The International Cessna^® 170 Association

Hi All,

I am sorry I keep blowing up the forums with questions! I have the airplane down fixing the fuel gauges and I am trying to knock out as many of the squawks as I can.

At the annual I had my mechanic try to see if he could find what was making a loud noise behind the panel. It turns out it was the Garwin Pressure Relief valve for the vacuum system. It starts buzzing rather loudly at around 800 rpm. Do any of you know a way that I can fix it or know of a replacement?

Thanks in advance!

Max

So I would guess you have a vacuum pump. Most of us do not.

There are a few replacements. They are pricey. So being cheap I'd look for a used example that would fit your set up with little modification.

Bruce,
I assumed he was talking about the valve shown in Fig. 77-13.My suggestion would be to disassemble and clean the valve.
Edit: Looking at the picture Max posted of his plane earlier it looks like Bruce is correct as two venturis have been removed from the right boot cowl.

I have disassembled several vacuum regulators of various mfr and found them dirty, damaged, or mis-assembled. I’ve never “heard” of anyone who “heard” one before. I wonder if the vacuum pump is missing a vane and “chattering”.... IE... if it’s not sucking intermittently. Do you have a vacuum gauge? Does it fluctuate simultaneously with the noise?
Removing the regulator and applying vacuum (shop vacuum might work) could held diagnose perhaps.

Thank you all for the insight! Sorry for the delayed response!

wyoflyboy wrote:Thank you all for the insight! Sorry for the delayed response!

What has been your discovery and solution?

My mechanic has to come out and take a look at it again. I mentioned to him that it might be a broken blade in the vacuum pump. When he comes out we are going to check it out. I will keep the group posted with what I find out! Again, I appreciate all the insight!

Thanks,

Max