Engine/Transmission (1998.5 - 2002) Tips for Drilling/Taping hole for EGT.

[IWeiny]

I know there are instructions out there for doing this and I have read them but I had a friend who suggested something different.



He suggested drilling with smaller drills and working my way up to the 5/16" hole. I am very afraid of destroying my turbo on this one, but I don't have a choice as I need the guage on and I don't have anyone to do it for me. Can't be that hard right?



Anyway I am going to do the boost guage first to get some practice with not leaving any pieces on the inside edge. I have a problem with doing this when I drill other things. I can just see something comming off and going through my turbo.



Any tips?

Thanks,

Ira

 

[Rob Thomas]

No need to drill in several smaller holes first, you can drill the 5/16" hole right off the get go.



Center punch exactly where you want the hole to be (2" from the center of the turbo/manifold flange, and 5/8" back from the center line on the manifold), then coat the drill bit with grease, and drill slowly, this will contain most if not all the metal fragments.



Do the same with the tap, coat with grease and tap the manifold accordingly. It is very simple to do, no worries.



Another tip would be to coat the probe fitting with anti-sieze, for future removal, for whatever reason.



Where are you planning on putting the boost fitting? Most people use fittings that don't required drilling/ tapping. TST has a boost fitting that replaces a fitting allready on the engine, and Piers has a bolt/fitting that replaces a bolt in the intake horn, these two options are very simple.



Rob

 

[IWeiny]

I was planning on drilling the intake manifold as per my Geno's instructions. It said that was the prefered place.



I was not worried about this as I can easily take the rubber off the manifold and the shavings will fall to the ground... (assuming I cover the other tube!)



This is on a 99 24V in case the fittings are for the older models.



Thanks,

Ira

 

[Deezul1]

I have done 6 of these and the grease on the drill and tap work good. Get a pencil magnet that will fit in the hole to get the rest of the debris and probe all around and you will be ok.

 

[IWeiny]

What if I messed up?

Let's say that someone got the idea that drilling the last part of the hole with the engine running was a good idea.



Then there were a few big chunks around the edges which probably went through the turbo.



How would one tell if the turbo was damaged?



On the bright side the guage is working. I can't hear anything funny at idle but I have not driven the truck to get the turbo really wound up. Plus I have never really listened to the turbo that closely before...



Oh well live and learn.



Thanks,

Ira

 

[illflem]

The problem isn't chips passing though the turbo but rather a chip wedging in-between the housing and impeller stopping it dead. When this happens the impeller warps from exhaust heat and the turbo needs to be rebuilt. After seeing this happen firsthand I spend the extra five minutes to remove the turbo before drilling.

 

[IWeiny]

Well it is spinning

I am pretty sure it is spinning.



Back when I was in the power generation industry I used to watch the GE guys work on the gas turbines. The clearances in those engines were incredible. I guess what I am really concerned with is having nicked a blade and the turbo being unbalanaced. I have seen pictures of gas turbines which have riped themselves appart when they are not balanced properly.



Since I have never seen the inside of this turbo I am wondering what the clearances are. I guess I really don't have a choice but to just drive it and see if something happens. But being the paranoid fool that I am I have visions of the turbo ripping into the head of the engine after comming appart...



I know I am being paranoid, but this truck is sort of my baby and the wife will be really dissapointed if I tell her we have to buy a new truck...



Thanks for all the help and especially listening to me ramble on.



Ira

 

[rashwor]

Ira...

worst case, it gives you an excuse to buy a modified / bigger turbo to feed bigger shower nozzles! There is a silver lining in every cloud... sometimes it is just hard to see. Trust me, I know this.

 

[IWeiny]

Yea tell that to the wife!!!

 

[rashwor]

I understand...

I have a wife and it is a balancing act. I just put a new injector pump on my '99 to the tune of $2200 (new and installed) and she says that if many more repairs are necessary, it will be time to shop for new truck! GOD, I love my wife! Oo.

 

[dremelts]

Originally posted by illflem

I spend the extra five minutes to remove the turbo before drilling.

I'm with you. It's really not that hard to remove the turbo. I put a piece of tin over the turbo opening and after I had the manifold drilled and tapped just started the engine and let the stuff blow out.

 

[NETim]

I have yet to do this myself and no, I did NOT stay at a Holiday Inn Express last night, but I have read that when the hole is tapped, it should only be tapped far enough to get the probe in the exhaust flow and no more. You do not want to bottom the probe tip out in the manifold and break the probe.



Also, use a hi temp anti seize compound here. Not all anti seizes are created equal!



Yeah, I know, there's no substitute for experience. Gauges will eventually be installed.



Tim

 

[IWeiny]

Well I know I did not bottom out the probe, although I think I taped it a little to far, like 1 turn? no big deal. I did screw up and the drill wandered a bit so it is like 1 7/8 " rather than 2 in from the gasket. 5/8" back. All in all I think I did an ok job. If the turbo still works and is not going to fly apart from some damage to the implellor I think I will be ok.



I worried this much when I put the DD mag-hytec pan on!!! I am still a bit worried that the filter is swimming in the bottom of the pan because I did not torque the screws down!



Anyway, Thanks SO much for all the help and advice. I will surely email after my first run.



Rob, I did order the Piers fitting for the boost guage. It does seem like the easier way to go.



Thanks again, I can't wait until our local members get together again and I can start thanking people in person.



Ira

 

[Oil Burner]

Boost fitting works the best! You can also tap all the way through the manifold for the EGT. Just position the probe in the compression fitting to it does not bottom out on the inside of the manifold. I measured my clearance and pulled the probe back about a 1/4 inch. No problems.

-Jason

 

[DLeno]

Seems to me that running the engine while you finish off the hole is a good idea. turn on the exhaust brake or plug up the tailpipe and things should blow outa there pretty good. I haven't put mine in yet either -- so I'm still working on what method I will use . I'm assuming that the cast iron manifold is very hard and that a high bit speed and low applied pressure would work well. The engine would blow the particles back out through the new hole. no grease, no magnet.



Another suggestion I heard was to put in a post-turbo thermocouple first (easier). two thermocouples are a good idea anyway since you can switch between them and monitor either post or pre as appropriate. Anyway, the risk of the post install is less because if you get a large chip it just ends up in the bottom of the intercooler.

 

[Oil Burner]

drilling the elbow is the safest way to go since anything that gets into the pipe is now downstream of all moving parts and passes through the exhaust. (some of us saw that at muncie this year at the truck pulls). anyway, drilling the actual exhaust manifold is no big deal IMO. I have found that the manifold drills a heck of a lot faster and easier than you might think. I drilled and tapped it dry (one of the machinists at work suggested drilling and tapping the cast iron dry). Just use a snake magnet to get all of the chips out. small stuff will blow right by.

my . 02

-Jason

 

[illflem]

Originally posted by DLeno

I'm assuming that the cast iron manifold is very hard

Quite the opposite, I've drilled wood that's harder.

 

[Oil Burner]

I second what Bill says. That's what I tried to say in my previous post. He is absolutely right that you will have probably drilled wood that was harder that your exhaust manifold. It drills so easy that you'd better watch you don't drill right through the other side! Just kidding.

-Jason

 

[Deezul1]

Installing the thermocouple post turbo is the safest way if you are drilling and tapping but only safest for the turbo. Post turbo readings will be slower and lower than pre turbo so while you protect the turbo you are putting your pistons at risk. Very few folks have any trouble with the drill and tap procedure getting chips in the turbo. Just be careful and use the techniques described above and it will go well. Pulling the turbo before drilling is a simple job if you are a worrier but worth it for a pre turbo install.

 

[Oil Burner]

Deezul1 is right on. I have a buddy with the same set up as mine with his EGT post turbo. Mine is pre-turbo. Granted, we have different gauge manufacturers but my readings are very fast and his seem much slower to react. His may be in the danger zone for a few seconds before the gauge registers. The benefit of post turbo thermocouple mounting is cool down. Mine goes to 300 when i take my foot off of the throttle. post turbo reads what the turbo experiences. For a totally stock truck, i might go post turbo. Any mods, and i vote for pre turbo or both.

just my . 02

-Jason