If you’ve been around this site, you know I like to delve into the cause of failures. If that does not interest you, now is the time to bail out…
So I had a purge valve I replaced with a genuine GM OEM valve. I found out later, it was DOA. So I took it apart to find out why-
Here’s the guts of the valve in assembly sequence:
Closer look inside the black portion where the solenoid is encapsulated:
The pin goes into the smaller hole and is a guide for the spring/valve to center the shoulder in the bore. This is so it goes straight in/out when the solenoid is on/off:
Here’s the view of the spring and valve face:
Now look at it from the other direction showing how it mates to the inlet nipple assembly:
I think you are correct. The white plastic picture is a bit fuzzy but the locator pins are quite “proud” which can’t hold the spring disc. Makes me wonder how you miss this in the assembly process. You’d have to melt (or ultra sonic deform) the pins down before the top and bottom go together and it should be apparent. But it wasn’t.
Reminded my of my cruise control on my 86 park ave. I took it apart and found the little plastic valve would not seal properly in its seat so would either not engage or lose speed. It was about a 25 minute job to take it apart and put a little faucet grease on it every once in a while. Never did replace it but a little better engineering on either the stem or the seat would have resolved it.
Exactly. Probably two misses. During fabrication and then I can’t imagine they don’t do some sort of post assembly compliance test. Perhaps it is an AQL level test but I’m going to suggest 100% testing in the future
FWIW- I assembled it, formed the pins over the disc and reassembled the valve. It works as expected now. Destined for the trash bin however…
I’ve done similar when it was a relatively easy to access part. Those kind of deals always seem to be temporary and need to be revisited. Eventually the problem goes away when I either get rid of the car or finally replace the part when I get sick of attending to it.
You didn’t mention the year of the GM auto you were working on… But is it 8 years old or more,
The Delphi and GM bankruptcies may have shifted that tooling to a manufacturer that doesn’t have much in the way of quality control. Delphi divested themselves of a lot of their divisions that made parts like these to companies that 1) Don’t understand the design, 2) Don’t give a rat’s hiney about quality checks because the unit cost is a tiny fraction of the sale cost, 3) The parts are being sold not under their brand name (ACDelco… instead of Sheap Shina Parts Quality Yum Yum) so their reputation cannot be damaged, 4) Are offshore in countries where they can’t be sued and finally, 5) ACDelco has no alternative source and no engineering resources to develop one.
Like my ACDelco fan clutch for my '04 Avalanche that did not perform as the original did.
So why bother with 100% functional tests? Eat the return cost, they are still making money and ACDelco can’t do a thing about it!
Interesting post, thanks OP. I guess I’d prefer each replaceable part of my own car be functionally tested prior to being placed in its box for sale at a dealership or parts store; but I might not be as keen on this idea if doing so increased the part price significantly. The part manufacturer may feel random sample testing is best both for them, b/c it lowers their costs, and their customers, b/c it lowers the part price. To form a conclusion I’d have to know what % of these parts are failing right out of the box, and what price increase would be required so that each would get a functional test.
These sorts of quality control decisions probably vary as well depending if the part is intended for a new car build, vs a replacement part. For a new car build, where the car has thousands of these sort of parts, each part must have a very low chance of failure for the entire newly manufactured car to pass its own quality control testing. I’m guessing the part manufacturer builds two sets, one for shipment to the new car manufacturer, and one to the parts stores. And each set may have a different % reliability.
Most electrical parts are sold as non-returnable. You open the box, you own it. Does that change the calculus? BTW- this part was around $50.
The quality doesn’t vary by application. However, the cost burden is different. The manufacturer will discover a DOA part quickly and demand a replacement from the supplier. If they get too many, then they will camp out at the supplier to ensure quality improves or move to a different supplier. For aftermarket parts, it’s us weeding out the failures with very little leverage to improve the situation. As mentioned, many times with electrical parts, you install it, you own it. Frankly, I normally do not want an exact replacement anyway after I find one dead on arrival. Time to switch suppliers…
Mustangman detailed the scenario I am familiar with. Once the production line ages out, they sell the tooling to third party suppliers that may have little focus on quality.
Just to say something, I had my tires rotated. The guy said the ball joint was worn so I needed a lower control arm. I had replaced them both 70,000 miles before so not unexpected. But he said the part had a lifetime warranty. I still had the invoice plus it was on their computer, so $80 labor only. Never noticed when I did struts and brakes but never checked and not sure I’d know anyway. I’m not looking a gift horse in the mouth but thought how are they gonna make money on parts? Don’t know the brand used since the part numbers didn’t match current moog or Gm but a surprise anyway. How are ya gonna argue with a true lifetime warranty ?
I guess it depends who is offering the lifetime warranty. The muffler shops used to use that approach to retain customers. They warranted the parts for life but expected them to fail in a few years. The labor made up for the cheap parts cost to them and still provided a profit.
Loaded control arm for $80, pretty good deal! Hopefully quality is equal to the prior one installed…can’t argue with 70k miles out of it…
