Cooling problem

HELP....

74 Plymouth Duster 225 slant six - factory A/C ( COMPLETELY RESTORED ).

New Modine radiator (1997) new thermostat, hoses, flexfan, shroud, new temp pickup etc.

Annoying problem of slowly overheating in traffic in the summer in 90 degree temp with A/C on.

Currently have a (18"x22", 1 1/4", 2 core. radiator).... is there anything larger I can put in the car WITHOUT cutting. I am wondering if the cooling system was just not large enough to handle the A/C in HOT weather.

Any suggestions - ( done just about everything with no luck )

julie-roth@woz.org

I had a problem with a blocked Heater core. In fact, it is one of the reasons the previous owner sold the car. Once I replace the heater core, I never had any overheating problems.

Killin5@yahoo.com

5 years is long enough time for debris from the block to work itself loose and restrict radiator flow. Might want to flush/backflush the radiator.
( done just about everything
: with no luck )


rjwoerly@ucdavis.edu

Replace the thermostat with a high quality unit, these do wear-out.
Check the actual coolent temp to the guage reading, sometimes the guage just reads high. (faulty sending unit or guage)
An electric fan installed in front of the radiator could help. Also a 3 or 4 row radiator core is a "last resort" if everything else checks-out OK.
DD

everything in the above posts are really good...

If you get down to needing some more inmprove-ments:

A 26" radiator from a volare/aspen will bolt in and work ok (3-4 core is much better).
Another nice option with the 26" is many F-bodies came with clutch fans (7 blade) and fan shrouds to draw the air through the radiator batter, and not tax the engine until it was hot...

These items can be found for A-bodies, but are much rarer to find intact (I think many A/C cars came with them standard...is yours so equippped?)

-D.Idiot

res0aus2@verizon.net

I live in south east Texas and it can be anywhere from 95 to 100 degrees with 200% humidity during the summer. I had a 68 Valiant with A/C and no overheating problems. It could idle in gear all day long with the A/C running and never overheat. The setup I used is the HD radiator for a 73 to 75 Dart or Valiant with a fan shroud, 7 blade fan, 195 degree thermostat, overflow bottle and a 50/50 mix of antifreeze and water. It sounds to me like you are using a 160 or 180 degree thermostat. When I used a colder thermostat the temp gage would climb slowly. As soon as you started moving it would cool back down. The 195 degree thermostat will allow the water to stay in the radiator longer thus cooling it more. Also as in the other posts make sure the radiator is clean by at least back flushing it. I hope this helps. Also make sure your A/C is fully charged. If it is a little low on freon it will actually generate more heat.

mwhiteho@hotmail.com

What do you mean by "slowly overheating"????
Do you have coolant loss or not?
If your temp gauge is running on the high side of the normal range and no coolant loss it might be the gauge reading high. Possible causes for that are bad instrument cluster voltage regulator or the sending unit in the enigne. I have a Dodge truck right now that the temp gauge reads way high on hot days. I could find nothing wrong. I changed sending units and the gauge stays at the bottom area of the normal range now.
What kind of flex fan are you using? It may not be moving enough air. Same Dodge truck as mentioned above, had a 5-blade flex fan from the factory (truck has factory AC too) , I swapped on a 7-blade clutch fan from a Cordoba and then the temp gauge ran lower even with the same sending unit that caused the gauge to read high on hot days.

My 1976 Valiant with slant 6 and factory AC came with a solid drive 7-blade fan from the factory. It really moves air! I think the part number on the blade is the same as was used on some of the V-8 hemi cars. (Sshhh..... don't tell the Hemi guys they can find Hemi fan blads on AC equipped slant 6 cars). My Valiant did have a problem with the temp gauge reading high on hot days too, had the radiator cleaned out and has worked fine the past 10 years even on the hottest days with the AC running. The radiator is the factory installed 22" wide unit with original 2-row core.



cfield@ll.net

Just to add to what has already been posted... check your spark timing. If your timing is retarded (even a little), your car will tend to run hotter. Especially at idle and low speeds. You should verify your gauge reading by checking the coolant temp with either a thermometer or an infared heat gun. Remove the radiator cap and measure the temp of the coolant in the radiator.

Mitch

m5black@aol.com

First let me say... thanks for all the responses. This site is GREAT with a great bunch of guys.

There is enough coolant in the rad.... always full with the over flow jar and 80/20 mix ( 20% water ). There is a new temp sending unit. The flex fan is a 6 blade, 18" fan in a shroud. Have 2-core rad 22" wide ( new in 1997 )

I only get the overheating when the ambient air out side is high ( 80's - 90's ), and am running around town or after I come off the freeway. The A/C only exacerbates the issue. The temp just slowly creeps up. It may take few miles with stop and go, but it will get right up to the low end of the mark on the temp gauge saying its overheating....... and will not come back down even if I put the car in neutral and rev the engine.

From the suggestions made here, I will take the rad. out to be checked at a local shop, put in a 195 thermostat ( I have been running 180 ) and change the water pump while I am at it ( its been on the car close to 15 years ). Also check the gauge that it is reading right, however I do believe its OK. I found that Flex-A-Lite makes a flex fan with 7-blades, so I may also try that althought I can't see that going from 6 to 7 blades will make much of a difference

If all this fails, I found a place that will make my rad, into a 3-core unit.

Again, many thanks for the help. I never feel any question is too trivial to ask on this forum.


julie-roth@woz.org

Water cools better than glycol. A 50/50 mix would work better. If you live in a warm part of the county, water with rust inhibitors will be even better.
:
: The flex fan is a 6 blade, 18" fan in a shroud.

I've never thought musch of flex fans. If you can fit a viscous drive or clutch fan with the same diameter and number of blades, you have better results. The closer the shroud fits the fan, the better it performs.

dwordinger@earthlink.net

If you are still in doubt after the 50/50 mix, try to find a Redline product called water wetters...it helps break down the surface tension of the water going through your radiator and makes better heat transfer (err...something like that). It's really meant for race car drivers, but has helped some guys in my area running 360 powered duty trucks that used to overheat when loaded down...
:
: I've never thought musch of flex fans. If you
: can fit a viscous drive or clutch fan with
: the same diameter and number of blades, you
: have better results. The closer the shroud
: fits the fan, the better it performs.

I'm with Dave, my take on flex fans are:

1) they are lighter and thus put less drag on the pulley system which might equal more hp (or so).
2) the flatten out at high rpm since there should be enough air running through the engine compartment at 70mph to cool the powertrain...
3) the flat fan creates a dam that air passing through the radiator can't easily get around and makes a "dead" spot in the middle of the radiator
4) if your fan flattens out and you have a shroud on, no air at higher rpms is getting through the radiator so well.
(warm air next to the radiator and no air flow makes for good insulation)...

try to find a clutch fan (5 or 7 blade) off a 1973+ A-body or F-body(Volare/Aspen) and don't over look the V-8 cars either...

let us know what becomes of your adventures in "heat" management...or is that entropy control?

-D.Idiot



res0aus2@verizon.net

If you remove the water pump, check that the impellor is tight on the shaft. Sometimes the impellor loosens and causes it to freewheel, resulting in poor water flow.

ceh52@quik.com

From all my experiences with fans, I have found a good steel flex fan will pull more air at low speed than any other. I use a 19" Flex-a-Lite with a shroud, a two row Modine radiator and a 180 Robert Shaw thermostat in my 1980 Aspen. In 95 degree heat, I've measured a consistant 185 degree coolant temp at the thermostat housing with the A/C on. The car never runs hotter than this.

Mitch



m5black@aol.com

<FONT COLOR="0000ff">Julie,

I'm a little late on this post so I hope you see this. One other thing I have seen on a new motor is that the head gasket loosens up a bit and the engine overheats. I have had to go back and re-torque the head gasket, maybe adding 5 lbs. to the torque spec. If all else fails, this might do it.

Chuck</FONT>


sl6@omnipages.com