How far back does the fan need to be from the radiator?
#744592
07/10/10 09:26 AM
07/10/10 09:26 AM
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Joined: Sep 2004
Posts: 1,226 Cookeville
Chilort
OP
Will Work For Mopars
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OP
Will Work For Mopars
Joined: Sep 2004
Posts: 1,226
Cookeville
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I'm having a little trouble keeping my old truck cool on these hot hot hot summer days or while sitting in traffic. The temp really wants to creep up. I've got a fan shroud, the rad was re-cored a few years ago, I've got a big 7-blade fan, water pump is new with the anti-cavitation plate, the coolant is a little on the water side of a 50/50 mix but not too much with Water Wetter, t-stat is new and works properly, original factory water pump housing, and the viscus clutch is new and a heavy duty unit.
I've been throwing parts at it and nearly everything I've done has helped but nothing has solved the problem. I'm wondering exactly how far back does the fan and clutch need to be from the radiator? I can squeeze my hand between the fan and the face of the clutch and that's about it (so an 1", maybe 1.5"). Is that too close?
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Re: How far back does the fan need to be from the radiator?
[Re: Chilort]
#744593
07/10/10 09:34 AM
07/10/10 09:34 AM
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Joined: Jan 2003
Posts: 28,068 Irving, TX
feets
Senior Management
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Senior Management
Joined: Jan 2003
Posts: 28,068
Irving, TX
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The fan needs to be a little more than half way in the shroud. If it is, that's all you've got.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind. - Stu Harmon
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Re: How far back does the fan need to be from the radiator?
[Re: Chilort]
#744597
07/10/10 11:14 AM
07/10/10 11:14 AM
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Joined: Mar 2003
Posts: 4,848 Memphis
HemiRick
master
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master
Joined: Mar 2003
Posts: 4,848
Memphis
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Its sounding form the symptoms that the rad does not have enough capacity or is too small.
Take care, Rick 68 Coronet R/T 440 & 68 Charger 528 Hemi,and 5 Challengers! 6 cyl, 318, 360, 383, 451
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Re: How far back does the fan need to be from the radiator?
[Re: Crizila]
#744599
07/10/10 03:38 PM
07/10/10 03:38 PM
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Joined: Nov 2003
Posts: 135 So. Oregon
ron1320
member
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member
Joined: Nov 2003
Posts: 135
So. Oregon
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Not to hijack the thread, but how much modification can you get away with on the engine before you start having problems with a stock type setup? How modified is your engine combo?
69 R/T 440
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Re: How far back does the fan need to be from the radiator?
[Re: ron1320]
#744600
07/11/10 01:26 AM
07/11/10 01:26 AM
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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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Check to make sure your exhaust flapper vlave isn't stuck closed.
If turning on the heater helps drop the coolant temp, you have a cpacity issue with the radiator.
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: How far back does the fan need to be from the radiator?
[Re: ademon]
#744602
07/11/10 04:08 AM
07/11/10 04:08 AM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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overheating at speed, what Crizila and hemirick said. I would toss the stat for 1 day on the off chance it is not opening 100%, might get lucky
live every 24 hour block of time like it's your last day on earth
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Re: How far back does the fan need to be from the radiator?
[Re: Lee446]
#744604
07/11/10 01:38 PM
07/11/10 01:38 PM
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Joined: Jun 2004
Posts: 893 Tustin, CA
pishta
super stock
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super stock
Joined: Jun 2004
Posts: 893
Tustin, CA
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How far back should the fan be from the radiator? How about as far as the shroud lets it while still keeping the fan 1/2 out of the shroud. Check out a V6 Tbird. The fan is about 12 inches from the radiator, but the shroud is also that long. Make sure your shroud is sealed around the radiator and is is doing what is designed to do: allowing the fan to pull the maximum amount of airflow across the entire surface of the radiator. Also check for clutch slippage/seepage, cold spots in the radiator surface, that would show areas of blockage. Does your radiator look good inside ie. low/no corrosion? Take a STRAIGHT coathanger and put it down one of the tubes, does it go in smoothly? Might just need a rod out or a solid fan coupler.
12 Grand Caravan 06 T&C 02 T&C 96 Breeze 65 Barracuda "S"
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Re: How far back does the fan need to be from the radiator?
[Re: crlush]
#744606
07/12/10 07:16 PM
07/12/10 07:16 PM
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Joined: Sep 2004
Posts: 1,226 Cookeville
Chilort
OP
Will Work For Mopars
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OP
Will Work For Mopars
Joined: Sep 2004
Posts: 1,226
Cookeville
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Sorry, y'all for the slow reply. I went on a trip for my 1 year wedding anniversary with my wife to Savannah, GA and we left our electronic devices with access to the internet at home... fun trip.
Anyway, I can't say how "new" the problem is. I never drove the truck in this kind of temperature until this year when my '86 Daytona bit the bullet (going to try to rebuild her but it will be a bit) and I didn't have a great paying job up until last week so a newer car should be in order very soon. In short, I may have had this problem since I bought the truck several years ago and just never knew it. It has been in the mid to high 90s here with heat indexes over a hundred and the air coming up off the interstate is probably pushing boiling.
The details on the build are going to get messy so hold on (but not as modified as Feets):
1968 D100. Engine was recently rebuilt (though not original) and has less than 3500 miles (but is close to 3500 miles). It is a 440, 0.040 over and the pistons are .100 in the hole (reuse - no budget - don't poke fun), with stock rods and a forged crank. Heads are Eddys (purchased a few years ago) that have been milled for a final compression ration of 9.2:1. Cam is a Lunati 60303 with Lunati lifters and Trend custom pushrods because I'm running Harland Sharp rockers (and that's where the budget went). The oil pump was rebuilt to stock specs and I get great oil pressure even without an oil limiter to the heads. I am running full length headers and 2.5" dual exhaust. The torque converter is from Turbo Action. I run a small oil cooler in addition to a deep trans pan. The fan is a 7 blade from a '76 or so Chrysler C-body of some kind. The water pump and t-stat are new Milodon units. The water pump housing is a factory Mopar unit. The fan clutch is a new thermostatic heavy duty unit made by Hayden. It get very stiff when the engine is hot. The fan moves a lot of very hot air. The rad cap is a newer 15-16lb unit that could be found on any Mopar from the 80s and 90s. The carb is the cheapo Holley 750 (74 jets in the front and a plate equal to 75 jets in the secondaries). I run 18* initial timing and 32* total. I have a Mopar Performance dizzy that I've set up based on advice from here. The total timing doesn't come in until 3500 rpm and the vacuum advance has been pulled back quite a bit. Plugs look great (Champion RC12YC).
The radiator itself has been recored. It is from a '68 C-body that had a 440 and AC (according the the part number). Unfortunately, the radiator and engine are not in the same exact orientation in the truck as they were in the car (the rad sits an inch or two higher) and the the fan is a few inches bigger in diameter than what was used in the original application. While I do have a correct fan shroud (in perfect freaking condition), I cannot use it. I ran without a shroud for a long time but when the air temps got over 85 or so I had to add the shroud. I hacked up a shroud from an '80s Dippy. It actually fits very well. I've sealed around the top and bottom with double sticky sided foam tape and the sides are more well sealed than they were in the Dippy.
Because the radiator was a recore (though via a reputable local shop) I am a little worried it wasn't done well and isn't flowing water evenly. I do not have one of those fancy laser guided temp deals so I guess I need to invest in one.
The temp gauge is the stock factory gauge. When things are humming along nicely in cooler weather the gauge points straight up (between the letters "E" and "M" in the word "TEMP). But now that it is warmer moves to the right (past P) and I get nervous. Once again, I guess I need to confirm how hot it is getting but it does want to start pushing out coolant when it gets real hot. I have no puke tank.
Thanks for all the help guys. I guess I have some things to look at.
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