cooling problems

[401chief]

i got this cooling problem that i cant figure out. i will stay cool between 30 and 75. i am assuming that under 30 is because the eletric fan just isnt enough, but i dont understand why it is that when i go over 80mph (3000 rpms) on the freeway the temp will just climb from 185 to over 240.

anybody go any ideas?

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<IMG SRC="http://www.pixhost.com/pixt/tyson42/jeep4sm.jpg
">
Red '76 Cherokee Chief w/ 401(no cat)
Edelbrock carb and intake
Edelbrock Performer cam
Milidon timing gears
MSD 6a offroad ignition
MSD distributor
Heddman headers w/ dual exhaust
half dead th400
noisy QT
missing glove box
no radio
worn suspension w/ original shocks from 1976
a black fender
and a saggy head liner that hits my head every time i go over a speed bump
tyson42@earthlink.net


"If it ain't broke, then fix it 'till it is"

[JeepFreak]

Is your 401 over bored??? There is a tech article on the cooling for the 401 on Froadin.com. They say that the 401 when bored over needs to be upgraded to a 4 core radiator to keep it cool. I do know that my 390 has problems cooling at high speeds but I fixed that with an aluminum water pump and new 4 core rad.

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JeepFreak

[This message has been edited by JeepFreak (edited June 25, 2001).]

[tucsonrick]

is the high speed air flow over powering your fans?

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tucsonrick
69'wag (mostly stock)

[BobBarry]

Have you absolutely positively eliminated any vacuum leaks? If not, the leak could be leaning out your fuel mixture, causing it to run hot.

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Bob Barry<UL TYPE=SQUARE>* '78 Cherokee 4-door
* '88 Grand Wagoneer[/list]http://studentweb.providence.edu/~rbarry/wheels/

[401chief]

pretty sure, all 3 vacuum things are new(vac. advance, booster and modulator). besides plugs look good, maybe just a tad on the rich side


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<IMG SRC="http://www.pixhost.com/pixt/tyson42/jeep4sm.jpg
">
Red '76 Cherokee Chief w/ 401(no cat)
Edelbrock carb and intake (soon to be holley pro-jection)
Edelbrock Performer cam
Milidon timing gears
MSD 6a offroad ignition
MSD distributor
Heddman headers w/ dual exhaust
half dead th400
noisy QT
missing glove box
no radio
worn suspension w/ original shocks from 1976
a black fender
and a saggy head liner that hits my head every time i go over a speed bump
tyson42@earthlink.net


"If it ain't broke, then fix it 'till it is"

[Chris Bishop]

Is your EGR working? If not this could cause
a lean mixture.
CB over and out

[401chief]

the egr is present, and it is not hooked up. but the truck really isnt tuned for any smog equipment

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<IMG SRC="http://www.pixhost.com/pixt/tyson42/jeep4sm.jpg
">
Red '76 Cherokee Chief w/ 401(no cat)
Edelbrock carb and intake (soon to be holley pro-jection)
Edelbrock Performer cam
Milidon timing gears
MSD 6a offroad ignition
MSD distributor
Heddman headers w/ dual exhaust
half dead th400
noisy QT
missing glove box
no radio
worn suspension w/ original shocks from 1976
a black fender
and a saggy head liner that hits my head every time i go over a speed bump
tyson42@earthlink.net


"If it ain't broke, then fix it 'till it is"

[Crazy_Jeepman]

I doubt it has anything to do with the fans as 20 mph will move more CFM of air through your radiator than any fan could, thus the reason for electric and thermatic fans as fans are not needed at driving speeds. I would be checking for poor circulation as in water pump impeller wore out (seen that more than once, other than that maybe time for a new radiator, or check the other sugestions posted. HEY GET COOL!!!

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1970 Wagoneer! Dauntless 350/Th 400/D20/44s. Posi In My Rear. Currently Getting A Frame Off Restore, And a Few Mods. The To Do List Is Longer Than The Wagoneer Is!!!!
http://images.andale.com/f2/116/106/4651773/990532060948_sigjeep.JPG

[401chief]

actually, both the radiator and water pump are new

------------------
<IMG SRC="http://www.pixhost.com/pixt/tyson42/jeep4sm.jpg
">
Red '76 Cherokee Chief w/ 401(no cat)
Edelbrock carb and intake (soon to be holley pro-jection)
Edelbrock Performer cam
Milidon timing gears
MSD 6a offroad ignition
MSD distributor
Heddman headers w/ dual exhaust
half dead th400
noisy QT
missing glove box
no radio
worn suspension w/ original shocks from 1976
a black fender
and a saggy head liner that hits my head every time i go over a speed bump
tyson42@earthlink.net


"If it ain't broke, then fix it 'till it is"

[tuck]

I thought the 401 came factory with a 4 row radiator, was it just an option?