Jeep Enthusiast Forums banner

Should I be able to see coolant moving?

4K views 52 replies 13 participants last post by  Gigemags05 
#1 ·
I noticed recently, that my temp gauge is creeping closer to the H than it ever has. That being said, this is probably the warmest weather I have driven it in since getting it on the road. Still feeling uncomfortable with the gauge reading I decided to change the thermostat. Ran it without radiator cap to burp it and did not see any "flow" when looking in the radiator. Temp gauge went really close to the H again so I decided to shut it off. Should I be seeing movement of the coolant?
 
#9 ·
Missed it BUT did you test it in some hot water? Ive had one fail right out of the box before due to swarf/rust on the shaft. Ive also seen mechanic's put them in upside down and they wont open. Check for an airlock too. If all else fails remove the top pipe and make sure water is pumping out. Could be a blocked radiator, bad waterpump. In AU we generally wont run them as it doesnt get that cold here to need it.
 
#10 ·
First thing you will want to do is check the actual coolant temp. You can do this either with a candy thermometer or with an IR gun.
If the coolant is too hot, then you need to look at the thermostat (bad or backwards), radiator (plugged or blocked) hoses (lower collapsed), bad radiator cap (won't hold pressure), or you may need a shroud.
If the temp is good, then you have a problem with the gauge or sending unit.
 
#13 ·
I havent been able to try the other things yet, but I did a quick test on the sending unit. I read on another thread to do this. I removed the wire going to the sending unit and touched it to a ground. This made the temp gauge peg out on the hot side. Does this mean the sending unit is bad, or is it functioning properly?:confused:
 
#14 ·
#20 ·
Have you tried flushing the radiator? I know on my 86 with stock radiator you do see coolant moving. I would guess plugged up or the water pump is getting tired.
If I remember correctly, when I ran a hose through the radiator when I had it out a while back. There was flow but I dont remember how much. I have seen some suggest to take it out and fill it up with water with the bottom outlet plugged. Then release the bottom plug and water should shoot out around 9 inches or so. I didnt know about this at the time but may end up doing that if the sending unit is good.
 
#25 ·
Ok, just got back from picking up the voltmeter. I will be checking the temp sending unit next but will have to save that for tomorrow.

Earlier, I was able to crank and immediately drive the CJ around the block (almost 1 mile) and by the time I got back the temp gauge was almost pegged on hot. Shut it off and checked the radiator cap a couple minutes later. No pressure noise, ans coolant inside was luke warm. But the top and bottom hoses and heater hoses felt hot. :dunno:
 
#31 ·
Ok. Had a little bit of time to try some things. Given the symptoms it has showed so far, I decided to skip right to checking the water pump. I pulled the top hose off the radiator and cranked the engine and let it warm up. Within 5 minuted or less the temp gauge got almost to the end of the green line towards the H. The most coolant flow I saw was maybe a trickle, if that.

This definitely means the water pump is bad right? I just want to cover all my bases and not miss anything. If I will be changing the water pump, I will probably pull the radiator to do a flow check as well.
 
#34 ·
I decided to go ahead and check the temp sending unit. I am wondering if it is actually getting too hot in under 2 minutes like the gauge reads. If it is not, then maybe thats why I am not seeing any flow from the top hose. So I cranked it and let it warm up. Gauge went right up next to the H within 2 minutes...and this is what I got. Crappy iPhone pics below.

Lead to ground

Lead to sender post

Meter reading .1 ?
 
#35 ·
I am new to testing electrical stuff, but followed the directions on the John Strenk page. Also listed on the page are readings you might see for various temps.
C (cold)........................ 130 degrees--73 ohms
Beginning of band........ 171 degrees--36 ohms
Top of band.................. 242 degrees--13 ohms
H (hot).......................... 270 degrees---9 ohms

So how am I supposed to look at the ".1" I got on my meter???
 
#36 ·
Try putting your meter to 200 Ohm (instead of 200k Ohm) and try again. With the setting as you have it, you are reading 1000's of Ohms, rounded to the nearest hundred. So your 0.1 represents anywhere between 50 and 149 Ohm. But it's also at the very bottom of the measurable range for that setting, so I wouldn't trust it.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top