Engine driven air compressor questions

[ShortBox88]

I was curious if anyone had attempted to use 99+ WJ 4.0L drivers side engine accessories (PS pump and AC compressor) + the mounting brackets on the older Renix or HO XJ/MJ engine blocks?  I've read a number of threads on various sites where it is stated that these are incompatible because bosses on the block are either missing, not in the right place or not drilled tapped for the newer style accessory brackets (although the context usually seems to be adapting the older HO or Renix accessories to the later model redesigned 4.0 block found in later TJs and WJs 1999 or 2000+? in the case of engine block swaps).  In my case the 88 Renix 4.0 still has working AC that I'd like to keep.  After briefly poking my head under the hood of a 99 4.0 WJ at the salvage yard last week, it seemed like one possibility for on board air would be to use the WJ brackets and accessories on the drivers side of the engine block and use the 99+ WJ 4.0 AC compressor converted for air compression duty and retain the original AC compressor and alternator on the passenger side of the engine block as they were from the factory in 88.  Just wondering if anyone has tried this?  If so, what did you find out?  Did you need to use the later horseshoe style intake to make the brackets/pulleys/etc. work?  What about adapting the later model belt tensioner and belt routing?  It'd be great if there was a mostly "bolt on" solution to add a second AC compressor for use as an on board air system.

Aside from a tank, compressor and high pressure line I believe I have the rest of the components (drip oiler, filters/separators, pressure switch w/unloader, check valve, etc...) from an engine driven on board air setup that I kept from my old CJ5...

 

[schardein]

I can tell you that switching to the "horseshoe" style intake also requires using the corresponding power steering pump bracket.  And, that bracket has a more user friendly belt adjustment than the earlier style.  I have done this swap on three 1991 4.0HOs.  The p/s pump brackets bolted up with no issues.

 

So based off that, I think if you use the driver side accessories, the manifold would be required also.

 

That's all I got, not familiar with the WJ setup.

[gogmorgo]

What's better about the belt tensioning system? I've only ever used the earlier one. 

[ShortBox88]

After looking at images of 4.0L engines online I think I've determined that this isn't likely to work out in a bolt on manner.  I'm still tempted to head to the salvage yard and fool around with mixing and matching parts to see if something will work out, we'll see if I get motivated tomorrow.  Here is a photo of a later WJ/TJ 4.0:

 

 

You can see that there is a boss cast into the block near the oil pan towards the front of the engine that I believe supports the AC compressor in the later model/post redesign configuration that puts the AC compressor below the PS pump.  Also notice that the water pump inlet projects out to the driver's side nearly horizontal (routing the lower rad hose between the PS pump and AC compressor), whereas on the older HO and Renix 4.0 the water pump inlet points downward from horizontal in a way that I suspect that would try to run right through the AC compressor location on the later WJ/TJ location...  Hmmm...    

[schardein]

1 hour ago, gogmorgo said:

What's better about the belt tensioning system? I've only ever used the earlier one. 

The earlier system has a several adjustment bolts to loosen, then turn the adjustment bolt, which is below the pump with its head pointed sort of down and towards the inner fender.

 

The newer system, loosen the idler pulley nut and turn the adjustment bolt, which is on the top sort of facing the water neck, easier to access and you can see it as you put the wrench or ratchet on it.  Then tighten down the pulley nut.  It's more user friendly.  Almost like a mechanic designed it.

 

Then later versions have the self adjusting tensioner... which maybe a WJ has?  I don't know.  The newer intake & p/s pump bracket swaps I did came from 1999-2001 XJs.  

 

First two pics are earlier style, last pic is the later style, the adjustment bolt is in the upper left corner, facing the corner of the pic.

[gogmorgo]

Oh. Yes, much easier. Good to know.

The earlier style is definitely better than the old v-belt technique of shoving a prybar in and pivoting the whole accessory while you crank down the mounting bolts, but it definitely isn't as accessible as a tensioner pulley. The recent ones where it's just an idler on a spring-loaded pivot are great, slip belt over most pulleys, pull the tensioner back, slip the belt on the last one, then let go, perfect tension. 

I usually end up leaving one of the rear bolts on my power steering pump loose because it's difficult to get tools onto. Hasn't caused me a problem yet. 

[Minuit]

The old style belt tensioner isn't so bad once you learn how to reach all 17,000 bolts you need to mess with to adjust belt tension, and assuming you keep the adjustment bolt lubricated. The one on the lower rear of the P/S pump bracket (the one with a fuel line in the way) is a pain. I find it easier to get it from the bottom. OK, maybe it is a PITA after all...

 

I do wish it had an auto-tensioner every time I need to mess with the belt though.