Running too cold

Its hard to tell if I'm losing coolant because I don't drive the Jeep too often but I have found myself topping off the overflow bottle so I think I am.

When I noticed the "sludge" in my oil pan I started changing my oil more frequently.

Now I just need to find the time to change the head gasket. Yay...
 
Glad this thread has been brought back...

I've been recently thinking my head gasket is bad too. I changed radiator caps because my system wasn't building any pressure, put a new 16#cap on it, and just started noticing wierd sludge buildup on the tip of my dipstick. I'm thinking that the actual buildup of pressure revealed a leaky headgasket which is causing the swinging in temperature. I drive the jeep at least 50 miles a day, so I find it hard to believe that its just moisture in the crankcase. I'l take a picture of it to see if OkieXJ's looks the same.

Is there something else that could cause the weird sludge on th dipstick? I just changed my oil yesterday and it's still there.
 
There could be sludge left over in the oil pan that didn't drain out. I know that isn't the case with mine though because I changed my rear main seal and completely cleaned my oil pan and it was still there the oil change after. I'll try to get a picture up later tonight.
 
Going to give this thread a thorough read, I am having a similar issue where I am operating much below temp.

However I changed the 'stat a few days ago and am now flushing my system of the old rusty stuff, so we'll see how it is after that.

I just can't get my electric fan to turn on any more?? It's the stock one, is there a fuse for it somewhere?
 
XJ-Mayhem said:
Going to give this thread a thorough read, I am having a similar issue where I am operating much below temp.

However I changed the 'stat a few days ago and am now flushing my system of the old rusty stuff, so we'll see how it is after that.

I just can't get my electric fan to turn on any more?? It's the stock one, is there a fuse for it somewhere?
Click to expand...

Hope you find something useful. There are probably a couple dozen threads on electric fans not working so without getting too thread derailed here is a thread that might help:
http://www.naxja.org/forum/showthread.php?t=929104
There should also be a few links to similar threads at the bottom that should be useful as well. You'll want to post your year, engine etc as well so the veterans don't get too bent out of shape and people can help easier.
 
OkieXJ said:
Hope you find something useful. There are probably a couple dozen threads on electric fans not working so without getting too thread derailed here is a thread that might help:
http://www.naxja.org/forum/showthread.php?t=929104
There should also be a few links to similar threads at the bottom that should be useful as well. You'll want to post your year, engine etc as well so the veterans don't get too bent out of shape and people can help easier.
Click to expand...

Thanks for the link, not sure I need that as of right now because I am still operating well below temp.

Did my flush and refill with coolant, although I probably did a %80 coolant %20 water mix, not sure.. and I still hover around 165-170 but sometimes get up to the 210 mark, mostly when idling but not always.

My gauge fluctuates very rapidly though, almost as if with a turn the needle itself just floats one way...within seconds it seems to drop/rise a good 30*. Is this normal or could I have a faulty gauge?

I'll most likely try getting some cardboard to block the half the radiator the elec fan is supposed to go (currently just running without it) until I find the problem.
 
Sounds like you might have a faulty gauge or wiring. The gauge on your year might be referenced to the engine block ground, what year is your jeep and how are your grounds? 96 and earlier the gauge sender is a 1-wire block ground referenced design.
 
quick question for the intelligensia......is there a difference in the resistance values between a renix-era temp sending unit and an HO one? Mine's a renix (87) but I'm running an HO gauge cluster, the gauge is working indicating the thermo is opening/closing, but it's staying consistently at the 150 degree mark. I shot the thermo housing both in front of and behind the t-stat with a thermal gun and saw a distinct difference in temps while the stat was closed (about 95-100 in front, steadily increasing temps behind until about 195-200 until the stat opened). Shot the back of the head area around where the sender screws in and it roughly corresponded to the temps I measured behind the stat).

I've put three different senders in the block, so I'm inclined to think they were/are all working, but they were all renix units. Maybe I should try splicing an HO sending unit into my harness and see if it corrects the gauge reading?

Jeff
 
You should be able to swap yours out with an HO and fix your issue. The temp sender is just a variable resistor and it doesn't get read by the ECU. The sender is only connected to the block and the gauge cluster.
Judging by your thermometer reading though I bet your problem is somewhere else besides your sender and gauge.
 
Bump to this old thread.

I had to have the head off of my 94 to have the exhaust studs drilled out in the process of replacing the exhaust manifold. Upon reassembly I find that the engine seems to be running cool as indicated by the dash gage. I had hoped to get a slight increase in fuel mileage due to having the cracked exhaust manifold replaced, but what I seem to find is actually a slight decrease.

Ok, so I verify the temps using an IR thermometer. At the thermostat housing it shows around 175* and at the rear, which is difficult to get a good read on, I see about 145*. I was surprised to see that difference in temperature between the two. Also I read that while the thermostat should open at 195*, the engine should actually run a 210*. Ok, 210* reading taken where? Is that only from the inaccessible interior of the engine? I think I'm going to replace the thermostat with a 195* model. Seems if I remember correctly that the one in it is a 185* thermostat. That was changed before all of the head work, though. I don't know what could cause a thermostat to go bad nor what I might have done to make this one go south. I'll clean the contacts on the sending units, but I don't think that's the issue either.

Anyone see any flags there, things in particular I should check into?
 
Your '94 has a temp sensor/sender at the rear of the head, on the driver's side. It has a single wire connection, it grounds through the block (don't use Teflon tape to seal it. It's also brass and is NPT. It doesn't take much torque to get it to seal.)

I'd put in a 195 thermostat. Thermostats do fail, and do need to be replaced.
 
Decided to start simple so I bought a new thermostat. Upon removing the old one it was apparent that it wasn't closing. Replaced the thermostat and fixed. Great when stuff fixes easy.
 
You're fortunate. I haven't gotten around to replacing my head gasket yet but I still plan to at some point.
 
Found this post to be extremely helpful (thank you).

I have an 01 with 117k, no engine mods and it just started running cool yesterday, at least that's when I noticed it. I haven't done anything except check the dipstick for sludge and it's fine (phew). So my question is: What do I do next? Buy a new Thermostat? If so, where is it located and how long does it usually take to replace?

Next question: Could this be my water pump?

The following issue has been going on for about 8 months. Not sure if this is related but I am getting an Evap Leak Code as well and a whistling sound that seems to be coming from the left side of the motor (same side as the air box). The whistling sound goes away when I am on the accelerator and would go away entirely when the motor warmed up. Now it seems to stick around longer. A couple months ago I sured up a couple of hoses and the evap code and whistling went away for a little while. I took it to a shop for another issue and they said a hose was off of my gas tank. Again, the code went away but now it's back along with the whistling souind.

Again - not sure if these are realted to the low temp but any suggestions would be most welcome :-)

thanks.....
 
Silly question - were you running cold? Forgive my ignorance but I always thought if a Thermostat failed it would cause over heating, not the opposite.....

jworth said:
Decided to start simple so I bought a new thermostat. Upon removing the old one it was apparent that it wasn't closing. Replaced the thermostat and fixed. Great when stuff fixes easy.
Click to expand...
 
How do you know you are running cold? Temp gauge reads cold, bad mileage etc? My Jeep was running cold according to the gauge and my mileage is terrible (~12mpg). If your Jeep is running cold, its very likely not your water pump. It is most likely running fine so don't bother replacing it. Thermostats can fail and stick open or closed. If they stick closed, then you will likely have an overheating problem like you stated. However if they stick open, that could be the cause of your cooling issues. The thermostat is pretty easy to replace. I'd give it about 2 hours if you've never done it before and that should be ample time. I could probably do it in 20 minutes including topping off the coolant after I'm done. Its a pretty easy job even if you've never attempted it before. I would start be replacing the thermostat. Stop by the parts store and get a new thermostat, thermostat housing gasket, and some coolant to replace what spills out. Its also a good time to switch out some of the hard to work with original hose clamps to some of the worm style host clamps so consider picking up a variety pack of those as well, I can't remember what sizes the thermostat housing uses. Also there are a dozen threads on here about the best brands of thermostat. You might check them out as well to buy a high quality one. Make sure your coolant is the proper mixture as well. This can fix a lot of cooling problems by itself. If these things don't fix your issue, then you might have a bad sensor or something more serious wrong.

Not sure about the whistling sound, it could be a number of things. I know on my Jeep the butterfly valve on the throttle body leaks and makes a whistling sound. It could also be caused by a vacuum leak or any of the various intake or exhaust gaskets but most likely intake.
 
^^^^^^THANKS^^^^^^

My temp gauge is at around 160. I don't have the tools to do any sort of temp tests. I also talked to a buddy of mine here at work (he does a lot of engine work) and he also feels it's the Thermostat Stuck Open. I have found a couple of sites with step by step instructions on how to replace it. I'm ok at wrenching, I just don't have a lot of engine experience so I will make sure to take my time and do it right.

Thanks for the tip on the whistling sound - I haven't checked the butterfly valve yet.

I love NAXJA. Everyone here is extremely helpful and I really appreciate it.
 
Later in the week the temp was running normal bit I still decided to swap out the Thermostat to be on the safe side. Not a difficult project at all. So far so good - Thanks for the advice. I also found a couple of video's on youtube that helped :-)
 
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