Re: [Chrysler300] 300G Radiator fan shroud over heating problems
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Re: [Chrysler300] 300G Radiator fan shroud over heating problems

I was getting ready to say that crud in block , at least in theory would not prevent heat from getting to water. Where else can it go? Crud or not. Crud is wet . Water still boils at  212 plus. Even if in crud.if it boils there it carries  the heat away, as steam , then immediately condenses back to water   — point is heat is carried? If it did boil locally it would push crud off ? I have trouble with it causes the  overheat ( in block) as then block metal gets hot and water does not = not our problem . Heat concentration around cylinders kind of low too, compared with say exhaust port . The Water when “ cooling fails” is in fact very hot. Too hot . Block too . 
But restricted  flow you mention is another whole game . That stops radiator from rejecting the heat . And “cleaning out block “ cleans out the head openings . So experience quoted is 100%  correct , and correct advice . 

Excellent post, great info  ; 

only way for water to carry heat is to move . And move fast . Only way out of block for hot water after pumping into the block front is through the heads via those small holes  . They added more of them in motor home head. ( hmmmm) So if head entry water passages are restricted at at all at gasket surface, by a “crust” or deposits it is the same thing as a thermostat not  opening fully  .  Restricted flow. 
So we have some new info? New to me that it does this. Has to be a good radiator —AND the water has to move fast and free . What rodding radiator does  , also. 
Old posts about a year or two back also got somewhat into incorrect 440 pumps given to you at parts  counter as 413 replacement, “for all B block”  , there was some kind of impeller depth change and  a metal water distribution plate behind impeller in some early B blocks . If wrong combination causes overheat ,due to  gap or fit behind or around impeller , does not move water fast enough . I am still not clear on this myself , re: what years , but for sure is out there.  
Pump and housing will interchange together , cannot mix up . Then And add in AC pump vs regular pump . Possibly 4 pumps? The parts number guys might look into this .. or we look for the steel plate inside next time open, start a data base . How far in impeller goes from gasket face?!
different pump number means what ?oddly AC pump has fewer vanes I think . Yet must be more gpm. 
Too bad there is not some way to measure or judge gpm or flow when any of this happens . Compare two hot cars at neck at 1500 rpm? 
See if radiator same temp top to bottom ( = fast flow, best total cooling) In the meantime those holes must be clear. 
Sent from my iPhone

On Oct 30, 2017, at 8:51 AM, Richard Osborne <reomotorsports1@xxxxxx> wrote:

I wil second Andy’s comments. I bought my G coupe almost 18 yrs ago. It had been parked for approximately 20 years prior to my ownership. It ran when I got it, but I changed oil, plugs, etc…. As soon as I did a garden hose flush, I started fighting overheating issues. I had the radiator rodded out, recored, change thermostat, hoses, re-flushed…. all to no avail. At this point I knew there had to be something wrong internally. As soon as I pulled a cylinder head, this was confirmed. The water passages had barely 1/8” hole due to crusty junk being built up in what should be probably a 1/2” diameter water passage.

In my circumstance, the engine rebuilder could not get the passages cleaned out with the normal Hot Tank process. They ended up sending my block and heads to Redistrip, the place where they dip entire car bodies to strip away paint and rust. This worked. I rebuilt the engine to stock specs (as far as the cooling system is concerned) and have had no issues. This includes driving across country and back, including through the Mojave dessert at 113F degrees. 

This issue is what prompted the entire restoration of that car. I have probably put 40,000+ miles since on the car and have had no cooling issues (other than freeze plugs, which is another story).


On Oct 30, 2017, at 2:34 AM, Andy Mikonis r41hp@xxxxxxxxx [Chrysler300] <Chrysler300-noreply@xxxxxxxxxxxxxxx> wrote:

I agree with Keith. These cars worked when new as designed and still will. In my case I battled overheating in my G for years. A new radiator or a proper rodding-out would work for a while. Ultimately it ended when I took my engine to George Riehl for rebuild. He wouldn't just have blocks hot-tanked, but he took them to a place for a shot-peen type process. The block came back looking like a fresh casting. No heating problems since. Point being, you can throw all the fancy radiators you want at your car, but if there's 40-50 years of rust and gunk in the block cooling passages then it won't help. And a radiator shop or garden hose "flush" isn't going to do it.

Good luck!

On Oct 29, 2017, at 11:58 PM, Keith Boonstra kboonstra@xxxxxxxxxxxx [Chrysler300] <Chrysler300-noreply@xxxxxxxxxxxxxxx> wrote:


I have no technical words of advice to offer, but I will be a cheerleader.

I recall a trip of 200 miles I took in my C in the summer of 2016 when the temperature was over 95, the sun was blazing, the humidity was in the 90s, and I got caught in construction traffic jambs. I had put in a recored radiator (of unknown composition) in 2011, I have the factory fan shroud, and everything else in the cooling system is factory except for a temp-controlled fan clutch. I ran my A/C with its big ole RV-2 compressor full-bore that day, but the temp gauge hardly budged over center.

All I'm saying is keep working at it, and stay with the factory setup. Those engineers were pretty good at their craft. Get all of it right and to spec and you will eventually win.

Keith Boonstra

On Sun, Oct 29, 2017 at 10:44 PM, Steve Albu saforwardlook@xxxxxxxxx [Chrysler300] <Chrysler300-noreply@xxxxxxxxxxxxxxx> wrote:

I would agree with John, but maybe a 3 row high fin density core would work fine without going to a 4 row if your cooling issues are generally only in low speed traffic.  If you are having issues with higher speed cooling as well, then a 4 row would definitely be advised.  Generally low speed cooling requires a large frontal area and high fin density whereas high speed cooling requires more rows of fins as well.  I personally would go to a reputable radiator shop with my original radiator and have them put in a new high efficiency core.  

On Sun, Oct 29, 2017 at 2:24 PM, John Grady <jkg@xxxxxxxxxxxxxxxxx> wrote:
Second that . Need 4 row core and they cost $!. A 3 row “rated 4row “ is not the same . Has to be radiator — if all that is new and on correctly? Not sure why anyone would  cut the shroud? It was designed correctly , if the original one? Have to have that right . A front fan should not be needed , all this worked stock without it , and might not help as ac core is a distance in  front of cooling core. Plus it blocks air flow some in center where motor is . Plus they take 20- 25-amp . The car alternator will not like that with Ac system running ,
In Mopar magazine , the one out of New Orleans, someone advertises newly made Mopar radiators including 4 row for restoration , mainly  geared to big hemi etc . But says real  4 row, but almost 1000. I think all of them use similar cores in the large sizes , within # of tube rows . 
Big $—  but used or old is a crap shoot ... ?? 
I had electric , only, on a 480” non ac 440, it overheated even at idle . Went back to pump mounted , not finished yet , used a flex fan . ( due to lack of knowledge and cost about various clutch fans and ac fan , which I think has 7 blades, but not sure of that either) . If you have all original ac stuff it should work , if radiator good. Hope this helps 

Sent from my iPhone

On Oct 29, 2017, at 4:00 PM, Steve Albu saforwardlook@xxxxxxxxx [Chrysler300] <> wrote:

Having a "new radiator" doesn't mean anything.  What matters is whether you have a core in it that has very high fin density.  If you didn't pay somewhere in the $500 range out the door for it, it doesn't.  Nothing else substitutes for a good radiator.  A standard replacement is junk.  I live in California where temperatures are well above 95F much of the time, so I have some experience with a/c cars.  

On Sun, Oct 29, 2017 at 11:08 AM, thomas tibbie ttibbie@xxxxxxxxxxx [Chrysler300] <> wrote:

Hi everyone, I'm back on the same subject over heating on my 300G with A/C, with new radiator, recovery tank and new clutch fan.  I live in the San Antonio Texas area and during the summer months when our temperatures reach 95 degrees + I have an over heating problems. If the temperatures stay below 90 degrees no problem. The radiator shroud  has been cut back so the fan is not covered by the shroud. So I'm looking for radiator shroud that will fit the 300G.  One other question has anyone used an electric fan in front of the A/C radiator to help cooling problems? Thanks      


Posted by: John Grady <jkg@xxxxxxxxxxxxxxxxx>

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