EGT drill and tap question

7.3Lariat · #1 (**permalink**) 06-11-2010, 02:01 PM

So I recently had my turbo back put on. The prior owner put a BD-X in there for boost, egt and tranny. Well he put the egt probe in the downpipe. It had like a bung welded on. The shop where I got the exhaust put on didn't have one to match. Will like a regular nut welded on work or can I just drill and tap the exhaust manifold? I feel like it might be too long without the extra distance of the bung/nut welded on.

You can see the little piece I am talking about in this pic.

powerstroketom · #2 (**permalink**) 06-12-2010, 02:31 AM

drill and tap the manifold. You will get a true egt reading then.

cman962 · #3 (**permalink**) 06-12-2010, 04:29 AM

As I understand, the manifold is the most accurate location. I did mine a few months ago. It is pretty easy drilling. The tricky part is there is not much room to work. There is not much room for a drill or to spin a tap handle. I had to make a 1/2 turn and then pull off the tap handle and make another 1/2 turn etc. Not hard just time consuming. Most pyro fittings are 1/8 tapered pipe thread. You will have to watch the depth of the tap when threading it as it determines how deep the fitting goes into the manifold. If you search around I'm sure you can find a how to article with tips like putting grease on the drill and tap to keep chips out of the manifold.
Hope this helps.

Ryan Rønning · #4 (**permalink**) 06-12-2010, 04:39 AM

You will be fine tapping the manifold and that is what most of us do.

7.3Lariat · #5 (**permalink**) 06-12-2010, 07:28 AM

Thanks for the replies. I guess my original post wasn't very clear. I want to get it done in the manifold for sure. My question is can it be done without welding. How thick is the manifold, ie is there enough to be able to hold the probe in?

Duzitall · #6 (**permalink**) 06-12-2010, 07:44 AM

Quote:

Originally Posted by 7.3Lariat

Thanks for the replies. I guess my original post wasn't very clear. I want to get it done in the manifold for sure. My question is can it be done without welding. How thick is the manifold, ie is there enough to be able to hold the probe in?

Yes, no welding required. Mine has been tapped directly in the manifold since 2001 without any problems. I recall the material is about 1/4" thick. It's enough to hold the probe.

As you are aware you need to find an area that is deep enough for the length or the probe. Mine is at the bend where the manifold is widest. I was also careful to tap as shallow (narrow) as possible so more threads would be exposed outside of the manifold rather than inside. This gives you another chance in the future to re-tighten the probe if it gets loose from heat/cool cycles, and it might loosen a a little bit a couple times till it sets. Mine did.

When the engine is cold you might feel the probe is the tiniest bit loose until you snug it up a little after first install. Never really got loose and never was a problem.

Work slowly and cautiously. Try to recover any metal chips by using grease on the drill bit and tap then use a shop vac to make sure no chips are in the manifold.