GM Air Throttle Noise

richard5933 · September 08, 2020, 03:06:25 PM

Any suggestions on which thread sealant to use when reinstalling the brass elbows on this thing? Lots of choices from Loctite and Permatex - not sure which is ideal for this application, or if not ideal which is correct.

chessie4905 · September 08, 2020, 03:09:07 PM

The one you show looks right for pedal end the one I was talking about is the engine end actuator. Sorry for the confusion. Been two years since I did them.

richard5933 · September 11, 2020, 03:03:24 PM

Rebuild kit came in today. Rain stopped for a while, so I was able to get the pedal assembly pulled and on the bench. The kit had apparently sat on a shelf for a while, but everything in the kit looked good and correct, including the rubber o-rings and such. The only thing that looked odd to me was the brown grease they supplied - where they had pre-applied some to a part it was looking chunky. So, I substituted some Parker O-Lube I had in the shop. Hope that was an okay substitution.

Pulling the pedal was not too bad once I got the access port opened. Still basically working blind, but it went without problems. Going back in will be more difficult, as I'll have to reinstall the elbow fittings and then try and line up the copper lines and their compression fittings. I've got some nylon air lines I can use to replace the last bit of each one if lining up the copper proves too difficult.

The rain came back just as I was about to reinstall and test. Drats. Hopefully Sunday will have better weather. In the meantime, I hooked up the pedal assembly to the shop's air supply to do a little bench testing. Looks like everything works, and good news in that the free play in the pedal is gone. The photo below will show that it was a good thing I decided to rebuild the pedal assembly, as the crud in there was only going to continue to make problems for me.

chessie4905 · September 11, 2020, 07:27:24 PM

When I rebuilt all of my air system, I replaced almost of the lines under there with dot nylon. Much easier to connect, especially the brake valve.

richard5933 · September 11, 2020, 07:42:53 PM

Quote from: chessie4905 on September 11, 2020, 07:27:24 PM
When I rebuilt all of my air system, I replaced almost of the lines under there with dot nylon. Much easier to connect, especially the brake valve.

Still might do that, but only on the air throttle. No real need to touch the brake valve right now - it's not in my way and there are no leaks.

The feed line for the air throttle connects to the air regulator in the tool compartment and terminates at the air throttle, also in the tool compartment. It's easy to reach on both ends and will be easy to replace with nylon if needed.

The output line is a 1/4"OD line going from the air throttle back towards the bulkhead. There is a union coupling about 12" rearward of the air throttle, so if I find it difficult to reconnect the copper line I can replace the piece from the air throttle to the union. Not as easy to get to at the feed line, but doable.

First attempt will be to reuse what's there. If that takes too much work I'll switch to nylon. I have enough left from the wiper valve replacement to do the change if needed.

chessie4905 · September 12, 2020, 05:31:32 PM

I went to nylon on the brake valve lines because there was no way to get those big copper lines reconnected without cross threading. Remember, I was working through the under driver's compartment. I didn't discover the access panel in spare tire compartment till after I was done.

richard5933 · September 12, 2020, 06:05:16 PM

I got the pedal reinstalled today. Went pretty well. The 1/4"OD output line reconnected with minimal struggle. The nipple for the 3/8"OD supply line ended up about 30 degrees off where it was before, so there was no way to get the copper back on. I installed nylon to replace it and carried on.

Not sure I like the nylon so much though. I checked on the lines I installed last year on the wipers and found them to have developed a few minor leaks. Took a turn or two on each to snug them up. I don't like that they settle in so much.

chessie4905 · September 13, 2020, 04:33:18 AM

Maybe you didn't tighten enough in the first place.

richard5933 · September 13, 2020, 08:07:43 AM

Road tested the pedal today and everything seems fine. Pedal felt pretty much as it did before, only with less free play and no more farting noise when letting up on the pedal. I'm calling this one completed.

Quote from: chessie4905 on September 13, 2020, 04:33:18 AM
Maybe you didn't tighten enough in the first place.

Just how tight is 'tight enough' with the nylon air lines? Always afraid I'm going to over tighten the fittings, even with the metal insert inside the tube.

chessie4905 · September 13, 2020, 04:00:05 PM

Probably a spec somewhere. Did you use dot style ferrules or the smooth sided barrel shaped? I do mine by feel from personal experience.

richard5933 · September 13, 2020, 04:20:24 PM

Quote from: chessie4905 on September 13, 2020, 04:00:05 PM
Probably a spec somewhere. Did you use dot style ferrules or the smooth sided barrel shaped? I do mine by feel from personal experience.

DOT for everything. I'll have to dig a little and see what specs are out there. Wonder if they even make a torque wrench for stuff like that though.