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Part# AN4062-1
MFR Model# MS27215-2


These plugs are used to prevent rust and corrosion in engines while in storage. Contain silica gel which turns from blue to pink when moisture is absorbed. Reusable and refillable. The pink silica gel may be reactivated (after removing from reservoir) by heating for 16 hours at 250F.

DISCOUNT: LESS 10% ON 25, 15% ON 50, 20% ON 100.

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The Dehydrator plugs perform as expected. Very good product.

Scott K
February 16, 2021

The ones I purchased many years ago are great. No problems screwing them in the spark plug holes. I dont know about the latest versions and the present day quality control. The main things Im disappointed with is, the lack of parts for them especially the rubber gaskets, as they dont seem to last especially when exposed to oil.

December 23, 2020

Just what I needed for the time between installing the exhaust on my experimental aircraft and first engine start. Gives some peace of mind as the clock ticks.

Mark E
February 28, 2019

John R
March 8, 2018

Used this dehydrator plug to replace the ones that came with the Tanis kit. Far superior quality, easy to refill dehydrator with fresh desiccant when needed. Definitely recommend this for engine preservation.

Dennis O
June 13, 2017

Ive used two different sets of these plugs and both sets fit so tightly that I couldnt turn them all the way in. I used an 18mm x 1.5mm pitch thread die to cut down the threads and the plugs fit tight against the gasket. After just a couple weeks, I can tell by the color of the desiccant beads that they seal much better than when new.

Donald M Verified Purchase


November 17, 2021

These plugs threaded ends are not accurately cast and will break if forced all the way in to seat in the spark plug boss. BUT there is a workable fix that is very effective. I use these plugs in my Taylorcrafts overhauled C85. As received the threads are oversize, the fit is excessively tight and hand threading is nearly impossible. On their first use, one of them broke off when almost fully seated screwed in the cylinder. A sharp knife wedged into the plastic extracted it. I then purchased n 18 MM thread cutting die, not a rethreading die but one for original cutting of new threads. Using this die, and an open end wrench I first removed the rubber gasket from each plug then holding the dessicant plug with my left hand, not a vise, I carefully screwed the die all the way on. You could see it cutting the plastic threads as it progressed. After the first cut I repeated it four more times using only my hand. Every plug, all eight of them, will now easily screw in by hand with a precise fit and fit all the way in to compress the plugs gasket, sealing it to the cylinder. If you do this, they work great. Every week or two weeks, I check them and if they are turning white, I change the dessicant. Very easily done now that they fit so well. I would have given these plugs 5 stars if I did not have to rethread each one, but it was simple, easy to do, cost effective and it works.

Randall R
January 28, 2021

I like using these if Im doing maintenance on my airplane that might take several weeks to complete. The plugs are easy to regenerate at low temp in a toaster oven (I remove the silica gel to regenerate and then pour it back in when done). The units do not thread in very well, though - even on a new cylinder. Seems like I might get one thread or so engaged, but that is good enough to work well (doesnt seem to have a significant leak that causes fast deterioration of the desiccant.

July 19, 2019

Plugs work fairly well, only they dont screw in as easy as they should. I had mine in my engine for a year, and the silica slowly turned pink showing they were absorbing water vapor. It only took one hour in the oven to bring back the dark blue color....ready for use again. They are kind of fragile...handle with care.

Forrest M
November 8, 2018

I dont give the 5 stars only because my A&P had a little trouble installing them due to the rubber part doesnt turning easy. My husband had those installed years ago in another engine and he didnt have trouble. I dont understand.

July 25, 2017


Please note, Aircraft Spruce's personnel are not certified aircraft mechanics and can only provide general support and ideas, which should not be relied upon or implemented in lieu of consulting an A&P or other qualified technician. Aircraft Spruce assumes no responsibility or liability for any issue or problem which may arise from any repair, modification or other work done from this knowledge base. Any product eligibility information provided here is based on general application guides and we recommend always referring to your specific aircraft parts manual, the parts manufacturer or consulting with a qualified mechanic.

Q: Do the dehydrator plugs come with silica gel/desiccant or do you have to buy it separately?

The AN4062-1 Dehydrator plugs come with the silica gel / desiccant. It is sold separately in case customers need more gel but already have the plugs.

Q: What size are the threads for the dehydrator plugs?

The thread size is 18mm threads.

Q: Do you have 14 mm dehydrator plugs?

No. We do not stock 14MM dehydrator plugs, but if you let our sales staff know how many you need, we can try to special order them for you.

Q: Will I need 8 or is 4 sufficient?

It is our belief you would want one in every spark plug hole, but that would depend on the engine manual recommendations.

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