Hi guys,

I'm going through the process of installing a new short block in my FD. I'm trying to test as much stuff as possible before installing the engine.

The original TCA has 100,000 miles on it so I figured I should test it. Here's a video of me testing it with a hand pump:

It seems to work properly, but the pressure bleeds off quickly. Maybe that is the way they are supposed to operate?

Any constructive input would be appreciated!

 

That looks to be bad. It should hold pressure/vacuum.

One side normally gets pressure and one side gets vacuum. There's a diaphragm in there that pushes on a spring. If the diaphragm is torn/cracked/ripped, it will not hold pressure and will bleed off.

You can also push the rod by hand then cap one of the nipples with your finger. It should move a tiny bit then stop with suction on your finger, take your finger off and it comes all the way out.

Dale

 

I've done what Dale suggested. I blocked off the other hose going to the TCA and now the arm will only move a little bit.

Then I tried a second test where I pumped air into hose 1 with hose 2 being blocked. When I do that, the arm moves exactly the same as in the video, and then the air bleeds off in the same way. Maybe this is how it is supposed to operate?

Does anyone have a "known good" TCA that they can test to see if it behaves in the same way?

Thanks all for your input!!!

 

As stated, it is bad. The vacuum side is bleeding over to the boost side and vice versa. Diaphragm is torn.

Dale

 

Update - I found a replacement TCA locally. I tested the replacement using a MityVac on the center port. It held vacuum nicely and the arm moved at about 5 lbs vacuum so I installed it. After installing it, I took a closer look at the old TCA and found that the new hose I installed had a pinhole leak. Apparently when I installed the spring clamp over the hose I accidentally cut the new hose.

I'm embarrassed to admit that this was the issue all along, but I thought I should mention it so others can check for similar issues if they have issues with their TCA. The center port on the TCA is considerably larger than the vacuum pipe that it connects to - so you have to use a vacuum line small enough to fit on the pipe and large enough to fit on the TCA port. Stretching the new vacuum line over TCA center port and accidentally cutting the vacuum line with the hose clamp is what caused my issue.

 

Glad you sorted it out! I had a similar thing happen a while back on a friend's FD, the vacuum line got cut in the installation and leaked.

Dale

 

Those damn irritatin' leaky vacuum hoses! They are in terrible spots, sometimes and you gotta be aggressive to get them in place. The downside of being too aggressive is the hose can be damaged.

I test my accautors with a MityVac hand pump directly on the nipple itself, no hose. Apply 8 PSI pressure or vacuum as appropriate. The arm will only move with one or the other. Do not apply more than 12 PSI!
Walk away.
Return later and the MityVac should still read 8 PSI.

I've read that some people like to bake actuators and solenoids to 250° F before pressure testing them.