rack is filled with pots and bowls that block water to the upper rack. Another thing to remember is that beginning with the 19 series, KA DWs only give one after rinse so it is best not to use the thick liquid Cascade because it leaves deposits in one rinse machines. If you like to play with water, there is a purge after the main wash in these machines. It fills with one quart of water to flush the filter. Once the machine has filled, open the door and quickly pour in 3 quarts of hot water then restart it. That will give the machine a gallon of water in the sump, enough to give the pump enough pressure to rinse the top rack. The drain period is long enough to pump out the gallon of water. This procedure will probably give you adequate rinsing while you are finishing up the Cascade. Make sure your rinse agent dispenser is filled and operating properly.

Post# 1156055 , Reply# 3 8/5/2022 at 13:27 (627 days old) by chachp (North Little Rock, AR)
*This post has been removed by the member who posted it.*

Post# 1156057 , Reply# 4 8/5/2022 at 13:30 (627 days old) by chachp (North Little Rock, AR)
Checkrate/Likes 1 *Wasn't that the 21 Series* I thought the single rinse came along in the 21 series machines so I checked the guide. My KDS-20 had more than one rinse and it looks like the KDP does too. Here is the cycle data for the 20 series. Definitely check the water supply tube to the upper rack. Mine split one time and it wasn't easily noticeable. View Full Size

Post# 1156065 , Reply# 5 8/5/2022 at 14:29 (627 days old) by qsd-dan (West)
Checkrate/Likes 3 *KA Perfornace Issues* First thing to check is that the dishwasher is filling to the proper level. This dishwasher is time filled. Buildup occurs on the inlet screens of the water valve overtime causing a restriction, especially under hard water conditions, and the dishwasher will underfill. Water should crest just over the filter once it stops filling. If the water level is below this height, it's underfilling and a new water valve needs to be installed. Water Valve Part# WP4171000. Speaking of filter, you have cleaned the filter, yes? Most who never read the instruction manual or are not the original owner(s) are unaware that the filter should be cleaned after each load. Check for any calcium buildup. Remove the upper spray arm water deliver tube in the upper rack and carefully inspect for cracks, signs of deterioration, and a loose fit. Part# 4171544. Give the lower wash arm a good hefty spin. If it chatters, the wash arm support and/or wash arm bushing are worn. This is common at this age with heavy use and will drastically cause performance issues. Remove the wash arm and inspect the wash arm support bearing. It should be rock solid with no lateral or vertical movement. The newer wash arm supports have been redesigned for better wear characteristics. Wash Arm Support Part# 4162724. Wash Arm Part# 4161484. The cycles in these dishwashers are FAST. They're designed for HOT water and heavily phosphated detergent that contains chlorine bleach. NO PODS, they will sudslock the machine in under 2 minutes even with rock hard water conditions. No liquids, they will leak out of the dispenser. You may squeak by with liquid in the pre wash cup but the main wash cup will be nearly empty by the time the main wash cycles begins. The detergent cups in these are designed for powdered detergent ONLY. No enzyme based detergents in these machines, the cycles are far too short for enzymes to do their job. Until recently, Cascade Fryer Boil Out detergent was best option as this was the formula originally designed for these dishwashers using both phosphates and chlorine bleach. This formula has recently been discontinued. You will need to find a powdered detergent with chlorine bleach and add STPP in each cup.

Post# 1156067 , Reply# 6 8/5/2022 at 15:36 (627 days old) by Tomturbomatic (Beltsville, MD)
Checkrate/Likes Sorry, it was the constant rinse that was removed in the 20 series. I had a KDSS21 with the one rinse that I bucket fed.

Post# 1156068 , Reply# 7 8/5/2022 at 15:40 (627 days old) by qsd-dan (West)
Checkrate/Likes 18 series was the last Hobart Kitchenaid dishwasher with a constant rinse. Single rinse machines began with the 21 series.

Post# 1156150 , Reply# 8 8/6/2022 at 11:13 (626 days old) by valvashon (Seattle, U.S.A.)
Checkrate/Likes First picture is of a complete fill in a KDI-58, looking at the right rear corner where the fan vent thing is. That should give you some idea of how much water should be in a complete fill. "qsd-dan" is correct about where the water level should be but this fill level was easier for me to see and take a picture of. Mine fills to the point of having the float switch trip so I'm reasonably sure it's filling properly. Second picture is of the "Cleancult" dishwasher tablets that we use. We were using them in our Bosch before we traded it out for "Phil" (the KDI-58) and they work really well. No suds lock, clean dishes with just some occasional grease spots on the non-stick pans used for cooking burgers, eggs, etc. This is probably due to the somewhat low water temp that Phil encounters. I need to turn the water heater up again; Phil is the farthest thing from the water heater and supplied through un-insulated galvanized pipes. If it's ever even 130� in there I'd be surprised. Even with the lower water temps these things get the dishes quite clean. I usually break them into 4 pieces (leaving it in the wrapper) and put it into the main wash compartment. FYI, they aren't cheap but they are easy on the environment and the packaging is 100% recyclable. Photos... < > Photo 1 of 2 View Full Size

Post# 1156178 , Reply# 9 8/6/2022 at 14:59 (626 days old) by qsd-dan (West)
Checkrate/Likes The 18/58 series dishwashers have a 3 gallon fill (except for rinse and mold and the final rinse, those are 2 gallons). The 19 and 20 series KA's fill with 9 quarts (2.25 gallons).