160°F Thermostat Service Kit for MerCruiser Built 4-Cylinder Engines, 1976–1982 – Excludes 470
160°F Thermostat Service Kit for MerCruiser Built 4-Cylinder Engines, 1976–1982 – Excludes 470 is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
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160°F Thermostat Service Kit for MerCruiser Built 4-Cylinder Engine...
160°F Thermostat Service Kit for MerCruiser Built 4-Cylinder Engines, 1976–1982 – Excludes 470 is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket 160°F (71°C) thermostat service kit is intended for MerCruiser-built 4-cylinder marine engines that are not Chevrolet-based, with applications from 1976 through 1982. It is designed for the applicable MerCruiser stern-drive and out-drive cooling systems described below.
Important fitment limitation: this kit does not fit the MerCruiser 470 engine. Confirm that your engine is a non-Chevrolet MerCruiser-built 4-cylinder model and that the year and thermostat-housing configuration match before ordering.
- 160°F (71°C) thermostat for the specified marine engine applications.
- Service-kit configuration with the thermostat, rubber ring, and gasket listed below.
- Useful replacement references include MerCruiser part numbers 27-74830, 27-896561, 76270T, 991551, 99155A1, 99155T1, and 99155T2.
- Aftermarket replacement; verify the original part, housing, and reference numbers before installation.
Part Number Matrix
The following numbers are manufacturer or aftermarket reference numbers associated with this product. They are provided for identification and cross-reference purposes only; confirm physical compatibility before installation.
| Brand or Source | Part Number | Reference |
|---|---|---|
| MerCruiser | 27-74830 | Listed manufacturer reference. |
| MerCruiser | 27-896561 | Listed manufacturer reference. |
| MerCruiser | 76270T | Listed manufacturer reference. |
| MerCruiser | 991551 | Listed manufacturer reference. |
| MerCruiser | 99155A1 | Thermostat reference for the included thermostat. |
| MerCruiser | 99155T1 | Listed manufacturer reference. |
| MerCruiser | 99155T2 | Listed manufacturer reference. |
| Sierra | 18-3555 | Listed aftermarket reference. |
Engine & Model Compatibility
Use the combined engine construction, cylinder count, year range, and exclusion below when checking fitment. The supplied product data does not establish compatibility with every individual model designation within this range.
| Brand | Engine Construction | Cylinders | Years | Exclusion |
|---|---|---|---|---|
| MerCruiser | MerCruiser-built, non-Chevrolet engine | 4-cylinder | 1976–1982 | Does not fit MerCruiser 470 |
Technical Specs
- Product Type
- Marine engine thermostat service kit
- Thermostat Rating
- 160°F (71°C)
- Application
- MerCruiser-built, non-Chevrolet 4-cylinder marine engines
- Application Years
- 1976–1982
- Engine Exclusion
- MerCruiser 470
- Installation
- Replacement installation using the applicable thermostat housing procedure
What’s in the Box
- 1 x Thermostat, reference 99155A1
- 1 x Rubber ring
- 1 x Gasket, reference 27-33918
Installation Notes
- Allow the engine to cool completely before beginning service.
- Confirm the engine is a MerCruiser-built, non-Chevrolet 4-cylinder application from 1976–1982 and is not a MerCruiser 470.
- Drain coolant as necessary to prevent spills when opening the thermostat housing.
- Remove the thermostat housing and note the original thermostat and seal orientation.
- Clean the mating surfaces carefully without damaging the housing or manifold.
- Install the thermostat, rubber ring, and gasket in the correct position for your housing.
- Reinstall the housing and tighten the fasteners according to the engine manufacturer’s service procedure.
- Refill the cooling system with the specified coolant, run the engine, and inspect the housing for leaks.
Troubleshooting & FAQ
How do I know if this thermostat kit fits my engine?
Check all fitment conditions together: the engine must be MerCruiser-built, non-Chevrolet, 4-cylinder, and from 1976–1982. This kit specifically excludes the MerCruiser 470. Compare the thermostat, housing, and reference numbers with your original parts before installation.
What is the thermostat opening temperature?
The thermostat is rated at 160°F (71°C).
What parts are included?
The service kit includes one 160°F thermostat, one rubber ring, and one gasket identified by reference 27-33918.
Which reference numbers are associated with this kit?
Listed references include MerCruiser 27-74830, 27-896561, 76270T, 991551, 99155A1, 99155T1, and 99155T2, plus aftermarket reference 18-3555. Reference numbers alone do not replace the need to verify the complete engine and housing application.
Is this an OEM component?
No. This is an aftermarket replacement service kit. MerCruiser and aftermarket part numbers are shown only as product-identification and cross-reference information.
Safety & Important Info
- Work only on a completely cool engine and follow the appropriate marine-engine service procedure.
- Do not use this kit for a MerCruiser 470 engine.
- Verify engine construction, cylinder count, year, thermostat housing, and original part appearance before purchase.
- Professional installation is recommended if you are unsure about the cooling-system service procedure.
About Sea Sierra
- Marine Parts Support — We provide replacement components for marine service and repair applications.
- Application-Focused Listings — Product information is organized around engine, year, and component-reference details.
- Replacement Value — Aftermarket options help support practical maintenance and repair needs.
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