# PITA needle in the haystack P0171 code.



## Merc6 (Jun 8, 2013)

NickD said:


> First happened yesterday morning pulling into my driveway. Camshaft cover bolts were loose again, everything else looked like new. Took it on a 50 mile trip last night, traffic, interstate, everything was fine.
> 
> Pulled into a parking lot, no engine hesitation, but the CEL came back on again. Reset the code with my Torque OBD smartphone, drove home, again in all kind of driving conditions, engine ran perfectly and made it all the way home with the CEL off. Still off.
> 
> ...



2012? Have you recently got the newest one? The newest newest one I believe even changes the oil cap as well.


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## Robby (Mar 1, 2013)

Yep, appears to me the newest cover has a oil fill extension and a baffle below it so the fill cap doesn't have to control so much splash.

Nick, I believe the cover bolts are torque to yield so the odds are by tightening them you are only further stretching them.

If the cover ends up being the cause of the code it is covered under powertrain so warranty isn't an issue.

Rob


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## NickD (Dec 10, 2011)

Oil cap O-ring reminds me of the Challenger Space shuttle O-ring, after being baked at 220*F for 33,000 miles has a flat in it.

Torque to yield with only 71 inch-pounds of torque? Ha, the usual problem I run into by using rolled thread CRS bolts in aluminum, electrolysis sets in welding the bolts, and end up breaking the heads off trying to remove them.

Curious as to what kind of gasket, Chevy is using, if like the old cork ones used for years in the stamped steel valve covers would compress causing the screws to become loose. Found Pro-Fel valve cover gaskets for my 454 that had spacers in them that ended constant oil leaks to those red hot exhaust manifolds. But never was an engine fire reported with these engines. Maybe because they didn't have an under engine shield. 

Is possible that camshaft gasket is compressing.

Guess I will take a ten mile trip to that dumpy Chevy dealer up north to learn what they have to say. No fancy waiting room with coffee, WiFi, and a large flat screen TV. Matter of fact, sit on an old apple crate. But at least they have a service manager and mechanics with brains. Don't find this with my local super fancy dealerships.


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## spacedout (Dec 7, 2010)

Is this now design 3 for the valve cover? anyone have an image of the newer one?


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## Robby (Mar 1, 2013)

Nick, the gasket is a 'O' ring seated into a channel cast into the cover.
When tightened to spec, the cover is actually seated on the head surface with the ring being the sealing element.

This design removes the potental warping of the cover once tightened to spec.

I suspect the silver finish on the bolts may be a corrosion blocker of sorts.....gang at the dealer have not experienced any fastener breakage on this engine during service.

Rob


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## NickD (Dec 10, 2011)

Shop manual description of the P0171 code does not even mention the camshaft valve cover nor the oil cap.

For whatever reason, the engine is running over 5% lean as detected by the O2 sensor not going positive a sufficient number of times per minute that indicates a rich fuel mixture or lack of oxygen. So the problem can be with the O2 sensor itself as the key sensor. Or with running lean too much oxygen that causes the O2 sensor to output a low voltage.

Or lack of fuel, low fuel pressure partially plugged injector, low injector dwell that will cause a lean mixture.

Or too much oxygen from external sources like a leaking brake booster, a purge valve that stays open too long or not returning to its closed position, or a crack in the carbon canister that can let in too much air. Don't even mention the PCV system with a bad check valve allowing additional air directly into the intake manifold. Even mentioned a leak in the exhaust system before the O2 sensor that can insert extra oxygen. 

Car was okay this morning taking my wife to work. One traffic light, two stops signs, but the engine was cold and apparently in open loop mode. But when I took my foot off the gas to make a left turn to her front door, the CEL light popped backed on. Should be in closed loop mode at this time, temperature gauge was at the quarter mark.

Sounds like a complex problem and why when I took my foot off the gas? Vacuum should be at maximum at this point, and why would the engine be running lean? Unless a coincidence with the fuel evaporation system, but no codes are shown in this respect.

Ha, tempted to trade it off. 

Or simply


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## jblackburn (Apr 14, 2012)

Keep a look out for CEL and erratic idle. Usually the signs of the PCV valve integrated in the valve cover failing.


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## spacedout (Dec 7, 2010)

Isn't that code the typical one for a bad valvecover/PCV? Since the code keeps coming back and this is a known issue I would suspect this is what the problem is. Nick have your looked at which version of valve cover your car currently has? The thread below has photos of version 1 & 2, believe the 1st version was even more trouble prone. 

Some members have mentioned being able to hear an air leak from the large plastic circle under the ecotec cover, have you checked yours? 

http://www.cruzetalk.com/forum/129-...-replace-valve-camshaft-cover-1-4l-turbo.html


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## Robby (Mar 1, 2013)

Nick, the manual is not a bible......it is a road map pointing out various things that can cause the code but not all things that can trigger the system.

Since you indicate a engineering background you are falling into a trap that every engineer I've been around gets into.
You hyper anyalize......in this case, a lean condition.

Backing up the bus a bit, a simple example.......this code can be set with something as simple as a dipstick not fully seated....the manual assumes one has already taken the basic steps of diagnostics.

Knowing that all new vehicles are hyper sensative to any crankcase vacuum disruption, and seeing all the posts indicating the integral pcv cover and related parts have had a rather high incedence of failure resulting in a vacuum leak, the first step for the DIYSelf type should be to pull the coil cover and give it a listen.......as well as putting your finger tip against the equalizer hole to be certain this is not the cause.

The o2 is reporting a too lean condition to the ecm......the ecm is trying to enrich the fuel trim to compensate, the o2 screams it is drowning, the ecm trims lean.........back and forth till it gives up and throws the code.......now it won't go into closed loop....it's in 'get home mode'.

Keep in touch,

Rob


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## NickD (Dec 10, 2011)

Ha, first step was to take a nap, that crazy bipap machine they put me on keeps me up half the night, but tell me if I don't wear that mask will wake up dead. Can't complain too much, least I am a zillion years old. Was young people there with the same problem during the sleep study.

Second step was to do a visual inspection of my Cruze top and bottom, just to make sure nothing fell off. Looked at the PVC hose and wondered if I could disconnected it without breaking it off. They don't make em like they use to. 

I know I am not looking for an earthquake like a rush of air through cracks in the valve cover. I do know I need a new O-ring for my oil cap, but the way they do parts today, probably only comes with a new engine. 

Next step is to drive up to my Chevy dealer, with experience now, know to bring my own coffee, chair, and flat screen.


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## brian v (Dec 25, 2011)

That's Nice Nick take it easy !


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## NickD (Dec 10, 2011)

Decided to drive up, actually 12.6 miles, had an entertaining BS session with the service manager and three mechanics. Service manager said, with the low mileage, five days after warranty expired is close enough.

Made a 1:00 PM appointment for this Monday. Said they will fix me up. Let's see what happens. 

Left the CEL when driving up, just in case, but when I got back into the car, turned on Torque, have an ICar with a switch on the other end, can leave that plugged in all time. Bluetooth works well with the Samsung for both that and the phone through the radio.

Reset the code, stayed off all the way home, but CEL clicked on again when pulling into my driveway. Mentioned this to the service manager, not looking for an earthquake.


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## JerTM (Dec 12, 2014)

Do you have a way to monitor/graph upstream 02 sensor voltage? Graphing would be most helpful, but you could get away with just a live data parameter. If you can graph it, take a can of brake clean and do short bursts at places you suspect the vacuum leak is while monitoring the upstream 02 voltage. If the voltage spikes and stays there for a bit you have found your vacuum leak.


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## NickD (Dec 10, 2011)

Will let my dealer take a crack at it first since its covered under warranty. Weird, reset the code before leaving this morning, and drove it faster than normal coming back home. Code never set. Again it was only P0171.

Shop manual said another thing that could set this code is a near empty fuel tank, topped it off last night.

Ford was checking the spacing between ignition pulses to determine if a misfire was occurring. Made it too tight, AC kicking on or a load on the alternator would trigger a misfire code, so had to loosen up that spec. Cruze could be the same way with this P0171. Heck will let Chevy work this out, unless they would give me access to the source code. 

Finding a decent Chevy dealer is the problem, think I found a good one. Awfully careful when using solvents around an engine, already burnt the hair of my head when I was a kid, but it grew back. May not grow back anymore at my age.

Some brake fluid is non-flammable but can do damage to plastic and rubber. Soap and water works fine in an old Windex bottle.


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## JerTM (Dec 12, 2014)

I use brake clean as it will show up as rich on an oxygen sensor data parameter, I am not sure about soapy water. You can also make a setup using propane and a valve and some vacuum line to pinpoint a vacuum leak, but again that does need a way to monitor voltage from the o2. GM uses a few data parameters, but misfires is not one.


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## NickD (Dec 10, 2011)

I know you are trying to be helpful and appreciate it. What weird about this code, and reset it, start the engine and let it idle, it doesn't come back. But as soon as I am in traffic, like behind five cars waiting for that light to turn green. Have to start off slow waiting for people to wake up in first gear and then its when it sets.

At a stop sign with nobody around, take off normally, and can even drive 50 miles, it won't set. Trying to emulate the conditions when the code is set, would be difficult to monitor the O2 sensor, already know the O-Ring on the oil cap needs to be replaced.

As Robby stated, well know conditions sets this code, redesigned oil filter cap and camshaft cover. And found a dealer willing to replace these under warranty. Comes to around 60 bucks worth of parts, a lot more it the intake manifold is the problem. Major problem for us Cruze owners is trying to find a dealer that shows concern and aware of the problems. Sure don't have this with my two GM dealers in town.

Already had fits with a GM CMFI system on a 4.6L engine with both minor fuel pressure and vacuum leaks. Chevy dealer in town wanted 700 bucks for that piece of plastic regulator and some plastic tubes. Found one on the internet for two hundred bucks.

Was told would be lucky to hold 56 psi fuel pressure for five minutes, was a bad joke the way that fuel pump was mounted in the tank. Three fuel lines ran on top of the frame, real easy to mount in production before they dropped the body on it. And every place they had a bare metal clip a pile of rust. Formed and painted new fuel lines and taped those areas where the clips were with a coat of silicone. Where the entered the intake manifold, grommets were shot. 

This was a job, but by doing it right, could hold fuel pressure at 56 psi for over 24 hours, and ran well for another 85K miles without problem until the body started to rust away. 

Think about the good old days when only had one fuel line to be concerned about, but wasn't much of a problem because they weren't dumping tons of salt on the roads. Could make a fuel pump like new again with a one buck kit. These new ones are really a bad joke with a slot car motor inside with brushes, could at least use a brushless motor. Then they want 250 bucks for this piece of plastic crap and have to drop the tank to change them.

And they call this progress? Another fit are these fuel evaporative systems with problems clear back from the tank up to the engine. 

Then to be told by two expert Chevy dealers, nuttin wrong with your brakes, even though your pedal is going to the floor, you still have brakes and we ain't getting any codes!

Also learning in was use to be a fender bender type of accident, these cars are totaled with a one piece unibody. Ha, enjoying watching new videos on Cuba with still plenty of 40's and 50's American made cars on the road.


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## JerTM (Dec 12, 2014)

A p0171 can be a difficult code to chase without a way to watch data. It won't set right away, it takes the pcm some time to determine it is a permanent concern so it isn't surprising it seems intermittent. Let us know what your dealership says.


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## NickD (Dec 10, 2011)

At the rear left on the camshaft cover is like a 2" diameter cylindrical extension formed in the plastic with peep hole in the front of that. Under that is like a rubber diaphragm that acts like some kind of seal that was dried up and not making good contact. This is the source of the leak. 

Mechanic did not understand the reason for this, all he knows is that under the camshaft cover has to maintain at least 18"/Hg of vacuum. And my 1.4L was not doing this, only cure was to replace the entire camshaft cover that came with a new gasket and 15 new torx screws. 

Not even sure about the source of this vacuum, neither am I, something new. But apparently the EPA wants to make sure that blowby is vacuumed up, just a speculation on my part. But some how this leak is getting air into the intake manifold to cause that lean burn with the next question, why isn't the O2 sensor increasing the injector dwell to compensate for it.

Typical in FI engines, get an rpm increase with a vacuum leak, and the idle control valve does the same thing. So for now until more book learning is done, may get some answers to these questions. Mechanic was no spring chicken either, we were BSing about EGR and non-hardened camshafts from the early 70's. He was curious why this vacuum is not sucking out the engine oil. But just does a vacuum check and finds the source of the leak. Sure not using any oil.

Also questioned the flat on my O-Ring on the oil cap, he felt it was okay because on this new camshaft cover, the old cap was a lot tighter. He was correct on this, is a lot tighter.

Maybe someone else understands the reason for this high vacuum in the crankcase and under the camshaft cover. And why a minor leak causes a lean burn.

Oh, was repaired under the PT warranty, didn't cost me a cent.


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## spacedout (Dec 7, 2010)

NickD said:


> At the rear left on the camshaft cover is like a 2" diameter cylindrical extension formed in the plastic with peep hole in the front of that. Under that is like a rubber diaphragm that acts like some kind of seal that was dried up and not making good contact. This is the source of the leak.


I suggested you check this in post 9 of this thread, you can hear the leak when this occurs(there is a few videos on youtube). Also if you check out the link(also in post 9), there is pictures of how this part of the valve cover has a different design now.




NickD said:


> Oh, was repaired under the PT warranty, didn't cost me a cent.


It was also mentioned before in this thread that this is covered under the powertrain warranty, should read the page below as it lists everything that is covered. 

Chevy Warranty Information | Owners | Chevrolet


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## NickD (Dec 10, 2011)

Did read Xtremes' post and his reason for replacing his camshaft cover as a preventative measure with the new design that is exactly like the camshaft cover that came with my Cruze. Already had the new design, and the one that replaced it is exactly like the one that was in there.

And then this code was never set at idle. So I am gathering whatever this new design was suppose to cure with the old design hasn't cured it. Then the code was only set while driving in gear at low speeds, around 3 mph. And we discussed, why is this code permanently set when ever what set it, the problem went away.

That led to the canister vent valve doing the same thing. With the canister and this valve mounted way back by the fuel tank and exposed to road salt sludge, just the slightest bit of moisture can cause this valve to seize and not fully close also setting a permanent code. But after it warms up its okay again, but yet that code is still set! Even though the problem is no longer there.

And with that vent valve opened with the purge valve also opened, can really suck a lot of air into the intake manifold, but not the problem. This never was a problem when the canister and vent valve were mounted high on the firewall, is now. And whatever the problem, that same exact check engine light comes on and stays on causing panic to the driver. Stupid!!

Another guy was in the waiting room with a 2012 4WD Siverado with BB just about to expire. For the first time his traction control light came on and wanted it check, his mechanic said he couldn't find anything wrong. Couldn't help but interject, with my Cruze, FWD drive, traction control light always comes on. All it takes is one tire running a bit faster than the other. And if this isn't bad enough kills the engine. It reduces the engine speed to idle regardless of where you foot is on the gas, and under load, the engine with no speed will die. Almost caused an accident on the road. Another really stupid idea. 


So have to hold that traction control button down for eight seconds to turn the darn thing off. Will have to do this, this morning, more rain that changed to ice and snow. 

Dealer offered me an Impala at the same price as the Cruze, besides poor fuel economy, uses that crazy plastic intake manifold cradled between the heads with a different expansion ratio than the heads that always causes leaks. The worse with coolant entering into the combustion chamber really causing major damage. Chevy knows this, but still using a plastic intake manifold.

Feel plastic is the problem, never was when Honda and Toyota was using aluminum for these same parts, is now.


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## Blue Angel (Feb 18, 2011)

NickD said:


> Dealer offered me an Impala at the same price as the Cruze, besides poor fuel economy, uses that crazy *plastic intake manifold *cradled between the heads with a different expansion ratio than the heads *that always causes leaks. The worse with coolant entering into the combustion chamber *really causing major damage. Chevy knows this, but still using a plastic intake manifold.


Nick, are you sure there's coolant running through that plastic intake manifold? AFAIK, no composite intakes have coolant flowing through them. Most cars have eliminated coolant flowing through the throttle body as well, even though these are still aluminum (for now, anyway  ).


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## NickD (Dec 10, 2011)

Not sure about the latest V-6 or V-8 engines, but sure an age old problem with the older ones using that plastic intake manifolds.

Never was a problem when the block, heads, and intake manifold were all made of cast iron, coefficient of expansion was not only minimal but all the same. Now have a cast iron bock, aluminum head, and a plastic intake manifold with three very different coefficients of expansion.

No much of a problem with a plastic intake manifold on a four cylinder. Just kind of hanging there, no coolant and not cradled in like on a V-6 or a V-8.

Cast iron manifold requires a lot of machining and very high casting temperatures. Plastic requires very little at much cooler molding temperatures and are far cheaper to manufacturer. So wonder why they are asking a huge fortune for replacements, and replacements are necessary to boot. Plastic becomes brittle and with thermal cycling, cracks, so has to be replaced. Cast iron never had this problem.


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## JerTM (Dec 12, 2014)

I suspected the VC, I have replaced a few of them for this exact issue. As far as coolant going through the plastic manifold, that is a NO. GM is has been going towards a dry intake for quite a few years now. The only plastic manifold I remember having coolant go through was the 3.8L v6, and that was a pretty lame design and caused all sorts of intake issues. I do change quite a few gaskets on the v8's, but haven't had to replace a manifold yet. I would guess they anticipated the heat cycles it would have to endure and use a specific plastic to combat the heat cycle issues.


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## jblackburn (Apr 14, 2012)

Coolant in intake manifolds was a dumb idea no matter what it was made of.


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## NickD (Dec 10, 2011)

While the PCV valve appears to be connected to the intake manifold, it routes into the head casting apparently where the camshafts reside. Other end feeds into the turbo intake for the vacuum source. But also shares a rather large opening from the air cleaner intake.

So difficult to conceive why a super minor leak for the camshaft cover would cause a lean burn code, especially when the same TB that eventually gets this leak is getting tons of air from the air cleaner. Whatever, same driving this morning, CEL stayed off. 

Said I wasn't sure about the later GM engines with coolant in the intake manifold, but did look up a photo for the intake manifold gasket, only six holes for the AF intake, no extra coolant holes. And not even cradled anymore, ha, still consider the 3.8L to be a new engine.

Sure want a fortune for the Cruze 1.4L intake manifold, around 315 bucks. Ha, thinking about removing it and storing it my safe with a lot less valuable stuff.

Can see where these intake manifold gaskets can be a problem.










Been a problem in other vehicles, with the heat of the head would turn to dust. They use to use copper intake manifold gaskets that lasted forever. Came with a Vector overhaul gasket kit could purchase for about 4 bucks back then. Not only your engine, but two others because Vector wanted to save on inventory cost. Had to match all those extra gaskets with yours and pitch better than half the others away. 

But see its only ten bucks for these rubber bands.


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## jblackburn (Apr 14, 2012)

I think the plastic intake manifold will crack before the gasket goes. I have one of those gaskets on another car, and it was good for at least 10 years before I had to remove it to do a PCV system.

Any small air leak will throw off the MAF and O2 readings. Cars are incredibly sensitive these days.


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## Blue Angel (Feb 18, 2011)

I had a similar issue with the Wife's '01 Corolla a few years back, turned out to be a gummed up MAF sensor. Some sort of varnish/slime would build up on the heated wire of the sensor and throw off the A/F ratio calibration. The ECU would compensate up to a certain point by altering fuel trims, but beyond that it's programmed to throw a DTC.

Read up about it on line, cleaned the MAF with brake cleaner, reassembled and hooked it up. The car would barely run at first, stumbling and stalling like crazy. A short trip around the block had everything reset and running better than ever. In hindsight, disconnecting the battery to reset the fuel trims would have been smart and may have avoided the painful relearning process.

I wonder if this sort of thing will ever manifest with the Cruze MAF? I should pull mine out and see if it shows any signs of being fouled up.


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## BowtieGuy (Jan 4, 2013)

But if you clean the MAF, ONLY use dedicated MAF cleaner. Never use brake cleaner.


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## JerTM (Dec 12, 2014)

The rubber in the intake gaskets will not and does not last anywhere near as long as the plastic intake manifold. I make quite a bit of money from intake manifold gasket replacement on the V8's, haven't changed a single manifold. A vacuum leak is a vacuum leak, no matter where the leak occurs, and the emissions standards are so incredibly tight even a very miniscule leak will show up as a lean. I've have to chase some very difficult leaks before and have found some very odd ones. DO NOT use brake clean on a MAF, there is a cleaner specifically to clean them without damaging the sensor.


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## Blue Angel (Feb 18, 2011)

BowtieGuy said:


> But if you clean the MAF, ONLY use dedicated MAF cleaner. Never use brake cleaner.


I'll keep that in mind!

Looking into it a bit, it seems some cleaners (carb and electronics) leave residue behind in the form of protective lubricants, which could insulate the heated wire of the sensor. Not ideal.

Some brake cleaners apparently have harsh chemicals that may react with the metal wire in the sensor. Also not good if true.

I've never seen dedicated MAF cleaner before, but I'll pick some up if I ever do. Thanks for the tip Bowtie!


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## jblackburn (Apr 14, 2012)

Yeah they usually have something like this in auto parts stores here. 

http://m.advanceautoparts.com/mt/sh..._v_cookiecheck=on&un_jtt_redirect=un_jtt_iosV


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## Blue Angel (Feb 18, 2011)

"Proven to add 4-10 hp at the WHEELS!"

Now I feel like an idiot for using brake cleaner... I got NOTHIN at the wheels using that garbage!


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## NickD (Dec 10, 2011)

Two platinum wires, one buried for the reference, other for sensing the thermo-conductity of air flow, heated and expose to the environment.

A q-tipped swab works for me, dipped in denatured alcohol and a very gentle hand, then use the other end of the stick to dry it off. Sure don't need a spray can that blast crap all over the place just to clean a tiny wire. Cruze wire is fairly robust and access is easy by removing two phillips head screws. Ha, don't drop them.


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## JerTM (Dec 12, 2014)

You can use a q-tip as Nick has said, but be warned if you aren't as gentle as you think and break the wire there is no repair and you will have t buy a new one.


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## NickD (Dec 10, 2011)

Find it to be absolutely incredible the amount of chemicals you can find in a grocery or a hardware store shelf. But even way back in the 70's, the EPA or OSHA could walk into your plant at anytime without notice. And if they found a can of that stuff would give you a heavy fine. 

Even checked women's purses and found a can of hair spray she wasn't even using, was fined for that. But had both the EPA and OSHA in the plant at the same time, so argued who was going to get the money. Ain't lying on this.

First thing to go was our trichloroethylene metal degreaser, had to go back to soap and water, some kind of word like biodegradable that was new at the time. This was a huge expense for us. Only to learn that the EPA gave DuPont permission to use trichloroethylene in the manufacture of R-134a refrigerant that was an overnight change in the kind of refrigerant we were allowed to use.

Heck even with leaded gas that really was dangerous to human health, gave about a 15 year phaseout period. 

We also did government contracts, and while we had perfectly good biodegradable printed circuit board cleaning methods. Forced us to reclean the boards again with CFC's that was banned just about ten years later. Not a bit of difference in performance. 

Can only conclude we live in a very hypocritical world. Government was using over 60% of the total manufactured CFC's. But the person really hit, was a single mom that wasn't permitted to buy a can of R-12 anymore and was forced to pay a small fortune to convert to R-134a.

But now they are claiming that R-134a is one of the causes of global warming and even talking about using HC's as a refrigerant that they also outlawed due to its fire hazards.

I quit.


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