Looking to upgrade my air compressor pump

[Tmejia]

I currently have a husky 6.5 hp air compressor with a 60 gal. Tank. It's about 5 yrs old and has stopped building pressure after checking it out I believe pump is bad so before spending on replacement pump is there any way for me to upgrade the pump to have quicker refill of tank and less times turning on to fill? I guess to upgrade a little bit without spending much more then actual replacement? Any help would be appreciated It currently delivers 135 psi max. With scfm 11.7@40 ps, 10.2@ 90 psi Thx.
My garage is 20+20. And use a lot of air tools for auto body repairs not daily but at least 2 days a week

 

[redmondjp]

There is not much you can do to improve the performance of your existing unit without upgrading to a larger motor - you'll burn your existing motor out if you try to run a larger pump (or spin the same size pump faster to increase the flow rate). And for the cost of buying a larger motor and pump for your tank, you might as well buy a complete compressor (unless you are buying used and can get a good deal on a motor).

For the use that you have described, you need a larger compressor - something with a TRUE 5HP motor (yours is around 3.2HP running, despite what it may claim as peak HP) minimum. There are hundreds of compressor threads on this site which completely cover this topic.

The cheapest thing to do now is to figure out what is wrong with yours and rebuild the pump (if that turns out to be what it needs - it may just be carbon buildup on the reed valves in the head that needs to be cleaned off). It won't cost you anything but time to tear into yours to see what is wrong.

Bang-for-the-buck, for a larger, affordable compressor I would check out the Harbor Freight Item #93274 ($800 now, but may come on sale at times, and unfortunately the 20% off coupons don't apply to compressors from my recollection of reading the fine print) as this should do what you need it to do.

But search other compressor threads here - tons of good info and other opinions as well.

 

[eddiemeddiem]

Another option would be to buy a compressor off of craigslist with a rusted out tank. If you're patient, they are fairly cheap when the right one comes around. Them swap the pump/motor/electric over to your tank.


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[sberry]

How did you come to the conclusion the pump was "bad"

 

[Major Ramifications]

Yes, the pump shouldn't be "bad" after 5 years of occasional use. What is it doing/not doing?

 

[Tmejia]

Thank u soo much for great advice! Will do!��

 

[Tmejia]

Thank u. Sounds like an idea��

 

[Tmejia]

Well the compressor turns on but does not build pressure ! I checked oil level and noticed there's oil leaking from somewhere on pump also just keeps running without building any air.any suggestions?

 

[redmondjp]

Well the compressor turns on but does not build pressure ! I checked oil level and noticed there's oil leaking from somewhere on pump also just keeps running without building any air.any suggestions?

I would disconnect and remove the line from the discharge of the pump to the tank first. Then put your thumb over the output when it is running and see if any air is coming out (it will be very loud if there is).

The oil leak? Probably has nothing to do with why the pump is not working properly.

The next step is to remove the head of the pump to gain access to the reed valves. These are thin strips of metal that act as check valves to make the pump operate. They can get carboned up and leak, or they can weaken and break. You should be able to find a rebuild manual online, or check Youtube as somebody has already done the same and posted a video of it, no doubt.

There is no reason to completely take the pump apart at this point - pull the head, inspect/take pictures, and let us know what you find.

Parts are readily available for your pump and are not that expensive online.

Happy fixing!

 

[Tmejia]

Will do and thank u for the Help. Much appreciated! I will be able to get to it this weekend and will keep u informed, regards. Tony��

 

[Tmejia]

K I finally had a chance to check pump and take apart to find complete pump was destroyed- Pistons in pieces and block cracked. I've been researching replacement and seems like it will be close to $300. With shipping�� but my new question is Ive been researching the Harbor Freight 5hp 145 psi twin cylinder comp pump. Would this be recommended for only $179.99. ? Reviews seem good but I don't want to spend the money or time for cheap products or time? Can someone let me know if this is do able ? And what modifications I would need to do if any? My current pump is part# vt470000kb. From a 6.5 hp husky compressor 60 gal tank I use it with air tools and for car painting any help would be appreciated. Thx

 

[redmondjp]

I see two units @ HF right now, both on sale for $179.99:

Item # RPM CFM@40 CFM@90 Stroke Weight LBS
60754 1070 17.9 15.4 2.36" 66.8
67698 655 17.5 15.2 2 9/25??? 72.0

So here's the deal - both of these pumps, at their maximum speed, will require too much horsepower from your existing motor (which is around 3HP) and burn it out. That's not to say that you can't use them - whichever one that you pick, you're going to have to spin it at approximately 2/3 of its maximum RPM so it will only require 3HP of power (the flow numbers will also be lower, of course). So you're going to have to look at the flywheel size on these pumps and then figure out what size pulley you are going to need on the motor. Either pump will work, but I'm guessing that the 1070 RPM max. one will be easier to use (you can use a larger pulley on the motor than with the other one which will need to only spin at approximately 400RPM.

And then, once you get it up and running, you should check the motor running current with a clamp-on ammeter to ensure that you are not exceeding its rating.

 

[Tmejia]

Thanks soo much for info. But kinda confused . I have a 6.5 hp motor are u saying it's really a 3 hp?

 

[redmondjp]

Thanks soo much for info. But kinda confused . I have a 6.5 hp motor are u saying it's really a 3 hp?

Yes, exactly. Maybe slightly higher than 3HP, say 3.1 - 3.3HP.

Compressor manufacturers essentially lied for years about motor power ratings and kept inflating the advertised numbers (the same thing happened with vacuum cleaners and lawn mower engine HP numbers) to the point at which there was a class-action lawsuit against the industry to stop this practice about ten years ago. They also lied-by-omission by listing "SPL" on the motor nameplate where the HP rating was supposed to go. This way they could get away with inflating the HP number on the compressor label.

You will notice now that in stores today your size of compressor will have words something like "3.3 HP running" on it. The 6.5HP as used on your compressor was a peak number that the motor could achieve for only a few seconds w/o overheating. It was essentially a meaningless number.

You can tell the approximate HP of a motor by how much current it draws. True 5HP single-phase motors draw 22-28amps @240VAC (depending upon their efficiency). Yours probably draws about 15-16 amps.

So, pick a new motor pulley to spin one of those two HF compressor pumps at about 2/3 of its maximum RPM, and then measure your motor current. If you are at or under your nameplate amp draw, you are golden! If you try to draw more, it will shorten the motor life. You may be able to get away with 5-10% higher-than-nameplate current, but personally I wouldn't push it on that consumer-grade motor (on a true industrial 5HP motor there is more margin for overload and you could probably get away with that for intermittent duty use).