One stage compressor issue

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Good morning,

First mods move this as needed. I have a tool issue and thought I might get an answer at WW.

I have a 20 year old craftsman one stage compressor. It is only lightly used, nailers, shop air, tires etc. It was beginning to bog down in the compression cycle. So I tore it down and found that the piston sleeve and rings were worn. I purchased a replacement set. Did a light cleanup. The head fins are very clean. Has good air flow from the integral motor fan blade.
I’ll show a picture below. Anyway I put it back in service.

I did a light break it. It seems to work fine. Compressed fast. Here’s the rub. When it runs for about 4 minutes, it gets hot since the head is heating up as normal. Then it starts generating a sickly sweet smell. Not electrical but something else. I thought crappo so I opened it back up and tore it down. Nothing. All new parts look perfect. Rings and sleeve look fine. No scoring. Smell motor. Nothing. That’s why I’m stumped. So I put it back together. I still doesn’t seem right. So I turned down the press shutoff switch to 95 psi. Basically I need to pause the compression to get to 95 to avoid the cooking smell.

Not a huge priority but it would be nice if I could solve this. I’m remiss about running it to hard.

Regards.

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Here is the break out picture



Here are the replacement parts. This included the small gromet for the press tube



I will also mention the head still has the same reed valves. These look fine, good springiness. They don’t show any signs of stress.

[Sberry]

Drive it till it blows up.

[scsmith42]

During break in there is increased friction between the rings and the cylinder, so the compressor runs hotter than usual. After it's broken in the friction drops and the heat is reduced.

So your problem may go away after it's broken in for a few hours.