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  #1  
Old November 3rd, 2013, 20:25
G2WANIT G2WANIT is offline
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Double Sanden compressors!

Write up and pictures on my Double Sanden mod:

One of the things I love about my XJ is the ability to take the whole family wheeling in comfort. I like the heater on in the winter and the AC blasting in the summer (at least on the way to the trail). For the past few years my on board air (OBA) has been a $50 4WheelParts compressor. Airing up my 37" MTRs at the end of the trail was bringing the poor girl to her knees... Time to add a second
Sanden AC compressor converted a to OBA!!

Quick background for those who may be unfamiliar: AC Compressors for the XJ are made by Sanden. They compress Freon for your AC system but can be converted to compress ambient air to use for your air lockers, airing up tires or anything else you want to use air for on the trail. The Sanden SD709 is rated around 9 CFM at 40 PSI!! (That's better than my 1.5 HP 3 Gal compressor sitting in my garage...) So with a Sanden compressor converted to OBA and a small air tank you can expect to be able to use air tools on the trail. (Some people go so far as to call this mod "endless air")

Alright, so that's the why, lets get to the HOW!

First, my Sanden mod has been in "progress" for a while now ... it started last year when I relocated my battery to make room in the location I wanted to put the 2nd Sanden (read about that in my build thread, scroll to post 29.)

So with the room under the hood it was time to shop for a compressor off to the Pick-N-Pull!!

Here's my donor vehicle, sorry, I neglected to grab the year:



Basically these compressors are found on XJs and ZJs and TJs and YJs and MJs and ... you get the idea. They are stamped on the body with "709" or "509" you want the 709 because it has 7 pistons, whereas the 509 has ... wait for it ... 5 pistons! 7 pistons = more airflow (more CFMs) The only real difference between years on these compressors will be in the suction and discharge ports. I recommend simply buying one with ports that will suite your application.

When sourcing my compressor I wanted to ensure that the clutch switch was still working. The best way to test was to take a cordless drill battery with me. I attached the single wire coming off the compressor to the positive post on the battery and then ran a wire from the negative post to the compressor body to ground it. When I did this I could hear an audible "CLICK" once the circuit was complete which told me the switch was functioning. Next, with the clutch engaged, I spun the pulley and could feel significant resistance. This indicated (hopefully) that the pistons still had good compression.






So I paid my $20 for the compressor and took it home to get started.

These compressors are usually lubricated with oil in your Freon. When running normal air through them I had 2 options for lubrication: run an inline oiler or do a mod where the compressor is packed with grease. I chose the grease.

I took the compressor apart and cleaned it in preparation for grease, this is very simple, and I'm not going to go into too much detail as there are some other great sources covering this (links at the end). Just 12 bolts got me to this point:



Components flipped:



When doing the grease mod, I had to plug one hole internally (hence it's called a "mod" ). The hole is here at the bottom of the cylinder body:



Here is a close-up, it is easily identified because it has the notch to the 5-oclock position, and it is the only one that goes all the way through the housing (aside from the cylinders...)




If you can weld aluminum, then you could just fill that hole up. I don't tig... so another option is to tap the hole and use a set screw or grub screw to plug the hole. (The screw head has to sit below the cylinder head) TO SAVE MY LIFE I could not find either type of screw in the size or thread pitch I needed... So I simply picked a tap I already owned and made my own screw out of a bolt that was the right size and thread pitch:







Not perfect, but it will work!
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  #2  
Old November 3rd, 2013, 20:37
G2WANIT G2WANIT is offline
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Re: Double Sanden compressors!

Next I tapped the aluminum body and installed the screw:





Now since I had the compressor apart I decided to drill and tap the discharge port to 1/4" NPT:







The suction port was larger than 1/4 NPT, so I decided to leave that and figure it out later.

Lets grease this pig!!



Now, I decided some time ago that the simplest solution for mounting a second Sanden to an XJ was to put it side-by-side with the OEM compressor. The bracket turned out to be one of the easiest parts of this whole modification.

I started out with a plate to mount the second Sanden to, I took some square tube, cut it in half, drilled holes and welded nuts inside for the bolts to screw into. Then I welded those to the plate:







Then I took some more plate and cut strips. These were welded to the opposite side of the plate and will sandwich the OEM compressor:




In a strange twist of luck, when I was at the metal recycler they had an XJ and in the trunk was the already pulled Sanden so I was able to pick up yet another compressor for about $7. This helped because It gave me a second compressor for mockup outside of the engine bay. My biggest concern was to make sure the pulley would line up, so I was able to accomplish this very nicely:





The 1/4" plate top and bottom added enough length to the bolt size that I had to source some longer bolts - these are metric so had to go to a farm supply store with a good selection:





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  #3  
Old November 3rd, 2013, 20:51
G2WANIT G2WANIT is offline
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Re: Double Sanden compressors!

The mount painted up and installed:








One of my goals for this mod was to keep the upper radiator hose stock... but I failed. The compressor sits just a hair too high and the pulley makes contact with the upper radiator hose. I'm not sure how much lower I could have put it, I already had to massage the AC lines going into the radiator:





I still wanted to use an OEM hose so I came up with a workable solution; by using some copper elbows and cutting an XJ hose I made it work:



The first cut connects the bottom of the elbow to the radiator:





The next cuts get rid of a bend and then gave me a piece to connect the two elbows, and the rest of the hose connects to the top elbow:







Not the most eloquent solution but it worked with no leaks. However, since I have a brother-in-law who is a plumber I had him braze the elbows together for me and eliminated 2 hose clamps:




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Old November 3rd, 2013, 21:00
G2WANIT G2WANIT is offline
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Re: Double Sanden compressors!

So here is the final mockup, it clears the belt fine and does not make contact with the hood:







Another goal was to be able to bypass the new compressor should the need arise. As you can see I can still run a stock serpentine belt along the OEM route:



Speaking of the belt, something I learned along the way, the Part numbers for belts have the length of the belts in them. So a stock XJ Dyco serpentine belt part number is 5060950 which has a 95" circumference. So by changing some numbers I can get longer or shorter belts, depending on what I need. I ended up with a belt length of ~102" or Dyco part number 5061020 (actually I bought a Gates belt, PN K061020, but the same principle applies.)


Enough of the part number gibberish, on to final configuration!

Here you can see the suction and discharge tubes at the back of the compressor discharge on the bottom with the 90 elbow:



To get clean, filtered air into the suction port I Tee'd off the breather port from my intake:



I've read that the discharge port puts out some seriously hot air and others have melted their air hose because of it. The remedy is typically copper line in a coil for a bit to allow the air to cool. For me, space was at a premium so I used a few feet of colant hose in the line to my air manifold. The coolant hose runs from the compressor to the firewall and over to the driver's fender:



I could not find a 1/4" NPT to 5/16" barb so I ended up using a 1/4" NPT to 1/2" NPT connector and clamping the 1/2" end inside the 5/16" coolant hose. There is some leakage there but I have a check valve installed at the input line to my air manifold, so it keeps my air tank pressurized between compressor cycles:



(My rear bumper is an air tank with ~1.8 gal capacity and I have a pressure switch turning the compressor on at 105 PSI and off at 150 PSI; it gives me a dozen or so ARB cycles before the compressor kicks in.)

Here is a bird's eye view with some notes calling out the pertinent pieces (for write-ups on relocating the fluid reservoirs check my build thread):





The end result: pure awesomeness!
Previously it took my compressor about 10 min to pressurize my system up to 150 PSI, with this Sanden it takes less than 30 seconds! Airing up my tires literally takes just a couple minutes. I haven't used it to power any air-tools so I can't speak to that, maybe I'll give that a shot this weekend.


Here are some other links for more information on running a Sanden:
Thread on S10 Forum, lots of good info:
http://www.s10forum.com/forum/f125/o...thread-215865/
Article on Grease mod:
http://www.fourwheeler.com/how-to/en...rd-air-system/
Good writeup, but the pics are MIA...
http://www.wranglerforum.com/f19/san...ics-82579.html


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  #5  
Old November 4th, 2013, 07:48
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Ivan Ivan is offline
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Re: Double Sanden compressors!

Subcribed! Awesome write up!
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  #6  
Old November 4th, 2013, 08:25
ert01 ert01 is offline
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Re: Double Sanden compressors!

Agreed!

Very nice work. Seems like a lot had to go into this project but it looks well thought out. I ran my factory sanden as oba on my old jeep and never knew about plugging that hole for the oil... very neat idea. I like the idea of a grease packed compressor also. Curious though how that will hold up over time considering it was never designed to be run like that.
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  #7  
Old November 4th, 2013, 09:19
G2WANIT G2WANIT is offline
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Re: Double Sanden compressors!

Thanks for the props guys.

Just realized that I hadn't posted the link to my washer reservoir and coolant overflow relocation - it's here in my build thread. (Actually, I just posted it )

Quote:
Originally Posted by ert01 View Post
Curious though how that will hold up over time considering it was never designed to be run like that.
Good point! From what I've read on the S10 forum, most guys can run it for a year or two in their application before it fails. Of course they have crazy cycle times (airing airbags up and down) and they run them with 3-5 gal tanks at anywhere from 200-400 psi... From what I've read on some forums, in off-road applications it can last 2-5 years before failing.

Recently I read a post where the user claims to have discovered the reason behind the failures, which can be resolved with an additional grease zerk install. I plan to do this additional mod this winter:
http://4bangerjp.com/forums/index.php?topic=10713.0
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Old November 4th, 2013, 12:23
WB9YZU WB9YZU is offline
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Re: Double Sanden compressors!

I never heard of that mod either.
If you install a tool oiler before the compressor an an oil separator after it, all you need to do is add oil once and again. No disassembly required. Lots of info on this right here on the forum. I use ATF because it is light and has very good lubricating properties. Oil hole on inside of oiler goes down so it sits in the oil.

Nice write up, always nice to see another way of skinning the cat. Hopefully someone will archive it.

Last edited by WB9YZU; November 4th, 2013 at 12:26.
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  #9  
Old November 4th, 2013, 13:37
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Re: Double Sanden compressors!

Quote:
Originally Posted by G2WANIT View Post
Good point! From what I've read on the S10 forum, most guys can run it for a year or two in their application before it fails. Of course they have crazy cycle times (airing airbags up and down) and they run them with 3-5 gal tanks at anywhere from 200-400 psi... From what I've read on some forums, in off-road applications it can last 2-5 years before failing.

Recently I read a post where the user claims to have discovered the reason behind the failures, which can be resolved with an additional grease zerk install. I plan to do this additional mod this winter:
http://4bangerjp.com/forums/index.php?topic=10713.0
Interesting... I would have thought the failures occurred because there was no lubrication between the pistons and the cylinder walls.
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Old November 4th, 2013, 18:10
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MrShaft696 MrShaft696 is offline
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Re: Double Sanden compressors!

very cool mod, hard for me to fathom because I don't require a/c in my jeep, & have less that 100bucks in OBA, nice job.
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Old November 4th, 2013, 18:27
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kastein kastein is offline
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Re: Double Sanden compressors!

That is really, really cool. Thanks for posting it.

Only one question, and you may have answered it... where the bracket sandwiches between the stock compressor and the stock bracket, you add like 1/8" in height. Did you space the other two feet on the stock compressor up the same amount to avoid bending the bolts or is the stock compressor mounted at a slight angle now?

edit: pretty sure that's a 92, 93, or 94 donor. There are very very few differences from 91 through 96 though when speaking about the AC compressor, the next change was in 97 and all they did was redesign the suction/pressure port design on the compressor. The later style uses the weird aluminum block and bolt setup, which is actually easier for OBA, since it's got two aluminum tubes brazed into it you can simply cut them to a convenient length and use them as hose barbs.
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Last edited by kastein; November 4th, 2013 at 18:30.
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Old November 4th, 2013, 19:14
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Re: Double Sanden compressors!

My question is this: do the two compressors and alternator have enough surface contact with the belt for heavy duty cycles? You may want to consider an idler pulley or two.

Other than that, awesome!
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Old November 4th, 2013, 19:19
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Re: Double Sanden compressors!

Quote:
Originally Posted by raneil View Post
Interesting... I would have thought the failures occurred because there was no lubrication between the pistons and the cylinder walls.
I think tapping in to the intake at the breather may let the engine blow-by take care of that. Might want to run an air oil separator after all.
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Old November 4th, 2013, 20:25
G2WANIT G2WANIT is offline
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Re: Double Sanden compressors!

Quote:
Originally Posted by kastein View Post
where the bracket sandwiches between the stock compressor and the stock bracket, you add like 1/8" in height. Did you space the other two feet on the stock compressor up the same amount to avoid bending the bolts or is the stock compressor mounted at a slight angle now?
Actually, I added about 1/4", HAHA, and I bought washers to space the other side evenly. When I was mocking it up I saw there was soooo much slop in the air compressor holes that I didn't feel it was necessary... I suppose time will be the final judge on that but I'd be very surprised if I ever have an issue there.

Quote:
Originally Posted by four_shot View Post
My question is this: do the two compressors and alternator have enough surface contact with the belt for heavy duty cycles? You may want to consider an idler pulley or two.
My original plan was to place an idler pulley between the two compressors (I've seen another setup that way) I even grabbed a couple from the JY but I just couldn't justify the extra effort without trying it this easier way first. I've read that the AC should have around 75% surface contact with the belt, but I just don't see how the amount of coverage I have won't be sufficient... I mean, we've all felt how tight that belt is! And the AC compressor under load, up to 150 PSI just isn't going to require that much friction (IMO). Now these compressors are rated up to something crazy like 1600 PSI - perhaps at THAT pressure you'd need all that surface coverage! The alternator may be another story, but it only lost a little bit of coverage... Don't get me wrong, I think an idler pulley would be the better way to do it, I was just able to justify my laziness I suppose!

I'll be sure to post up if I have any trouble, I'm happy to admit when I'm wrong.

Quote:
Originally Posted by four_shot View Post
I think tapping in to the intake at the breather may let the engine blow-by take care of that. Might want to run an air oil separator after all.
You know, there's a lot more I don't know about these engines than I know... for instance: is engine blow-by good or bad or expected or optional?? On my 2000 that hose to the valve cover is bone dry up at the air intake... even down at the valve cover it sees drops oil, if any at all. I'd worry but she purrs like a kitten, responds when I mash it and the fluids always check out...

You know, I should run a separator on the discharge anyway just to see if it catches any oil - or grease for that matter! I'll have to start shopping for one that will make sense in my application (Probably in the rubber line just down from the compressor...)
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Old November 4th, 2013, 21:06
ert01 ert01 is offline
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Re: Double Sanden compressors!

I wouldn't worry too much about an oil seperator... for that little amount you will get from the blow by tube, the oil will collect in your air tank and keep the inside nice and rust free. I doubt if any oil would make it to your tires. Just drain the tank once in a while and you're fine.

But that's just my opinion. I'm sure the will be a few who disagree. The internet is full of opinions. Haha
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