When does the vacuum modulation unit get replaced?

[chromebumpers]

just thinking since I'm under the TH400 right now and cleaning up the oily mess the leaky pan caused I noticed the sludge around the Vacuum unit and the short piece of black hose. What are the signs to look for in a failing unit? Do they just get replaced after so many miles? They don't appear expensive at $12 to $35 depending on brand.

 

[Grumpy]

its a rather common failue and like you said easy and cheap to replace.


I was talking with one of my old high school friends a while back,(damn that was like 50 years ago)
he reminded me that , even back then guys panicked and failed to research problems,
I had a friend sell a 396 1967 chevelle back in about 1970 when the "ENGINE BLEW UP"
there was no rod knock noise,
just tons of oil smoke out the exhaust and it ran like crap, all the plugs oily...
the other friend bought it for $1800,
diagnosed the problem and replaced a transmission modulator valve that was leaking trans fluid into a vacuum line for under $40
obviously those days are long gone and be sure to verify the part matches the application

http://www.summitracing.com/parts/tci-350001/overview/

http://www.summitracing.com/parts/bmm-20234/overview/

 

[chromebumpers]

I forget, what is the amount of Trans fluid needed after the filter is replaced?
Any preferred brand or performance level fluid to use?
I just did the Th400 in a 72 vette last winter, getting too old I guess?

 

[chromebumpers]

Thank you Grumpy, the answer I was looking for and where to get it to. Anything else to look out for?