A/C Compressor Vibrates

[FeFranco]

I'm curious, what kind of shape are all your AC pulleys? Anything on them that is barely noticeable, but enough to through off the belt a bit? A ding maybe? How are the bolts and bracket mounts?

[bcomo]

Franco:

I'll check for any pulley imprefections and reply back.

This engine was just rebuilt, so I had a chance to handle and paint every part. The AC bracket was perfect, and the bolts are new 8 grade bolts and washers.

[tbird430]

Bart do u have ALL 4 bolts on the bottom of the A/C compressor now? I spoke with my father at lunch, he says u need to tighten the the compressor down even tighter. So it sounds like u need another set of hands down there for help holding that pry bar while u tighten those lower bolts down.....

-Jon

[bcomo]

Jon:

I now have all 4 bolts on the compressor, and they are tight, with a liitle less that 1/2" flex on the belt (manual says 1/2"). Still have a fluttering belt at idle and worse with AC on.

Franco:

I checked both the AC and Fan AC pulley's. There are no imperfections on either one. And both of them track straight when they run (no side to side, or up and down movement that I can see)

*****
What I did notice is that the fan spacer between the pulley and the fan blade wobbles, and this makes the fan wobble. I don't know if this has anything to do with it -- anyone know if fans can wobble without a problem?

Is there enough room to remove the front bolts on the fan and spacer without taking out the radiator -- in case I want to replace the spacer?

[tbird430]

Yes the fan blade & spacer can be removed w/o pulling the radiator. I would recommend u slide a piece of thin cardboard or construction paper behind the radiator, otherwise u will end up with some real bloody knuckles...

[bcomo]

Jon:

Do you guess that the spacer and fan wobble could be causing this?

Even though I can see the spacer and fan movement, the pulley still looks like it's tracking straight side to side and up and down.

I'm runnng out of ideas as to what is the cause.

[FeFranco]

Well, not to get too far off track, but I don't think a wobble coming from the spacer between the pulley and the fan blade is doing your water pump any good. I would replace that, if anything, for the sake of your water pump shaft bearing. It might also be the problem. You might be able to squeeze it out without removing the radiator, just like Jon said.

[bcomo]

Franco:

I was thinking the same thing after I noticed it. Don't ask me why I didn't notice it till now -- I guess not seeing the forest because of the trees.

How could a spacer be off center like that??? Everything behind the spacer is flat against the water pump flange, so it would have to be the spacer -- correct?

[FeFranco]

I think, if you can take that fan blade out without nicking the radiator (cardboard please) this is to easy to overlook. Check your bolts, fan, spacer and even the neck of the waterpump. Keep us posted and good luck. That car is very beautiful!

[bcomo]

AC Fan Belt Vibration -- Update

I removed everything down to the water pump. The pulleys are flat and true, and the water pump, being new, is tight. The 5 blade fan is not dinged, and all of the blades measure the same height from the table.

I did notice that the front face of the spacer is not perfectly flat against the fan. This makes the fan sit at an angle, depending on how the bolts are tightened.

I have another spacer coming from Thunderbird Ranch.

The only other thing that could be a factor is an out of balance fan. I don't know if I can have that checked -- does anyone know?

If it's not any of those items, then the problem could be in the A/C itself. But, it easily spins straight and true by hand.

Question:

Can someone with A/C please run their engine at idle, with the compressor engaged, and look at the fan belt to see how much vibration there is in the belt itself?

Thanks

[ncbird]

fan

Bart, you can check the fan by taking a piece of dowel that fits through the center hole snugly but still allows the fan to spin freely. Put it in a vise horizontally and put the fan on it. If it has a heavy side that will rotate to the bottom. We do it with props all the time. The other thing you could do is put the pulley back on the engine with shorter bolts and with out the spacer and fan(A/C belt on). Fire the engine up cold and check it. Not having the fan on it for that short of time wont hurt a thing, just watch water temp. I doubt that is the problem though and would be curious as to why the spacer didnt fit flat. Did the nose on the spacer fit the fan correctly? I use universal spacers I get from the local parts store..not going for points. Didnt you say it only shakes when the A/C is on? If so then the belt is still running over this pulley when the clutch is disengaged so you should still have the slap.

[bcomo]

Grant:

I can try to see if the Fan is balanced using a dowel. I fly RC planes, so I know what you mean about the props.

I can try running it without the fan and spacer. I'll have to get the shorter bolts to do that. Very good idea.

The nose diameter of the spacer fits perfectly on the fan with no slop. The front face of the spacer looks like it may have been crushed down on one side enough so it doesn't fit perfectly flat against the fan.

The AC belt shakes even when the AC is not engaged, BUT not very bad -- like when a belt is not tight enough (but my belt IS tight). When the AC is on, the belt shakes about 1" up and down in the center, and that's what vibrates the compressor -- scares the heck out of me.

[ncbird]

need reference

Bart I think your idea of having some one else with a 430 with A/C check theirs is the best idea. This may be a common thing with this setup for some reason. We may be trying to solve a non-problem. At least if some one says theirs does not move you know you are working on a real issue. It would also be good to get a good picture of another one that doesnt flex to see if maybe there is a missing idler or something. Just ramblings.... Grant

[tbird430]

Well, u will have 2 wait about 30 days for me Bart.

Anyone else??

[bcomo]

Yes -- It may be a common problem, but unless I can get a comparison from someone, I might be chasing my tail.

The 430 AC belt only goes around the compressor pulley, and the AC fan pulley.

I'm not sure how it is on a 352. But even a comparison against a 352 might give me a clue.

Anybody?