Jump to content

Has Anyone rebuilt the power steering pump and/or the air cond compressor?


Recommended Posts

I have an 86 720 st that needs both of the above rebuilt or replaced.  In addition I need to fix the blower control to give me more than the highest setting on the panel (5).  If I place the lever in any other position the fan won't function.  I would prefer to rebuild the original parts depending on how difficult that route would be.  If any of you experts out there would let me know how successful the rebuild route has been I would greatly appreciate your comments and advice.

Link to comment
  • Replies 19
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Posted Images

Sounds like your blower resistor is bad. That's why it only works on full high.


You may need a press to rebuild the P/S pump. Never had an A/C compressor apart, but they can be rebuilt. Trouble may be in finding parts to rebuild it with. You'll probably have to get them from a rebuilding house or A/C specialist.

Link to comment

Power goes to the fan motor, from there the selector switch selects multiple paths to ground through resisters with no resistance being the fastest speed. The resistors are in the fan housing where the air passing them keeps them cool for safety.




It's the plug above with all the blue wires and two screws holding it in place. You may fins one of the wound wire cores broken. Replace it or maybe try joining the wire ends by twisting securely together.


PS pumps rarely fail to work. Not sure how you would determine that it isn't working and it's not something else. The FSM covers mostly replacing of O rings if there is a leak. Just replace with a used one from a wrecking yard.


Same with the Air Con compressor. They are very reliable. If air con not working there are many reasons other than the compressor.


Link to comment

P/S pumps can get gunked up and fail from overheating. If it still works, but is making noise, try flushing the fluid and adding new, then with the engine running, turn to full lock and hold it there for about ten seconds. Go back and forth doing this at each stop a few times and likely you will clean the gunk buildup out of the bypass, making it run quietly and smoothly again. Flush and add new fluid once more and you're done. If it leaks, that's a different story, but can be easily repaired.


Also, the fan blower switch could be dirty. I just went through this on my 1979 Chevy K30 where bees had built a mud nest inside the switch causing the contacts to get dirty. I took the switch apart and cleaned it then reassembled it and everything worked fine.


One reason the blower resistors go bad is from leaf or debris buildup around the coils, causing them to overheat and pop. If you're replacing the resistor, take some time and clean out the HVAC box while you're at it. If it's out of the truck, take it apart and hose it out to get it clean as new. I even replace the foam on the doors with bulk rolls from McMaster Carr. If you want the HVAC box to be air tight and rattle free, try replacing the foam.



Edited by Stoffregen Motorsports
Link to comment

 FSM states that only the sealing parts are replaceable and anything else requires the unit to be replaced.




Make sure your belt is adjusted and not slipping. PS belt deflection is measured half way between the pump and the adjuster pulley pushing with thumb and is 0.5 to 0.75." 


Have the operating pressure tested and save yourself time bother and expense. Normal idle pressure is 1,100 to 1,200 PSI.

Link to comment

Mike, I stopped at my buddies place and had him put the pressure gauge on the PS pump. It turns out that the high pressure hose is leaking. Is the 86 an early or late model?  According to RockAuto there are two versions of the hose.

  • Like 1
Link to comment

My '86 was made in April of 1985. I have had multiple issues with getting parts for an '86 but it turns out the '85 was what I needed.  Brake parts, air cleaner, and I think maybe the high pressure PS line too, can't remember it's been a while.  I always search for both years and if the parts differ, try to figure out which is the right one. I am assuming my truck sat somewhere for a few months before being shipped off for sale and by then they had rolled out the '86 MY.

Edited by MaddieCycle
Link to comment

April '85 IS and '85 through till about June build dates. Nissan may not call it an '86 because not a complete year but from August through November build dates would normally be an '86 model year and then the new D21 Hardbody was built.  

Link to comment
1 hour ago, datzenmike said:

April '85 IS and '85 through till about June build dates. Nissan may not call it an '86 because not a complete year but from August through November build dates would normally be an '86 model year and then the new D21 Hardbody was built.  

Strange, mine is titled as an '86.

Link to comment

Some titles reflect when they were purchased, some don't . This is a DOT mess up. Build dates don't lie. They determine what parts properly fit your truck.


I now see that '86 model year 4x4s actually were built in May of '85 (pretty darn close tho April) while a few 2wd changed to '86 model years in June. Does your VIN number end above # JN6 ????Y??? 100011 

Link to comment

I have ordered the high pressure PS hose from RA.  As soon s I can I will change the hose.  I need to clean my shop to find the AC cannister and line to replace the one currently in the truck (bodged copper line for a connector).  More questions later.  Thanks for all of your excellent help!

  • Like 1
Link to comment
  • 1 month later...
  • 3 weeks later...

Hi all, I replaced the upper and lower ball joints without too much trouble and am now trying to replace the power steering high pressure hose.  It would appear that the fittings are original and I can't seem to budge them.  Anyone have this problem?  How did you get them loose without rounding them off? 

Merry Christmas to all.

Link to comment

If you're going to replace the hose and fitting. try cutting it off to get a socket on the hex. Unless you have the correct size line wrench, an open end spanner will almost always round off stuck nuts.


Have you tried applying heat? Heat the area around the nut and try right away. If it still doesn't budge, squirt with WD40 and let it cool, then try it again.

Link to comment

Stoffregen you were a life saver.  I cut the line as you suggested and the fitting was removed with some additional pressure from a six point


socket.  Thanks!

Now that I have a stout frontend and shocks that work she drives like a dream.  I now have a tiny rattle sound coming from somewhere under the dash.  It goes away in a few minutes or if I turn up the radio volume.  Something to be checked when I tackle the heater fan resistors and the air conditioning.

  • Like 1
Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...

Important Information

By using this site, you agree to our Terms of Use.