The thermostat housing body controls coolant routing between engine and radiator, and it has to seal perfectly through thousands of thermal cycles while carrying the sensor, bleed and bypass ports your calibration depends on. Ningbo Ruican investment casts and CNC machines the housing to your print, holding the thermostat seat, flange flatness and port threads so the unit seals first time on the line and never becomes a warranty leak.
Specifications
| Item | Specification |
|---|---|
| Casting process | Silica sol lost-wax investment casting, near-net port and flange geometry |
| Material options | Aluminium A356-T6, AlSi9Cu3, cast iron GJL-250, stainless 304 and 316 |
| Dimensional tolerance (ISO 8062-3 CT grade) | CT5-CT6 as-cast, CT4 on thermostat seat, flange face and port bores |
| Machining | 4-axis VMC and CNC turning; flange face, thermostat seat, sensor port threads and hose spigot machined |
| Surface finish (Ra) | Ra 3.2 um as-cast, Ra 1.6 um on machined faces, Ra 0.8 um on sealing seat |
| Weight range | 0.25 kg – 1.8 kg per housing |
| Typical lead time | Tooling 25-35 days, samples 15 days after tooling, production 30-40 days |
Key features
- Thermostat seat machined square to the flange face within 0.05 mm for a leak-free seal.
- Cast-in sensor, bleed and bypass bosses remove brazed-on fittings and their leak paths.
- Flange flatness held within 0.08 mm across the sealing face after T6 heat treatment.
- Port threads machined and gauged to 6H, compatible with automotive coolant sensors and bleed screws.
- Pressure decay tested for leak-tightness before shipment, with results recorded per batch.
- Anodised, powder-coated or passivated finishes supplied to your corrosion and appearance specification.
Applications
- Passenger car and light commercial vehicle petrol and diesel engines
- Heavy-duty truck and coach engine thermal-management modules
- Construction, agricultural and generator set diesel engines
- Battery-electric vehicle coolant distribution and battery chiller modules
- Marine inboard and sterndrive engine cooling circuits
- Stationary gas engines and combined heat and power units
Quality & compliance
Ningbo Ruican manufactures thermostat housing bodies under IATF 16949, running APQP from feasibility and DFMEA through to PPAP level 3 or 4. The package includes EN 10204 3.1 material certification with heat-lot traceability, T6 heat-treatment records, full dimensional reports with capability data on the thermostat seat and flange face, and 100% pressure decay leak testing with batch traceability. Thermal cycling between minus 40 and plus 140 degrees Celsius, salt-spray exposure to ISO 9227, and coolant-immersion corrosion validation are performed on request before series production begins.
FAQ
Can you guarantee a leak-free thermostat housing?
We hold the thermostat seat square to the flange within 0.05 mm, control flange flatness to 0.08 mm after heat treatment, and pressure decay test 100% of production parts. Test results are logged against the batch, and we can raise the test pressure or hold time to match your engine platform specification.
Which material is best for a heavy-duty diesel housing?
Cast iron GJL-250 remains a strong choice for heavy-duty and generator engines thanks to its dimensional stability and thermal mass, while aluminium A356-T6 is preferred where weight and heat-up speed matter. Stainless 304 or 316 is specified for marine coolant circuits and for battery-electric coolant modules using glycol mixtures.
Do you machine the sensor and bleed port threads?
Yes. Sensor, bleed and bypass ports are drilled and threaded to 6H and individually gauged, so coolant temperature sensors and bleed screws torque to your specification without cross-threading. We can also machine the hose spigot with a bead profile or groove to your hose retention design.
How do you handle thermal cycling durability?
We validate housings through thermal cycling between minus 40 and plus 140 degrees Celsius in coolant, then re-pressure test and inspect the sealing face for distortion or cracking. Cycle count and acceptance criteria follow your engine platform specification, and full reports are included in the validation pack.
Can you consolidate several housings into one casting?
Yes. Customers often combine the thermostat body, bypass spigot, sensor boss and a bracket into a single investment casting, which removes joints, fasteners and gasket faces. Send the current assembly and we will return a consolidation proposal with tooling cost, piece-price and weight comparison.
CTA
Send your thermostat housing drawing, material specification, leak-test criteria and annual volume to Ningbo Ruican for a build-to-print quotation and tooling proposal. Contact Wendy She — sales@cnsandcasting.com — WhatsApp +86-13777124360 for RFQ support, sample status or APQP documentation.
