Grimmer Schmidt mono compressor wont hold pressure

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by mitchel
(edon ohio usa)

I’ve got a 105 cfm grimmer Schmidt mono compressor.

I’ve replaced a 413 dollar part like mats in Dayton oh said so. It worked fine last year. Its got a 302 industrial engine in it.

Grimmer Schmidt mono-compressor
Grimmer Schmidt mono-compressor

Here’s the problem once I get it running the governor won’t hold air pressure at 90 psi its all over the board. If I open the valve all the way up I lose everything and the engine idles to normal its like the pistons are not holding air.

Mats in Dayton told me take and and blow air through the lines and if u here a pop the valves are working properly. Odd I can’t get any to pop?


Mono compressor
by: Doug in

You can download the manual, free.

I’d start with the pressure sensor that drives the engine control.

Good luck.


Mono compressor
by: Kevin in Toronto

Where do you find a operator and repair manual for this unit?

I’ve found one for the 100Q mono block, but not the 105. Are they the same??


My bad
by: Doug in

Either I mis-read, or maybe that one went away.

It probably depends more on the engine – but only you can see if one or another of the others is useful. They probably share many components.

Get a couple and see if they are the same or similar.


Grimmer Operational Issues
by: Anonymous

There are a couple of ways for us to help customers with operational issues.

One, we do offer technical help in 20 minute increments on our website.

Two, you can simply call in and speak with our Grimmer Guru Jody.

This problem you are experiencing is fairly common.

Without more information I am unable to locate which part you purchased from us. A search in our system for the $413.00 amount did not come up. So this must be a rounded up or generalized dollar amount.

Let us know how we can help.

(Unfortunately, the commenter did not provide any contact info. If you visit Chicago Pneumatic ( will see that they own Grimmer Schmidt compressors. Perhaps the reference to their “Grimmer Guru Jody” speaks to contacting CP? – Moderator)

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