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Hello everyone,

 

I had an overheating problem last friday on desert drive. So I took the car to workshop and I want to get your opinions before I give a green light for any work or replacement. There are two things I realized so far;

1- Blowing Noise 

When I usually give gas or accelerate, I hear a loud blowing noise along with the engine noise coming from the fan. I assume, it is because the fan is working on a high speed. However sometimes it stops doing that. So the fan working on low speed I presume. I recorded a video when it stops giving that blowing noise. The technician says, one of the cable in the sensor was cut (I believe the one ECM uses to read speed of fan) Therefore fan was working in full speed all the time. He says he repaired the cable and it varies now.... Might be true but I'm still not satisfied with the answer. Because sometime even the engine is hotter then usual -say 105 degree-, blowing noise doesn't come... It should work with max speed at that heat shouldn't it?

2- Increasing Temperature on Highway

I had a test drive with the technician and OBD connected. After half an hour while I was driving with 105km/h with AC on, heat gauge started  to raise up to 110degrees. At that particular time readings on OBD were;

           - Engine RPM: Somewhere around 2000rpm

          - Desired fan speed: 840rpm 

          - Actual fan speed: Close to desired fan speed. 

840rpm for fan is almost  the idle speed for fan when the AC is on. That is strange. 

 

Technician says, he needs to change fan clutch and AC pressure switch. I am not very sure changing these 2 things will sort the problem. Can anybody tell me whether this is true or not? 

BTW; there is no fault code on OBD regarding fan at all. 

 

Edited by Denizzalbayrak
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Well in such overheating episode,fan clutch is first to doubt and often missed component, as people start running around circle for radiator, coolant, aux fan etc.

However, assuming your radiator, coolant and all other engine cooling component are in good shape, then surely viscose clutch fan needs a change. I know it must be expensive, but its needed.

I'm not sure about what's the connection with AC pressure switch, @Barry @treks @desertdude might be able to reason this out.

Hey while at it, get your heater working, as in all desert cars when car overheats, we can dissipate lot of engine heat with heater blower in few seconds. Its kind of last emergency tool for rescuing overheating cars.

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Let's root for each other & watch each other grow.

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The viscous fan will indeed regulate the fan speed:

 

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"Go as far as you can see; once you get there, you'll be able to see further."

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"Go as far as you can see; once you get there, you'll be able to see further."

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American's of Carnity :D

IMG_20200527_123245.jpg

Edited by sertac
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Thank you for your replies @Gaurav and @Frederic I watched those videos the next day of overheating 

I told the technician to change the clutch. But I will change AC switch later. For the heating thing I will try to get it done as well. But I am almost at the limit of this month's budget for the car. Maybe I can postpone it to June. I am waiting their quote for that:D 

However I still have a doubt that there might be an softwere or electronical problem but technician couldn't find one...Let's see. I will try it first on some sand nearby to tarmac before entering to desert  

Thanks again.

Edited by Denizzalbayrak
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Man what a messed up cooling fan system you car has a hybrid of electrical and mechanical.

Well if it is working variable now that means it's fixed. I just lightly skipped through the video and it says engine is close to overheating and 265F which is almost 130C so 105C is well within normal operating range.

Also at 100kph 115C seems normal to me. Fan shouldn't be working anyways at this speed because radiator is getting cooled by ambient air passing over it. 

Engine fan is it there to provide extra airflow it when your car is stationary or moving slow and not enough is air moving through the radiator. Because a mechanical fan robs quite some horses from the engine so moving at highway speeds is just adding extra stress on your engine if it is also turning the fan.

AC switch has nothing to do with this. It controls the condersor fans which helps the AC cool. If you AC is cooling fine then there is nothing wrong with it. 

BTW is you temp needle going up when it's all 115?  Car gauges are calibrated to show normal temp between the entire range of normal operating temp. For example it would show normal from 80 all the way up to 125. Because that range is considered normal engine operating temp

Because of it didn't your needle would always be dancing up and down. Because when you stop tem starts to climb when you start moving it starts to go down when you push your car it starts to go up again. As you might have seen in the obd readout

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Causes of overheating when driving are 

Faulty water pump

Thermostat stuck closed

Blocked radiator

Weak or incorrect coolant

Pressure loss, ie bad radiator cap, loose pipe or a hole in a pipe


Also just to reiterate a point made by @desertdude don’t trust the factory dashboard gauge. It’s designed to always read normal through a wide range of temperatures. Otherwise the mechanics would have their day ruined by people panicking thinking all their cars are going to blow up. I assume you were taking the temperature from OBD?

Anyway, and this is for all you off-road guys, you should have a separate aftermarket temperature gauge installed if you’re going to be working your engine hard. They aren’t expensive and they’re easy to install the sensor using an adapter kit where you splice a hose and put the adapter in the join. 532B5B51-5354-44EF-B1DB-390FB0775819.jpeg.8922654c229bece7fdda65991bbcb74e.jpeg

I use aftermarket gauges to supplement the factory gauges in almost all of my cars. At bare minimum, temperature, oil pressure and voltage. These are important tings to monitor and as you watch them over time, you will learn what is normal operating range for your engine. There are some sexy mounting pods available too. 
56D3BC5F-58EC-415F-9E61-AB3EADDC09A4.jpeg.6a29899740a6905ca28b1a74f6a40a6f.jpegCA418C48-0440-418A-9A78-1875039FB21D.jpeg.c16a5a2dda6ae591d7eb562752f69b59.jpeg

Also, there is a difference in running hot and overheating. An engine running hot is no problem, it’s designed for it. Overheating is when the engine gets so hot it blows steam from the radiator cap. 
 

I don’t know why your mechanic is suggesting to change the AC pressure switch. My guess is that he doesn’t know what’s going on and is more than happy to spend your money trying parts to satisfy his experiments. 

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After spending 5 hours today in the workshop -just left from there- I had the same issue in the test drive. Engine got heated again Gauge went up to somewhere around 115degrees (Last time yes we checked it with OBD but this time only with Gauge) and coolant water was dripping from reserve tank (I'm not sure if it is the right name for it)...

Clutch fan, water pump, thermostat has changed. They told me that pressure loss might be a reason as well due to cap fault but after that I kind of got frustrated and left the shop... Anyway they will check the pressure thing tomorrow. Also mechanic says he checked all the sockets, cables, fuses and relays regarding fan and he says there is no problem on electrical components...

 

Would there be any other possible problem If the pressure in radiator is also fine ??

 

On 5/27/2020 at 7:52 PM, desertdude said:

Man what a messed up cooling fan system you car has a hybrid of electrical and mechanical

I think I quite agree with you. 

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A faulty radiator cap can be the issue and since it's cheap start from there. If that is not the issue and you are 100% sure water pump and thermostat are good 

Then it's the radiator. A partially blocked radiator will start overheating on highway runs cause pressure buildup which will lead to the cap venting. 

Using improper coolants and not flushing the coolant when required can cause hard deposits to form inside blocking off radiator lines. 

Specially if the radiator is designed with narrow lines. Old land Rovers also had this design issues.

One day while I was coming back from Abu Dhabi midday peak summer season I stopped to refuel on a highway gas station and noticed my temp gauge moves up by a quarter and some coolant also dripping from the cap. 

Luckily I was close to home. So I made it 

Next day I tried to repeat the same at the same time of the day. But my just wouldn't heat up.

But still no wanting to take a chance I replaced the radiator.

And when opened up the old radiator. Literally 60% of the radiator was blocked with a very hard silicone type build up. 

I have a picture of to some where let me see if I can find it

P.S : As mentioned in my first post fan has no role to play at high-speed all the cooling the radiator is getting is from the ram air speed effect

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