Moisture in vacuum lines?

[JHZR2]

Ive started to try to dig in more into my S-10 vacuum system, since the hoses are all good (replaced two small sections that are dry rotted).

Will probably put a separate thread on that...

but when I was looking at the vacuum differential actuator, I found water in the tube going to it... and white wet gunk, I think the mold release agent from the tubing.

(Last pic is white gunk and water that I shook out of the line).

Vacuum goes I believe from intake to a set of connectors, to a switch, to this item. There’s no cross contamination of anything, no moisture in the oil, no loss of coolant, etc.

The line holds vacuum if I pull vac on it with a mityvac.

So any idea how/why? Id think if anything vacuum woukd cause moisture to boil out. Granted limited use of 4wd woukd resukt in no vacuum there.... that said, vacuum is getting there, which is why my diff is grinding. So any ideas?

thanks!

 

[KrisZ]

My guess would be the moisture is probably getting in from the actuator side somehow. You said your diff is grinding, so the vacuum is always there being pulled through the actuator instead of short periods of time when needed. it probably sucks in outside air and it accumulates in the hose.

 

[JHZR2]

That makes sense. The actuator hold vac perfectly, as does the line.