Onboard Air System

Defender200Tdi · 7th March 2005, 10:41 AM

There's plenty of resources available for this, but not much specific to Defenders. I have this as a work in progress at the moment, so I thought I would provide an ongoing record as it develops.

So far, I have gathered most of the required bits, being a Sanden SD508 A/C compressor (from an old Sigma), a 12 litre air tank from a Ford Trader (via the truck wreckers), a pressue switch, filter and oiler.

In practical terms, I've only managed to mount the tank so far:

Here's the tank:

Where the tank goes (left rear wheel well):

Tank inplace:

Reinforcing for the tank mounting:

That's it so far. I'll update this thread as the work progesses over the next week or two.

Paul [img]style_emoticons/<#EMO_DIR#>/biggrin.gif[/img]

xtremeslug · 7th March 2005, 01:54 PM

Looks like you are doing a great job please let us know where you fit the pulley for the a/c compressor.

**VladTepes** · 7th March 2005, 02:18 PM

Will keep a close and interested eye on this.

Does your truck already have air con ?
Where the hell are you going to fit the new compressor and what will you use to drive it ?
How are you going to arrange the lubrication?

No doubt the answers to all these questions will come....

**Phoenix** · 7th March 2005, 02:31 PM

looks like an interesting project, and a very interesting one, i'll be watching this as well.

Defender200Tdi · 7th March 2005, 02:42 PM

<div class='quotetop'>QUOTE</div><div class='quotemain'>let us know where you fit the pulley for the a/c compressor[/b][/quote]

<div class='quotetop'>QUOTE</div><div class='quotemain'>Does your truck already have air con ?
Where the hell are you going to fit the new compressor and what will you use to drive it ? [/b][/quote]

I can answer this one right now.

Yes, I do already have A/C, and no, there's not enough room to run yet another pulley on the crank. However, the Sanden compressor has exactly the same lug mount dinmensions as the existing Diesel Nikki pump, so I plan to mount the new pump off the lugs on the existing A/C pump. Sort of sideways piggyback, if you get my drift. The existing pump has a twin pulley (as does the new pump), but only one pulley is in use. On the other pulley I'll use a very short belt to drive the new pump. I'll then pivot the new pump from the existing one on the top two lugs and tension with slotted brackets on the bottom two lugs, alternator style.

In effect, the existing A/C belt will end up driving both the A/C and new pump. Whether it is up to the job of driving both, I don't know, but I'll just make sure the A/C isn't on at the same time as the compressor. That way the A/C will be just freewheeling so it shouldn't be a problem.

As for lubrication, I'll just fit an inline air tool oiler on the suction side of the pump. An air/oil separator on the discharge side will make sure no oil gets into the tyres.

Anyone have any idea what the appropriate lubrication level should be for one of these pumps in operation i.e. how many drips per minute?

Also I haven't been able to get a definitive answer as to what level of filtering is required to remove the oil. Some have said that 10 microns is OK, others have said much less (0.1 microns). A 3 micron filter is pretty common and I can get 1 micron OK, but 0.1 microns is in the serious $$$ category and the airflow is much lower for those too.

Paul [img]style_emoticons/<#EMO_DIR#>/biggrin.gif[/img]

Hellspawn · 7th March 2005, 03:54 PM

Just on the how much oil bit.

The airdriven airless sprayer we have is around the 4 drips per minute. The little reservoir holds about 200ml of oil on the inlet side of the pump. The pump only makes 10~13 cycles per minute so it doesn't need much oil but consumes 8~10CFM.

So comparitively 4 drips would be enough for the air compressor.

**sclarke** · 7th March 2005, 05:27 PM

Great Stuff. Now here is a bloke with an idea...

**VladTepes** · 8th March 2005, 11:25 AM

Paul I don't know if you've seen this thread on outerlimits but its a good one for you:

http://www.outerlimits4x4.com/PHP_Modules/...8&highlight=lpg

Defender200Tdi · 8th March 2005, 11:38 AM

Yep, saw that one. Mine will be very similar, except I'll have the pressure switch on the right side of the check valve. :wink:

There's actually quite a lot of info on various sites for this stuff, whether using a Sanden or York style compressor. It's just that no-one seems to have put up one for a Defender, so I thought it may as well be me. [img]style_emoticons/<#EMO_DIR#>/biggrin.gif[/img]

http://www.jeepaholics.com/tech/OBA/oba.htm

http://home.san.rr.com/rambler/jaircomp.htm

http://www.jeepshots.com/tech/air.html

http://www.jedi.com/obiwan/jeep/yorkair.html

http://www.huv.com/jon/jeep/Air/index.html

http://jeepfrog.com/78cj5/mods/air/

Paul [img]style_emoticons/<#EMO_DIR#>/biggrin.gif[/img]

Defender200Tdi · 16th May 2005, 04:50 PM

Ok, after a fine start, this little project stalled for quite some time. Numerous other matters intervened meaning it's taken until yesterday before I had a chance to do any more. However, I've now moved to the next stage. [img]style_emoticons/<#EMO_DIR#>/biggrin.gif[/img] The compressor has been cleaned up, the old A/C flare fitting mounts have been milled off the head, and the head has been drilled and tapped with some more normal threads to make final hookup easier and neater.

I've now mounted the compressor

ops: and quickly realised that my original idea of pivoting off the A/C compressor for belt tension wasn't going to work.

Here's the compressor in place:

Side view showing the brackets mounting to the A/C compressor:

From underneath, showing the brakects. Ignore the swag of washers taking up the surplus length of the too long bolts. It's all held temporarily in place until I'm sure I'm satisfied with the result, then I'll get some new bolts of the right length.

There simply isn't enough room to tension the belt alternator style off the other compressor, so I had to go to plan B. This involved installing a tensioning pulley, much like that used on the existing A/C belt. Obviously a bracket needed to be fabricated, and the whole lot squeezed into what little space there is.

Here's the tensioning pulley:

Another minor problem that had to be overcome was the bonnet stay rubbed against the belt when the bonnet was closed. :roll: It wasn't really apparent until after I'd settled on the pulley arrangment, but having reached that stage, I wasn't up for a re-design then. The solution was a small piece of flat bar that allowed the folding bonnet stay to slide along away from the belt.

Like this:

As can be seen in this last photo, there's very little clearance between the top of the compressor and the closed bonnet. Just enough, if I've calculated right, to allow for an elbow to attach the inlet hose. Fingers crossed. :wink:

The fittings in the inlet and outlet ports of the compressor are just there temporarily to stop muck getting in. They obviously don't belong there.

Well that's as far as I've managed this weekend. Next is to install the pipework, cooling loop, pressure switch, filter, oiler, manifold etc, and plump it all in to the tank. Probably only another day's work. [img]style_emoticons/<#EMO_DIR#>/biggrin.gif[/img]

Paul [img]style_emoticons/<#EMO_DIR#>/biggrin.gif[/img]

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