B. toys 160°F Thermostat Kit for OMC & Volvo Penta 4.3–5.8L V6/V8 — Gasket & O‑Ring Replacement

B. toys 160°F thermostat kit is a complete replacement set (thermostat, gasket, O‑ring) designed to restore proper cooling operation on specified OMC Cobra and Volvo Penta 4.3L, 5.0L, 5.7L and 5.8L V6/V8 sterndrive engines.

This kit contains a 160°F thermostat, a matching gasket, and an O‑ring packaged new for direct replacement of worn or leaking parts on compatible marine sterndrive engines. It replaces OEM numbers including 3856961 and aftermarket references like Sierra 18‑3677, and is intended for the smaller thermostat size used in many Volvo installations. Before ordering, confirm the part matches your engine year and model—especially since OMC and Volvo used different designs and Volvo used both small and large thermostats.

Which engine models and years does this thermostat kit fit?

This kit fits a range of OMC Cobra and Volvo Penta sterndrive applications built on Ford and GM blocks. It covers 4.3L, 5.0L, 5.7L and 5.8L V6 and V8 engines for the model years listed, and is the small Volvo thermostat variant. Always cross‑check the OEM part numbers and physical dimensions against your existing thermostat housing.

• OMC Cobra: 4.3L (1994–1997), 4.3HO (1994–1997), 5.0L (1994–1997), 5.8L (1994–1997), 5.8EFI (1994–1997)
• Volvo Penta codes: fits combinations labeled 4.3GL, 4.3GS, 4.3Gi, 4.3Gi5.8FL, 5.0FL, 5.0Fi, 5.7GL, 5.7Gi and 5.8Fi/5.8FSi where the small thermostat is used
• Replaces OEM 3856961 and related aftermarket numbers like 18‑3677 and 383307

How do I know if I should replace my thermostat, gasket, and O‑ring?

Signs that the kit is needed include engine overheating, coolant leaks around the housing, or a thermostat that sticks open or closed. Because the gasket and O‑ring commonly degrade when removing a stuck thermostat, replacing all three parts at once prevents repeat service and improves sealing.

• Overheating or inconsistent temperature at cruising RPMs
• Visible coolant seepage or dried residue at thermostat housing
• Thermostat sticking, failing to open at 160°F specification
• Routine preventative maintenance when performing thermoregulation service

What does the kit include and how does it compare to OEM parts?

The kit ships with a 160°F thermostat, a molded gasket, and an O‑ring sized for the matching thermostat housing. It is manufactured to replace the listed OEM and aftermarket numbers, but it is not compatible with 4‑cylinder engines or larger Volvo thermostat variants—measure and compare to avoid fitment issues.

• One 160°F thermostat (replacement for OEM 3856961)
• One gasket (replacement for OEM 3852111)
• One O‑ring (replacement for OEM 3852071)
• Compare physical size to the existing thermostat; this kit is the smaller Volvo size

Who is this kit for? Boat owners, marine mechanics, and DIY technicians working on OMC Cobra or Volvo Penta sterndrive engines built on Ford/GM 4.3L–5.8L platforms who need a dependable, ready‑to‑install 160°F thermostat replacement. Choose this kit when you require the small Volvo thermostat variant, want a complete gasket and O‑ring set for leak‑free installation, and have verified compatibility with the engine year and OEM numbers listed. If unsure, remove the old thermostat and compare dimensions and part numbers before purchase.