Boost Installation on '09 LMM

[richp]

Hi,

Next week, I'm set to pick up my new K-2500, and can't find any information on the best (and hopefully easiest) location for tapping for the boost gauge.

I'm installing the Banks gauges from my old truck, and have the pyro location and procedure figured out. But on the old truck, there was a hose that we tapped into to for the boost line. Is there a similar hose location on the LMM, or some other relatively quick way to read boost pressures? Or do I have to drill and tap somewhere, and if so, where?

Thanks for the help.

[More Power]

Rich,

You should drill/tap into the aluminum between the intake air heater and the intake manifold. Pick a spot where you can separate the piece, then drill/tap without depositing aluminum bits into the intake. This is similar to what is done for the LLY.

You can see how it's done here (http://www.thedieselpage.com/reviews/gauges2005.htm). Just scroll down that page once it's loaded.

Jim

[richp]

Hi Jim,

Thanks -- just what I needed. Looks like I need to call Banks and get a different fitting, and maybe new tubing to feed the gauge.

Have a good one.

[DmaxMaverick]

What fitting? The gage kit should have included a 1/8" NPT fitting. The hole should be drilled/tapped for 1/8" NPT, and the fitting installed. In any case, you should use 1/8" tubing to the gage. Get the correct fitting for the tap location. Don't change the tubing, or you'll have to use an adapter anyway, at the other end. If you don't have the correct fitting, they are very common at any hardware store. You'll need a 1/8" NPT to 1/8" compression tube fitting, and should cost no more than a dollar or two.

[richp]

Hi Dmaxmaverick,

I don't have a current kit for an LMM -- just the bits and pieces from removing the gauges from the old truck. On the LB7, the fitting in question was a plastic T that was in-line in a rubber hose (the MAP line?). It had a small orfice on the end that the tubing screwed into, suggesting that it wasn't just a stock "T" from the local auto parts store.

So I talked to Banks today, and they're sending me the proper fitting for tapping into the inlet tube. As you estimated, it's going to be about two bucks.

Also, out of an abundance of caution, I'm installing a new probe and wiring for the pyro. I'm not sure I could get the old one out after all those years in the exhaust stream. And even if I did, putting such an old unit in -- pre-turbo -- seemed to me possibly inviting at least a modest risk of disaster, should the old probe fail.

Thanks for the further help.

[DmaxMaverick]

Ah, the Tee. The kit's aren't necessarily vehicle or engine specific. The pressure source can be either an existing line (like the LB7 WG line), or tapped into the pressure plumbing. I have an LB7, and tapped into the plumbing much like illustrated in the article. With either the LLY, LBZ or LMM, you could Tee into the manifold pressure sensor bung, if you were dead set against drilling/tapping into your plumbing. It isn't rocket science, and the principal is very simple. All you need is a method of tapping the manifold pressure.

Old pyro probe removal shouldn't be a problem. You can either remove the probe, and plug the bushing (recommended to prevent future cracking), or remove the probe and bushing, and plug the threaded hole in the manifold. Either way, it should come out pretty easy. The threads are tapered on both. It wouldn't hurt to soak it with some PB Blaster for a few hours if needed (don't run the engine during this time), or wick some wax into the threads after a hot shutdown. If it's still too tight, you can use a propane torch or heat gun (paint/flooring stripper) to heat the surrounding manifold (wash it down with water first if you used penetrating fluid, it's flammable). If the probe is installed w/o a bushing, it may very well be stuck. That's why a bushing is normally used (prevents the probe from seizing into the cast iron).

The fitting Banks is sending you is an off-the-shelf fitting, as I described before (or it should be). I would have just made a trip to my local hardware store and left Banks out of it, but it's your choice. The fittings are not "vehicle specific", but very common for use in refrigeration, plumbing, and the like. Installation isn't too difficult, but you'll still need to drill/tap the hole to accept the fitting. Same for the pyro probe.

[richp]

Hi DmaxMaverick,

I'm for easy installations if possible, and sure would avoid drilling and tapping if there's a location that is more convenient.

Where's the manifold pressure bung located on an LMM, and what does it look like?

Thanks for the tips.

[DmaxMaverick]

I don't know. I haven't had that much underhood time with the LMM. It should be a familiar sensor bung, with the sensor threaded in it. You'll have to locate a Tee to adapt the 1/8" tube fitting, or fabricate one. No big deal, any machine/welding shop can do it once you locate a fitting that can fit between the sensor and bung. If the sensor is a composite (pressure and temperature, etc.), it may be more difficult. I just don't know, and don't have a manual in front of me. You can go to a parts store, or a GM parts counter, and get your hands on a sensor for matching. Then, the only problem left is clearance, which may or may not be an issue. There may be other more simple options, but I haven't looked into it. Just one option, of possibly many.

Nearly just as simple, would be to remove a CAC pipe (intercooler plumbing), and have a bung welded into it. This may be the most simple method, as you can choose the location.