[Jaggu]

Originally Posted by headers

Spike, IIRC, it is 70 to 90 deg C. This is the optimum coolant temperature for most IC engines.

I think 60 deg so that coolant has a buffer to accommodate the additional heat once the load is applied on the engine. 90 deg, the moment you add load wont the engine overheat and in certain cases even warp the head?

[SPIKE ARRESTOR]

Originally Posted by headers

Spike, IIRC, it is 70 to 90 deg C. This is the optimum coolant temperature for most IC engines.

What Arka mentioned above is right, revving while starting for the first time followed by idle for some time will allow for some lubrication, then the regular process is followed.

@Headers, how do you know that it is 70-90 deg, are you going by the gauge calibration marking on Jeeps? It depends. But I agree, it will be slightly on the higher side as experimental tests are done in controlled environment leading to slightly different results. Also because of global warming

@Jaggu bhai, a very valid point^^, I agree.

Spike

[headers]

Originally Posted by Jaggu

I think 60 deg so that coolant has a buffer to accommodate the additional heat once the load is applied on the engine. 90 deg, the moment you add load wont the engine overheat and in certain cases even warp the head?

Originally Posted by SPIKE ARRESTOR

@Headers, how do you know that it is 70-90 deg, are you going by the gauge calibration marking on Jeeps? It depends. But I agree, it will be slightly on the higher side as experimental tests are done in controlled environment leading to slightly different results. Also because of global warming

@Jaggu bhai, a very valid point^^, I agree.

Spike

Guys, The coolant temperature can exceed 100 deg. Infact the boiling point of water soluble coolant is in excess of 100 deg C.


@ Spike - How does the load on the engine affect the coolant temperature?

IMO, unless you run for prolonged distances in extreme conditions where the engine is strained and the water pump / radiator / cooling system is not working fine, only then will the coolant temperature increase.

..

[SPIKE ARRESTOR]

Originally Posted by headers

@ Spike - How does the load on the engine affect the coolant temperature?

IMO, unless you run for prolonged distances in extreme conditions where the engine is strained and the water pump / radiator / cooling system is not working fine, only then will the coolant temperature increase.

@Headers, your understanding is incorrect. Engine load affects coolant temperature. This is the single reason why vehicles are loaded to GVW condition or attached to a draw bar load and run around the region of max torque in-order to simulate worst case scenario, this is for a non AC vehicle. For an AC equipped vehicle AC load is also inculcated.

Spike

PS- Have you seen sometimes the engine coolant temperature rises during towing a vehicle. What happens when the vehicle is suddenly stopped after a hot run, what happens when it is allowed to idle? Think think...

Mods- I hope we are not going OT here, please delete if found inappropriate.

[headers]

Originally Posted by SPIKE ARRESTOR

@Headers, your understanding is incorrect. Engine load affects coolant temperature...

"How" is my question..

Originally Posted by SPIKE ARRESTOR

PS- Have you seen sometimes the engine coolant temperature rises during towing a vehicle. What happens when the vehicle is suddenly stopped after a hot run, what happens when it is allowed to idle? Think think...

Hey thanks..now let me try to answer your question.

When a vehicle is suddenly stopped after a hot run. The temperature rises as the engine cooling is stopped abruptly. If the engine stops, the water pump stops and if the water pump stops the water circulation stops and hence the engine temp goes up..

Is the above correct?

[SPIKE ARRESTOR]

Originally Posted by headers

"How" is my question..

When a vehicle is suddenly stopped after a hot run. The temperature rises as the engine cooling is stopped abruptly. If the engine stops, the water pump stops and if the water pump stops the water circulation stops and hence the engine temp goes up..

Is the above correct?

LOL, you are right (score 5/10, as the answer was incomplete). What happens if it is allowed to idle?

Let me give you an example:- you are taking a 50 kg and then a 100 kg load on your head through a 15 degree incline. Which puts more stress on you the 50 kg load or a 100 kg one? You have to give an extra effort in-order to negotiate the climb isn't it?

This means for a fixed volume of coolant in the circuit the engine has to work harder in-order to dissipate the heat quickly, as the coolant is circulating much quicker now its temperature rises.

Spike

[Sutripta]

Originally Posted by SPIKE ARRESTOR

LOL, you are right (score 5/10, as the answer was incomplete). What happens if it is allowed to idle?
If the initial design of the cooling system is OK, temp will start coming down.

Let me give you an example:- you are taking a 50 kg and then a 100 kg load on your head through a 15 degree incline. Which puts more stress on you the 50 kg load or a 100 kg one? You have to give an extra effort in-order to negotiate the climb isn't it?

This means for a fixed volume of coolant in the circuit the engine has to work harder in-order to dissipate the heat quickly, as the coolant is circulating much quicker now its temperature rises.

Spike

Can't understand what you are saying here.

Regards
Sutripta

[Jaggu]

Originally Posted by headers

Guys, The coolant temperature can exceed 100 deg. Infact the boiling point of water soluble coolant is in excess of 100 deg C.

What i meant was the old diesel engines, especially some Peugeot models cant handle high temperature. That's all, so sometimes one needs to keep a watch on the temp though the vehicle is running coolant etc.

[lugnut]

Mods this is a late reply to an OT topic - feel free to relocate as needed.

The following is largely observational - with coolant running

My Xd3P runs between 70 to 80 degrees with the A/C switched off - irrespective of traffic conditions

The moment the A/C is turned on , it shoots upto 80 degrees, and tends to linger there ~80+ degrees - while the car is in motion (at 25 to 30 kmph minimum)

The needle rises upto 85 to 90 degrees in stop-start traffic, long periods of idling with A/C switched on -

This would also support the theory that XD3P based Army Jeeps usually move slow, and in convoys..

I am guilty of having blown my engine's head gasket due to novice experimentation

But I suspect in hardcore off-roading situations, the above load conditions would be similar - low levels of radiator air flow (read:slow movement through obstacles) and greater loads -

I believe there are 2 commonly accepted ways to fix this :
1. Swap the fan with an Electric fan that provides sustained airflow (even in idling conditions) - this is usually popular with Aussie offroaders - where the natural shade temps are 40 C

2. Swap the radiator with an aftermarket one that allows greater cooling at low air flow rates

One thing that I do not account for, here, is the amount of coolant flowing via the water pump..

Gurus please help - what's a better choice here and details in the indian context (what's available, prices etc..)

[ex670c]

Originally Posted by lugnut

Mods this is a late reply to an OT topic - feel free to relocate as needed.

The following is largely observational - with coolant running

My Xd3P runs between 70 to 80 degrees with the A/C switched off - irrespective of traffic conditions

The moment the A/C is turned on , it shoots upto 80 degrees, and tends to linger there ~80+ degrees - while the car is in motion (at 25 to 30 kmph minimum)

The needle rises upto 85 to 90 degrees in stop-start traffic, long periods of idling with A/C switched on -

This would also support the theory that XD3P based Army Jeeps usually move slow, and in convoys..

I am guilty of having blown my engine's head gasket due to novice experimentation

But I suspect in hardcore off-roading situations, the above load conditions would be similar - low levels of radiator air flow (read:slow movement through obstacles) and greater loads -

I believe there are 2 commonly accepted ways to fix this :
1. Swap the fan with an Electric fan that provides sustained airflow (even in idling conditions) - this is usually popular with Aussie offroaders - where the natural shade temps are 40 C

2. Swap the radiator with an aftermarket one that allows greater cooling at low air flow rates

One thing that I do not account for, here, is the amount of coolant flowing via the water pump..

Gurus please help - what's a better choice here and details in the indian context (what's available, prices etc..)

Hi Lugnut,

Till the Gurus contribute, I'll try to fill in.

1) Check if you vehicle has a thermostat (Inside Top Flange of the Water Pump)

2) If you have a Thermostat; has a venting/bypass hole in the body (IIRC4mm) Drill the hole to 8mm and make another 8mm hole on the opposing side.

3) If you don't have a thermostat, then get one and do the above.

I have blown the head gasket twice in my vehicle, and both the times in summer without the thermostat.

But previously I have run the vehicle with the thermostat and no engine problems.

By venting the thermostat, you allow the coolant to circulate more freely. This has two effects, the engine takes longer to heat up and cools down much faster.

Also flush the engine block water jacket and radiator and switch to a coolant. The biggest advantage of coolant is, reduces scaling, and you can always spot a leak.

Please check the coolant over flow bottle and Radiator Cap (7-10Psi) works well with the M&M Vehicles.

Regards,

Arka

[headers]

Originally Posted by ex670c

Also flush the engine block water jacket and radiator and switch to a coolant. The biggest advantage of coolant is, reduces scaling, and you can always spot a leak.

Please check the coolant over flow bottle and Radiator Cap (7-10Psi) works well with the M&M Vehicles.

In addition to the above, check water pump bearings or blindly replace them..

I have a stock mm540 and 7psi works fine..