SuperCooler — Install Guide

GT40 Marine | SKU GT40-SD-SC-230300325 | Auxiliary Engine Bay SuperCooler | Rev 1.0 — 2026-05-24

Before You Start — SuperCooler vs Open Loop Cooling Decision

The SuperCooler is NOT the same as the Open Loop Cooling Kit (GT40-SD-OLC-300). The two address different cooling problems:

| Feature | SuperCooler (this kit) | Open Loop Cooling Kit |

|---|---|---|

| Purpose | Adds auxiliary cooling capacity to factory closed-loop system | Replaces factory closed-loop entirely with direct water flow |

| Install time | ~2 hours | ~4-5 hours |

| Reversibility | Reversible — can revert to stock | Irreversible — once installed, requires factory parts to revert |

| Required at | Stage 2 and above (recommended) | Stage 3 and above (mandatory above 280 HP) |

| Pairs with | Tubing kits, intake upgrades | Stage 3 exhaust, full Stage 3 builds |

| Saltwater service | Standard (no specific protocol) | Requires 5-min freshwater flush after every saltwater run |

If you are not certain which you need: SuperCooler is the lower-risk choice for Stage 2 builds. OLC is required for serious Stage 3+ builds.

Fitment

| Platform | Model | Year | Engine |

|---|---|---|---|

| Sea-Doo | RXP-X 230 / 300 | 2017–present | 1630 ACE 230 / 300 |

| Sea-Doo | RXT-X 230 / 300 / 325 | 2017–present | 1630 ACE 230 / 300 / 325 |

| Sea-Doo | GTX 230 / 300 / Limited | 2018–present | 1630 ACE 230 / 300 / 325 |

| Sea-Doo | GTR-X 230 | 2017–present | 1630 ACE 230 |

| Sea-Doo | Wake Pro 230 | 2017–present | 1630 ACE 230 |

Not for: 1503 4-TEC (different cooling architecture). Not for Spark (smaller engine, no auxiliary cooler benefit). Confirm engine code (1630 ACE) before install.

In the Box

• (1) GT40 SuperCooler heat exchanger, aluminum, marine-grade
• (1) Mounting bracket, billet aluminum, anodized black
• (2) Hose barbs, 3/4" NPT × 3/4" hose
• (4 ft) Reinforced silicone marine hose, 3/4" ID, blue
• (4) Stainless worm-gear hose clamps, #12
• (4) M8 × 25 mm SHCS — bracket mounting
• (4) M8 stainless flat washers
• (4) M8 nylon-insert lock nuts
• (1) NPT thread sealant tube, marine-grade
• (1) Tee fitting, brass, for splicing into factory cooling line
• (2) Spring hose clamps for the tee fitting splice
• (1) GT40 product registration card
• (1) This guide

Verify all components present before starting. Missing parts: support@gt40marine.com.

Tools Required

• 10 mm / 13 mm sockets + ratchet, 3/8" drive
• T25 + T30 Torx drivers
• 5 mm + 6 mm hex (Allen) keys
• 3/8" drive torque wrench, 5–25 Nm range
• Hose-clamp pliers (spring-clamp removal)
• Hose cutter or sharp utility knife
• Marine-grade thread sealant applicator
• Shop towels
• Flashlight or headlamp

Safety

Read in full before starting.

1. Battery disconnected for the duration of the install.
2. Cold engine only. Factory cooling system can be hot for over an hour after operation.
3. Eye protection when handling NPT thread sealant and cutting hoses.
4. Proper coolant capture. When you splice the factory cooling line, residual coolant will escape — capture in a pan and dispose properly.
5. No smoking / open flame.
6. Tee splice caution. The tee fitting joins the factory cooling line — install with care to avoid air pockets that can cause cooling-system airlock.

If you are not comfortable with PWC cooling system work, take the install to a certified marine technician.

Pre-Install Checklist

• [ ] Watercraft on stable trailer or stand
• [ ] Battery negative disconnected and isolated
• [ ] Engine bay clean and dry
• [ ] Factory cooling line routing photographed before disassembly
• [ ] Coolant capture pan positioned (1 quart capacity minimum)
• [ ] Marine-grade thread sealant ready
• [ ] Final SuperCooler mounting location identified — typically the upper-outboard engine bay wall, where airflow is best

Step-by-Step Install

Step 1 — Access the Engine Bay

Remove the seat and engine bay top hatch. Lift the rear storage bin on RXP-X / RXT-X.

Disconnect the battery negative terminal. Secure the cable away from the post.

Step 2 — Identify the Factory Cooling Line Splice Point

The SuperCooler splices into the factory cooling line at a single point. The splice introduces auxiliary cooling capacity without changing the factory closed-loop architecture.

1. Trace the factory cooling line from the engine block to the reservoir
2. Identify a straight section of the line at least 4 inches long, positioned to allow the SuperCooler to mount within hose reach (~30 inches)
3. Mark the splice point with a small piece of tape

Step 3 — Mount the SuperCooler Bracket

1. Position the GT40 bracket on the chosen mounting boss
2. Hand-thread the 4 M8 × 25 mm SHCS with flat washers and lock nuts
3. Snug all 4 evenly, then torque to 18 Nm (13 ft-lb) with a 6 mm hex key
4. Verify the bracket is plumb and the SuperCooler will sit horizontally (or with a slight outboard tilt for airflow)

Step 4 — Install Hose Barbs on the SuperCooler

1. Apply marine-grade thread sealant to the NPT threads on each 3/4" hose barb
2. Thread one barb into the SuperCooler inlet
3. Thread the other barb into the SuperCooler outlet
4. Snug by hand, then 1.5 turns with a wrench — do not over-torque NPT in aluminum
5. Confirm both barbs point in directions that allow clean hose routing

Step 5 — Splice the Factory Cooling Line

1. Position the coolant capture pan under the factory line splice point
2. Cut the factory cooling line at the marked point with a hose cutter or sharp utility knife — capture residual coolant
3. Slide a spring hose clamp onto each cut end
4. Insert the supplied brass tee fitting into the cut, with the tee branch facing toward the SuperCooler mount location
5. Secure both ends of the tee onto the factory line with the spring clamps
6. Verify no kinks in the factory line at the splice point

Step 6 — Route the SuperCooler Hoses

1. Measure the run from the tee fitting branch to the SuperCooler inlet
2. Cut the supplied 3/4" silicone hose to length, leaving 2 in. of service slack
3. Slide a #12 hose clamp on each hose end, push the hose onto the tee branch, then onto the SuperCooler inlet barb
4. Tighten both clamps to 3 Nm (27 in-lb) equivalent (snug, no hose-wall cut)
5. Measure the second run from the SuperCooler outlet back to a downstream junction on the factory cooling line
6. Cut the hose, route with #12 clamps on each end, tighten as above
7. Verify routing has no kinks, no contact with exhaust manifold, no zip-tie pinch

Step 7 — Top Off Coolant and Bleed Air

1. Open the factory coolant reservoir
2. Top off coolant to the factory fill line — this replaces the coolant lost during splicing
3. Squeeze the SuperCooler hoses gently to expel air bubbles from the new circuit
4. Top off again to the factory line
5. Replace the reservoir cap

Step 8 — Reassembly and First Start

1. Walk the engine bay — every clamp, every bracket bolt, every hose run
2. Confirm no tools, rags, or removed hardware remaining
3. Reconnect the battery negative terminal — torque to 10 Nm (89 in-lb)
4. Replace engine bay hatch, storage bin, seat
5. Connect the cooling flush hose
6. Start the engine on the trailer
7. Idle for 90 seconds — listen for any leak, watch for coolant migration at the tee splice
8. During idle, watch the coolant reservoir for any drop in level — top off if necessary as air finishes bleeding from the SuperCooler circuit
9. Scan with BUDS or compatible OBD diagnostic — no fault codes expected
10. After shutdown, visually inspect all hose joints and the tee splice for any seepage

If clean: install complete.

Post-Install

Break-In

No break-in cycle required. The SuperCooler begins providing auxiliary cooling capacity immediately.

Tuning

The SuperCooler is mechanical-only and does not require an ECU tune. It pairs well with Stage 2 and Stage 3 builds, increasing the thermal envelope for sustained full-throttle operation.

Service

• Inspect all hose clamps every 25 run hours — retorque if any have relaxed
• Inspect the SuperCooler external surface annually for any aluminum corrosion (rare in freshwater operation, more common in saltwater)
• Top off coolant at the first 10-hour service — small additional bleed of air may be needed
• Inspect the tee splice every 50 hours for any seepage
• Replace silicone hoses every 3 seasons or 300 hours (whichever first)

Pairing recommendations

The SuperCooler delivers maximum benefit when paired with:

• GT40-SD-TUBE-230300-BOV or GT40-SD-TUBE-325-BOV — the matched tubing kit's BOV ceiling is consistent with the SuperCooler's thermal headroom
• GT40-SD-INT-CF or GT40-SD-INT-325 — intake improvements increase thermal load that the SuperCooler then offsets
• GT40-SD-EXH-ST3 — Stage 3 exhaust increases mid-RPM heat which the SuperCooler reduces

Troubleshooting

| Symptom | Likely Cause | Fix |

|---|---|---|

| Coolant leak at NPT joint | NPT under-sealed | Drain, remove fitting, re-apply thread sealant, reinstall |

| Coolant leak at tee splice | Spring clamp under-tensioned | Replace spring clamp, retighten |

| Engine temperature unchanged | SuperCooler not in active cooling path | Inspect tee orientation — branch must point to SuperCooler, NOT bypass it |

| Coolant overflow at first start | Trapped air pocket | Bleed via the squeeze-and-top-off procedure in Step 7 |

| Hose vibration during operation | Insufficient hose support | Add a zip-tie support to the longest hose run |

| Coolant reservoir level drops repeatedly | Pinhole leak at the splice or hose joint | Pressure-test the cooling system, isolate the leak |

| Air bubbles in reservoir | Incomplete air bleed | Repeat Step 7 — squeeze hoses, top off, repeat |

If symptoms persist after the checks above, contact GT40 Marine support before further operation.

Torque Reference Summary

| Fastener | Torque |

|---|---|

| Bracket to engine bay mounting boss M8 SHCS (all 4) | 18 Nm / 13 ft-lb |

| NPT hose barb into SuperCooler | Hand + 1.5 turns (do not over-torque NPT in aluminum) |

| #12 hose clamps | 3 Nm / 27 in-lb (snug, no hose-wall cut) |

| Spring hose clamps at tee splice | Hand-set, no torque |

| Battery negative terminal | 10 Nm / 89 in-lb |

All torque values nominal — refer to current Sea-Doo factory service manual for any conflicting OEM specifications.

Warranty

GT40 Marine warrants this kit free from defects in materials and workmanship for ninety (90) days from date of purchase. Warranty covers replacement of defective GT40-supplied components. Warranty does not cover:

• Damage from improper installation
• Damage from operation outside design intent
• Normal wear of consumable items (hoses, clamps)
• Coolant loss from improper splice or hose joint sealing
• Use on craft outside the listed fitment matrix

To submit a warranty claim: email support@gt40marine.com with order number, photographs of the installed kit, and a description of the failure mode. Response within two business days.

Support

• Email: support@gt40marine.com
• Site: gt40marine.com
• Install help: include the GT40 SKU above and your hull serial number in any support correspondence

Built in the United States. Designed for buyers who want the best.

This guide is © 2026 GT40 Marine. All rights reserved.