Pajero Owners Club of South Africa

NOTES:

• EGT = Exhaust Gas Temperature
• Safe EGTs are those below ±700 deg C (dependant on specific engine design)
• EGT is most probably the second largest contributor to diesel engine failures, after failures due to over-heating of the coolant.
• EGTs and coolant temperatures are only remotely related.
  Even with the coolant temp. very low, the EGTs can be very high. (If you really try, you can have dangerously high EGTs within seconds of starting up a cold engine).
  Conversely, high EGTs don't necessarily show up as high coolant temps.
• High EGTs cause failures to
  • pistons
  • valves
  • valve seats
  • rings
  • heads

High EGTs occur when the combustion mixture is to rich.
This condition will occur when:

• 1. The fuelling system is faulty, delivering to much diesel for the volume of air (oxygen) available
• 2. There is a restriction in the inlet tract, such as a dirty/clogged air filter
• 3. The rpm is to low for the throttle opening.
  The "throttle" on a typical diesel engine acts like a valve. Step on the load pedal and the pump will dump diesel into the combustion chamber, regardless of the load or rpm.
  (This differs from the petrol engine, but that is another discussion)

Items 1 & 2 are mechanical problems, and item 3 is a "driving style" problem.
Even if the engine is in 100% mechanical condition, it is possible to have high EGTs, due to an incorrect driving style.

Does it mean that driving "like a hooligan" will always cause high EGTs? (sorry Simon, but you triggered this )

I would say "No!", not necessarily, if "driving like a hooligan" means "working" the engine.

The worst thing to do to a diesel engine is to increase the throttle opening when there is no immediate resultant rise in speed/rpm.

Although a diesel should not be revved beyond ±3500 rpm, leaving is to labour in a high gear is not good either.
Driving like Granny (as against driving like a hooligan) is often very bad for a diesel engine.
(Driving like granny = putting the car in top gear and then leave it there to labour it's way to higher speeds / loads)

Once you have fitted an EGT gauge to your diesel engine, you quickly learn how to adjust your driving style to keep the EGTs low.
eg
Rather change down earlier than having the engine labour in a higher gear (even though this may look like driving "like a hooligan").
There may be times when the road / load dictate that you lower the speed, eg when towing up a long steep gradient.
(You might be able to hold the vehicle at 120 km/h, but if you had an EGT gauge fitted, you would see the EGTs rise to 750+ deg C )

So what is my conclusion?
Driving a diesel incorrectly is not necessarily "driving like a hooligan".

My new k-type probe is in the mail so as soon as it's fitted ill take some video of the egt's in the non common rail 3.2Di-D and post up so we can see what it does when you accelerate foot flat and give full throttle on uphill when speed doesn't increase and dropping gears at same speed etc.

This should be helpful for gen3 owners but for me I wish manufacturers would fit standard from the factory. The more vitals you can monitor will result in earlier spotting of issues.

Cht gauge
Egt gauge
Coolant loss alarm
Oil temp
Oil pressure
Trans temp

I suspect they don't do it as they will be selling a lot less.

Thanks guys for a great post, appreciate all the advice. Marius, looking forward to the vid
J

Hi Marius.

I found this device on landy online which does (monitors with alarms) all of what you woiuld like to see going on in your engine, EGT, Coolant temp, pressure and presence, Oil temp & pressure, Batter voltage, and other interesting data.

http://landyonline.co.za/shop/product_i ... ucts_id/62

Have a look, I am alomost certainly putting in my Gen 3 petrol, to keep tabs on goings on whislt on the road.

Nick

Ja Marius I just wish someone would try and explain that to SWAMBO as she is always driving in highest gear in town with her Jetta-----thinking she is saving fuel. After numerous explanantions I will show this post to her hopefully she will realise she is wrong
That is also why I appreciate a auto so much more as it will rarely drive right into the torque band and will change down if torque is tooo high in high gear.

4ePikanini wrote:My new k-type probe is in the mail so as soon as it's fitted ill take some video of the egt's in the non common rail 3.2Di-D and post up so we can see what it does when you accelerate foot flat and give full throttle on uphill when speed doesn't increase and dropping gears at same speed etc.

This should be helpful for gen3 owners but for me I wish manufacturers would fit standard from the factory. The more vitals you can monitor will result in earlier spotting of issues.

Cht gauge
Egt gauge
Coolant loss alarm
Oil temp
Oil pressure
Trans temp

I suspect they don't do it as they will be selling a lot less.

It will be interesting to compare again to my readings once yours is done.

CATS