EGT Probe, Drilling Exhaust Manifold

[Keith Eilers]

I am in the process of installing pyrometer and boost pressure gages. The gages are installed on the A pillar, wire and tubibg is in place. The boost gage is operational. All that is left is to install the pyrometer thermocouple. Having done some research, I have decide that installing on the exhaust manifold upstream of the turbo is the best location to measure max temperature. I plan to remove the turbo before drilling.

Now comes the dilema. Two people whose mechanical advise I trust (a retired mechanical engineer and a practicing aircraft mechanic) have advised me that drilling and tapping cast iron is risky. They claim that I am at high risk of cracking the exhaust manifold.

Has anyone actually cracked the manifold in this procedure? What precautions should be taken to avoid this problem?

 

[QRTRHRS]

Kieth,

Search the archieves. There is a ton of info on this subject. Drill size etc, etc. Essentially, if you drill the manifold in place, you put some grease on the bit to catch the chips. Then use a magnet that fits into the hole and a vacuum to remove any chips. Make sure the tap is square to the manifold and mind the depth that you run the tap in.

Mine was easy. I had the ATS aftermarket manifold drilled and tapped by my machinist friends. As for the cracked manifold, the risk is minimal if you follow the instructions in the archieves. Again, read, read, read.

 

[Davison]

I'm gonna keep an eye on this posting. Should be interesting!

Here's what little I know. I was told NOT to drill on the casting seam. Makes sense. After removing turbo, shove a shop rag up the manifold so no metal chips can stray up there. Don't forget it's in there! Hey doctors leave sponges in patients! Gotta be careful... . and finally there's an anti sieze goop in a tube that is good to put on the threads of your pyro... .

Good luck.



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2001. 5 2500 SLT+, QC/LB 4x4, ETH, 6spd, 3:54 LSD, camper/tow equip. , NV241HD, Bright Silver, Snug Top, Ispro w/3 pod pillar w/tweeter, Pyro, Boost & Mag Hytec cover w/temp guage, "Plain Wrap" (no decals or emblems)

 

[Turbo Thom]

Kieth:
I just finished my gauges today. Drilled the manifold with no trouble. I used an 1/8 bit, a 3/16 bit then the 7/16. I used grease like everyone has said and the magnet. As you can tell, I left my turbo on. The grease and magnet really clean up the job. The main thing I noticed is to drill slowly. Keep a firm grip on the drill with the 7/16 as it will want to grab and pull itself into the manifold. Not bad to do at all. Go for it.
Good luck... ... ... ... .
Preston

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96 3500, Black SLT, 5 speed, turbo diesel, , with US Gear overdrive, Rhino liner, Reese 15,000 lb. fifth wheel hitch, US Gear de-celarator exhaust brake, muffler elimination kit, Amsoil lub. , Mag-hytec rear cover, dual-remote by-pass filters, and Roadmaster Active system

 

[HEMI®Dart]

Kieth,

The manifold won't crack while you are tapping it. Over time it could cause it to crack.

Lets see , there must be 3,000 of us with tapped exhaust manifolds. I have heard of 1 or 2 developing a crack over time. It's mostly caused by the exhaust manifold expanding & contracting. The guys with high EGT will get a crack first.

Its really nothing to worry about. IMO

You can pull remove your turbo if you wish. I think its a waste of time. Get a good strong shop vac and hold the nozzle down at the drill bit. Grease and a magnet to get any chips that might have escaped the vacuum.

I small metal chip or two going thru your turbo at idle won't hurt anything. IMO

[This message has been edited by HEMI®Dart (edited 01-28-2001). ]

 

[LSMITH]

Cast iron can crack when you drill it. If the drill grabs and pulls into the manifold it could crack the manifold. Either use a cordless drill with clutch on the chuck set fairly low or go very slow with a corded drill. Tapping the hole can crack it too. Just go easy and take your time backing up a half turn for every turn in. When you put the thermocouple in use high temp anti-seize on the threads only and just snug it in. If you get happy tightening it you will crack the manifold. Unless you are a ham fist with a gorilla grip the odds of the manifold cracking are really low.

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99 2500 QC 4X4 AUTO SB 24V LARAMIE SLT 3. 5 LSD 285-75-16'S Everything but leather NRA Member

 

[One Old Dog]

I'll go along with Turbo Thom, do as he did and you will be ok. Just grab a beer and getit. Have fun

 

[Bigsaint]

Just take your time and you should not have a problem. Tapping into cast is not bad, trying tapping into Ruger hardened steel for a real challenge #ad


Scott W.

White 2001. 5 3500 ETH/DEE 4X4 Quad cab SLT,tow package and camper prep,Husky liners front and rear,DiPricol pyro,boost and oil temp gauges,Edge EZ,Mopar tonneau,Lund bug shield,PM tractor utility back up lights,Penda bed mat and blow by bottle is bye bye !!! I love the smell of diesel in the morning, it reminds me of... . VICTORY !!!
<A HREF="http://albums.photopoint.com/j/AlbumIndex?u=1231655&a=9089608" TARGET=_blank><font color=red>My Truck</font></A>
<A HREF="http://albums.photopoint.com/j/AlbumIndex?u=1231655&a=9089604" TARGET=_blank><font color=red>THE SAINTS</font></A>

 

[Shleets]

I drilled and tapped the manifold two weeks ago. Had anxiety up the kazoo but followed instructions posted in the forums and encountered absolutely no problems at all (besides excessive worry before I started). Did not remove the turbo. Used grease and a strong magnet as suggested. Just step up to the plate and swing... you will have no problem. And oh yea, save the beer for after the tapping not before #ad
#ad
.

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Mark Schlueter
2001. 5, QC, 4x4, ETC, K&N RE0800, White sport package. Kodiak Sidewinder Steps (front and rear). Mag Hytec diff. cover. Wet Okole seat covers with Rams head logo. VDO Vision Gauges. Three hole "A" pillar mount from Geno's. CATZ "MSC" Amber fogs, Mopar Performance trans pan, Snugtop rear cover.

 

[Bud Fox]

Used my 18v cordless and took my time no problem(until I lost the magnet in the manifold-Dont remind me) You guys talk about removing that turbo like it is cake- I messed with it for over an hour but could never get a wrench on that bottom turbo housing bolt- finally yanked the exhaust manifold and turbo together to get the magnet out IF any of you guys know a trick for that bolt you should post it -Could help a fellow member in the future!

 

[JR2]

I drilled and taped mine last summer and I stumbled onto a nice trick that may help. When I was getting all the tools together I stuck the bit and tap on this big magnet I had laying around. Then I went and had lunch. By the time I got back the bit and tap were magnetized. They held the cuttings from the bit while I was starting the hole. Same with the tap. I still used greese on both, but the magnetized bit/tap could not hurt.

 

[WOWZY]

When drilling cast material, you should only drill one small pilot hole. Too big of a hole could cause the primary bit to bite too much material and you could break off a large chunk of casting or break the bit or even worse it could cause you to drill a triangular hole. Not a very good hole to thread.

I drilled a 1/8 pilot hole and then went straight to the primary bit and it went smoothly.

 

[R.ebel]

Just be sure that you don't over tighten the fitting. NPT stuff is a tapered thread/fit. Over tightening the fitting is like putting in a wedge, causing unnecessary stress in the manifold that will lead to a crack in the long haul. IMHO

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1997 2500 Ext Cab 4X4,5 spd,3. 54's,Pac brake,Rancho 9000's,Centerforce clutch,K&N airfilter,
Isspro gauges,TST #11 plate (280hp/680tq),AFC medium spring, Jardine 4" exhaust and 370 Diamond B marine injectors.

 

[Sean Flanagan]

I tapped my manifold for the EGT probe two years ago (70k miles since then). The manifold cracked recently but not at the probe. The crack was between cylinders 3 and 4 in the vee. By looking at it, you could tell that the crack was NOT caused by the hole. Also 2 manifold bolts were sheared off at cylinder 6. The manifold must be under a lot of stress when running hot. I never run above 1300 but have run it close to that for extended periods.

The dealer replaced the manifold under warranty last week. I get to drill a new hole this week. (maybe tonight)

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98. 5 2500 QC LB 4x4 5spd, white. BFG 285x75x16
Cummins 24v w/ TST PowerMAX w/EGT and Boost gauges on A-Pillar. VanAaken CPC. K&N In the factory air box. Stock Injectors, Stock Exhaust (Geno's Muffler Eliminator). Re-routed breather stink tube, 2WD-low kit, SnugTop, JJ Stainless Running boards, Tow Hooks, Bushwacker Street Flares, and a Cup Smoothie.
83,000 miles (1/10/01)

 

[Keith Eilers]

Thanks for all the great advice. Y'all have convinced me to proceed without removing the turbo. Now if only I would get a reasonably warm day to do the drilling. 7000 feet elevation in Wyoming is cold and windy this time of year. My truck is garaged, but there isn't enough room left to work on it without backing out a bit.

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Keith Eilers, 99, 2500, 5sp, LB, QC, 4wd