reverse light switch, high resistance and leaks, why? Options

[davesprinkle]

OK, I'm now on my third reverse switch, with a consistent problem:

After a few hundred miles, the switch contacts become high-resistance (50 Ohms or so) and the switch leaks tranny fluid, filling up the wiring boot. By the way, the last two switches were brand-new Porsche replacements. I'm running Swepco 201, by the way. Anybody have any suggestions about what might be going on?

[GeorgeRud]

I've never had one go bad on me, so it seems odd that you had several show the same problem. Is it possible that the transmission fluid level is too high and the Swepco is somehow affecting the internal sealing on the switch?

[ejm]

Maybe the actuating pin is little too long causing internal damage to the switch. If the original was lost someone may have made thier own.

[Joe Ricard]

That's what I would guess.
As well as the metal washer/gasket

[Dr Evil]

Did you ever remove the actuating pin? It may be in backwards, or as already stated it may be too long or a make shift replacement. I have some spare used ones if you need. This is the only common part to the whole works.

I have some good used switches, too.

[davesprinkle]

I've never had one go bad on me, so it seems odd that you had several show the same problem. Is it possible that the transmission fluid level is too high and the Swepco is somehow affecting the internal sealing on the switch?

Regarding the fluid level -- I just added oil until it started spilling out of the fillhole. That's the way you do it, right?

[davesprinkle]

Did you ever remove the actuating pin? It may be in backwards, or as already stated it may be too long or a make shift replacement. I have some spare used ones if you need. This is the only common part to the whole works.

I have some good used switches, too.

No, I've never removed the pin. I'll take a look at it and see if it's got a problem.

Hey, since you know everything about 901s, where is the vent located? Is it possible that the vent is plugged, thus pressurizing the case and forcing oil out of the switch?

[kconway]

Vent is oposite side of the case top just before the bell housing transition.

[Dr Evil]

Did you ever remove the actuating pin? It may be in backwards, or as already stated it may be too long or a make shift replacement. I have some spare used ones if you need. This is the only common part to the whole works.

I have some good used switches, too.

No, I've never removed the pin. I'll take a look at it and see if it's got a problem.

Hey, since you know everything about 901s, where is the vent located? Is it possible that the vent is plugged, thus pressurizing the case and forcing oil out of the switch?

Not impossible, I guess, but I have never heard of it and it would be pretty dang hard to do (IMG:style_emoticons/default/smile.gif)

Yes, you fill the box until the oil reaches the fill hole.

Do you have the crush washer under the switch? Its pretty thick and without it you can destroy your switch and have leaks.

[davesprinkle]

Did you ever remove the actuating pin? It may be in backwards, or as already stated it may be too long or a make shift replacement. I have some spare used ones if you need. This is the only common part to the whole works.

I have some good used switches, too.

No, I've never removed the pin. I'll take a look at it and see if it's got a problem.

Hey, since you know everything about 901s, where is the vent located? Is it possible that the vent is plugged, thus pressurizing the case and forcing oil out of the switch?

Not impossible, I guess, but I have never heard of it and it would be pretty dang hard to do (IMG:style_emoticons/default/smile.gif)

Yes, you fill the box until the oil reaches the fill hole.

Do you have the crush washer under the switch? Its pretty thick and without it you can destroy your switch and have leaks.

Yeah, crush washers were always in place. When you buy the switches, the washers are staked in place so they're difficult to remove. You'd have to be really committed to improper assembly...

[Drums66]

That's what I would guess.
As well as the metal washer/gasket

*echo* (IMG:style_emoticons/default/idea.gif)

[Demick]

I've had the reverse switch leak through the switch itself. I confirmed this by tying an uninflated balloon over the switch body. Fluid accumulated inside of the balloon, meaning that it leaked through the switch, not around the threads and seal area.

So it can and does happen.

Demick

[ejm]

Vent is oposite side of the case top just before the bell housing transition.

If you remove it make note of where the vent hole is and return it to the same position or you will have a leak.

Pulled the switch and pin out of a box at the shop today. This pin had a bit of wear on the inner end, a new pin may be a few thou's longer.

[davesprinkle]

I've had the reverse switch leak through the switch itself. I confirmed this by tying an uninflated balloon over the switch body. Fluid accumulated inside of the balloon, meaning that it leaked through the switch, not around the threads and seal area.

So it can and does happen.

Demick

Hey Demick, thanks for the pointer. I just put a compressed-air nozzle against the hole in the switch -- fluid came OUT of the electrical sockets. This explains the leak-path.

Dammit. This is a BRAND-NEW $85.00 switch, less than 400 miles. And the second switch, currently on the tranny, is showing the same failure, filling up the electrical boot with oil. Mmmm, smells nice...

[Maltese Falcon]

I've had 2 new ones go bad, all leaking at the elec. portion in the switch body. The shop that installed it put replacement ones in under warranty; still leaked.
The fix: a funky old used one from the bottom of the toolbox !
Marty

[ssstikircr]

I could just be a bad batch when those were made. I have been in the auto parts game for over 20yrs n it does happen.
(IMG:style_emoticons/default/idea.gif)

[Katmanken]

Seals,

We don;t need no stinking seals..

Probably the made in China low cost replacements... They either have no seals (aka cost reduction without letting Porsche know) or the seals the factory received from their relatives seal factory were incompatable with oils.

They make and ship ANYTHING no matter how bad, and wait for the customer to find out the problem and complain.

Wanna buy some melamine, er.. I mean pet food, er ...I mean baby formula????

Ken

[davesprinkle]

I've had 2 new ones go bad, all leaking at the elec. portion in the switch body. The shop that installed it put replacement ones in under warranty; still leaked.
The fix: a funky old used one from the bottom of the toolbox !
Marty

Same for me. Two brand new switches, same problem. Clearly, Porsche sent through a bad batch of switches. Dr. Evil, you want to sell one of your used switches?

[Dr Evil]

Dave, I'll sell you a used one for cheap (IMG:style_emoticons/default/wink.gif) PM me

[astronomerdave]

Pulled the switch and pin out of a box at the shop today. This pin had a bit of wear on the inner end, a new pin may be a few thou's longer.

Can the pin be removed from the outside of the transmission without taking the tranny apart?

So, I definitely also have a bad switch (when removed I can fully press in the switch with a punch and it never makes contact) but I don't know about my pin. Does anyone know the position of the pin should be relative to the outside of the transmission?

With the switch removed and the transmission in Reverse, the end of the pin is about 3 mm inside, measured from the outside edge of the threaded hole (in other words, from the face where the crush washer would seat to the tip of the pin is 3mm inside).

When in any other gear the pin is about 5.3 mm inside.

See photo:



Based on measurements of my existing (bad) switch, my switch would be pressed in about 1.5 mm. Presumably this is enough to activate the switch. Maybe someone knows these numbers.



Sent PM to Dr Evil to buy one of your switches.

tnx,
Dave