CJ-5 Heater Fan Upgrade Questions

I used a Corvette four core cross flow in my CJ-2A because of size
restrictions, you mentioned. We disagree BIG time on running it low, the
coolant doesn't back up enough even at high RPM to use any channels above
the level. Making the pressure cap and recover tank, you mentioned critical!
Probably the biggest reason we don't see any Renaults on the road.
God Bless America, Bill 0|||||||0
http://www.billhughes.com/pismo.htm


"reboot" > wrote in message
...
>
> I've got to join in with SnoMan on this one... and as a cooling system
> design engineer I can vouch for his statements.
>
> With a cross-flow radiator you get more core face area under a low
> hood line. You also have fewer tubes (within some limits) which means
> lower cost to produce.
>
> Down flow radiators do operate at near full capacity even if the top
> few inches of the tubes 'run dry' - they don't really run dry because
> the coolant in the top tank still passes through these tubes in normal
> operation and dissipate heat the passing airstream.
>
> On a cross flow otoh, when the tubes are dry they really are dry since
> the coolant in the side mounted tank falls to the bottom of the tank
> before it enters a tube.
>
> Car makers run a test call 'pull down' to ascertain how much coolant
> can be lost and still maintain effective cooling. Down flow radiators
> have a greater margin than cross flow.
>
> And a coolant recovery system with a good cap is the best way to
> ensure effective cooling. Replacing the cap every year when you
> change your coolant is a good idea too.
>
> reboot
>
>
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reboot wrote:
> On Sat, 24 Mar 2007 21:33:39 GMT, SnoMan > wrote:
>
>> On Sat, 24 Mar 2007 14:20:34 -0400, Mike Romain >
>> wrote:
>>
>>> SnoMan wrote:
>>>> On Sat, 24 Mar 2007 13:26:17 -0400, Mike Romain >
>>>> wrote:
>>>>
>>>>> The newer rad systems are designed to use an overflow bottle and have
>>>>> the rad full to the top all the time.
>>>>>
>>>>> This means as they warm up, the coolant comes out of the rad into the
>>>>> overflow bottle. The rad cap is a two way cap. As the rad cools down,
>>>>> the coolant sucks back into it.
>>>> Yess this is what it was designed to do
>>>>
>>>>> I currently have no overflow bottle on my CJ7 so I can only have the
>>>>> coolant just covering the cores by 1/4" or so or it will puke out on the
>>>>> ground.
>>>>>
>>>>> The older rads with the side tanks and horizontal cores were better for
>>>>> the open systems. You could just have the fluid down a ways on the side
>>>>> tank and still not worry about dry cores.
>>>> This makes no sense at all.
>>> The design engineers thought it made sense. If you have 4" of a side
>>> tank open to air, then 20" or more of cores are still fully filled with
>>> fluid.
>> No you do because the engineers came up with the coolant recovery
>> system to better deal with this problem.
>>
>>> The side tanks had a 'full hot and full cold' mark on them even.
>>>
>>> If you are down 4" on a top tank 'all' the core tops are open to air and
>>> only the ones at the very edge below the top rad hose will run coolant
>>> when the pump flows, the rest are air locked with stagnated coolant.
>>>
>>> Emissions mandated the closed systems, not hood designs.
>> THey did noi mandate horizonal cores, lower hood lines did that
>> because it allows longer core time for coolant than a shorter path in
>> a vertical core.
>>
>>> Mike
>>> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
>>> 88 Cherokee 235 BFG AT's
>>> Canadian Off Road Trips Photos: Non members can still view!
>>> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
>>> (More Off Road album links at bottom of the view page)
>> -----------------
>> TheSnoMan.com
>
> I've got to join in with SnoMan on this one... and as a cooling system
> design engineer I can vouch for his statements.
>
> With a cross-flow radiator you get more core face area under a low
> hood line. You also have fewer tubes (within some limits) which means
> lower cost to produce.

What 'are' you fools going on about?

The horizontal cores with side tanks that I said are better for an open
system is the 'old' way of doing things in a Jeep CJ because you always
have some cores full of coolant.

The new CJ and TJ rads have top tanks with vertical cores and don't work
as open systems due to the reasons I gave above that 'all' the core tops
get air locked when low on coolant.

Snoman likes to take words out of place and reply to seeming nonsense.

Look at the 'header' of this thread 'very carefully'. On my PC it says
CJ-5 and pointedly mentions a 350.

I will repeat. Closed systems came into being because of pollution
concerns about the coolant puking out on the ground. PCV systems also
came into being because of pollution controls as the downpipes were
leaking lots of oil onto the road also. Charcoal canisters or gas tank
vapor recovery systems also came into being so fumes didn't pollute.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)