EGT 's good or bad guys ??

[mudmuncher]

Hi All and Merry Christmas !!

I have a 1986 90 with a 300 TDI engine in it.

The fuel pump has been tweaked and the turbo wound up a bit (by the previous owner)

I love the extra power and drivability !!!

I decided to fit an exhaust gas temp gauge as i want to keep an eye on the engine as i still need reliabilty !!

The readings i have are

Tickover = 220 celsius

Normal driving = 350 -500 celsuis

Flat out uphill =600 celsuis

Would you say these readings are safe ??

Many thanks guys

Chris

[western]

there's lots of info about EGT on Tdi engines, a search will find them, around 720 is getting into worry time IIRC.

[David Sparkes]

snip.

The readings I have are

Tickover = 220 celsius

Normal driving = 350 -500 celsuis

Flat out uphill =600 celsuis

Would you say these readings are safe ??

I'll endorse Western's comment about doing more research, but my own answer is 'Yes', I think those readings are safe

The EGT isn't just a safety gauge, it's also an economy gauge for diesels. Similar to but more effective than a vacuum gauge used on petrol engines.

To copy something I wrote earlier:

One additional but often unappreciated action, which if used correctly will help both economy and engine life, is to install an EGT meter.

Assuming you are making the progress you are content with, or what the traffic and road will allow, then always aim for the lowest temperature possible. It seems a very basic point, but this shows you are using the least amount of fuel for the power you are using. I'll repeat the point in different words, you often don't need maximum power.

Analyse the results and you will find it's often better to stay for longer in a low gear at a higher engine speed, or change down earlier rather than later when accelerating.

When your road speed is restricted by conditions or traffic it's very nice to let the engine speed drop, floor the throttle, and let the torque pull you back to speed, all in the same gear, but watching the gauge will show you that you use a lot of fuel, and this means you are creating a lot of cylinder pressure per combustion stroke to get the performance. In terms of engine stress it's better to do more revs at lower pressures. This will also give you the best economy.

HTH

[suggs]

were does the sensor fit, do you have to drill and tap the turbo or manifold?

[Mo Murphy]

The exhaust manifold.

Mo

[Turnip]

Got any pics? Where is the best place to get the gauge and sender..............before Vat goes up!

[western]

Got any pics? Where is the best place to get the gauge and sender..............before Vat goes up!

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[JimAttrill]

I have had an EGT gauge fitted for about 10 years now. Actually mine is a Shinto furnace controlling computer. I have programmed the switch for 720c coupled to a buzzer in case I forget to look at it. And I have tweaked my injector pump. No real point in having the gauge if you don't do that I overtweaked it at the first try and could hit 800c so it is lucky I fitted the gauge or the engine would be history.

I find your readings a bit strange compared to mine (and others that I have checked with). Your idle temp is very high. Mine idles at 150c when hot and 170-180 with the a/c on. I always let the engine cool down to 200c (an arbitrary number) before switching off. This is, I believe the great advantage of having an EGT gauge. Note that my turbo has done 290000 kms

My temps will hit the 'red line' at 720c only on very long uphill pulls. In the area I live there are no places that I can get it that high.

[Turnip]

Ive had a look at various EGT gauges on the net and I see both digital and simple analogue rotary gauges. I quite like the simplicity of analogue gauges because like an analogue watch, you can get a position at a glance? Before i spend my Christmas money..........any pros and cons??

[David Sparkes]

I never tested an analogue gauge. I found that the temperatures were fairly stable in steady conditions, any rate of increase due to a sustained high workload was quite small. When temperatures did increase rapidly it was because I had opened the throttle in a lowish gear, and was busy dealing with the rapidly changing view through the windscreen.

It never happened that I hurriedly changed what I was doing because of what the EGT gauge said, so monitoring the detail wasn't important. With a digital gauge you get a sense of rapid change when the reading changes in steps of 100 or 50 degree steps.

If you have an analogue gauge that clearly shows the difference between 100 and 120, and the difference between 700 and 720, it's going to be a big dial.

For EGT I preferred Digital, for boost I preferred analogue.