[headers]

Originally Posted by Samurai

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

Just Drive for around 2000 kms or so. Sometimes, it is normal for a slight overheating in a new system. The system should bed in by then.

Also, is the fan sucking air from the radiator or blowing air into the radiator? This may be a very important point!

[tsk1979]

Samurai, were you able to do the incline test. If that causes overheating then its definitely water pump issue.
You can also park on steep incline, and see of water pump can move the coolant.

[SirAlec]

Originally Posted by Jaggu

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

No way dieselpump can be the reason! As i guess pickup is good enough. Am I right?

[headers]

Sir, a diesel pump if it is not calibrated properly or does not provide proper fuel when required could also lead to overheating. IMO

Pick up is NOT the only way to check a fuel pump setup!

[Samurai]

Originally Posted by headers

Sir, a diesel pump if it is not calibrated properly or does not provide proper fuel when required could also lead to overheating. IMO

Pick up is NOT the only way to check a fuel pump setup!

If the diesel pump is at fault, shouldn't it cause problems in straight road driving too. For example, I drove hard non-stop for 5 hours covering 220Kms, often hitting 60-70kmph without any overheating, that too in sunny weather.

Originally Posted by tsk1979

Samurai, were you able to do the incline test. If that causes overheating then its definitely water pump issue.
You can also park on steep incline, and see of water pump can move the coolant.

Yes, today after lunch I drove to a tiny hillock and parked it using two stones to stop it from rolling back. The angle was roughly 25 degree, which is much more than the normal driving uphill. I kept the engine on for 15 minutes, often revving it. The temperature never even hit 70C during the entire period. The normal temp is 80C while regular driving.

[Jaggu]

Originally Posted by SirAlec

No way dieselpump can be the reason! As i guess pickup is good enough. Am I right?

Header addressed my point.

Originally Posted by headers

Sir, a diesel pump if it is not calibrated properly or does not provide proper fuel when required could also lead to overheating. IMO

Pick up is NOT the only way to check a fuel pump setup!

Yes i was amazed with the change in a Fiat 137 D engine, after an overhaul of pump at the Bosch service center, long time back. Engine became crisp, efficient and a nasty overheating issue (while AC ON) was resolved.

If one over rules the cooling system, then obvious check should be pump before moving on to other things. Also compression check and all can be done along with pump overhaul, and a properly set pump will anyday benefit the engine.

[DKG]

There are two main elements in a diesel injection/pump setup. The bar pressure at injectors and the timing of when the injector should fire. Both affect the performance of an engine. A retarded timing of the pump means the combustion occurs post the ideal firing point thereby rendering the transformation of the explosion into motive power inefficient. Instead the energy gets transformed into heat. Under load this becomes very stressful and a retarded setting causes the engine to overheat. So sometimes the pump setting can affect heating too. The bar pressure of the injectors affects the combustion quality, as it controls the degree of atomisation of the fuel.

PS To the best of my knowledge as long as the compression of the engine is sound it fires easily (that's the beauty of the diesel engine) however power development and fuel economy is affected by the timing and the injector settings. Someone please correct me if I am mistaken about this

[Samurai]

Can a road side mechanic diagnose these diesel pump/injector timing issues? Seems quite complicated requiring complex equipment.

[DKG]

Originally Posted by Samurai

Can a road side mechanic diagnose these diesel pump/injector timing issues? Seems quite complicated requiring complex equipment.

A small device is required to set the bar pressure. But calibrating the pump does require a special machine.

Setting the timing is something he can do. There's a technique where a few drops appear on a small pipe he has to attach to outlet for injector one, as he swings the pump in/out. That's how you set the timing. Best done by someone who understands these engines thoroughly

[DKG]

Samurai I forgot to mention that timing issues usually you can tell by a visible loss of power, ie the engine struggling. If your Jeep's engine feels crisp and acceleration is fine then this may not be the problem.

Do please rule out the water pump through a flow test before you head for fuel pump/compression tests etc.

[bblost]

Found this while searching something else but thought it might add value to the overall issue (overheating):

How To Tell if Your Car's Thermostat Is Stuck Closed | eHow.com

Step 1:Warm up the car but don't let it overheat--don't let the temperature gauge go into the red.

Step 2:Turn off the engine.

Step 3:Open the hood.

Step 4:Find the upper radiator hose. It's black, is made of rubber and is about 2 inches in diameter, with metal clamps on either end. The upper hose goes into the top of the radiator.

Step 5:Locate the lower radiator hose. It looks similar to the upper hose except that it attaches to the bottom part of the radiator.

Step 6:Touch each hose very carefully (they can be extremely hot). If the temperature gauge is indicating that the engine is warmed up but one hose is hot and the other is cold, the thermostat is probably stuck closed, and the coolant isn't circulating through the radiator.

Step 7:Have the thermostat replaced if this is the case.

[Samurai]

This Jeep has no thermostat. People in warmer climate have it removed.

[BaCkSeAtDrIVeR]

A retarded timing of the pump means the combustion occurs post the ideal firing point thereby rendering the transformation of the explosion into motive power inefficient. Instead the energy gets transformed into heat. Under load this becomes very stressful and a retarded setting causes the engine to overheat. So sometimes the pump setting can affect heating too. The bar pressure of the injectors affects the combustion quality, as it controls the degree of atomisation of the fuel.

The flywheel of a diesel engine has numbered markings. The shaft of the fuel injection pump, where connects to the engine, too has a wheel, and there are "tension plates" between the wheel on the fuel pump and the timing wheel of the engine. Both these (timing) wheels will have marks which correspond to each other and the markings on the flywheel. While installing a fuel pump, the mechanics usually prop up one of the wheels, put the vehicle in gear, and turn the wheel by hand to align the markings on the flywheel with the markings on the fuel injection pump. That is how it is done on vehicles I have come across. It is posssible that the jeep too has similar mechanism. Getting those markings properly aligned ensures that the injection is timed correctly for each cylinder.

AFAICT, if timing is not correct, the engine will require more cranks to start, and and will also loose power.

Can a road side mechanic diagnose these diesel pump/injector timing issues? Seems quite complicated requiring complex equipment.

See above. Fuel pump calibration is a different ball game altogether. Depending which make your injection system is (MICO or Lucas-CAV) you take the pump / vehicle to the relevant service station (both MICO and Lucas CAV have separate shops - not workshops / garages) doing only fuel injection overhaul. Like that next door lube shop you never noticed, this shop too is likely next door.

Essentially, there are two components of a diesel fuel system - the nozzles, which are mounted to a housing and go into the head, and corresponding "elements" which are found inside the fuel injector pump. Both are replaced in case of overhaul. (rest being bearings and consumables - gaskets, washers, etc.)

I would rule out fuel system problems here unless you have poor FE AND considerable loss of power. What is your FE?

This Jeep has no thermostat. People in warmer climate have it removed.

Did the older jeeps have a thermostat?

[headers]

Originally Posted by Samurai

The angle was roughly 25 degree, which is much more than the normal driving uphill. I kept the engine on for 15 minutes, often revving it. The temperature never even hit 70C during the entire period. The normal temp is 80C while regular driving.

Sharat, I was positive this will not yield any result.

Originally Posted by DKG

There are two main elements in a diesel injection/pump setup. The bar pressure at injectors and the timing of when the injector should fire. Both affect the performance of an engine. A retarded timing of the pump means the combustion occurs post the ideal firing point thereby rendering the transformation of the explosion into motive power inefficient. Instead the energy gets transformed into heat. Under load this becomes very stressful and a retarded setting causes the engine to overheat. So sometimes the pump setting can affect heating too. The bar pressure of the injectors affects the combustion quality, as it controls the degree of atomisation of the fuel.

PS To the best of my knowledge as long as the compression of the engine is sound it fires easily (that's the beauty of the diesel engine) however power development and fuel economy is affected by the timing and the injector settings. Someone please correct me if I am mistaken about this

Sir, Timing IMO should be exact at the TDC, no advance, no retard. This is the bestl setting. Generally, the local mechanics advance by 5 to 10 degrees to achieve better acceleration and FE. But the engine will get screwed up positive. By retarding by a degree or two increases the torque!

Originally Posted by Samurai

Can a road side mechanic diagnose these diesel pump/injector timing issues? Seems quite complicated requiring complex equipment.

No a roadside mechanic may not be able to do it.

Originally Posted by BaCkSeAtDrIVeR

AFAICT, if timing is not correct, the engine will require more cranks to start, and and will also loose power.

Essentially, there are two components of a diesel fuel system - the nozzles, which are mounted to a housing and go into the head, and corresponding "elements" which are found inside the fuel injector pump. Both are replaced in case of overhaul. (rest being bearings and consumables - gaskets, washers, etc.)


Did the older jeeps have a thermostat?

I agree, if the timing is improper, the engine will require more cranks to start!.

All post 50s vehicles had a thermostat!

[simplyself]

It is better to take away thermostat altogether in warmer climates as it doesnt have much use there.