Thermostat 17670-94402 17670-94400 18-3684 60C for Suzuki Outboard DF DT PU 9.9-70 HP
Thermostat 17670-94402 17670-94400 18-3684 60C for Suzuki Outboard DF DT PU 9.9-70 HP
Product Overview
Thermostat for Suzuki outboards, opening at 60 degrees C, the part that holds the engine at running temperature instead of letting cold water pour straight through it. It replaces Suzuki 17670-94402 and the 17670-94400 family and crosses to Sierra 18-3684, and it fits the 9.9 HP to 70 HP motors in a 15 x 10 x 5 cm box.
It is the thermostat for the DF four stroke EFI range from 9.9 to 70 HP, the DT two stroke 35 and 40 HP, and the PU commercial 40 HP. The body is high grade stainless and brass, so it does not corrode into the housing the way a plain steel unit does in salt water.
A thermostat fails in one of two ways. Stuck open, the motor runs cold, never reaches temperature, makes oil and never burns the fuel off properly. Stuck closed, it overheats within minutes and the alarm sounds before the powerhead is damaged. A 60 degrees C unit also matters where the wrong 70 degree thermostat has been fitted: the ECU on a DF motor reads coolant temperature and runs the wrong fuel map.
Specifications
| Specification | Detail |
|---|---|
| Condition | New / New with tags |
| Type | Outboard thermostat |
| Opening Temperature | 60 degrees C |
| Material | High grade stainless steel and brass |
| Horsepower Range | 9.9 HP to 70 HP |
| Engine Series | DF four stroke, DT two stroke, PU commercial |
| Net Weight | 76 g including packaging |
| Pack Size | 15 x 10 x 5 cm |
| Country of Origin | Taiwan |
OEM Cross Reference
| Brand | OEM Part Numbers |
|---|---|
| Suzuki | 17670-94402 |
| Suzuki | 17670-94403 |
| Suzuki | 17670-94404 |
| Suzuki | 17670-94401 |
| Suzuki | 17670-94400 |
| Sierra | 18-3684 |
Compatible Engines
| Series | Models | Horsepower |
|---|---|---|
| DF four stroke EFI | DF9.9 | 9.9 HP |
| DF four stroke EFI | DF15 | 15 HP |
| DF four stroke EFI | DF25 | 25 HP |
| DF four stroke EFI | DF30 | 30 HP |
| DF four stroke EFI | DF40 | 40 HP |
| DF four stroke EFI | DF50 | 50 HP |
| DF four stroke EFI | DF60 | 60 HP |
| DF four stroke EFI | DF70 | 70 HP |
| DT two stroke | DT35, DT40 | 35 HP, 40 HP |
| PU commercial | PU40 | 40 HP |
What's Included
| Component | Detail | Qty |
|---|---|---|
| Thermostat | 60 degrees C, stainless and brass | 1 |
| Gasket and housing cover | Not included, check the old unit | 0 |
| Bolts | Not included, keep track of the old ones | 0 |
Open or Closed Thermostat
| What You See | What It Means | What To Do |
|---|---|---|
| Motor runs cold, gauge never rises | Thermostat stuck open | Renew the thermostat |
| Overheat alarm within minutes | Thermostat stuck closed | Stop the motor, renew the thermostat |
| Tell tale strong, motor still hot | Water bypassing a stuck open unit | Renew and check the poppet valve |
| Overheat only at idle | Thermostat opening late | Test in hot water before ordering |
| Cold running and black plugs | Engine never reaches temperature | Renew the thermostat |
| Housing corroded solid | Salt water and a steel thermostat | Renew the thermostat and clean the housing |
Suzuki Cooling Layouts
| Engine Series | Thermostat Position | Note |
|---|---|---|
| DF 9.9 and 15 HP | Top of the powerhead, small housing | Short bolts, they seize in salt |
| DF 25 and 30 HP | Powerhead, next to the anode | Check the anode while the cover is off |
| DF 40 to 70 HP | Powerhead housing with a poppet valve | Renew the poppet spring if it is tired |
| DT two stroke | Cylinder head cover | Flush the passages before refitting |
| PU commercial | Same housing as the DF range | Check the water pump at the same service |
| Motors used in salt water | Corrosion between thermostat and housing | Clean the bore, do not force the new unit |
Fitting Notes
| Step | Action |
|---|---|
| 1 | Check the number on the old thermostat, 17670-94402 crosses to Sierra 18-3684 |
| 2 | Let the engine cool completely before opening the housing |
| 3 | Keep track of the bolt lengths, they are not all the same |
| 4 | Clean the housing bore and check for corrosion before fitting |
| 5 | Fit the thermostat with the air bleed hole at the top |
| 6 | Use a new gasket, an old one will weep under pressure |
| 7 | Tighten the cover evenly, the housing is thin aluminium |
| 8 | Run on muffs and watch the gauge climb to normal and stay there |
Condition & Warranty
| Item | Detail |
|---|---|
| Condition | New / New with tags |
| Warranty | 3 year |
| Packaging | Sealed retail packaging |
Before You Buy
- Check the number on the old thermostat, 17670-94402 and Sierra 18-3684 interchange
- 60 degrees C opening, the standard rating for these Suzuki motors
- Fits Suzuki DF 9.9 to 70 HP four strokes, DT 35 and 40 HP, PU 40 HP
- Also replaces 17670-94400, 17670-94401, 17670-94403 and 17670-94404
- This is the thermostat only, the gasket and housing are not included
- Check the water pump while you are in the cooling system
- 30-Day Easy Returns
- Ships from our warehouse with tracking
Couldn't load pickup availability
Boat Owners' Review
Before You Buy
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