How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Trevor Witting Your Own Question

Trevor Witting
Trevor Witting, UK Car Mechanic
Category: UK Car
Satisfied Customers: 1260
Experience:  NVQ 3, Modern Apprenticeship, MOT Tester, 15+ years experience diagnostic technician
15853224
Type Your UK Car Question Here...
Trevor Witting is online now
A new question is answered every 9 seconds

MG ZT 1.8T, Engine running hot, needle on temp gauge ok but

Customer Question

MG ZT 1.8T, Engine running hot, needle on temp gauge ok but fan always running after switching engine off (9 mile commute). new water pump but problem persists, also tried to bleed cooling system. engine approx 23000 miles old.
Submitted: 4 years ago.
Category: UK Car
Expert:  Trevor Witting replied 4 years ago.

Hi

 

Welcome to Just Answer

 

The engine in your car is the 'k' series engine, they are proned to head gasket failure, but what you are describing dosent sound like this, as the temperature guage has not risen too high, and I'm assuming you are not using water or having to top up regularly.

 

I have pasted below a generic guide that I have written for the cooling system, if you follow it, it will help you to diagnose the problem.

 

It is likely to be th engine coolant temperature sensor, there is no switch on your car, the fan is ECU controlled, and takes its reading from the sensor.

 

Hope this helps, if you need more info, such as the cooling wiring duagram, please let me know.

 

Regards

 

Trev

 

You need to start with the basics, check the coolant level, if it is low top it up and look for any signs of a leak, if it was low and you cannot see any leaks, then get a block test done on the car at a garage, it will cost around £10 and will give an indication as to head gasket failure.

Over pressurising may also be a sign of head or head gasket failure.

Next I will describe the operation from cold of the cooling system, any point that does not happen will indicate a fault with that part of the car, so follow the guidelines below and it will lead you to the cause.

If possible use a laser thermometer, otherwise be careful when testing for heat or temperature.

With the coolant at its maximum level, and the bonnet open, start the engine.

Turn the heater on to hot, and the blower on low

As the engine runs, the WATER PUMP circulates the coolant around the engine, test this by ensuring that the heater pipes start to get warm and blows warm air into the cabin, also the engine should get warm evenly and have no hot spots.

As the car warms up, the TEMPERATURE GUAGE in the car receives different resistance signals from the TEMPERATURE SENSOR and the gauge will rise.

As the engine reaches between 80-95 degrees C, the THERMOSTAT should start to open, and the top radiator hose should start to warm up, and the radiator will in turn start to warm up from the top downwards.

The warm water should flow steadily through the RADIATOR and out through the bottom hose indicating that the radiator is free from blockages.

As the coolant in the radiator reaches between 90-98 degrees C, the FAN SWITCH closes the circuit and sends battery voltage to the RADIATOR COOLING FAN, which in turn starts up and cools the coolant in the radiator.

For Cars with a viscous fan, usually rear wheel drive cars and vans, the fan should become stiffer to turn as the engine heats up

When the engine and coolant are hot, the coolant becomes pressurised, this stops the water from boiling and causing air locks, the pressure is controlled by a valve incorporated in the CAP of the cooling system and the correct operating pressure will be marked on the cap in bar, the cap can be tested with a special tool.

By reading this, and following it as the engine is running, you will understand how the cooling system works, and anything that doesn't happen as it should will lead you to a potential fault.

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

What Customers are Saying:

 
 
 
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
< Last | Next >
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex Los Angeles, CA
  • Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult. GP Hesperia, CA
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin Kernersville, NC
  • Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around. Esther Woodstock, NY
  • Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know. Robin Elkton, Maryland
  • He answered my question promptly and gave me accurate, detailed information. If all of your experts are half as good, you have a great thing going here. Diane Dallas, TX
 
 
 

Meet The Experts:

 
 
 
  • Marty

    European Car Expert

    Satisfied Customers:

    349
    ASE & Bosch Certified Master Tech. Over 30 years experience.
< Last | Next >
  • http://ww2.justanswer.com/uploads/EU/eurotec/2012-6-11_13153_mpjaphoto.64x64.JPG Marty's Avatar

    Marty

    European Car Expert

    Satisfied Customers:

    349
    ASE & Bosch Certified Master Tech. Over 30 years experience.
  • http://ww2.justanswer.com/uploads/IN/indytech/2013-8-8_102717_SantoDomingo146598x6402.64x64.jpg Greg's Avatar

    Greg

    Shop Owner

    Satisfied Customers:

    1040
    17 years Shop Owner /Technician. 27 years experience,
  • http://ww2.justanswer.com/uploads/CR/crzydrvr00/2013-11-3_12123_246347.64x64.jpg Richard's Avatar

    Richard

    UK Car Mechanic

    Satisfied Customers:

    472
    12 years as a technician at a Ford and Jaguar dealer Ford and Jaguar factory certified
  • http://ww2.justanswer.com/uploads/35/350matt/2012-6-7_182356_matsavatr.64x64.jpg Matt's Avatar

    Matt

    Mechanical Engineer

    Satisfied Customers:

    4034
    BEng hons Mech engineering, in auto industry 22 years
  • http://ww2.justanswer.com/uploads/NA/nabilc/2011-1-24_205715_jap500.64x64.jpg Billy's Avatar

    Billy

    Trainer/Master tech.

    Satisfied Customers:

    1276
    Trainer - master tech., SAE member
  • http://ww2.justanswer.com/uploads/witt0018/2009-02-09_180738_trev2.jpg Trevor Witting's Avatar

    Trevor Witting

    UK Car Mechanic

    Satisfied Customers:

    815
    NVQ 3, Modern Apprenticeship, MOT Tester, 15+ years experience diagnostic technician
  • http://ww2.justanswer.com/uploads/RO/RobMechanic/068.64x64.JPG Rob's Avatar

    Rob

    UK Car Mechanic

    Satisfied Customers:

    811
    city and guilds level 1 2and 3. mot tester , 28 years experience set up training college in afghanistan
 
 
 
Chat Now With An UK Auto Mechanic
Trevor Witting
Trevor Witting
MOT Tester/Mechanic
821 Satisfied Customers
NVQ 3, Modern Apprenticeship, MOT Tester, 15+ years experience diagnostic technician