KD18 Advice before purchase

These are great machines and wash like crazy when operating properly and fed the proper temp water and detergent but there's a few things required for great results and longevity.

The 18 models do not preheat the water nor stall the timer during their fast wash cycles so they need 150F water at the faucet tap (KA recommends 140-160 but 150F provides much better results) to operate well, generally requiring you to crank up your water heater to 160F, especially if there's a long hot water line run to the dishwasher from the water heater. These dishwashers were designed with hot water, phosphates, and bleach for their quick cycles, not enzyme based detergents that were forced upon us starting in 2008.

Common problems with these machines pushing 50 years old:

Water valve underfilling. There a single valve replacement that's still readily available. There's also a goofy square seal on the original dual valve that leaks after 5 decades and there's no replacement for it, the entire valve has to be replaced. Part# 4171000

Seal and impeller replacement. When the lower seal goes out, water makes its way down the motor shaft and takes the bearings out in the motor. Replacing the seal will guarantee this doesn't happen. Always replace before the leak occurs or it's too late and its a matter of time before the motor needs replacement....and they are EXPENSIVE. I've never been inside a 18/19/20 series KA that didn't have glass in the sump which tears up the drain impeller. The seal and impeller come as a kit. Hobart wants $300 for this kit (was $50 like 10 years ago) now but I know of some old NOS ones for $10 using the old part#.

Worn upper wash arm support. At 50 years old, most of these are worn out. The wash arm rides on the upper support bearing also wears out, killing wash performance. These can still be found but getting tricky since they were obsoleted a quite a long time ago now. I know of NOS wash arm supports and wash arms.

Upper constant rinse is sheared on most of these from people not paying attention to upper rack items. The original design was kind of weak and broke easily, the newer design is more sturdy and available on Ebay. Virtually all of these machines have a missing the constant rinse.

Spray arm delivery tube. There's a flexible blue tube that runs to the upper wash arms that deteriorates overtime and causes washing problems. These were obsoleted and getting very hard to find a few years back but it looks like someone is remaking them. They're probably aftermarket parts using the old part# so keep that in mind. Part# 4171544.

Accordion seal. There's an accordion seal that mates with the upper rack delivery tube that deteriorates/rips overtime. They're impossible to find and have been for many years now. Only used on 18 series dishwashers, redesigned for 19+ models. I have an NOS seal and want to use it as template for making new ones.

The upper rack on the 18's had a shorter wash arm that was replaced with a longer wash arm beginning with the 19 series. Stealing 19 to 20-somthing series upper rack is generally preferred to the original short arm 18 series rack for better performance.

Not a bad idea to have a spare timer and control switch on hand. I know of an NOS timer and NOS program switch.

I have all of the part#'s for these but I won't post the Ebay links here as lurkers generally swipe the parts before the poster gets a chance. Email me directly and I'll send you the part#'s and Ebay links.


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Post# 1226993 3/22/2025 at 12:30 by OatmealMan (United States)
Checkrate/Likes I have the opportunity to buy a KD-18 that supposedly works. I hear these are highly regarded models. I was curious as to what type of maintenance or what to check for before using it. Also, how is part availability? What are common things that go wrong with them? Is it worth getting if parts aren't available? Any advice is appreciated, thanks!

Post# 1226996 , Reply# 1 3/22/2025 at 13:46 by qsd-dan (West)
Checkrate/Likes These are great machines and wash like crazy when operating properly and fed the proper temp water and detergent but there's a few things required for great results and longevity. The 18 models do not preheat the water nor stall the timer during their fast wash cycles so they need 150F water at the faucet tap (KA recommends 140-160 but 150F provides much better results) to operate well, generally requiring you to crank up your water heater to 160F, especially if there's a long hot water line run to the dishwasher from the water heater. These dishwashers were designed with hot water, phosphates, and bleach for their quick cycles, not enzyme based detergents that were forced upon us starting in 2008. Common problems with these machines pushing 50 years old: Water valve underfilling. There a single valve replacement that's still readily available. There's also a goofy square seal on the original dual valve that leaks after 5 decades and there's no replacement for it, the entire valve has to be replaced. Part# 4171000 Seal and impeller replacement. When the lower seal goes out, water makes its way down the motor shaft and takes the bearings out in the motor. Replacing the seal will guarantee this doesn't happen. Always replace before the leak occurs or it's too late and its a matter of time before the motor needs replacement....and they are EXPENSIVE. I've never been inside a 18/19/20 series KA that didn't have glass in the sump which tears up the drain impeller. The seal and impeller come as a kit. Hobart wants $300 for this kit (was $50 like 10 years ago) now but I know of some old NOS ones for $10 using the old part#. Worn upper wash arm support. At 50 years old, most of these are worn out. The wash arm rides on the upper support bearing also wears out, killing wash performance. These can still be found but getting tricky since they were obsoleted a quite a long time ago now. I know of NOS wash arm supports and wash arms. Upper constant rinse is sheared on most of these from people not paying attention to upper rack items. The original design was kind of weak and broke easily, the newer design is more sturdy and available on Ebay. Virtually all of these machines have a missing the constant rinse. Spray arm delivery tube. There's a flexible blue tube that runs to the upper wash arms that deteriorates overtime and causes washing problems. These were obsoleted and getting very hard to find a few years back but it looks like someone is remaking them. They're probably aftermarket parts using the old part# so keep that in mind. Part# 4171544. Accordion seal. There's an accordion seal that mates with the upper rack delivery tube that deteriorates/rips overtime. They're impossible to find and have been for many years now. Only used on 18 series dishwashers, redesigned for 19+ models. I have an NOS seal and want to use it as template for making new ones. The upper rack on the 18's had a shorter wash arm that was replaced with a longer wash arm beginning with the 19 series. Stealing 19 to 20-somthing series upper rack is generally preferred to the original short arm 18 series rack for better performance. Not a bad idea to have a spare timer and control switch on hand. I know of an NOS timer and NOS program switch. I have all of the part#'s for these but I won't post the Ebay links here as lurkers generally swipe the parts before the poster gets a chance. Email me directly and I'll send you the part#'s and Ebay links.

Post# 1229550 , Reply# 2 4/22/2025 at 11:49 by newvista58 (Northern NJ)
Checkrate/Likes *THANK YOU...* For this information. Very Helpful.