Stuck brass bushing in EGT port on stainless mixing elbow

[Edward Shaughnessy]

I am in the process of changing out a dead EGT type K thermocouple in a Cummins 330 hp engine exhaust elbow. Compression nut is completely loose but the thermocouple will not pull up and out of the compression fitting. Looks like there is a 1/4 NPT port on the stainless elbow, with a brass 1/4NPT – 1/8 NPT reducer bushing screwed into the port, and a made in China thermocouple using a brass 1/8 NPTcompression nut fitting. Nothing wants to unscrew below the compression nut and I don’t want to round the brass fittings trying to apply brute force. Have used PB Blaster several times but hoping someone here has a trick for disassembling these dissimilar metal fittings. Thanks very much for the help.

Topic

[pwrobert]

It is my understanding that EGT fittings need to be steel not brass due to high temps. <br />may try an impact wrench and if it rings off then drill it out. Should go easy since it is brass. Do to exhaust build up in the tube it will probably not pull out so just need to cut or break it off and move on. <br />looks like you have a welded or brazed on fitting to the turbo so just need to concentrate on the other fittings. Try and protect the fitting welded on. 

[Author]

Replies