Thermostat Housing Kit – Fits MerCruiser 7.4L/454 & 8.2L/502 V8 Engines (Replaces 90736A24)
Thermostat Housing Kit – Fits MerCruiser 7.4L/454 & 8.2L/502 V8 Engines (Replaces 90736A24) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Thermostat Housing Kit – Fits MerCruiser 7.4L/454 & 8.2L/502 V8...
Product Details
This Thermostat Housing Kit is a complete assembly for MerCruiser GM 7.4L/454 and 8.2L/502 V8 engines that use an offset diagonal bolt pattern. It is an essential component for regulating engine temperature for optimal performance. Crucially, this kit does not fit high-performance or 540 CID engines that feature a straight-across housing bolt pattern.
This kit serves as a direct interchange for MerCruiser part number 90736A24 and GLM 13221.
- Direct bolt-on replacement for straightforward installation.
- Made from corrosion-resistant cast aluminum for durability in marine environments.
- Includes a 142°F (61°C) thermostat, all necessary gaskets, and mounting hardware.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| MerCruiser | 90736A24 |
| GLM | 13221 |
Engine & Model Compatibility
Confirm your engine model in the table below. It is critical to verify your engine uses the offset diagonal bolt pattern.
| Brand | Model | Rated HP | Stroke | OEM Part No. | Notes |
|---|---|---|---|---|---|
| MerCruiser | 7.4L/454 CID V8 | Varies | 4-Stroke | 90736A24 | Standard engines with offset diagonal bolt pattern |
| MerCruiser | 8.2L/502 CID V8 | Varies | 4-Stroke | 90736A24 | Standard engines with offset diagonal bolt pattern |
Technical Specs
- Product Type
- Thermostat Housing Kit
- Installation
- Direct bolt-on replacement
- Fuel Type
- Gasoline
- Housing Material
- Cast Aluminum
- Housing Color
- Silver (unfinished aluminum)
- Dimensions
- 11.0" x 19.0" x 20.0"
- Weight
- 5.24 kg (11.55 lb)
- Thermostat Rating
- 142°F (61°C)
- Mounting Pattern
- Offset diagonal bolt pattern
- Mounting Hardware
- 3/8-16 x 4-1/4" grade 5 bolts
- Other Technical Attributes
- Includes tee with checkball valve assembly
- Warranty
- 1 year limited warranty (TMP Global)
What’s in the Box
- 1 x Lower Thermostat Housing (MC-29-90736)
- 1 x Thermostat Housing Cover (MC-29-47442)
- 1 x Tee w/ Checkball Valve Assembly (22-98477A2)
- 1 x 142° Thermostat Kit (18-3651)
- 1 x Thermostat Retaining Sleeve (23-47508T)
- 1 x Thermostat Gasket w/ Ground (18-2917)
- 2 x Thermostat Housing Grade 5 3/8-16 x 4-1/4" Bolts (10-60410)
- 2 x Lock Washer 3/8-16 (1133893)
Installation Notes
- Ensure the engine is completely cool and disconnect the battery.
- Drain the engine coolant to a level below the thermostat housing.
- Disconnect hoses attached to the old housing assembly, noting their positions.
- Unbolt and remove the old housing. Note the orientation of the bolts and components.
- Thoroughly clean the engine block's mating surface to remove all old gasket material.
- Assemble the new thermostat, sleeve, and gaskets into the new housing.
- Position the new assembly onto the engine block, ensuring correct gasket alignment.
- Install and hand-tighten the new bolts, then torque them to the manufacturer's specifications.
- Reconnect all hoses and secure the clamps.
- Refill the cooling system, reconnect the battery, and start the engine to check for any leaks.
Troubleshooting & FAQ
Will this fit my MerCruiser 454 high-performance engine?
No. This kit is specifically for standard 7.4L/454 and 8.2L/502 engines with an offset diagonal bolt pattern. High-performance models that use a straight-across bolt pattern are not compatible.
What is the most common installation mistake?
Failing to completely clean the engine's mating surface of old gasket material, which can cause coolant leaks. Always clean the surface thoroughly and torque bolts to the manufacturer's specifications.
How do I know if my old thermostat housing is failing?
Common signs include visible coolant leaks around the housing, cracks in the cast metal, or engine temperature issues (overheating or running too cool), which may indicate a stuck thermostat.
Does this kit include everything I need for installation?
It includes the core components: housing, cover, thermostat, sleeve, tee-valve, primary gaskets, and mounting bolts. Depending on your engine setup, you may need additional hose clamps or specific sealants not included. Always compare the kit contents with your specific needs.
Why is the bolt pattern so important?
The bolt pattern determines how the housing physically mounts to the engine block. This kit will not align with engine blocks drilled for a straight-across bolt pattern, making it physically incompatible.
What are the signs of a faulty thermostat?
If a thermostat is stuck open, your engine may not reach its proper operating temperature. If it is stuck closed, the engine will overheat. Both situations can cause poor performance and potential engine damage.
Is this an OEM part?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials and is manufactured in an ISO 9002 facility, with batch inspections for consistency.
What are the shipping speed and cost?
We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free, and expedited options may appear at checkout where available.
What is the warranty and return policy?
This product is covered by a 1-year warranty against manufacturing defects under normal use. If an issue arises, contact our support team with your order details. Returns are accepted within our standard window for unused items in original condition. See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
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