Got Gauges

[Idle_Chatter]

Well, finally got around to installing my Isspro gauge set from Kennedy Diesel. Things didn't go too smoothly, but they're in, they're working and that's that. Had a few minor problems with finding gidgets and tapping the power. Biggest problem was tapping the exhaust manifold. I'm gettting the tap started, has just caught a thread. I move the wrench and *blink* the dad-blamed thing is puffed out of the hole and down inside the frame it goes! I start to scrabble around underneath and it is *GONE* I mean gonzo, outtahere, missing from this dimension! I look on crossmembers, cooling lines, A-arms, skidplates, *EVERYWHERE*! I finally decide that there's a welded-on frame box for the pittman arm with a "fishmouth" right below the manifold and it's scored a three-pointer right into the dang frame! Well, now I got a truck with a 7/16" hole in the manifold and no pipe tap and no magnetic pickup tool! After muttering a lot of obscenities and kicking some stuff around the garage, I start to look for how I'm going to drive 5 miles to the Home Depot for another tap with a holey manifold. I'm poking around in the toolbox and there's the factory drain plug I replaced with the fumoto valve. By golly, the magnet end of the plug is 7/16"! I stick it into the hole and wrap a 2-1/2" band clamp around it and off to the Depot I go! Got her all tapped, wired and mounted up now! :D

[mackin]

That was funny !!!!!! Sorry for your troubles but at least it's done.....

My truck ate a socket ...I know where it is tho ,down in the drivers side fender.....Perhaps some day I'll get it if I take the innner well off and try and retrieve it.....But I think it's way down low,out of reach.....


MAC :D

[Kent Tuttle]

Tom,
I also had a problem with my gauge install. While drilling the hole in the manifold with hot gases and grease coming at me I had one of the larger size drill bits break off, flush in the manifold. Talk about obscenities and kicking some stuff around the garage. Anyway I was able to grab a hold of the broken bit without it falling into the manifold and back it out. Felt very lucky that it did not fall in. Glad all turned out well for you.

[Idle_Chatter]

Well, now that I've had a couple of days to drive around on my new gauges: a couple of observations. These DMaxs sure don't boost much nor often in comparison to my 99 6.5TD Tahoe. I always rated engine horsepower output by how much it doesn't boost (or dumps boost). I guess the DMax has so much power that it doesn't need to close the wastegate much! Highest I've seen so far on a hard throttle run is about 16-18 and my "driving around" boost is typically between 1 and 6. EGTs, 300 at idle, driving around pretty steady between 550 and 750. First day I never saw higher than 900. I did get a steady climb up to 1000 on a long grade in cruise at 60. They really move on up under load, I can see where the pyro is really important on a long pull with a load! :eek: All of the last was in Juice level 2. Yesterday on the way home, I got caught at what I know is a long light, so I shut her down and reprogrammed from Juice 2 to 3 and refired. BIG EGT change! Level 3 was just like adding a 100 to 150 degree bias to the gauge! All the readings are up that much - EVEN IDLE! Because I had stock exhaust and no gauges, I programmed my Juice for level 2 normal and level 3 tow-haul. I've been doing all my normal driving in level 2 and been very happy with it. Level 3 in tow-haul was there just for the occasional wake-up call to the local aggressive drivers in Saturns, Hondas and mini-vans that think they'll jam the "slow truck" (doing only 5mph over the limit) in merge lanes and off corners. Impressive in short bursts, but kept to that because I couldn't check temps. Now we'll see how things work out in level 3 and I may even experiment with level 4! ;)

[Oongawah]

Hi IC,

I just installed the 4" exhaust last week and noticed an average 200 degree drop. Used to hit 1400 on hard accelleration now 1200 up to 70MPH in L4. Another thing I noticed that JK told me was a much quicker spool up of the turbo, and I'm also seeing a 10% increase in boost. If you want more boost you can plug the wastegate actuator hose which would gain about 10 lbs and 150 less EGT's. Have fun, Chuck.

[D/A]

I think the easiest way to tap the manifold was just take it off not hard to do at all. Lay it on the garage floor drill tap and get rid of metal shavings. Off drilled tapped in about 2 hours total. No worries this way!!!

[hoot]

Tapping the exhaust manifold is very easy once you've done it once. No need to remove the manifold.

Important things to know....

Only use brand new drill bits. Make sure to use standard ground machinist bits, not the aggressive split point style. They grab too easily.

Use high quality cutting tools. They hold up and don't break as easily as cheap Chinese junk.

The exhaust manifold is soft cast iron and is really easy to drill. You don't have to push hard (don't). The wall thickness where I drilled was probably only 3/16" - 1/4" thick. You don't want to be pushing hard as it breaks through.

I use a 3/16" or so size drill to drill a pilot hole first. Than I step up to the tap size.

Use low rpms. No hurry here.

Kerosene or diesel fuel makes a good cutting lube. Have the engine running while drilling and wear safety glasses.

With the hole drilled and the engine running, you hardly hear the exhaust coming out and it's not real hot. You can hold your hand on the exhaust stream without it burning.

When tapping use a good tap "T" handle, not one of those big tap handles. You need the clearance.

I didn't bother with grease on the tap cause the drier chips blow out easier. I used kerosene as a cutting fluid.

Start the tap straight and back it off when it starts to bind. Back it off enough to break the newly formed chip then continue. You probably can only turn the tap a half ot 3/4 turn at a time before you need to reverse it to break the chips.

After getting the hole tapped a few threads, start to see if your fitting will start. Once the fitting will start, you need to monitor how much more you tap. Make sure you don't tap too deep. You want the fitting to go in plenty enough to be engaged well but not so far as to run out of threads and still not be sealed.

When you're done tapping, make sure there are no loose chips hanging on the inside of the hole.

Clean the freshly tapped hole (engine still running) with solvent. Turn the engine off.

Put antisieze compound on the fitting and install.
Do not over tighten. Just tignten it firmly with a tweek. Remember, this has very low pressure so between the antisieze compound and the tapered threads, you won't leak easily.

Look at these pictures....

http://www.uscom.com/~hoot/cars/duramax/gmc/egt/

[ 12-03-2002: Message edited by: hoot ]</p>

[NFLDMAX]

Thanks for the great details hoot...Hopefully get some gauges for Christmas.

[6600Duramax]

Hoot, Really apprciate the extra effort on the post. Thanks, but I still have one question. You said not to tap to deep? I am new to tapping but if you tap the entire hole, won't your fitting just bottom out therefore sealing?

Just wondering, have had the guages for a couple months just haven't had the time.

Thanks again

[Idle_Chatter]

6600Duramax, when Hoot says not to tap too deep it's because you're using an NPT - national pipe thread - tap, and it is tapered. If you run the tap too deep, the brass bushing will thread in too far before sealing and wind up really intruding into your manifold. I ran the tap about 1/2 - 1/3 of the way in, then backed out and tested the bushing, it was just what I wanted.

[hoot]

Idle_Chatter is right.

If you ever did any plumbing with iron pipe, it's the same idea. The actual threads on the fitting get larger in dia farther back. This is what they mean by tapered thread. Pipe threads are tapered threads.

Similarly, the hole is also tapered. This is how pipe threads can seal water and gas.

The tap itself is tapered. If you tap too deep, the hole becomes too large and the fitting (tapered also) will thread too far in and run out of threads before you get good interference.

Thread interference seal the joint. Actually if you really want to get technical, without some kind of sealing compound, it will leak. You still end up with a spiral gap along the threads. That's why you use pipe "dope" in water and gas applications. This closes the gap.

Usually a pipe tap is designed so that if you don't go to the end of it's useful cutting teeth, you should be OK but do what Idle Chatter said and go about 3/4 of the way in with the tap. That should be plenty.

If your fitting is brass, make sure you use a good antisieze compound. Brass is nasty. Mine is stainless but I used the compound anyway.

Look close at this image and you can see how the thread "root diameter" gets larger the farther you go back on the pipe...
http://www.stoneagetools.com/products/fittingsnipples/p8thrd.gif

[6600Duramax]

Thanks Guys this really clears things up. Hope I get it right.

Thanks