Thread: 300TDi EGT probe position?

Looking at the gauge, it starts at 2(ie. 200) degrees, and rises from there.
Anything under 200 is pretty much irrelevant. And I reckon at idle, you'd be seeing 100-150°C if you had the probe at the EGR plate.
So you'd probably see the same effect on the gauge, that is, at idle or on a trailing throttle, it'll dip below 200°C and hence won't register on the gauge.
It does seem to climb quickly tho, and I reckon this is just a design of the gauge or maybe the probe's response or whatever.

I'd say it's working normally, but reading lower than it otherwise would if the probe was at the EGR plate instead, so you'd see higher temps than you do now.
You can see that EGT rises(as you press the accelerator) and then, a sec or so later, boost builds(you registered about 5psi) max on a couple of runs.

Originally Posted by AK83

Looking at the gauge, it starts at 2(ie. 200) degrees, and rises from there.
Anything under 200 is pretty much irrelevant. And I reckon at idle, you'd be seeing 100-150°C if you had the probe at the EGR plate.
So you'd probably see the same effect on the gauge, that is, at idle or on a trailing throttle, it'll dip below 200°C and hence won't register on the gauge.
It does seem to climb quickly tho, and I reckon this is just a design of the gauge or maybe the probe's response or whatever.

I'd say it's working normally, but reading lower than it otherwise would if the probe was at the EGR plate instead, so you'd see higher temps than you do now.
You can see that EGT rises(as you press the accelerator) and then, a sec or so later, boost builds(you registered about 5psi) max on a couple of runs.

Don't see mine rise and fall like that. Mine is digital, though.

Originally Posted by johntins

... Mine is digital, though.

yeah, me too.

I reckon it's the design of the gauge(maybe .. just a theory).
I remember wayyy back, my dad had an old International(truck). 70's vintage C1300.
It had VDO gauges as standard.
The fuel gauge used to drive me bonkers.
If it wasn't full, iand you were moving, it'd move all over the place.
At about 3/4's it'd start and it's swing madly from about half to full and back, in a similar manner.
At half a tank, it would swing from empty to full and back constantly. Temp gauge was similar, but smaller movements.

I remember this because his mate had a later vintage(D1300) too, and it's gauge just sat nice and steady.
On ignition, the C1300 would snap to it's fuel level instantly, where the D1300 would gradually rise to it's level position.

Originally Posted by AK83

yeah, me too.

I reckon it's the design of the gauge(maybe .. just a theory).
I remember wayyy back, my dad had an old International(truck). 70's vintage C1300.
It had VDO gauges as standard.
The fuel gauge used to drive me bonkers.
If it wasn't full, iand you were moving, it'd move all over the place.
At about 3/4's it'd start and it's swing madly from about half to full and back, in a similar manner.
At half a tank, it would swing from empty to full and back constantly. Temp gauge was similar, but smaller movements.

I remember this because his mate had a later vintage(D1300) too, and it's gauge just sat nice and steady.
On ignition, the C1300 would snap to it's fuel level instantly, where the D1300 would gradually rise to it's level position.

Yeah? Try the Veglia gauges in a Fiat! The SW in my MG was priceless as well.

Originally Posted by AK83

Looking at the gauge, it starts at 2(ie. 200) degrees, and rises from there.
Anything under 200 is pretty much irrelevant. And I reckon at idle, you'd be seeing 100-150°C if you had the probe at the EGR plate.
So you'd probably see the same effect on the gauge, that is, at idle or on a trailing throttle, it'll dip below 200°C and hence won't register on the gauge.
It does seem to climb quickly tho, and I reckon this is just a design of the gauge or maybe the probe's response or whatever.

I'd say it's working normally, but reading lower than it otherwise would if the probe was at the EGR plate instead, so you'd see higher temps than you do now.
You can see that EGT rises(as you press the accelerator) and then, a sec or so later, boost builds(you registered about 5psi) max on a couple of runs.

there is a photo of where the probe is in a previous post, just down near the exhaust pipe flange

Originally Posted by AK83

yeah, me too.

I reckon it's the design of the gauge(maybe .. just a theory).
I remember wayyy back, my dad had an old International(truck). 70's vintage C1300.
It had VDO gauges as standard.
The fuel gauge used to drive me bonkers.
If it wasn't full, iand you were moving, it'd move all over the place.
At about 3/4's it'd start and it's swing madly from about half to full and back, in a similar manner.
At half a tank, it would swing from empty to full and back constantly. Temp gauge was similar, but smaller movements.

I remember this because his mate had a later vintage(D1300) too, and it's gauge just sat nice and steady.
On ignition, the C1300 would snap to it's fuel level instantly, where the D1300 would gradually rise to it's level position.

last time i drove a truck with one of these {Pyrometer} it was a raod boss with 290 cummins and it didnt move hardly at all

Yep, saw the pic of the probe location: found some info on the net relating to EGT with the probe either before and after the turbo, and basing my comments with that info in mind.

the real test would be:
you're driving along a freeway(as an example) .. just any road where you can maintain a steady speed, say 80 km/h.
You may get some variation as the car will need throttle feathering every now and then.
But if you come to an incline, then you need throttle, preferably a climb where you need at least half to 3/4 throttle.
Once you're on the throttle, the EGT gauge will climb and/or sit steady at whatever value it does.
It shouldn't vary at all other than climb higher as you labour the engine more and more.
As you approach a speed where you then have to lift off the throttle, obviously EGT cools, gauge drops.

Only thing we're interested in is how steady does it read on the climb up. If it doesn't vary wildly and quickly like in the video, then it's extremely unlikely that there is any voltage, earth or gauge issues.
If it's giving a steady reading, which includes a steady increase with time, then I'd guess that everything is working as is, and it's just a design of the gauge.

Do you get a more steady gauge reading climbing up a hill, or does it still do the same thing in that type of situation too?
Considering that the probe is after the turbo in your car, you'd want to be weary of temps above 500°C or so.

But I reckon it would be a simple matter to relocate the probe to an EGR plate fixture, wouldn't cost a heap of $s and see if that makes a difference in any way.


Just another bit of side info:
You can get a multimeter that also does temperature readout.
They can also use K-type thermocouples(which is what an EGT system uses). As long as the multimeter temp range is within the same range as the temp probe you have it could be another way to get EGT readings.
Many multiple moons ago(x2) .. I got a Dick Smith Electronics multimeter(way back when they were an actual electronics parts store) and it has a 0-1000°C capable temp setting. Was cheap at the time(about $30-40)
I've never thought to test the multimeter on my EGT to see if it works, and how accurate it is too.

thanks all for the answers and i will comment on them in the next few days but the next question I have is
what is the maximum recommended temp considering the placement of the probe or in fact what temp variations
from the "plate" to where mine is