Engine/Transmission (1994 - 1998) 1/4" or 1/8" egt probe

[JRS]

I've decided to install the Westach EGT/Boost gauge. should I use the 1/4" or the 1/8" npt probe?

 

[Jim Fulmer]

1/8th is easier to tap in that thick manifold, can't see a reason to the 1/4... . remember there is a divider in the manifold snout.



Jim

 

[y-knot]

You can do what you want, but I like to tap them for 1/4", then use a 1/4" to 1/8" brass reducer. It makes it much easier to remove later. Most probes are stailess steel, and the manifold or turbo elbow are cast, they can be almost impossible to unscreew after awhile. The brass between them makes future replacement much easier. And don't forget to use anti-siez on the treads, and wipe some on were the probe locks in.

 

[Bug1]

Are you guys mounting the probe before or after the turbo?



I have heard people say that the 1/8 probe is too small for the heat seen before the tirbo (on diesels in general, not cummins in particular) and has the potential to melt and break up, which obviously would not be good for the turbo.



Just curious what the real-world experience is...

 

[y-knot]

All of the Autometer probes use a 1/8" , and most of the others also. I had an Isspro and it was 1/8". It would not make a difference one way or the other, as far as reading accuracy. I have one both pre and post turbo, I think most seem to go post, since it is easier.

 

[jhurst]

Go with the 1/8". That way, if you mess up tapping the manifold for 1/8", you can go to 1/4" tap and use a reducer down to 1/8".



I am running a 1/8" probe pre-turbo.



Justin H

 

[y-knot]

Way toomuch negative feelings and BAD karma, Never go into a job figuring you are going to FAIL, You just got beat before you started. Now go drill that danm thing and tap it 1/4".

 

[jhurst]

 

[illflem]

Originally posted by y-knot

I think most seem to go post, since it is easier.

Think you've got it backwards, most folks go pre because it's a much more reliable indicator of cylinder temps.

Just drill whatever size is needed for the probe you have, either size will work just fine.