What is the purpose of a thermostat valve?

This question was previously asked in
RRB ALP Mechanic Diesel 21 Jan 2019 Official Paper (Shift 1)
View all RRB ALP Papers >
  1. It does not allow the coolant to flow through the upper hose to the radiator till the coolant reaches 90°C.
  2. It allows the oil to pump.
  3. It does not allow the coolant to flow through the upper hose to the radiator till the coolant reaches 30°C.
  4. It allows the coolant to flow through the upper hose to the radiator.

Answer (Detailed Solution Below)

Option 1 : It does not allow the coolant to flow through the upper hose to the radiator till the coolant reaches 90°C.
Free
General Science for All Railway Exams Mock Test
2.1 Lakh Users
20 Questions 20 Marks 15 Mins

Detailed Solution

Download Solution PDF

Explanation:

Thermostat valve:

  • The thermostat helps to bring the cold engine to the operating temperature quickly.
  • It does not allow the coolant to flow through the upper hose to the radiator till the coolant reaches 90°C.
  • It is fitted in between the water outlet of the cylinder head and the inlet of the radiator in the water cooling system.
  • When the engine is cold, the thermostat is closed.
  • It does not permit water to enter the radiator.
  • Water re-circulates in the engine through the bypass hole and the engine reaches the operating temperature quickly.
  • Once the engine has reached the operating temperature the thermostat opens.
  • t closes the bypass hole and now permits water to enter the radiator tank.
  • Thermostats are rated to open at different temperatures.

Two types of thermostats are used.

  • Bellows type
  • Wax type

Latest RRB ALP Updates

Last updated on Jun 11, 2025

-> The RRB NTPC Admit Card 2025 has been released on 1st June 2025 on the official website.

-> The UPSC Prelims Result 2025 and UPSC IFS Result 2025 has been released @upsc.gov.in

-> Railway Recruitment Board activated the RRB ALP application form 2025 correction link, candidates can make the correction in the application form till 31st May 2025. 

-> The Railway Recruitment Board (RRB) has released the official RRB ALP Notification 2025 to fill 9,970 Assistant Loco Pilot posts.

-> The Railway Recruitment Board (RRB) has released the official RRB ALP Notification 2025 to fill 9,970 Assistant Loco Pilot posts.

-> The official RRB ALP Recruitment 2025 provides an overview of the vacancy, exam date, selection process, eligibility criteria and many more.

->The candidates must have passed 10th with ITI or Diploma to be eligible for this post. 

->The RRB Assistant Loco Pilot selection process comprises CBT I, CBT II, Computer Based Aptitude Test (CBAT), Document Verification, and Medical Examination.

-> This year, lakhs of aspiring candidates will take part in the recruitment process for this opportunity in Indian Railways. 

-> Serious aspirants should prepare for the exam with RRB ALP Previous Year Papers.

-> Attempt RRB ALP GK & Reasoning Free Mock Tests and RRB ALP Current Affairs Free Mock Tests here

Get Free Access Now
Hot Links: teen patti noble dhani teen patti master teen patti teen patti lucky