What could cause a TS II to fail prematurely?

[TrollFromDownBelow]

I know the quality of the currently available TSII's are not the best. However, my bus has gone through three in the past 1000 miles or so. To provide some context, I've got about 5k miles on the rebuild (shameless plug for Rich Sedoris - did a great job). First TSII lasted about 4k miles. Replaced it on the way home from a weekend getaway with one that had been rattling around in my toolbox for the last 20 years. That one lasted about 400-500 miles, then it went bad. This last one was a brand new URO brand, replaced it about 100-150 miles ago, and coming home from some local camping today, the bus started bucking.

In each case, the bus started bucking pretty badly/noticeably, and in each case, replacing the TSII completely resolved the bucking problem. The first one was a new URO, and I chalked it up to poor quality for failing after only 4k miles. The second, I assumed, had been mechanically compromised after sitting in my toolbox for 20 years, getting banged around on the top shelf with no protection. However, the last one was brand-new and lasted only about 100 miles. The failure frequency seems to be going up.

I recently bought the TSII 'kit' from the Samba supplier, and will put that in next. However, would like to know if there's anything I should look for/diagnose that could cause the TSII to fail prematurely.

Regards, Mike
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1976 Westy (aka Tripod)
2.0 liter FI solid lifters
212k miles

[raygreenwood]

It's the way they are made now as compared to how they used to make them.

It's a thermistor literally with a very short wire on each end, stuffed into a tight bore drilled into a 10mm bolt. It's packed in tight so the inner end wire stub is I hard contact with the metal of the bolt. The upper end goes through an insulating bushing usually packed in with an insulating adhesive and is crimped to the wire.

Originally they were soldered in the inner end...I think....with low temp solder.

What is happening with these newer ones is poor connection/crimping to the outer wire....so a reading of 0. Or, the insulation at the outer end sucks and the outer end makes contact with the metal bolt body....meaning....they have continuity but resistance is 0.

The third thing I am seeing/suspecting is that they are using cheap common thermistors that do not have a temp range much higher than the 450° or so you can get from heat soak and the thermistor dies.

Ray

[SGKent]

make sure the threads are clean. Run a thread chaser thru them, not a tap. I think they are 10mm x 1.0 . Use deoxit or something like that on the threads, or use some COPPER anti-seize. It may not be the TSII that is failing but rather the connection to ground thru the threads.
_________________
Canned Water - the new California approved parts cleaner (except in a drought in which case rub it with sand).

George Carlin:
"Most people don't know what they're doing, and a lot of them are really good at it."

Skills@EuroCarsPlus:
"never time to do it right but always time to do it twice"

[raygreenwood]

[KTPhil]

A potential alternate part below. I wonder if it has the same failure modes, or maybe it's a more robust design?
https://www.thesamba.com/vw/forum/viewtopic.php?p=10436939
_________________
Current Fleet:
- '71 Fastback
- '69 Westfalia
Retired:
- '67 Beetle
- '65 Beetle (x2)
- '65 Bus
- '71 Squareback

[TrollFromDownBelow]

[KTPhil]

[Hoppy Camper]

I chased intermittent bucking for years. Replaced many things, TS2 being one of them. Turns out my TS2 would just be loose in the threads. It's not bucking anymore.
_________________
1979 Mexico Beige Westy auto
The Wilds of New Hampshire!
www.hoppycampernh.com
https://youtube.com/@hoppycamper

[TrollFromDownBelow]

[raygreenwood]

[KTPhil]

And at the risk of derailing this thread, and more for others who may read this, not the OP here...

Often replacing a component SEEMS to fix a problem. Actually, the component itself may have been perfectly fine, but the act of unplugging and/or R&Ring it may have jostled something or made a connection (electrical or vacuum) better. So it would seem to confirm a bad component.

But then later the symptom recurs. And you have to ask... is it ANOTHER bad component, or just a return to the original external problem?

This issue plagued early FI repair, and gave it a bad reputation for having (expensive) parts fail, causing many mechanics to swear off even working on it, or replacing it with carbs. There is even the embarrassment of a shady mechanic who figured out the loose wire on the expensive FI component was the problem, but won't admit his overlooking the REAL cause to the customer. And he can't return the new part to his supplier, as most have a "no return on electrical/electronic parts" policy. So he blames VW for a bad design, and charges the customer for the unnecessary new part, and put the used but good part on his shelf (which he can charge a new customer/sucker for later - "win-win"!)

Again, I'm NOT saying that's the case here. I'm just warning others to be careful about damning the part, when the act of replacing it may have fixed the problem (even if temporarily).
_________________
Current Fleet:
- '71 Fastback
- '69 Westfalia
Retired:
- '67 Beetle
- '65 Beetle (x2)
- '65 Bus
- '71 Squareback

[raygreenwood]

[TrollFromDownBelow]

[raygreenwood]

[KTPhil]

I've always use Permatex silver anti-seize on muffler nuts/bolts, spark plugs, and lately for temp sensors. Of course only the latter two care about conductivity. I've had it for 20 years. I think it's this stuff:

Anti-Seize Color: Silver
Operating Temp. Range: -60 Degrees to 1600 Degrees F
Water Resistant: Yes
Military Standard: MIL-Spec A-907
For Use On Materials: Aluminum, Brass, Iron, Stainless Steel
Conductive: Yes
Net Fill: 8 oz
Anti-Seize Base: Aluminum, Copper
Odorless: No
Primary Additive: Graphite
Conductivity: Conductive
Primary Additives: Graphite

So it does have some copper in it.
_________________
Current Fleet:
- '71 Fastback
- '69 Westfalia
Retired:
- '67 Beetle
- '65 Beetle (x2)
- '65 Bus
- '71 Squareback

[raygreenwood]

[SGKent]

[Bnanwel]

To add to the data, I have a URO TS2 in the original spot under the tin above cyl 3 and a Vespa sensor as an installed back up at a tapped tin screw in front of the intake manifold on cyl 3. I have switched back and forth between the two and feel no difference. I keep another spare in the glove compartment. For the record, I have only driven this set up about 500 miles.
_________________
‘72 Karmann Ghia Conv.
‘73 Karmann Ghia Coupe
‘74 Karmann Ghia Coupe
‘70 Deluxe
‘72 Deluxe

[Xevin]

Not sure how many miles on this aftermarket TS2 had on it when it broke off, the PO installed. I had no idea a broken TS2 would instantly stop the engine. Fortunately I had a spare Bosch NOS in my stash. New TS2 Has about 8000 miles on it.
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Keep on Busin'

[Jetfxr69]