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Unread 09-19-2013, 07:40 AM   #16
dnuccio
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Quote:
Originally Posted by coralman View Post
Clogged cat?
how would i go about checking for this?

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Unread 09-19-2013, 07:43 AM   #17
zjosh93
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Quote:
Originally Posted by jabba974 View Post
I have to disagree with you...The radiator is not just a storage tank, it is designed to radiate the heat away from the coolant...You can have the biggest radiator they make, but if you do not restrict the flow, it does not have enough time to cool down... That is why even in racecars, they run a thermostat, or atleast a restrictor... allthough you do have a point when the thermostat is open, especially at temps above 220, it wont matter what degree t-stat you have...
I respectfully disagree with your disagreement. The reason race cars use thermostats is because a properly designed cooling system can shed more heat than the engine produces. You need a thermostat to keep the engine at the proper temp. Engines, especially race engines, are generally tuned to a given temperature so having the engine too cold or to hot can cost you a little hp and given how much race teams spend for a couple horsepower it makes a difference.

You also get a bump in dynamic pressure in the block from the pump pushing water against the restriction of the thermostat. This helps eliminate steam pockets, steam is an insulator. A lot of circle track racers don't use thermostats they just use a restrictor.

The rate of heat rejection of any heat exchanger for a given airflow is only dependent on the heat differential.

Say you have a radiator with coolant flowing in at 195 (the thermostat temp) and the outside temp is 100. If water flow is slow the outlet temp could be 100 and no less. But any portion of the radiator that is close to 100 is very inefficient because not much heat flows from a 101 degree radiator fin into 100 degree air. if you speed the water up until it's very fast without cavitating, the water entering the radiator is at 195 because of the thermostat but that 195 water spreads across more of the radiator so cooling efficiency is higher. The outlet temp may be only 180 degrees but you are actually rejecting more heat. The water leaving the engine is still only 195 but the engine temp is more consistent.

Put another way, for a given engine speed and load the amount of heat produced by the engine that the radiator needs to shed is constant. The radiator can shed all that heat and more for a well designed system. Faster moving coolant just gets the heat to the radiator faster. If you have a cylinder head at 220 degrees sitting in 195 degree water it doesn't matter how fast the water is moving the heat will flow from the metal to the water at the same rate. The same for the radiator, if you have a fin at 195 degrees and you are blowing enough air over it to keep the ambient air at 100 degrees the heat will flow from the fin at the same rate no matter what the water speed is.

Here's a link that agrees:

http://www.flowkoolerwaterpumps.com/cooling_faq.html
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Unread 09-19-2013, 12:18 PM   #18
JohnnyZJ
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mine always runs hot in the heat too. and cool in the winter.
efan won't help. she still heats up on the highway. at least it doesn't overheat in traffic anymore though. i also installed hood louvres, but i think that was more of a 'cool' thing to do (get it, haha) donno if they actually reduce the engine bay heat.

i would have said radiator (cause i think mines just old) but you put a brand new one in, so i'm not sure that would be it. theres only so many pieces to a cooling system, which it sounds like you've addressed.

you had the motor apart at some point right? maybe the head gaskets leaking? that can cause high running temps.
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Unread 09-19-2013, 12:48 PM   #19
Dubfire98
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a friend of mine had this same problem on his 5.2. He tried replacing EVERYTHING in the cooling system, to no avail. Finally he admitted defeat and took it to the stealership. They said something to do with the torque converter was causing it to overheat. I was like um... huh? whats that got anything to do with the cooling? Oddly enuf, since it was replaced his temps have been fine. Strange? Absolutely lol
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Unread 09-19-2013, 07:01 PM   #20
dnuccio
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Quote:
Originally Posted by JohnnyZJ View Post

you had the motor apart at some point right? maybe the head gaskets leaking? that can cause high running temps.
yes, i overheated it and replaced both heads (overheat warped a bunch of valves, reman'd heads were cheaper than getting my originals redone) and all the top end gaskets. i dont think a HG is leaking though, because theres no coolant mixed into the oil (oil is still a nice brown color) and it runs excellent.


i appreciate everyones input, keep it comin!
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Unread 09-19-2013, 08:12 PM   #21
dnuccio
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when i get some money, im thinking of getting this fan for it

http://www.summitracing.com/parts/hfm-zfb16s/overview/

i know it probably wont help my issue, but it sure would be nice to not have to listen to the jet engine when i get on the skinny pedal
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Unread 09-19-2013, 08:20 PM   #22
newfieZJ
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You mean the clutch fan roars ? That's probably your issue . Does it do it all the time . It is suppose to lock up when very hot . Mine never does roar .

If you bought a HD , from what I read , that's suppositely normal , but not to me .
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Unread 09-19-2013, 09:13 PM   #23
dnuccio
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Quote:
Originally Posted by newfieZJ View Post
You mean the clutch fan roars ? That's probably your issue . Does it do it all the time . It is suppose to lock up when very hot . Mine never does roar .

If you bought a HD , from what I read , that's suppositely normal , but not to me .
this is the one i bought
http://www.oreillyauto.com/site/c/de...ing+fan+clutch

it roars all the time. the old one only roared sometimes
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Unread 09-19-2013, 09:19 PM   #24
ZeeJay1997
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Quote:
Originally Posted by dnuccio View Post
how would i go about checking for this?
there's really no good way to do it other than take the o2 sensors out install some low pressure gauges and check for a differential.

i determined mine was bad by drilling 3 half inch holes in the front of it. made it run better and stop running like it was pulling a train. the temp would rise when i stomped it or climbed a hill.

most of the time if a cat is bad, it will rattle when whacked with a mallet or 2x4.

there are also some heat checks you can do with an IR gun, but i dont know the details
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Unread 09-19-2013, 09:28 PM   #25
newfieZJ
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Quote:
Originally Posted by dnuccio View Post
this is the one i bought
http://www.oreillyauto.com/site/c/de...ing+fan+clutch

it roars all the time. the old one only roared sometimes
I did some research on this for my motorhome . Clutch fan would kick on more than I'm use to . Turned out to be normal but read then about the HD clutches being a constant roar .

It should pull more air when locked but that only is good to a certain speed . Then , it can start blocking a certain amount of air from entering the rad .

What approximate ratio is your coolant mixed at ? Just curious

If turned on , how's the heater working ?
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Unread 09-19-2013, 09:34 PM   #26
dnuccio
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Originally Posted by newfieZJ View Post
it can start blocking a certain amount of air from entering the rad .*
What approximate ratio is your coolant mixed at ? Just curious

If turned on , how's the heater working ?
is the clutch fan a pusher or puller?

i dont know exactly, IIRC theres a little over a gallon of antifreeze in it, and the rest is straight water

heater works great
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Unread 09-19-2013, 09:38 PM   #27
MoparMech
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Make absolute sure you have ALL of the air out of the cooling system, purchase one of those Lisle cooling system filler funnels if you don't have one already http://www.tooltopia.com/lisle-24680.aspx . Leaking head gaskets, cracked heads is not uncommon on those vintage of 5.2's. The Torque converter could be the culprit as well. If the torque converter clutch is not locking and is slipping it can cause excessive heat, also a worn out torque converter will create more heat and less thrust. To test the torque converters efficiency do a stall test(foot on brake as hard as you can with parking brake applied, shifter in drive, and gas pedal to the floor) for about ten seconds, If the rpm goes to around 2500 and stays your ok, if it spikes up to redline you have transmission slippage issues. Fix your EGR issue. It may pass your test but that does not mean the valve is intermittently sticking or you have a lack of vacuum to the egr valve. Check for any vacuum leaks, spray some carb cleaner on all of the vacuum lines, intake gaskets, injector o rings while it is running and see if it stumbles. In reality if the EGR valve is fully open the engine will not run at idle. Make sure your thermostat isn't in backwards. I have seen it. Make sure the cooling system is clean. I have seen blocks completely full of crud, rust, and gunk from running straight water for WAY...... too long.........phew......ANYWAYS Thats what I would check.
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Unread 09-19-2013, 09:41 PM   #28
newfieZJ
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It pulls .

Sounds about 50/50ish to me

Had to make sure the heater core wasn't restricted .

Assuming the head gaskets are good , with everything you have done , only 2 things I don't like . 1 , the t-stat not being a proper 195 Mopar part . 2 , that clutch fan .

That's all I can think of , except .........brainstorm maybe .......... collapsing rad hoses .
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Unread 09-19-2013, 09:58 PM   #29
Uniblurb
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Quote:
Originally Posted by ZeeJay1997 View Post
there's really no good way to do it other than take the o2 sensors out install some low pressure gauges and check for a differential.

i determined mine was bad by drilling 3 half inch holes in the front of it. made it run better and stop running like it was pulling a train. the temp would rise when i stomped it or climbed a hill.

most of the time if a cat is bad, it will rattle when whacked with a mallet or 2x4.

there are also some heat checks you can do with an IR gun, but i dont know the details
Don't know if you've seen this video before Zee on checking a cat but think it's pretty good on using a scanner to read the o2 data while using an IR gun to check input/output temps on the cat itself. Believe it was posted before by coralman and while they're non-Jeep vehicles the principle is the same.

In fact I went out and bought a "General IRT207 Infrafed Thermometer" off Amazon for $20 for this purpose (haven't tried it yet) but thought it would come in handy around the house too. It must be the cold weather coming on but this same IR gun is now selling for $40-$50 when I paid $20 in July. I'm sure HF probably sells some in that price range I paid.

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Unread 09-19-2013, 10:35 PM   #30
Smokey1r
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Did you flush the engine block prior to connecting the hoses to the radiator?, just to get all the loose particles you can out and assure there's proper pump flow?
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