Overview
The Crown Automotive J0639651 is a thermostat retainer clamp for 4 and 6 cylinder Willys MB and early Jeep CJ engines. The manufacturer fitment list names the 1941–1942 Willys MB, the 1946–1949 Jeep Willys CJ-2 and the 1949–1952 Jeep Willys CJ-3.
The retainer clamp holds the thermostat in its housing. Because the part is small, match the part number against the clamp being removed before installing it.
Key features
- Thermostat retainer clamp design
- Suited to 4 and 6 cylinder engines
- Direct fit for the listed models
- Crown part number CROJ0639651
Thermostat retainer basics
A thermostat retainer clamp holds the thermostat in its housing so it stays seated as coolant flows. It is a small part, but a loose or bent clamp can let the thermostat shift and cause erratic temperature readings. Older flathead and early CJ engines often have worn housings, so check the seat as well as the clamp.
When removing the clamp, note the orientation of the thermostat and the housing surfaces. Clean any corrosion from the seat and check that the new clamp sits flat. Keep track of any spacers or washers removed during disassembly. Replacing the thermostat at the same time is common practice when the housing is already open.
- Clamp that is bent or loose
- Corrosion inside the housing seat
- Thermostat that sticks or does not open fully
Specifications
| Brand | Crown Automotive |
|---|---|
| Part number | J0639651 |
| Crown catalog number | CROJ0639651 |
| Type | Thermostat retainer clamp |
| Engine | 4 and 6 Cyl. |
| Fitment type | Direct Fit |
Vehicle fitment
The manufacturer fitment list covers the 1941–1942 Willys MB (Base), the 1946–1949 Jeep Willys CJ-2 and the 1949–1952 Jeep Willys CJ-3.
The list does not include the CJ-5 or CJ-7 models. Confirm your vehicle’s year, model and trim before ordering.
What’s included
One thermostat retainer clamp. No other hardware is described.
