Low Engine Temps

[langer1]

Well I like the closed system but the vents a good idea.

Generally with air in the system temperatures will run high but you still don't get heat.

 

[Jess]

I will update since I posted alot on this near the start of the thread.
My 89 still runs cold, but since my last post I have flushed the entire system-including the heater core-but it still runs cold. The heat is a little better now, but it has not been that cold here yet this year. I am not so concerned with it as my daily commute is only 6 miles round trip!!! My 89 only has 98K original miles.

 

[marcoleo]

I'd the same problem of engine too cold on '89 renix XJ and '93 HO ZJ, good quality thermostat and the problem go away.
I've found here in Italy an aftermarket German brand that has already the two holes for air bleed with a rudimentary valve on the holes, it work good in open/closed systems, not so cheap about 35usd!
I will post the brand name.

 

[Muad'Dib]

Im not sure if this helps, but i think it was the cause of my lower engine temps (or maybe not!)
I had to replace my exhaust manifold (and replace a broken stud), so i took it off as a unit with the head. Of course i replaced my Head Gasket, and i noticed the new one didnt have holes on the drivers side of the block/head for the water jackets. Its like this by design. I looked at my old gasket and noticed about 70% of the holes that were supposed to be blocked, were not any longer. Its like the water/coolant finally pushed through to the other side. Im thinking that this would cause lower engine tips possibly... or i could be completly off base.
I do know after after i did this job that my Jeep runs a little hotter (not quite 210) maybe 195?? Which in my opinion is a much better thing!

 

[OZNAD]

I HAVE A 90 CHEROKEE AND THE COOLANT BOTTLE CRACKED SO I REPLACED IT AND THE CAP. WHEELING WITH NO AIRFLOW IT RUNS AROUND 210 BUT WHEN I'M ON THE HIGHWAY MY TEMP IS JUST OVER THE 100 DEGREE MARK... THE HEAT IS NOT REALLY WORKING... I HAVENT CHANGED THE THERMOSTAT YET...

 

[Blaine B.]

Stant and OEM thermostats are ones I've had luck with. Mr Gasket and Robert Shaw are other's I've heard good things about.

AutoZone ones made my heat not work......so I wouldn't recommend. Just an FYI.

 

[89xj4.0]

had the same problem on both my 89's flush the entire cooling system for about 20 to 30 minutes to the point where the water coming out is crystal clear

 

[lumberxj89]

For those who are running cold and are looking for a temporary simple solution - place a heavy vinyl sheet or other solid material (cut a piece from an old window shade) behind the grill/in front of the radiator, big enough to cover at least 1/2 of the radiator. The size may need to be adjusted, depending on the weather and distance driving.

 

[Jess]

I walked out and found a puddle of antifreeze under my Jeep today. It turns out the lower hose had a pinhole in it. I replaced the lower hose and found my coolant was very dirty and my heater control valve was not properly functioning. I somewhat flushed the system until it was almost clean and cut the heater control valve out. It seems I have somewhat better heat, but I still need to do a good flush. The next warm day I will flush the system better and hopefully my original heat will be fully restored....if not I will put something in front of the radiator.

 

[F9K9]

I have basically read this thread over twice in the last few days and am having diffulty deciding if, it is about about getting a heater to blow hot air or if, the engine operating temperature is to low.

If, I have post in the wrong thread then please just point me in the right direction.

I have good heat in the passenger compartment but, we have not had many temps below 30°. What has perked my interest is the affects of an engine running cold and gas mpg. Cooler running engines means increased gas consumption. Mine is terrible but, it has been regeared and a am easy on the skinny when using as a DD. My gauge reads half way between 100° and 210° almost all the time except when on trails and it will overheat. T-stat has been replaced 2X and so has the cap (Stant). My coolant resevoir likes to empty itself through miracles or a crack but, I haven't worried about that yet.
It's a
'92 4.0
new t-stat(s)
new caps(s)
decent heat
bad mileage (10 mpg with data from GPS)
all new quality tune up parts

I'm leaning towards my temperature guage being incorrect but, would welome any other ideas.

 

[8Mud]

You don't really need an IR thermometer or anything fancy. The surface temperature of the thermostat elbow is within a few degrees of the coolant running through it. Any old thermometer will do.
The recovery bottle gets a shot of excess coolant most every time the motor heats up to operating temperature and then when the motor goes through a cool down cycle it sucks a quantity of coolant back into the radiator from the recovery bottle.
Leaks, even tiny ones, mess with cycle. Air is a lot lighter than coolant and flows better. We all know what air inside the cooling system does to an XJ, any XJ, not just the older closed system types.

 

[F9K9]

You don't really need an IR thermometer or anything fancy. The surface temperature of the thermostat elbow is within a few degrees of the coolant running through it. Any old thermometer will do.
The recovery bottle gets a shot of excess coolant most every time the motor heats up to operating temperature and then when the motor goes through a cool down cycle it sucks a quantity of coolant back into the radiator from the recovery bottle.
Leaks, even tiny ones, mess with cycle. Air is a lot lighter than coolant and flows better. We all know what air inside the cooling system does to an XJ, any XJ, not just the older closed system types.

Hmmmmmmmm, good advice, Thanks! I think I can borrow an IR thermometer from our HVAC/maintanance guy at work, try to find a pressure tester to check for leaks, research burping and go from there.

 

[8Mud]

A simple test to see if there is likely air in the system, is to squeeze the top radiator hose together at the highest point, with your hand. You can often feel that It's partially hollow.
I usually take a flashlight and use a small mirror and inspect all the joints for stains.
One spot that is often overlooked is the radiator itself, I've seen more than a few leak at the tank seam behind the fan shroud.
If you pump up the system, keep it bellow 30 PSI or you may be making leaks.

 

[F9K9]

Well, it's around 186-191° at the T-stat housing after 15-20 minutes of running. Outside air temp was 42°. The electric fan never kicked on but, that is expected. I'll check the upper rad hose when it cools and go from there. Thanks again for all the greeat tips.

Reed

 

[streetpirate]

i got a $10 harbor freight non contact thermometer, and it seems to be reasonably accurate and is very repeatable. my t-stat housing when fully warmed up and parked is 180-190, and the surfaec temp of the head where the gauge sender is about 165-170.

 

[8Mud]

i use a contact type thermometer, pad type for checking surface temperatures. Clean the spot to be tested smear a little conductive paste on there and can watch my thermostat work (temperature fluctuates some).
The thermistor probe for my ohm meter is nearly as accurate and gives much the same results with a dab of conductive paste applied.

 

[F9K9]

Well, the one I used was what I assumed to be an IR type. Point the laser at where you wanted it to read. It seemed to be fairly accurate when I was checking it out on diffrerent surfaces. THe top rad hose was still firm after a couple of hours. I'll check it out in the AM and attempt to locate or rent a pressure tester

 

[streetpirate]

so i replaced the plugs and o2 sensor, and that got my idle quality back and passed deq with flying colors.

i still notice that when fully warmed up, stopped, and at idle, my temp shows about 200, and when i take the rpms up to about 1500 while still stopped, the temp will quickly go down to 160.
is my water pump just that awesome?

 

[langer1]

so i replaced the plugs and o2 sensor, and that got my idle quality back and passed deq with flying colors.

i still notice that when fully warmed up, stopped, and at idle, my temp shows about 200, and when i take the rpms up to about 1500 while still stopped, the temp will quickly go down to 160.
is my water pump just that awesome?

No your clutch fans not that awesome.

 

[streetpirate]

then wtf?