Engine/Transmission (1998.5 - 2002) Pyrometer 1/8" or 1/4" ?

[dmhollister]

I have some snow plowing overtime money to spend and have decided to finish out my christmas present with the combo boost pyrometer gauge from westach. I am wondering which size to buy. I plan on installing pre-turbo.



Besides a smaller hole to drill what are the advantages to a 1/8" probe?



What are are advantages for a 1/4" probe?

 

[Shadrach]

1/4" npt is the standard in the industry for diesel trucks (semis ). If you are going to put in pre turbo the get one with adjustable depth. Shadrach

 

[16919]

The 1/8 responds a little faster if I remember right... . not that it matters that much, mainly a race set up I guess.

 

[bmoeller]

My Isspro gauge is 1/8", but came with a 1/4" adapter. Plus, if you screw up the hole for the 1/8, you can still drill and tap the bigger one. :-laf

 

[RustyJC]

Plus, if you screw up the hole for the 1/8, you can still drill and tap the bigger one. :-laf

... and use a 1/4 to 1/8 reducer bushing to still use the 1/8 probe if you wish.



Rusty

 

[DennyDay]

The 1/4" tap is a little tougher than the 1/8" Less of chance of breaking the tap. Just put a reducing bushing in the 1/4" hole to use the 1/8" fitting. Be sure to use antiseze compound on the reducer - - I prefer a steel bushing over a brass.



Denny

 

[Diesel Manor]

The Gauge kits we sell are 1/8"NPT. This is the thread size of the fitting, not the diameter of the probe. The probes are the same size no matter the size of the fitting. So reaction and accuracy are not effected by the thread size. The smaller 1/8NPT requires less drilling than the 1/4NPT.

 

[Joseph Donnelly]

10 years ago most of the gauge kits we bought had 1/4 but now most are 1/8" NPT. I prefer the latter, use 11/32 drill, cutting oil. clean out shavings with a small telescoping magnet. Never seez on threads.

 

[Bob V]

Cutting oil is not required when tapping cast iron

 

[dmhollister]

Thanks all for the replies. As I was thinking, I will order the 1/8" npt probe.

 

[McLaughlin]

Thanks all for the replies. As I was thinking, I will order the 1/8" npt probe.

When you drill the hole in the manifold you might consider holding a magnet near the bit. I had a really strong magnet laying around which I held close to the bit while drilling the hole. The metal from the manifold crumbled into really small bits (almost like dust) that were almost totally pulled to the magnet so when it was finished there was almost nothing to fall though the hole. If you use the magnet, it is easier to clean off if you cover it with a plastic bag first. As the filings piled up I had to remove them from the magnet and with the bag I could just pull it away from the bag and the filings would fall away. I didn't have to clean the magnet much that way.

 

[Bob V]

Having the truck running will blow the chips out as you drill/tap. Just make sure that you have glasses on and maybe a face shield, they come out fast and hot.

 

[NoSeeUm]

... and use a 1/4 to 1/8 reducer bushing to still use the 1/8 probe if you wish.



Rusty

Yeah... .



I have always used a reducer. Threads in pipe are sometimes hard to start with out cross threading. My thinking is that once I get the reducer in I can install and remove the T/C or drive pressure gauge with out worry of screwing up the threads in the manifold.



Jim

 

[dmhollister]

Thanks for all the replies, the gauges are on the way... .

 

[Diesel Manor]

We strongly advise not to do it with the engine running. This is from our installation instructions.



This is the location for thermocouple placement on a Gen. 3 Dodge 5. 9L Cummins. Make an impression with a center punch where the X is in this photo. You should be drilling in the center of the rear exhaust manifold port (for cylinders 4-6). Start with a small pilot hole and work your way up to a size "R" drill bit (0. 339") increasing 1 drill bit size at a time. This will cause all shavings to remain small and dust-like. There is no need to coat your bits with grease or lube. You want all of the shavings to remain dry so that they will come out without sticking when you vacuum out the hole. Using a 1/8" NPT tap, tap the hole. Apply a small amount of anti-seize lubricant to the threads of the thermocouple fitting and tighten. Insert the probe with its nut and ferrule. You want the tip of the probe to be in the center of the exhaust flow.



Tech Tip: Do not perform this while the engine is running. Some company’s recommend this practice, as it is their belief that the exhaust pressure going through the manifold will push the shavings out through the hole you are drilling. We do not subscribe to this belief. Working on a running engine greatly increases your chance of injury. Also, while uncommon, if your drill bit happens to break off inside the manifold, it has no place to go but through the turbo. If the engine were not running you can always take whatever action necessary to remove the broken piece before you start the engine. The practice of coating your drill bits with grease is also a very bad idea. The flutes of a drill bit are designed to remove chips outward. By loading these flutes up with grease, all you would be doing is making it more difficult for them to perform as designed. Also, grease will cause some of the shavings to stick on the inside of the manifold, making it difficult to remove later with a vacuum cleaner.

 

[Bob V]

We strongly advise not to do it with the engine running. This is from our installation instructions.



This is the location for thermocouple placement on a Gen. 3 Dodge 5. 9L Cummins. Make an impression with a center punch where the X is in this photo. You should be drilling in the center of the rear exhaust manifold port (for cylinders 4-6). Start with a small pilot hole and work your way up to a size "R" drill bit (0. 339") increasing 1 drill bit size at a time. This will cause all shavings to remain small and dust-like. There is no need to coat your bits with grease or lube. You want all of the shavings to remain dry so that they will come out without sticking when you vacuum out the hole. Using a 1/8" NPT tap, tap the hole. Apply a small amount of anti-seize lubricant to the threads of the thermocouple fitting and tighten. Insert the probe with its nut and ferrule. You want the tip of the probe to be in the center of the exhaust flow.



Tech Tip: Do not perform this while the engine is running. Some company’s recommend this practice, as it is their belief that the exhaust pressure going through the manifold will push the shavings out through the hole you are drilling. We do not subscribe to this belief. Working on a running engine greatly increases your chance of injury. Also, while uncommon, if your drill bit happens to break off inside the manifold, it has no place to go but through the turbo. If the engine were not running you can always take whatever action necessary to remove the broken piece before you start the engine. The practice of coating your drill bits with grease is also a very bad idea. The flutes of a drill bit are designed to remove chips outward. By loading these flutes up with grease, all you would be doing is making it more difficult for them to perform as designed. Also, grease will cause some of the shavings to stick on the inside of the manifold, making it difficult to remove later with a vacuum cleaner.

So do we have to use ALL the drill sizes?????? Number, letter, and fractional?????? That's a lot of extra work, and after the first hole all the chips will fall in as you drill the larger holes. If you drill just one hole the only chips that fall in are the ones that are made after the drill brakes through.

 

[dmhollister]

Just finished installing the gauges. Used a magnet to catch the threads on the exhaust manifold, and used grease on the tap. These caught almost all of the shavings. Dipped a small telescopic tool retrieval magnet into the manifold and came back with minute metal after the first dip. The real pain was finding the ignition hot without tearing the whole dash apart to get to the cig lighter. But the good ole test light worked great for searching a wiring lomb for ignition hot. Thanks to all we replied with suggestions.

 

[MACHINEST]

Center punch it and drill it with the tap size drill,a vaccum cleaner works great while drilling,tap depth count down 7 threads from the top of the tap and put tape on it..... Cast iron is grabby when drilling with a sharp drill,hope this helps.

 

[Diesel Manor]

So do we have to use ALL the drill sizes?????? Number, letter, and fractional??????

No,

What we do is use standard drill bits at the beginning (fractional). Then we finish the hole with the R bit. It's that simple. The size R is 0. 339". The closest fractional bit is 21/64 = 0. 3281". It helps to use shortie drill bits w/ a right angle drill or drill attachment. The RA attachments can be had at most home centers for abour $20. 00. Another alternative for those who don't have the RA drill is to rent one. Usually 12. 00.

 

[BGlidewell]

Do not perform this while the engine is running. Some company’s recommend this practice, as it is their belief that the exhaust pressure going through the manifold will push the shavings out through the hole you are drilling. We do not subscribe to this belief. Working on a running engine greatly increases your chance of injury. Also, while uncommon, if your drill bit happens to break off inside the manifold, it has no place to go but through the turbo.

The way it was explained to me, you start the engine and run at idle [after] the hole has been drilled and tapped for a short time and then turn off the engine.