Chasing gremlins in cooling system
#1316798
10/07/12 07:06 PM
10/07/12 07:06 PM
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Joined: Jan 2003
Posts: 5,902
Athens, Greece
Pyper70
OP
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Joined: Jan 2003
Posts: 5,902
Athens, Greece
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On the hunt for my cooling issues...I warmed up the engine today and hit 200ºF...I consequently shut the engine off and the viscous fan stopped spinning. I reached into the engine bay and the viscous fan still turns by hand. I know that if the engine was shut off and the fan was still spinning it was going to need replacing.
This was my first step since it didnt require removing anything.
Next up is the timing.
Is my viscous fan still good?
Does the the amount of blades make a difference? I have a 7-blade fan on the system now.
Family owned 1969 Charger R/T DualQuad 440/727/GVO/3.55s
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Re: Chasing gremlins in cooling system
[Re: Pyper70]
#1316799
10/07/12 07:15 PM
10/07/12 07:15 PM
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Joined: Sep 2007
Posts: 14,889
up yours
Supercuda
About to go away
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About to go away
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Posts: 14,889
up yours
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200 degrees isn't hot, why do you think you have an issue?
They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.
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Re: Chasing gremlins in cooling system
[Re: Supercuda]
#1316800
10/07/12 07:20 PM
10/07/12 07:20 PM
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Joined: Mar 2010
Posts: 1,880
Out in Left Field, NY
bobs66440
top fuel
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top fuel
Joined: Mar 2010
Posts: 1,880
Out in Left Field, NY
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200* isn't dangerously hot. But if you have a 180* t-stat, then it's unusual and may need attention. If the cooling system is working properly, it should rarely go above 180* or whatever your t-stat spec is. I run a fixed fan, but from what I understand, when you spin the fan with your hand, if the fan spins for more than 1 to 1-1/2 revolutions without resistance, or if it does not move at all, you need to replace it. Some say 3 revolutions, but that seems a lot to me. Also if there's a lot of slop in it.
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Re: Chasing gremlins in cooling system
[Re: Supercuda]
#1316802
10/07/12 07:44 PM
10/07/12 07:44 PM
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Joined: Jan 2003
Posts: 5,902
Athens, Greece
Pyper70
OP
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Joined: Jan 2003
Posts: 5,902
Athens, Greece
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well last weekend my Autometer gauge rolled over past 240ºF and was heading for the 0 again...As it idles in park for 15 minutes
Family owned 1969 Charger R/T DualQuad 440/727/GVO/3.55s
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Re: Chasing gremlins in cooling system
[Re: Pyper70]
#1316805
10/07/12 09:02 PM
10/07/12 09:02 PM
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Joined: Sep 2007
Posts: 14,889
up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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Swap it out and see if it works.
They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.
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Re: Chasing gremlins in cooling system
[Re: Supercuda]
#1316808
10/07/12 10:06 PM
10/07/12 10:06 PM
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Joined: Mar 2010
Posts: 1,880
Out in Left Field, NY
bobs66440
top fuel
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top fuel
Joined: Mar 2010
Posts: 1,880
Out in Left Field, NY
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Quote:
Quote:
200* isn't dangerously hot. But if you have a 180* t-stat, then it's unusual and may need attention. If the cooling system is working properly, it should rarely go above 180* or whatever your t-stat spec is.
That is exactly opposite of how a thermostat works. The thermostat controls the MINIMUM temperature, not the maximum.
Ahh, right. 
Quote:
Quote:
if it cools good at highway or even long steady city speeds,the cooling system is working(Rad is good) but at idle or crawling along in hot weather You are not drawing enough air through the rad...hence the fan issue...so if the fan is not spinning enough to draw air...the clutch is weak and should be replaced.
1 exception may be a clogged up radiator (water flow restriction). Mine would get too warm in traffic/at idle, but would cool down at speed. Took a look inside and the passages I could see were pretty clogged, almost closed. Had it flow tested and it was verified by the rad shop as being severely clogged up.
 Mine would run fine at highway speeds and heat up through town or at idle. I installed a new 26" aluminum rad and it was much better. I also installed a smaller water pump pulley to speed up the fan and the water flow and that also helped. Now it will idle almost indefinitely and stay at 180.
To the OP, I would just ditch the fan clutch and run a fixed fan. Fixed fans put a little more stress on the engine and rob a little HP, but nothing you will notice and they won't fail and cook your engine. 
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Re: Chasing gremlins in cooling system
[Re: stumpy]
#1316810
10/07/12 10:37 PM
10/07/12 10:37 PM
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Joined: Mar 2010
Posts: 1,880
Out in Left Field, NY
bobs66440
top fuel
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top fuel
Joined: Mar 2010
Posts: 1,880
Out in Left Field, NY
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Quote:
The thermostat doesn't control the high end of the temp. If you run a 165* stat you shouldn't expect the engine to run that temp. All the stat does is slows water flow until the engine reaches the stats open temp. If the engine runs above that,which most normally do, the stat will never close.
Right, I stand corrected and agree. The t-stat controls the lower end and the cooling system design controls the upper end. The t-stat just doesn't let it get below the spec temp.
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Re: Chasing gremlins in cooling system
[Re: bobs66440]
#1316811
10/07/12 11:49 PM
10/07/12 11:49 PM
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Joined: Aug 2010
Posts: 1,525
Eastern shore, New England
roadrunner69s
pro stock
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pro stock
Joined: Aug 2010
Posts: 1,525
Eastern shore, New England
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My '68 GTX 4 speed had similar problems with highway vs idle speed. On hot summer days it would run around 200-210 on the highway and at idle would easily get to 225 and keep going. Even after going through every cooling system component including a 3 row recore of the 26" radiator, nothing changed. I even got to the point of swapping back to an orig cam, rejetting the carb, advancing the timing, running a 98-100 octane mix, using infra-red heat guns, tighter gripping fan belts or better fitting pulleys, removing any vacuum leaks, and running 90% water with Redline water wetter. All of that helped....a little. After 3 yrs of trying I finally sold the car w/o ever solving the problem. No doubt an alum radiator with high capacity water pump would have helped some. It was annoying that between my Mopar mechanic and myself we could never find the smoking gun. The setup was basically stock with the proper 7 bladed fan/shroud and stock viscous fan. I do have to wonder if the new Year One repro fan shroud was part of the problem as they are not as deep as the originals, hence the fan blade protrudes out a tad. Could have made a difference. The idle engine vacuum ran around 8-12" as I recall which I felt was a symptom. Normal would have been around 14" or greater. My hunch was that a less than optimum fuel/air ratio was the source of the overheating.
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Re: Chasing gremlins in cooling system
[Re: roadrunner69s]
#1316813
10/08/12 08:53 AM
10/08/12 08:53 AM
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Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Challenger 1
Too Many Posts
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Too Many Posts
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
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Quote:
My '68 GTX 4 speed had similar problems with highway vs idle speed. On hot summer days it would run around 200-210 on the highway and at idle would easily get to 225 and keep going. Even after going through every cooling system component including a 3 row recore of the 26" radiator, nothing changed. I even got to the point of swapping back to an orig cam, rejetting the carb, advancing the timing, running a 98-100 octane mix, using infra-red heat guns, tighter gripping fan belts or better fitting pulleys, removing any vacuum leaks, and running 90% water with Redline water wetter. All of that helped....a little. After 3 yrs of trying I finally sold the car w/o ever solving the problem. No doubt an alum radiator with high capacity water pump would have helped some. It was annoying that between my Mopar mechanic and myself we could never find the smoking gun. The setup was basically stock with the proper 7 bladed fan/shroud and stock viscous fan. I do have to wonder if the new Year One repro fan shroud was part of the problem as they are not as deep as the originals, hence the fan blade protrudes out a tad. Could have made a difference. The idle engine vacuum ran around 8-12" as I recall which I felt was a symptom. Normal would have been around 14" or greater. My hunch was that a less than optimum fuel/air ratio was the source of the overheating.
Exactly right if everything else was right.
With todays alcohol fuel our fuel systems need to be richer with plenty of timing to run cool. 10% alky required jetting up even though guys will swear there right jetting wise because they have o2 sensor in the exhaust, there still lean and don't even know it and blame everything except the tune up.
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Re: Chasing gremlins in cooling system
[Re: Supercuda]
#1316815
10/09/12 02:46 PM
10/09/12 02:46 PM
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Joined: Jan 2003
Posts: 5,789
Hamilton, Ontario Canada
Magnum
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Posts: 5,789
Hamilton, Ontario Canada
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Quote:
That is exactly opposite of how a thermostat works. The thermostat controls the MINIMUM temperature, not the maximum.
The thermostat controls the maximum.
Anything under the temperature, it's regulating. Anything over and it's wide open with NOTHING LEFT.
We need to know when it's reaching 200. Idling, city cruising, highway. Will it recover? Does it ever maintain thermostat temperature?
69 Super Bee, 93 Mustang LX, 04 Allure Super
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Re: Chasing gremlins in cooling system
[Re: Pyper70]
#1316816
10/15/12 03:35 PM
10/15/12 03:35 PM
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Joined: Jan 2003
Posts: 5,902
Athens, Greece
Pyper70
OP
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OP
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Posts: 5,902
Athens, Greece
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I swapped out the old clutch for the fan with the new unit. i don't think anything was wrong with it but it doesn't matter. 15 minute job. I did bump the timing to about 18 degrees. (my timing tape somehow came off even though it was super glued on and clearcoated)...I need to perhaps try a little more...maybe 20 and play with the idle mixture screws a little. I got my vacuum up to 12" but I am also revving at 1100...So I need to bring that down with the next test and tune.
Family owned 1969 Charger R/T DualQuad 440/727/GVO/3.55s
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