Most of the work in a Partial Fill happens before the epoxy can is even opened, and the material doing it comes from the baking aisle. A bag of ordinary sugar decides how deep your EPOXY54 layer will be, keeps epoxy out of the lower water jacket, and then washes away so coolant can flow again. Get the sugar stage right and the pour itself is the easy part. This guide covers the sugar method on its own: what it does, how to set it up, and how to get every grain back out.
What the sugar is doing in your water jacket
An open-deck water jacket is a deep channel around the cylinders, open at the top. A Partial Fill only wants epoxy in the top ¾" of that channel, where it ties the tops of the cylinders to the outer block. Everything below needs to stay hollow so coolant can keep circulating, the way it does in a factory closed deck. How Does the Engine Cool After EPOXY54? explains that layout.
Liquid epoxy can't hang in mid-air, so something has to sit underneath it while it cures. That something is a temporary solute: sugar or salt. It acts as a removable floor. It holds the epoxy at the right height, and once the epoxy has set, water dissolves the floor away and leaves a hollow jacket under a solid cap. The glossary of engine block terms has the one-line definition; this guide is the hands-on version.
The EPOXY54 Installation Guide is written around sugar, so that is what we describe below. Salt is named as an alternative on the product page.
What to have on the bench before the first scoop
Everything in this list comes from the installation guide or the kit listings. Lay it out before you start, because the sugar stage and the pour run back to back.
- Sugar (or salt), enough to fill the jacket to within ¾" of the deck. It isn't included in any kit.
- Masking tape and a hobby knife for the coolant ports and the deck surface. Also not included.
- Red Scotchbrite and brake cleaner for cleaning the jacket walls first.
- A heat gun to warm the jacket surface.
- A level for the deck surface.
- Calipers to check the sugar depth.
- A stir stick, squeeze bottle and drill bit. The EPOXY54 Install Kit bundles these if you don't have them.
- The head gasket you will actually run. It becomes your drilling template after the cure, so have it in hand now, not on back order. Browse head gaskets if it isn't bought yet.
- A garden hose for the washout.
Setting the floor: sugar to ¾" below the deck
The guide's order matters here, because each step protects the next one.
Clean, warm and tape first. Scuff and clean the water jacket surface, then warm it with the heat gun until it's warm to the touch. Tape off the coolant ports so neither sugar nor epoxy can wander into them. Then tape the deck surface and cut the water jacket outline out with the hobby knife, so only the jacket opening is exposed.
Level the block. Put the level on the deck surface. The sugar will settle to whatever the block's attitude is, and so will the epoxy, so a tilted block means a cap that's thicker on one side than the other. On a V engine, each bank is leveled and filled on its own; Two Banks, Two Pours covers that.
Fill and measure. Pour sugar into the jacket until it sits about ¾" below the deck surface, then confirm the depth with calipers. Check more than one spot around the bores. If the sugar is too high, the cap ends up thin; if it's too low, you use more epoxy than the job needs and the cap reaches further down the jacket than a Partial Fill is meant to.
The pour sits on the sugar
Once the floor is right, the epoxy goes on top. Mix all of the hardener with all of the epoxy in the can; the guide says not to split the batch. Stir for about 2 minutes, until the mix is completely blue. From that moment you have about 25 minutes of working time.
Transfer the mix to the squeeze bottle and pour it evenly over the sugar in layers until it reaches 1 to 2 mm below the deck surface. About 30 minutes after pouring, pull the deck tape and clean up any spills. Then leave the block alone and let the epoxy cure for the time the installation guide gives before you touch the sugar again.
Drill first, then wash
It's tempting to reach for the hose as soon as the epoxy is hard. Don't. The cured cap now sits over the coolant passages, so they have to be reopened first.
Lay the head gasket over the block, mark the coolant passages with a marker, and drill through the cap at each mark using the bit size the installation guide calls for. The gasket is the template because those holes have to line up with the passages into the head. This is also why it pays to settle on your gasket before pour day.
Getting every grain out
With the holes drilled, flip the block upside down and run a hose into the main water port. Keep rinsing until all the sugar has dissolved and only clean water is flowing through the water jackets. Take your time here; the job isn't done while the water still carries sugar.
What's left is a hollow lower jacket under a solid epoxy cap, with passages drilled through it where the head gasket says coolant should go. If you planned machine work, the guide puts it after this step. EPOXY54 can go in before or after machine work without affecting dimensional accuracy, according to the product page.
Quick answers about the sugar step
Do I need sugar for a Dry Block? The solute is a Partial Fill step. A Dry Block fills the jacket completely and is for track use only, so instead of setting a sugar floor you measure the jacket volume with water to size the kit. See How to Measure the Right Amount of EPOXY54 for a Dry Block / Full Fill.
Sugar or salt? Both are listed as the temporary solute. The step-by-step guide uses sugar, which is why this post does too.
Is the sugar in the Install Kit? No. The kit has a stir stick, drill bit and squeeze bottle; sugar or salt and masking tape are on you. What the Install Kit is (and isn't) has the details.
Will this work on my block? If it's open deck, EPOXY54 is designed for it. Open Deck vs Closed Deck Block shows how to tell, and Seven Block Filler Myths clears up the usual worries about cooling. Parts for your engine are under Shop by Platform.
Ready to pour?
EPOXY54 brings 21,000 psi compressive strength and a thermal expansion rate closely matching aluminum, giving you closed-deck strength without machining in a DIY install. Pick your engine configuration and Partial Fill on the EPOXY54 product page, buy a bag of sugar, and keep the installation guide open on the bench. Questions before you order? Email support@epoxy54.com.