Thermostat Kit F664068 for Mercury Force 90 95 120 HP Outboard 130F 859620
Thermostat Kit F664068 for Mercury Force 90 95 120 HP Outboard 130F 859620
Product Overview
Thermostat kit for the Mercury and Force 90, 95 and 120 HP outboards, supplied as a thermostat with its gasket and oil seal. It replaces Mercury F664068 and 859620, it crosses to Sierra 18-3527, it opens at 55°C (130°F) and fits the 90 HP from 1993 to 1995, the 95 HP from 1996 to 1997 and the 120 HP in 1995, 1999 and 2000, and one kit ships at 92 g with packaging.
This is the thermostat that decides when the engine gets cooling water and when it does not. Below the set point it stays shut so the engine comes up to temperature, above it opens and lets water through, and on a 90 to 120 HP two stroke the whole cooling cycle depends on it moving freely.
They fail in one of two directions and both are expensive. Stuck closed, the engine overheats within minutes and the first you know is usually a horn. Stuck open, the engine runs cold, never gets out of its cold fuel map, and burns more fuel and fouls plugs while the driver wonders why it is down on power.
The gasket and oil seal come with it for a reason. The thermostat sits under a cover on these engines and the gasket that seals that cover comes off with it, so a kit without it means a second order or a reused gasket that weeps.
Check the horsepower and the year against the table. The 90, 95 and 120 HP use the same thermostat but they do not overlap in years the way you might expect: there is no 90 HP after 1995 and no 95 HP before 1996.
Specifications & Attributes
| Specification | Detail |
|---|---|
| Condition | New / New with tags |
| Type | Thermostat kit |
| Mercury Part Number | F664068 |
| Also Replaces | 859620 |
| Sierra Number | 18-3527 |
| Opening Temperature | 55°C / 130°F |
| Fits | Mercury and Force 90 HP, 95 HP and 120 HP outboards |
| Years | 1993 to 2000, see the table below |
| Kit Contents | Thermostat, gasket and oil seal |
| Quantity | 1 kit |
| Net Weight | 92 g including packaging |
| Packaging | Pack |
| Warranty | 3 year |
OEM Cross Reference
| Brand | Part Numbers |
|---|---|
| Mercury | F664068, 859620 |
| Sierra | 18-3527 |
Compatible Engines
| Power | Years |
|---|---|
| 90 HP | 1993 - 1995 |
| 95 HP | 1996 - 1997 |
| 120 HP | 1995, 1999, 2000 |
What's Included
| Component | Detail | Qty |
|---|---|---|
| Thermostat | 55°C / 130°F opening, Mercury F664068 | 1 |
| Gasket | Seals the thermostat cover | 1 |
| Oil seal | Fits with the thermostat in the housing | 1 |
| Cover or housing | Not included, reuse the original | 0 |
Key Features
| Feature | Detail |
|---|---|
| Complete kit | Thermostat, gasket and oil seal in one pack |
| 55°C opening | The set point these engines are built around |
| Direct replacement | Fits in place of Mercury F664068 and 859620 |
| Cross referenced | Sierra 18-3527 |
| Three power ratings | 90 HP, 95 HP and 120 HP covered |
| Years listed | 1993 to 2000 with the gap between the 90 and the 95 spelled out |
Signs The Thermostat Needs Replacing
| What You See | What It Means | Action |
|---|---|---|
| Overheat horn within minutes of starting | Thermostat stuck closed | Fit a new kit |
| Engine never gets warm on the gauge | Thermostat stuck open | Fit a new kit |
| Burns more fuel than it used to | Running cold, stuck on the cold map | Fit a new kit |
| Plugs fouling | Cold running from a stuck open thermostat | Fit a new kit |
| Temperature swings up and down | Thermostat opening late and closing early | Fit a new kit |
| Weep at the thermostat cover | Old gasket reused or gone hard | Fit a new kit |
Model Coverage Note
Some listings for this thermostat also name the Mercury and Force 75, 85, 125 and 150 HP. The engine data we hold confirms the 90, 95 and 120 HP listed above, so if yours is a 75, 85, 125 or 150 HP, send us the model and year and we will check the thermostat fitted to your engine before you order rather than guess.
Fitting Notes
| Step | Action |
|---|---|
| 1 | Check the horsepower and year against the table above |
| 2 | Drain enough coolant or water to get below the thermostat housing |
| 3 | Take the cover off and note which way round the old thermostat sat |
| 4 | Clean the gasket face on the cover and the housing |
| 5 | Fit the new thermostat, gasket and oil seal in the same orientation |
| 6 | Refit the cover and tighten evenly so the gasket seats flat |
| 7 | Run the engine on muffs and watch the temperature come up to normal |
| 8 | Check for a weep at the cover after the first run |
Condition & Warranty
| Item | Detail |
|---|---|
| Condition | New / New with tags |
| Warranty | 3 year |
| Packaging | Pack |
Before You Buy
- Replaces Mercury F664068 and 859620
- Crosses to Sierra 18-3527
- Opens at 55°C / 130°F
- Supplied with the gasket and the oil seal
- Fits the Mercury and Force 90 HP from 1993 to 1995
- Fits the 95 HP from 1996 to 1997
- Fits the 120 HP in 1995, 1999 and 2000
- 90, 95 and 120 HP confirmed, ask us about 75, 85, 125 and 150 HP
- One kit, cover not included
- 92 g with packaging
- 30-Day Easy Returns
- Free Worldwide Shipping
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Boat Owners' Review
Before You Buy
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