Thermocouple drilling techniques

[toadshade]

I am about to install my pyrometer but it kind of scares the hell out of me. I can't help but think of the tight tolerances right at the turbo with all those metal shavings. Even if those shavings are more iron dust. I have seen threads on using grease. I talked with someone about removing the turbo and putting duct tape behind the hole. I thought of putting a magnet inside after unbolting and moving the turbo to the side. I am hoping I can get some input to give myself some peace of mind.

 

[toadshade]

Also, are all thermocouples adjustable or would it be better to find one that is a fixed length?

 

[doug720]

IMHO

!) General location - I think the probe should be pre-turbo for most accurate readings. Not always possible, but that is preferred location.

2) Manifold Location - You want the probe as close to center of flow as possible. Best way to find location is to look inside manifold to locate best position. If not feasible, try to find a picture of the manifold you have to determine location of probe. Maybe someone else has posted a picture of the probe location.

3) Drill hole - don't worry about debris. No grease, use light oil. Clear the tap often and use a shop vacuum as you drill. Then try to seal vac nozzle over finished hole to clear debris. The balance will blow out exhaust.

4) Depth of probe - Probe should be as close to center of flow as possible

5) Use anti-sieze on probe fittings

6) Support and protect probe wire

Hope this helps.

 

[gerg]

I think grease and a small magnet are great ideas to debulk the shavings but honestly after working on turbos for quite a while I can say the turbines are extremely durable. Don't confuse a compressors soft light aluminum construction with a turbine. The two are vastly different. Turbines are designed to run in the absolute most demanding condition. They are extremely durable. Running at idle will clear the debris and the turbo will only be running hundreds of rpm. Which is basically nothing for them. Under load they do over a hundred thousand rpms. If you let it idle for 5min any debris that is loose would be blown out and anything that stuck would eventually be burned up. Metal filings have such little mass that impacting the turbine at low speed would be negligible. Let it idle, rev it up and that's it. Been done many times. I think we forget that the turbine does see chunks of carbon released that enter the exhaust and impact the turbine. We just don't know about it.

 

[toadshade]

That makes me feel better. I am surprised to hear that they are that durable. Good point about the carbon. I am about to order an Auto Meter with adjustable probe. I thought a fixed probe might be more reliable, but this way I can get the probe right where it needs to be in the center.

 

[IanB]

When you break through while drilling, and when tapping, if you idle the engine it will push the debris out rather than let it fall in the manifold.

 

[toadshade]

That's a good idea. But I just realized I have a better way. I took off my heat shield to get a look at what I am working with and just found a crack in my manifold . Looks like it is coming off anyway. This just got even more fun.