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I've got a 1956 Caribbean with the push button Ultramatic A/T and need a new vacuum modulator. Any leads appreciated.
Will the modulator from any other make of car work?

Thanks

Bill

Vacuum modulator??

Do you mean a Vacuum Advance for the carburetor(s)?

Nothing on an Ultramatic is vacuum operated. The only vacuum modulator is the advance mechanism on the distributor but the electric shift does have a pressure switch located on the side of the transmission which could be taken for a modulator. That is a completely different item so please provide a few more details as to what is happening or not working..

Quote:

I suspect you are referring to the shift motor??? Please explain in more detail. The only vacuum powered stuff on these cars is the advance, power brakes, wipers, and washer.

And what is WRONG with it in particular? It's not like you can just buy new ones off the shelf for $50 at NAPA; while all the parts are available and people rebuild them all the time, it will save you a great headache and some expense to describe the specific issue. Perhaps your motor has simply overtraveled.

Thanks for the quick reply.
I do apologize, I'm learning a lot from these cars.

Symptoms: Whitish smoke (no blueish tint) coming from right side of exhaust only even after warm up. Car shifted fine but now is sluggish to go into gear and the A/T fluid is low. I have not put the car on the lift to look at it yet. Not leaking A/T fluid. I thought (incorrectly) that it had a bad trans vacuum modulator and the A/T fluid was being sucked into the engine.

I'm not low on radiator fluid as my first guess was a blown head gasket. After 10 or 15 minutes of driving, the white smoke does disappear.


Bill

Low A/T fluid will cause shifting issue. So you want to top that off right away.

White smoke is usually oil being burned. Which could be blowby from worn or stuck rings, Also, head gasket, worn valve guide, etc.


Rare case would be brake fluid being sucked in through the vacuum lines, if the powerbrake booster had an internal leak.

Quote:

The only way the fluid gets low is from leaks; it does not evaporate. Example: walking up to a car parked 20-30 years and pulling the dipstick to find there's plenty of oil left is the norm, not the exception.

Point is, once you add it, it will start leaking... somewhere. So just be prepared for that. Probably when the transmission is running, unless it's leaking from the pan gasket or the things threaded into the pan.

Side note, to properly check the level, you set the parking brake then shift into neutral with the engine running, then wait 1 minute before taking the reading. This ensures the converter is full. Or: remove the plug in the rear of the case. Put a catch pan underneath. Add trans fluid until it starts to run out. Cap that, then add 1 more quart. Capacity is 11½–12 qts total.

Note: this rear case plug is different than the drain plug and the dipstick nut, both in the pan.

thank you.

Going to diagnose the problem this afternoon.




Bill