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overheating...no coolant going through top hose..

ninobrn99

NAXJA Forum User
Location
honolulu, hi
Ive seen the temp gauge shoot up today. Its the first time Ive noticed it since I installed the new gauges.

I checked everything and from what ive seen, the electric fan isnt coming on. I can collapse the top hose and i dont feel any coolant running through it. My synopsis: thermostat.

Now for the questions:
1. Has anyone replaced it w/o draining?
2. If I do have to drain, should I might as well flush it since I doubt its been done? The WP looks fairly new (not rusted). If neither work, I plan on replacing the fan clutch. thoughts...
 
did my 91 without draining. just let what little needed to spill out from the housing. removing the belt will make things easier but isnt necessary
 
okay......i just changed the tstat and the rad cap and no coolant is going through either hose. Is it that the WP isnt pulling or pushing or the rad is clogged?
 
are you waiting for it to get up to temp? it wont flow if it is under what the theromstat needs to open. I even put the thermo in backwards before, does the same thing. does the HO thermostat housing have the bypass nipple on it? if so you can check coolant flow thru that to see if it is the thermo.
 
You need to get rid of the air trapped in the high points in the t-stat housing and upper radiator hose. Generally, the easiest way to accomplish this is to remove the upper radiator hose from the t-stat housing and pour coolant into the housing until it's full. Replace the hose at the housing end, and remove the hose from the radiator. Pour more coolant into the hose and replace it on the radiator. Now, you can get coolant on both sides of the t-stat which helps it to open at temperature. I also remove the heater hose that connects to the t-stat housing and fill it and the heater core that way.

Also, remove the coolant temp sensor at the back of the cylinder head close to the firewall. Add coolant to the radiator until it comes out of the temp sender hole. This bleeds any air out of the water jacket around the cylinder walls.

Works for me every time.
 
A 94 with a 14 year old rad. I would look real close at that rad. That is a very long life for a rad.
If you got the bucks I would do the coolant system. Rad, pump, belt tstat etc.
Get it done all at once and you not picking at it, replacing the coolant 2 or 3 time as it blow out when you over heat.
 
in2fords,
the car gets to temp and well past and nothing. The upper hose and housing are both bone dry!

btw, when i bought the XJ, I noticed that my heater wasnt working. when I looked at it closer, I saw that the one of the previous two owners pulled the hoses that run from the heater core to the compressor and the one to the tstat housing. So i dont have any heat. I honestly dont have the money to buy a radiator and wp right now, so I have a 50/50 chance and have to hope I get it right the first time.

There is no coolant flowing from the top or bottom hoses. Ill follow the fill everything procedure and see if that helps.

I recently did a gauge swap and had to install a new coolant sensor (the one for the gauge or dummy light)
 
If the hoses are bone dry, you don't have enough coolant in it. You can't trust filling it up until it pours out the radiator neck - too much air gets trapped in the block. It's a very common problem on lots of cars since the late 80's with low, wide radiators.
 
ninobrn99 said:
in2fords,
the car gets to temp and well past and nothing. The upper hose and housing are both bone dry!



There is no coolant flowing from the top or bottom hoses. Ill follow the fill everything procedure and see if that helps.
Makes me think the fins on the waterpump are rusted off.
I have only seen this happen once. It was on my brother-in-laws car. (non-XJ)
He was having what sounds like the same problem.
If the "fill everything" dont work... I'd pull the pump and check it.


EDIT:
pull the thermostat and replace the housing W/O the thermostat and see if the water flows 1st.
 
Your heater control valve is probably clogged up, which is causing air to be trapped in the heater lines. That was the case on my 91 beater--when I first took the thermostat housing apart the upper hoses were all bone dry, and when I blew water through the heater control valve is dislodged a chunk of straw colored dust and scale.
 
not sure how the heater control valve has a part in this if there are not heater hoses connected. They're blocked off at the compressor and at the tstat housing.
 
part of the problem could be that since the bypass is blocked the trapped air cant get out.

take the hose's off both ends of the radiator, put water in the top, if it comes out the bottom at the same rate the radiator isnt clogged I would imagine?

I modified a radiator cap to plug a hose into it, crack open the highest part in the system to let the air out and fill untill water comes out.
 
i managed to break yet another coolant temp sensor. This is my third one now. :mad:

anyways, after bleeding the system and getting burnt, the temp is just 210-215 while driving, but it raises to about 235 at idle. Im waiting on it to cool down now, so Ill probably try another bleed.

I really want to avoid doing it from the rear of the head because that damn sensor is expensive ;)
 
You should park "up hill" to elevate the front of the motor, and the filler. This helps the air to move out of the system from the lower points trapped at the back.

Jackstands, a parking bumper, ramps, your neighbors Neon, whatever, getting the front up really helps. I understand the factories do a vacuum fill now because 1) they don't have time on the line 2) it gets the air out.

We're left to elevate it.
 
my driveway is at an incline, so the front of the jeep was foward. I parked in reverse yesterday, so the engine is on the decline side. Im gonna have to turn it around so I can get the air to the front again.
 
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