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Head Scratcher


DRangerd

Well-Known Member
Joined
Jan 4, 2008
Messages
49
Age
65
City
Aurora co
Vehicle Year
91 & 92
Transmission
Automatic
Ok, Gang, got a head-scratcher here, got a 91 Ranger,4.0,Auto,A/C (inop) E-case, Auto hubs and everything including 4hi and lo works, But lately if idling for a few minutes, it starts making an intermittent thump or clunk noise. It seems to be coming from the right front, mostly, but it seems to move around too, and sometimes its loud and sometimes you just barely feel it thru the frame. AND it does this even if I turn off the engine, for 2-3 minutes.
The only clue I've gathered is if I put it in 4hi, then back up, take it out, then back up some more, it stops until the engine is turned off, then starts again next time.
So I'm posting this here as I think it might be in the transfer case or maybe hub, but i am pretty stumped. Could the computer be trying to engage 4hi, or the hub trying to lock in?
Any ideas? experiences ?
 
Just to make sure I have this right -- it makes a thump when the vehicle is parked and turned completely off?

About the only thing it could be is air trapped in the cooling system. 4.0Ls are notorious for this because of the upper rad hose routing.
 
Yes, it does, for a couple of minutes, thats the wierd part,
So you're thinking air trapped in cooling system?
 
I did put a 3" B/L on it a couple months ago, I think thats about when this started...............
 
Well, that would change the routing. Take a good look. Is there any place air can get trapped?

Also, make sure it's pressurizing, or that can MAKE air (well, coolant vapor). Squeeze the upper rad hose when the engine is warm. It should be quite firm. If it feels the same as a cold engine, you have a leak. Go looking for it. Don't forget the water pump snout (from underneath), core plugs, spark plugs, and crankcase. If you can't find ANY leaks, replace the rad cap.

The knocking sound is the coolant boiling.
 
Last edited:
Ok, MAKG, this is makin sense to me, could this also be related to a minor cooling problem it has, sometimes the temp needle will go way up to the "m" in normal then drop suddenly back to below the "n"...........
 
Mine does exactly this i cant find any leaks and this is a new radiator? Just started after i put this in i have no clue i bought a thermostat but have yet to put it in, also my temp gauge acts like yous thats why i figured maybe the t stat?
 
like what was mentioned before, you have some air in the system......

l8r, John
 
Isnt it supposed to work itself out into the overflow? How do i get the air out without jacking thefront end 3 ft off the ground?
 
what i had to do, when the engine is cold, take off the rad. cap

start the truck up and let it idle......keep the rad. cap off

once the truck is started, the level in the rad. will go down some....fill up to the neck...keep the rad. cap off

once the truck warms up enough for the thermostat to open, the level in the rad. will go down again....fill back up to the neck and now put the cap on....

once the rad. has enough water in it to push the air out of the system, it will work through the overflow bottle.....

l8r, John
 
Ill give it a try after work pretty much what i did thought a few weeks ago when i put in the new radiator i let the t stat open up then filled it up and the overflow. Ill try again.
 
Still does it this is really annoying? My other ranger never has this problem, just fill it up and drive. What gives?
 
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