fix for bad TPSes

I was talking to an older engineer this weekend about pots. A pot is what the TPS is, and this guy can take a piece of gear as complex as an oscilloscope and refurb it to new. One bad spot for them, especially if left unused for a while, is that the pots will get 'noisy' - in other words, they lose signal or get erradic. The fix is to flood them with WD-40, which is one of it's originally designed uses (not general lubrication).

So, it may fix all these TPS sensors that go bad as well, especially after a washing. There may need to be some 'openning up' of the TPS, or even a small hole drilled into the side (enough for the nozzle), but flood it with WD-40 and it should clean it and displace the water.

If anyone is about to go out and get a new one, and it's just flaky, or it went out after getting wet, try this. Worst case, it does nothing. Best case, it makes it good as new with no TPS adjustment and no $. Just remember to flood it, and for the Renix ones, both of them.

Report back if you do this...
:wave1:

I only know of one possible use for WD-40, starting fires!

If you want to try cleaning a bad TPS (which I do not recomend) try brake cleaner, it actually might work. For my time and money, I would swap it out out as the carbon surface wears and looses contact with the mobil brush part of the pot over time. However if you filled a new one up with water flush it with brake or electronic cleaner.

Neither will displace water like WD-40, and brake cleaner could dissolve parts of it, like any internal plastic parts... I've tried the WD-40 on several "bad" pots now, and it brings them back to life.

How often have you used WD-40 for a purpose such as this? I've never found it to be much good as a long term lube, but it isn't supposed to be. Why are you down on it?

BTW, I know a guy who used to spray it on the vinyl roof of his Lincolns. They always looked great. I guess just like these missiles: http://www.wd40.com/AboutUs/our_history.html

I manufactured and sold WD40 replacements back in the 1980's. I see they have replaced the propane propellant (rocket fuel joke, LOL, but really they used propane, we used it for starting camp fires!!!) with CO2 since I looked at it last. But there are many better specialty products on the market.

Also quoting 8 mud from 2 weeks ago:
"If it isn't wax, it is likely some kind of resin. It leaves a coating with a fairly high electrical resistance.
Just to make sure I'm not full of it, I just went out and measured the resistance in a black steel brake spoon I'd sprayed with WD-40 a couple of days ago (mostly tack dried). It showed infinite resistance, I pressed down with aproximately twenty pounds of pressure and it still had infinite resistance. I scratched through the coating and had "0" resistance 200 ohm scale.
It sure enough leaves some kind of persistant coating. It may not be wax, but something with many of the same properties. It has been known to attack some kinds (compositions) of O rings.
I tried fresh oil on some blank steel, infinite resisitance with no pressure, "0" resistance (or nearly, the meter wandered some), with moderate (3 pounds or so) of pressure, 200 ohm scale.
WD 40 on most any low voltage connection, is asking for trouble.
I use WD 40 a lot, but am carefull what I use it on.
Most anything that leaves a persistant coating can't be good for an O2 sensor. I imagine they have designed around carbon, soot and other common coatings. I'd avoid unknowns or anything not labeled O2 sensor safe." Quoting 8mud from two weeks ago, and I agree with him, not good to use on electrical parts.

from:
http://www.naxja.org/forum/showthread.php?t=909575&highlight=WD40

The chlorinated brake cleaner (non-flamable, perchlorethylene or trichlorethylene) is OK on most plastics and should be OK on all under the hood plastics. I have not run into an automotive plastic that it damaged in over 20 years now. It will eat vinyl seat covers, acrylic and styrene plastics but those are not found under the hood. Also the brake cleaner leaves no residue behind that can dry up and gum up things like WD-40 does.

Most mechanics are down on WD-40 becuse people try an use it for everthing, the miracle in a can syndrome.

I have used it in a pinch to wash sand out of electric motors.

Last minute thought, you could clean it with WD-40 followed by brake cleaner!!! That way you ould get the water out first, then the brake cleaner gets the WD-40 oil residue out.

WD 40 probably works all right, but I'd use electrical contact or control cleaner, which is made exactly for this purpose. I don't know what's currently available, but Radio Shack used to sell a TV tuner and control cleaner that both cleans and lubricates with substances that won't bother components. Other places sell contact cleaner too.

The other advantage of these cleaners is that they're usually non-flammable, so you can even use them on things that make a spark, like motor and generator commutators.

As far as O2 sensors go, that's a whole 'nuther thing. Spray nothing in them.

I do have a scope that was 20 yrs old and the pots were so bad the display could blank out as you turned them, as well as jump around, create noise, etc. He gave them a WD-40 treatment 6 yrs ago and they've been fine ever since. Only now are they getting a little jittery. And there are few things as sensitive as some of the pots on a scope.

Steel is notorious for forming enough oxidation within minutes to cause resistance, which is why it isn't used as a conductor. I'd be interested in your test with some copper, and a before and after reading. Remember too, the pot wiper exerts a good bit of force at a small point (therefore, high psi), so if there were surface waxes (I didn't see any of that on the MSDS) it would/could cut through the little that would remain.

As I said, I just did a treatment to some very low voltage signal pots in an instrument and not only did they seem to travel more smoothly, but the noise and jitters it had went away. They continue to work fine, and I expect them to last as long as the scope ones did before needing more.

But as always, YMMV.

I would hesitate to use WD40 because it dries up to gummy crap. Yeah it's meant to displace water, but it's also meant to leave a waxy coating behind. Brake cleaner might attack the plastics and the resistive coating. Best to use contact cleaner which really is meant for cleaning potentiometers.

WD40 suposively makes dull paint finishes shine too.

An older gentlemen once told me he knew somebody with arthritis who would apply WD40 on their arms, and that would help them greatly. But thats damn dagerous if you're cooking too.....talk about a human fireball!

The only thing I use WD-40 for is metal stock in storage - the "WD" stands for "Water Displacer," which is what it does. However, don't use it for a contact cleaner - I've had to strip it off of a number of contacts, in the past...

I'm mildly surprised it works on pots. Good brake cleaner or electrical contact cleaner (based on either trichloroethane or methanol) works reasonably well - and if you get the TPS wet, try this...

Heat your oven to 225-250*.
When it gets up to temp, put the TPS in a pie tin and put it in the oven for three minutes exactly.
Remove and allow to cool in open air. You may direct a fan over it, but don't cool it too fast.

This has worked for me on wet pots a number of times. You get it just hot enough to boil off the water, without melting the plastic. Problem solved.

I've also used it on wet radios, and other simple electronics that get wet. I wouldn't suggest it on solid-state microelectronics, but if it's simple and it's got discrete components, it's likely to work.

Nothing to lose anyway.......if the oven thing doesn't work, well it wouldn't have worked anyway.

5-90 said:

The only thing I use WD-40 for is metal stock in storage - the "WD" stands for "Water Displacer," which is what it does. However, don't use it for a contact cleaner - I've had to strip it off of a number of contacts, in the past...

I'm mildly surprised it works on pots. Good brake cleaner or electrical contact cleaner (based on either trichloroethane or methanol) works reasonably well - and if you get the TPS wet, try this...

Heat your oven to 225-250*.
When it gets up to temp, put the TPS in a pie tin and put it in the oven for three minutes exactly.
Remove and allow to cool in open air. You may direct a fan over it, but don't cool it too fast.

This has worked for me on wet pots a number of times. You get it just hot enough to boil off the water, without melting the plastic. Problem solved.

I've also used it on wet radios, and other simple electronics that get wet. I wouldn't suggest it on solid-state microelectronics, but if it's simple and it's got discrete components, it's likely to work.

Click to expand...

Waters not all that bad, I wash my keyboards 2x a year, gets all the hair, food chips, bellybutton lint and whatever out. I wash them in the sink using spray a mix of water/dawn dishwashing detergent in an Amway spray bottle, then go over them with a long soft paint brush and then wipe the keys down with Fantastic. At that point I submerge them in water and then rinse them with hot water from the faucte for about 3 or 4 minutes till there are no more soap bubbles coming out, shake the snot out of them and put them on a shelf for a few weeks or months till I need to clean the 6+ that I have connected to machines all the time. Been doing this for years and my old IBM real keyboards are still good as new cept that some of the lettering is a tad worn on the keys.
NOTE: If you do this on a battery powered wireless keybord, TAKE THE BATTERIES OUT and LEAVE THEM OUT...BEFORE you wash it..

91% IPA (IsoPropyl Alcohol) from Walgeens works great too followed by a hair dryer/blower to blow off the excess IPA (and traces of DI water, the other 9% is DI water). Works great on electronic components like key boards and no need to wait weeks or months for it to dry.

I thought someone here took apart a TPS recently and said it was a carbon on carbon brush pot assembly of some kind? Any one recall the details?

Skippc,

On the Renix system the cast iron block is used as an electrical ground contact! You obviously have some successful experience with WD40 on electronic pots, but I would not use it on contact surfaces like pots. It is notorious for drying up like a resin based material. The MSDS lists several generic hydrocarbon names that can and probably do contain high molecular weight tar like materials that would be waxy or worse they dry to hard resin like material as the low molecular weight hydrocarbons evaporate. The names on the WD-40 MSDS are very generic and nonspecifc.

I was surprised to see that it is now nonflamable. The replaced the propane propellent with CO2 (carbon dioxide). Must have had something to do with the Houston bottling plant (where I live) blowing up in the 1980's.

WD40 is nonflamable now?

Blaine B. said:

WD40 is nonflamable now?

Click to expand...

Yap, it is now non :flame:, the online MSDS shows CO2 as the new propellant. It may still be slightly combustable, but with pure CO2 propellant there will be little oxygen around to support combustion while spraying it so it should be pretty darn safe now from a fire hazard standpoint.

RichP,

I gotta agree with you about water not being all that bad, after all I use it to wash my Jeep and windshield too!:laugh3: Had to just add that. Do you recall Robby the robot's reply when he was offered a drink of water? "no thanks, don't touch the stuff myself, it promotes RUST"!, LOL. (Forbiden Planet)

WD40 still makes a decent starting fluid, so it can't be completely non-flammable. The govt has been pushing hard to eliminate flammable and freon based propellants for quite a while.

After a cleaning with a safe solvent, the best thing you can do for a pot is inject it with GC Electronics-type Z5 silicone compound.
This is the same dielectric they use for anti-corrosion in turn signal sockets, etc.
Worked for almost 30 years for me in electronics.
The problem with a wash but no lube is the potentiometer tends to get sticky in it's response to motion.

I never put anything in my turn signal sockets and such.

We have an old 1980 Oldsmobile with less than 55 thousand miles. Whatever the factory put in the sockets was dried up and such. Had to clean it out due to one bulb not making contact and such....so I don't know what they did! My XJ seems to be fine without it.

I never used to. This is clear, pure silicone, safe for the job.
And designed for electronics applications.
http://www.gcelectronics.com/order/SubCatPDF/accessories%20Circuit%20boards%2058-64.pdf

and, you can lube up your plug wire boots and connections as well.