EGT Pyrometer Probes - Exposed vs Sealed Tips

[Robmacca]

Guys.....

I'm wanting to install a EGT Guage 'Pre-Turbo" into my LR and I've noticed that there's 2 types of Thermocouple Probes - Sealed Tip and Exposed Tip. Apparently the Exposed Tip responds quicker, but my concerns are it's durability if I install it Pre-Turbo where as the Sealed Tip ones would have a better life... I assume ?

What are people's experiences when installing the EGT Probe Pre-Turbo and what Probe did u use - Sealed or Exposed Tip?

Last thing I want is to install a EGT Probe that may fail and break off & then go through & destroy the Turbo.....

cheers...
Rob

[DieselDan]

I bought a thermocouple probe from Ian at Thermoguard ThermoGuard Instruments (http://www.thermoguard.com.au/index.html)

It's a sealed tip type and responds quickly enough!

[Duarte19]

I used one of these

EGT Probe - Diesel - Commercial Industrial Duty - 3/16" Diameter (http://thesensorconnection.com/egt-probe-thermocouples/sensors/exhaust-gas-temperature/egt_diesel_probe.shtml)

excellent quality

[Robmacca]

I bought a thermocouple probe from Ian at Thermoguard ThermoGuard Instruments (http://www.thermoguard.com.au/index.html)

It's a sealed tip type and responds quickly enough!


Yeah, I believe Ian recommends the Sealed Tip Probe if going PRE-Turbo.....?

[GuyG]

I was advised not to fit it in the blanking plate in case it does break and drop into the turbo, thus destroying it, but fit it to the end closest to the front of the car so that if it does break, it'll drop into the exhaust.

[Red90]

An exposed tip will not last. 3 mm sealed will give a fast enough response. don't do 6 mm. What is important is to get a decent sheath material. Inconel should be fine. Something like 316 stainless will get brittle and fail over time.

[Robmacca]

An exposed tip will not last. 3 mm sealed will give a fast enough response. don't do 6 mm. What is important is to get a decent sheath material. Inconel should be fine. Something like 316 stainless will get brittle and fail over time.

Whats wrong with the 6mm one? This is what Ian Sells.....

I haven't read too many incidents where the Probe has failed and gone through the Turbo but I think I remember Ian saying to make sure that's its not an exposed tip probe (he also indicated that stainless is good enough) and u should be OK to install it pre-turbo....

What is "Inconel" ??

[Red90]

The 6mm ones do not react fast enough and you will miss the peak temperatures.

Regular stainless will fail over time.

[ROAMER_AUS]

Uhmm interesting....
I'm in the process of installing EGT gauge myself.

What is the difference in response time between 3 and 6 mm probes? I wouldn't be comfortable running engine so close to damaging temparatures that I'm dependant on quick probe response. What are we talking? Seconds? Tens of seconds? Minutes?

Mounting probe to the front of exaust manifold. Won't exaust pressure push it into turbo anyway?

[DieselDan]

Yeah, I believe Ian recommends the Sealed Tip Probe if going PRE-Turbo.....?

Yep that's right. I also bought the blanking plate and compression fitting from Ian to go where the pre-turbo EGR blanking plate fits on the 300Tdi.

Red90 is more than likely correct that the 6mm ones react slower to temp changes, but in my experience with the 300Tdi, nothing happens quickly with that engine (with the possible exception of the way the temp gauge changes from 'normal' to 'you have now wrecked your cylinder head' without warning) so I have found the 6mm one to work well enough ;)