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12V Air Compressor Rebuild Kit

October 10, 2015, 06:17:17 am

Bought a rebuild kit for my 12V compressor (I have the old one I took out of the coach when it failed.

Rebuild kit is as follows:

P/N SK405DCMAJ
Description: Service kit includes conn rod valve plate, eccentric & bearing assy, front cover gasket,
head & cylinder o-rings, valving, valve screws, intake filter, ratchet fastener.
Suitable for model 405ADC38

Purchased for 135.00 from:

Combined Fluid Products Company
805 Oakwood Road
Lake Zurich IL 60047

Be advised that they also have the pump for the price of approximately $285.00 new plus shipping.

I will take pictures of rebuild and post when I get around to it.  My pump end failed when I had a big leak and let pump run too long (about three years ago), kept pump and am finally getting around to rebuilding pump.

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Re: 12V Air Compressor Rebuild Kit

Reply #1 – October 10, 2015, 09:31:55 am

The same thing at Zoro Tools where I got mine.  $105.

Thomas Industries Service kit, For 5Z349 SK405DCMAJ | Zoro.com

This is for the smaller compressor used in 2000 and 2001.  Maybe other years but I don't know.  Check the model number on the compressor. Zoro has new ones for $390.  $285 is a very good price.  About $800 if you get it from FT.

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Re: 12V Air Compressor Rebuild Kit

Reply #2 – October 10, 2015, 10:43:44 am

$450 for pump from MOT

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Re: 12V Air Compressor Rebuild Kit

Reply #3 – October 10, 2015, 11:03:52 am

The 3/4 horsepower "boxer" twin cylinder GAST 120 volt AC compressor used in older model U300 coaches costs about $700 as I recall and the rebuild kit was about $150 when I rebuilt mine last summer. It was a pretty easy job with good instructions included in the kit. It's a surprisingly rugged and powerful little compressor, but noisy of course. I wrote about the rebuild at that time but very few people commented on it and I never got any questions about it so it probably wasn't of much interest. The pump is still running well a year later so it was definitely worth rebuilding it instead of replacing it.

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Re: 12V Air Compressor Rebuild Kit

Reply #4 – October 10, 2015, 09:56:21 pm

I ordered a new 405ADC38/12 from Combined Fluid Products.  $281 with free shipping.  Installing it tomorrow.

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Re: 12V Air Compressor Rebuild Kit

Reply #5 – October 11, 2015, 07:28:33 am

Hi all just had a new 12v compressor installed and was wondering what pressure it is supposed to cut on and off at?  Been here in a park for two nights now the AP on the dash is now at 50 lbs and I haven't heard it come one once.

Thanks,
Woodie
93 40' GV

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Re: 12V Air Compressor Rebuild Kit

Reply #6 – October 11, 2015, 03:39:51 pm

It is for the hwh system and should not be putting air into the coach system so would not keep your air pressure gauges up

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Re: 12V Air Compressor Rebuild Kit

Reply #7 – October 11, 2015, 03:50:22 pm

That's funny that the tech that installed the new pump said it was inline with the coach air system.  I went to a facility that is certified to repair these systems per the manufacture.  Guess he didn't know what he was talking about.  So when the coach is level and in auto mode the pump only runs when it needs to inflate a bag the air isn't taken from some reserve tank then the 12 v pump replenishes it? I know when you have it in manual mode you can see the air pressure drop from the dash gage.  Just trying to understand how the system is supposed to operate.

Woodie

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Re: 12V Air Compressor Rebuild Kit

Reply #8 – October 11, 2015, 03:59:15 pm

The hwh system will take air from the coach air only until the air pressure drops to 60 lbs due to a protection valve on the air tank, then if the hwh needs air to inflate the bags the 12 volt compressor supplies that pressure only to the air bags

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