[DirtyDan]

Is the fan belt set at the correct tension? Could the belt be loose and slipping thereby not turning the fan fast enough to provide optimal cooling?

Same question for the water pump, is the belt slipping and allowing the pump to NOT turn optimally?

Above, if a bearing is going bad in the pump it will resist turning and the belt will slip. It will not pump enough water.

Are the radiator vanes all bent up or corroded on the outside so as to not allow good airflow? Similarly, is the outside of the radiator caked with dirt, crud, restricting airflow?

Does the coolant in the overflow tank go back into the radiator automatically after the engine cools down? If not, there is perhaps a leak somewhere in your cooling system.

[Samurai]

Originally Posted by DirtyDan

Is the fan belt set at the correct tension? Could the belt be loose and slipping thereby not turning the fan fast enough to provide optimal cooling?

The fan belt is new, it is not slack, many Jeepers at Coorg OTR checked and confirmed it.

Originally Posted by DirtyDan

Same question for the water pump, is the belt slipping and allowing the pump to NOT turn optimally?

Same belt right?

Originally Posted by DirtyDan

Above, if a bearing is going bad in the pump it will resist turning and the belt will slip. It will not pump enough water.

Mechanic says water pump is fine.

Originally Posted by DirtyDan

Are the radiator vanes all bent up or corroded on the outside so as to not allow good airflow? Similarly, is the outside of the radiator caked with dirt, crud, restricting airflow?

The radiator core is new, I had it installed recently.

Originally Posted by DirtyDan

Does the coolant in the overflow tank go back into the radiator automatically after the engine cools down? If not, there is perhaps a leak somewhere in your cooling system.

Yes, it does.

The engine stays at 80C while ripping at 70-80kmph on a level road under hot afternoon sun for hours. But, it rises to 100C climbing uphill for just 10-15 minutes in pouring rain. Could this be a coolant system problem?

[tsk1979]

Samurai, just a hunch.
1. PArk you car and idle for 15 minutes in sun and see what happens
2. If everything is okay, then park your car such that front wheels are atleast 1-1.5 feet higher than rear wheels, and then idle. See if she overheats

[DirtyDan]

Originally Posted by tsk1979

Samurai, just a hunch.
1. PArk you car and idle for 15 minutes in sun and see what happens
2. If everything is okay, then park your car such that front wheels are atleast 1-1.5 feet higher than rear wheels, and then idle. See if she overheats

Great idea! But, if it does overheat, what does this indicate and what does he do about it? Massive rear tyres and wheels are probably not an option. My guess is that if this clever test yields an overheat then it is still the water pump that is not moving enough coolant.

The only other thing I can think of is an obstruction within the engine water jacket itself and I can not imagine how that would happen except by long disuse and massive corrosion inside. This is unlikely. My bet is the water pump.

Samurai, my comments on your radiator were focused on the outside of it, the air flow, not the interior core.

[DKG]

Samurai

I was surprised to notice your thread hasn't progressed beyond the cooling issue!

Please go about it methodically and solve it. Two elements constitute cooling efficiency in an engine. Water/coolant flow and air excavation through radiator fins.

Poor water pump function, jammed thermostat, scaling of cylinders hamper effective circulation and contact with cylinders

Inadequate radiator size and fan hamper cooling of the water.

Check the following in sequence

1. Does the radiator on your Jeep match the engine it has? Sometimes when bigger displacement diesels are slotted in and the old smaller radiators left in this can happen.

2. Is the fan of the correct size and blades? Also is it at the correct distance from the radiator

3. If the system has a water flow control thermostat, have it taken out. You don't need these in non-snow climate conditions

4. Heavy scaling. As most people in India have traditionally used tap water for coolant a lot of scaling occurs around cylinder liners. Use some industrial grade descaling agents and see if that helps.

5. On petrol engines when the timing is retarded engines heat up. I don't know much about diesels but have your injector pump set for correct timing (unless it already is) and ensure the engine is not too retarded. At this stage also do a compression test to see if the engine is worn out.

Last but not the least if the engine on your Jeep is a modern lean burn engine then you require a pressurised radiator system as these engines run hotter and pressurizing reduces the boiling point of the coolant and maintains the quantum of coolant in the system even at close to boiling temps.

[DKG]

Originally Posted by Samurai

Mechanic says water pump is fine.

How has he concluded this? Without opening it? In which case all he checked was if the bearing was fine and there were no leakages. The culprit can also be a ineffective impeller which could either be of a smaller size or one thats come loose on the shaft.

Unhook the hose that inlets into the radiator and adding water through the cap inlet start the engine and see if the water pump output is fine. As you rev it should increase the water flow output.

[Samurai]

Originally Posted by tsk1979

Samurai, just a hunch.
1. PArk you car and idle for 15 minutes in sun and see what happens
2. If everything is okay, then park your car such that front wheels are atleast 1-1.5 feet higher than rear wheels, and then idle. See if she overheats

That sounds so interesting, I have to try it. First I need to find two really big bricks to stop it from rolling back.

Originally Posted by DKG

I was surprised to notice your thread hasn't progressed beyond the cooling issue!

Well, it is turning out to be an elusive problem. I live in a tiny town/village, don't have access to top mechanics who can feel out the problem.

Originally Posted by DKG

1. Does the radiator on your Jeep match the engine it has? Sometimes when bigger displacement diesels are slotted in and the old smaller radiators left in this can happen.

The engine is original, the new radiator occupying all the room available.

Originally Posted by DKG

2. Is the fan of the correct size and blades? Also is it at the correct distance from the radiator

Who can judge this? My mechanic thinks it looks fine.

Originally Posted by DKG

3. If the system has a water flow control thermostat, have it taken out. You don't need these in non-snow climate conditions

There is no thermostat.

Originally Posted by DKG

4. Heavy scaling. As most people in India have traditionally used tap water for coolant a lot of scaling occurs around cylinder liners. Use some industrial grade descaling agents and see if that helps.

I mentioned this to the mechanic, I got a puzzled look back. I don't want him to do something he doesn't understand. Do Mahindra service centers do this routinely?

Originally Posted by DKG

5. On petrol engines when the timing is retarded engines heat up. I don't know much about diesels but have your injector pump set for correct timing (unless it already is) and ensure the engine is not too retarded. At this stage also do a compression test to see if the engine is worn out.

That is on the cards.

Originally Posted by DKG

Last but not the least if the engine on your Jeep is a modern lean burn engine then you require a pressurised radiator system as these engines run hotter and pressurizing reduces the boiling point of the coolant and maintains the quantum of coolant in the system even at close to boiling temps.

The 2.1 Liter XDP 4.90 Peugeot Diesel is well known, I don't know whether it is lean burn or not.

Originally Posted by DKG

How has he concluded this? Without opening it? In which case all he checked was if the bearing was fine and there were no leakages. The culprit can also be a ineffective impeller which could either be of a smaller size or one thats come loose on the shaft.

Unhook the hose that inlets into the radiator and adding water through the cap inlet start the engine and see if the water pump output is fine. As you rev it should increase the water flow output.

I guess I have to talk to him again.

[DKG]

Originally Posted by Samurai

The 2.1 Liter XDP 4.90 Peugeot Diesel is well known

Measure the fan distance to radiator on any other standard Mahindra with this same engine which doesn't have a cooling problem to rule this out. Also verify if the fan and pulleys are correct for the above engine

As I don't know much about these engines check if it requires the pressurised coolant system and if that is fine too then do a flow test. The Shop Manual should give details of litres/minute @ a certain rpm for water pump efficiency. If the water pump tests fine then the problem is either scaling or a retarded engine (also weak compression), which you can eventually ascertain through a compression test.

Barring the undoing of the water inlet hose at the radiator to check on the flow test all the other checks do not require dismantling anything and you can do this at home if you have access to a Shop Manual. A compression test you can do at any garage with the meter

As a general rule for anyone maintaining an old vehicle I strongly recommend acquiring a Shop Manual and a Parts Catalogue as both are invaluable resource materials. Apart from their value in getting it right the first time you also avoid expensive mistakes while ordering parts.

[Spitfire]

The engine needs a overhaul.

[headers]

Originally Posted by Spitfire

The engine needs a overhaul.

How do you say that? Nowhere does it indicate that his engine is consuming oil and loosing power.

One does not just overhaul an engine for a mild overheating issue!

[Spitfire]

Originally Posted by headers

How do you say that? Nowhere does it indicate that his engine is consuming oil and loosing power.

One does not just overhaul an engine for a mild overheating issue!

Ok fine. Samurai, hope you get it sorted asap.

[Samurai]

Originally Posted by headers

How do you say that? Nowhere does it indicate that his engine is consuming oil and loosing power.

That's true, other than overheating in uphill driving, there are no other symptoms.

[khan_sultan]

Originally Posted by Samurai

That's true, other than overheating in uphill driving, there are no other symptoms.

Maybe it's time for you to visit Jammy along with your 340 and get him to sort this out for you .

[Spitfire]

Originally Posted by Samurai

That's true, other than overheating in uphill driving, there are no other symptoms.

Awaiting that compression test result.

[Jaggu]

Samu: Check your diesel pump calibration/settings, have a feeling that can be the reason.