Shade-Tree Mechanics and EXAIR Products

EXAIR most often sells business to business, but we also sell to individuals who need the right tools for their home projects.

If you frequent our blog it is no secret that I tend to have projects going on outside of work and I generally find a reason to have an EXAIR product when I am doing them. The first EXAIR application I had at home was in fact utilizing an E-Vac to build a motorcycle brake bleeder.  I still use that to this day, it is on my bench ready to help me rebuild my rear brake system on my bike once I decide to do it. I’ve blogged about that before. The most recent application I had was working on an early 1970’s Jeep with a close friend. He inherited the Jeep from his dad who no longer wanted to work on it. The Jeep hadn’t run in over a year and the original reason for parking it was ticking in the motor.

Broken parts removed – Time for cleaning.

Sure enough, once he got it up and running with some fresh gas and cleaning up the carb the tick had not gone away but he was able to narrow down that it was in fact coming from under the valve cover, so off it came.  We discovered that one of the bridges that hold down the valve rocker was broken, parts were ordered and we started cleaning everything off. The fix could all be had from right up top under the valve cover and should be easy enough once parts were in.  We cleaned up all the oil, removed all the bridges as well as the pushrods.

When we were removing the bolts from the valve cover and bridges there was a good amount of “sludge” and debris around the bolt holes.  When cleaning this all up some did go into the holes and we really wanted to try and keep all debris up top rather than going down into the motor. We noticed some crud around the top of the pushrod holes so we waited until we could use an Atto Back Blow Nozzle on a VariBlast Compact Safety Air Gun to pass down through the pushrod holes and effectively blow any and all debris back up to the top of the motor.  We also were able to use it on the blind holes of the bridge bolts and remove any fines or buildup that had fallen into the hole.

Cleaned up and ready for reassembly

After we were done cleaning up it was time to reinstall with the new part and having a clean top end made the job that much easier. Buttoned everything up, did an oil change, and then the Jeep fired right up with no ticking noise in the motor. Now he just has to clean up some wiring and get tags to put this classic back on the road.

Having the right tool for the job is always the best solution. Whether you are working on a car at home, or if you are career certified mechanic in a shop, the same goes across any industry. When using compressed air in an application EXAIR is the company that can supply you with the right tool to get the job done efficiently, safely, and quickly.

If you would like to discuss any point of use compressed air application, please contact an Application Engineer.

Brian Farno
Application Engineer / Shade-tree mechanic
BrianFarno@EXAIR.com
@EXAIR_BF

Torque Values and Tapered Threads – Do They Go Together?

IMG_20200202_155004_377.jpg

Over the past few weeks, I have been working on various cars in the garage with some good friends. We generally get together and help each other out to make the jobs go easier as well as help each other learn more about keeping our family’s vehicles safe and even helping out some others that don’t have the means to work on their own vehicles. Throughout these repairs, we always end up in some type of discussion over something fairly technical. Sometimes it is the proper installation of a part such as take the bolts to snug, back them out, then torque to half the total torque value, back off again, then finally tighten to the complete torque.

We also share different ways of doing the jobs, such as how to lessen the amount of hot oil you are about to pour all over your hand, or how to get that rusted bolt out without a torch and without breaking it. One discussion that comes up quite frequently is torque specs and then the torque spec for a tapered thread.

In case you were not aware, the NPT or BSPT (male) inlets on EXAIR products are both a tapered thread. Tapered threads are generally used on pipe fittings under pressure to seal better and provide a secure engagement. When comparing this to a standard bolt, or straight thread, one is generally accustomed to receiving a torque spec on just how tight to get the fitting or threaded product. For example, the 1/4-20 bolts used in our Super Air Knives are torqued to 7.5 ft-lbs. in order to properly seal the cap, shim, and body together. These are straight threads and thus a torque spec is often driven by the material, size, and thread of the bolt. Torque on tapered threads such as NPT or BSPT fittings is not as easy to find, and not really reliable.

For tapered threads, the engagement of the thread is not always at the same point due to differing tolerances on thread dimensions. These differences create different points of thread engagement with the corresponding thread it is tightening into. For these scenarios, the torque specification is not always best suited as a numeric value. If you search hard enough you can find a table like the one shown below, but again, not the best value to use when installing a tapered thread.

Size in-lbs N-m
1/16″ 5 0.57
1/8″ 7 0.79
1/4″ 16 1.81
3/8″ 23 2.6
1/2″ 30 3.39
3/4″ 54 6.1
1″ 78 8.81

I personally would not use a straight numeric torque when tightening something with stainless steel thread into a brass fitting, or other dissimilar materials together. For this scenario, I would recommend using something like the table below. The TPFT value is, turns past finger tight. This means you would snug the super air nozzle, vortex tube, or other fittings by hand to finger tight. Then using a wrench or two if needed, turn the fitting to the correct number of revolutions for the given thread size. By utilizing this method and the correct amount of thread sealant, see John Ball’s video blog below, you can ensure there will not be a concern on whether or not the joint will leak and also if the fitting is tight enough.

NPT Size TPFT
1/8″ 2-3
1/4″ 2-3
3/8″ 2-3
1/2″ 2-3
3/4″ 2-3
1″ 1.5-2.5

If you would like to discuss torque settings, installation of your engineered compressed air solution, or even what might be wrong with your minivan, contact us.

Brian Farno
Application Engineer/Garage Mechanic Extraordinaire
BrianFarno@EXAIR.com
@EXAIR_BF

One For The Gearheads

EXAIR Application Engineers are geeky about compressed air, but there’s a few gearheads at heart among us, too.  I’m one of them.  Read through my blog below for a dive into my most recent gear-driven fun!

1998 A4

Recently I took on a new project at home.  One of my friends called me to tell me about an A4 with a potentially blown motor that might find a happy new home for the right (low) price.  Seeing as how I’ve procured many a vehicle in just the same way, I’m always optimistic about these kind of things.

So, I made the trip to look at the A4 and found a clean interior, 80k on the clock, and a no-start condition.  After sitting at the dealer for over a month without an accurate diagnosis, the owner had it towed to his house where he put it on the market as-is.  Unsure of the problem, but confident I could find and fix whatever is needed, I bought the car.

AHA DOHC

Cranking the engine (2.8 AHA code) over, I could hear a lack of compression, so I pulled the plugs and confirmed with a gauge.  Bank one (cylinders 1-3) had virtually zero compression on any cylinder, and bank two (cylinders 4-6) was perfect.  Interesting…  My first thought was that there was a timing belt failure and valves were bent when getting readings on bank one.  But the perfect readings on bank two made me second guess.  Nevertheless, I pulled the front carrier/core support and tore down to the timing belt.  Sure enough, the teeth of the belt were chewed off at the crank!  But, the story goes on…

The repair in a case like this is to pull the cylinder heads, check all the intake and exhaust valves for leakage, and replace those that are faulty (or all the valves depending on their condition).  Some people call this a rebuild of the top half of the engine, which is pretty accurate.

When I removed the cylinder heads and began to disassemble them, I could tell something wasn’t right.  There’s a camshaft adjustment unit used to advance or retard valve timing that has a special landing and thread for a service tool.  On the bank one cylinder head, this landing was missing (see the photo below).  Strange!  And, normally, the camshafts can be removed fairly easily once their bearing caps are removed.  But, on this cylinder head, no dice.

VVT Unit

Ultimately I found that the landing for the camshaft adjustment unit broke off and wedged on the exhaust cam of bank one.  See the photos below for the gouge mark on the casting.  This cam seized, locked everything on the head, and forced the crank to chew the teeth off the timing belt.  Miraculously, the valves on bank two avoided any damage and triple checked out when disassembled.

Head Gouge 1

Head Gouge 2

This failure led to the damage of (5) valves.  Some of them are visible to the naked eye as seen below.

Bent Valves

Now comes the fun part of getting the engine back together, knowing that there’s a “new” car at the end of all the work.

Lee Evans

Application Engineer

LeeEvans@EXAIR.com

@EXAIR_LE