Pajero engine temperature rising at idle during extremely hot days

[RohanH]

Guys, I have similar issues but not to this extent where it immediately heats in traffic. Never happened like this. But temp increased above 50% for 4 to 5 times in last 1 year only when car is ideal in extreme outside heat. In fact last week after little heating may be 55% I switched off the car and went home came back in 5 mins and then I saw heat gauge was on almost at 70%. 

As per the above threads, I checked

1. Fluid levels are ok

2. When engine is off- Fan hardly rotates when tried to push it by hand. It move like max to max quarter to half rotation.

3. After engine switched off- Fan stops immediately. 

4. Tried to check before starting the car in morning if I could see some leak at both sides of fan clutch. No leak,I guess.  

5. Timing belt including water pump kit, thermostat kit, radiator hose ( almost all together 19 parts) changed before 20 K Kms in Al Habtoor agency.

6. Whenever I had the heat gauge increased more than 50% , I never observed the loud noise, in fact engine noise remains same.

Car model ,Pajero 2013, 3.8 ltr, 122,000 kms run as of now

In this case what should be the first thing to diagnose. Radiator or fan clutch? In case of radiator, will cleaning and flushing help? 

Edited July 28, 2020 by RohanH

[Gaurav]

1 hour ago, RohanH said:

6. Whenever I had the heat gauge increased more than 50% , I never observed the loud noise, in fact engine noise remains same.

If fan clutch is not engaging when 70% heat gauge rises, that means fan clutch is surely not working.

Technically there is no way to 100% test fan clutch getting fully engaged at high temperature, other than this absence of loud gushing noise.

So it's time to either change the fan clutch (expensive route), or make it direct (cheaper route) as 9 months out of 12 months are hot in Dubai. Also its your off-road vehicle that will have better engine cooling with loss of 2-5 hp and few ml of extra petrol. Example: full tank mileage of 325 km might become 320 km, if you are keeping a precise log.

I'm running direct clutch fan since 5 years and my exhaust makes more noise on road and highway than direct clutch fan.

If I have an option to double my clutch fan speed by spending extra money, ill do that too.

[Rahimdad]

Sorry @RohanH just to add. If the car starts heating up just little extra, like you said 55% don't switch off the engine. Just open the bonnet and spray water on radiator to give engine some fresh air to help it cool.

[RohanH]

1 hour ago, Rahimdad said:

Sorry @RohanH just to add. If the car starts heating up just little extra, like you said 55% don't switch off the engine. Just open the bonnet and spray water on radiator to give engine some fresh air to help it cool.

No problem at all @Rahimdad.

I have learned many things from you all. Your suggestions are always welcome.

1 hour ago, Gaurav said:

If fan clutch is not engaging when 70% heat gauge rises, that means fan clutch is surely not working.

Technically there is no way to 100% test fan clutch getting fully engaged at high temperature, other than this absence of loud gushing noise.

So it's time to either change the fan clutch (expensive route), or make it direct (cheaper route) as 9 months out of 12 months are hot in Dubai. Also its your off-road vehicle that will have better engine cooling with loss of 2-5 hp and few ml of extra petrol. Example: full tank mileage of 325 km might become 320 km, if you are keeping a precise log.

I'm running direct clutch fan since 5 years and my exhaust makes more noise on road and highway than direct clutch fan.

If I have an option to double my clutch fan speed by spending extra money, ill do that too.

Thank you @Gaurav Will work on the suggestions given by you. 

[Barry]

4 hours ago, Gaurav said:

 

If I have an option to double my clutch fan speed by spending extra money, ill do that too.

You can fit a smaller pulley and shorter belt if you want to make it spin faster. Done it with superchargers before to get more power. There are custom pulley makers who can do it or anyone who has a lathe should be able to machine one from a piece of billet. Could maybe even do some good old fashioned jugad and find something in scrap and drill it out to fit. Bear in mind that it’s connected to your water pump so you don’t want to go too crazy with a mega tiny one but I don’t see the harm in going a little bit smaller. If you could be bothered, the maths behind it would be pretty easy to work out in relation to pulley size and rotational speed. 

[Gaurav]

26 minutes ago, Barry said:

You can fit a smaller pulley and shorter belt if you want to make it spin faster. Done it with superchargers before to get more power. There are custom pulley makers who can do it or anyone who has a lathe should be able to machine one from a piece of billet. Could maybe even do some good old fashioned jugad and find something in scrap and drill it out to fit. Bear in mind that it’s connected to your water pump so you don’t want to go too crazy with a mega tiny one but I don’t see the harm in going a little bit smaller. If you could be bothered, the maths behind it would be pretty easy to work out in relation to pulley size and rotational speed. 

I wish if it was a belt driven, would have done that long back as I also thought of same idea of reducing pulley size.

But, the fan clutch is connected directly to the engine and all belts are connected to it.

[Gaurav]

On a second (super greedy) thought.

Is this pulley (red, black marked) moving with belt or engine.....?

[desertdude]

That's belt driven, the engine main pulley/harmonic balancer is the lower one. 

Edited July 28, 2020 by desertdude

[Barry]

I had a look at a 6g74 today and it is possible with 2 custom pulleys, and 2 new belts. The water pump is a 2 belt pulley so you need to make the bit that runs off the crankshaft to be smaller to make the fan spin faster and the bit that runs the steering needs to be bigger to compensate for the extra speed. You will also need a bigger alternator pulley as it also runs from the water pump pulley. AC compressor is fine as it runs on a separate belt and doesn’t route via the water pump. 
 

So totally doable if you could be bothered do some math and get a couple of custom pulleys made. Personally, I’d ditch the viscous fan and go electric and free up a few valuable horsepower. If you’re worried about the electric fan failing, you could always go for a dual fan system so even if one breaks you still have that airflow. Electric also gives you the advantage that it can be thermostatically controlled for everyday driving with the option of a switch for constant operation when you’re sending it. 

[treks]

I agree with @Barry about going for electric fans. However, electric fans can be tricky since they have to be built into shrouds to force air through the entire core's surface area. If you can manage that, and provided the electric fan can displace at least the same volume of air as the original viscous fan, your problems should be over.