cooling off that c4 corvette



Re: cooling off that c4 corvette

Postby grumpyvette » May 15th, 2013, 5:22 pm

vette96 wrote: I had a similar issue with the coolant fans not working,
I fixed the problem,

the codes are off now. the problem was with the connection between the I/P harness and the front body harness. it is located behind the battery.

the pins in that modular connector are covered with grease, thus it wasn,t connected well.
I cleaned it and now it is ok.



Im curious about that connector not being connected (WELL) and wonder if you could elaborate on what you found and any more info you cpould post, because Ive seen several 1995-96 corvettes display code P1641 and have the cooling fans show trouble codes yet testing fuses and relays and sensors proved to be a total waste of time and money

does anyone have a clear picture or diagram of that modular electrical connector and its location, or know if a replacement connector is available?
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: cooling off that c4 corvette

Postby grumpyvette » May 17th, 2013, 11:32 am

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SENSOR LOCATION INFO
viewtopic.php?f=80&t=728&p=1025&hilit=camaro+sensors#p1025
Sensor Locations
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I recently helped a local guy trouble shoot his 1996 corvette cooling fan issues,
it was partly caused by following the advice of the local advance auto parts counter guy ,when he found a code P1641 which according to the print out at the auto parts store indicates a failed fan relay, he purchase three new 4 pin relays, because theres three relays and he had no way to verify which relay failed and since all the relays were 17 years old he figured they were due to be replaced if one failed. and installed them after being assured that all three relays are interchangeable
(THEY are not IF YOU BUY 4 PIN INSTEAD OF 5 PIN RELAYS)

All 3 relays are in the dual cooling fan circuit----check fuse #29 inside the car--right side of dash when you open the passenger door---this is on the low current control side of the fan relays---both fans have this fuse in common--this should be either a 5 or 10 amp fuse---whether or not the fans come on at a given engine temp and /or if the A/C is turned on-- is ultimately controlled by the PCM .
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http://www.ecklerscorvette.com/corvette ... -1996.html

http://www.parts123.com/0000050f/244508 ... 244508.htm

viewtopic.php?f=57&t=3010&p=7916&hilit=relays#p7916

heres what the 1996 corvette shop manual says
The cooling fans are controlled by the PMC based on various sensor inputs.
Ignition voltage is supplied to all three cooling fan relay coils.
The PMC controls cooling fan #1 by providing the ground path.
The PMC controls cooling fan relays #2 and #3 together by providing a ground path.
The left and right cooling fans are connected in series.
this will enable both fans on low speed when the #1 fan relay is energized.
when all three fan relays are energized , both fans will operate at high speed.
the high speed is possible because the fan relays are wired in a parallel circuit.
when the PMC detects that certain DTCs are set, the PMC will enable the cooling fans.
the ECT sensor (ENGINE COOLANT TEMP)must be tested
Engine Coolant Temperature Sensor. 185 Ohms @ 210F, 3400 Ohms @ 68F, 7,500 Ohms @ 39 F.
the pmc will command the low speed fans to turn on at 219F and off at 207F and the high speed fans ON at 228F and off at 214F
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Re: cooling off that c4 corvette

Postby grumpyvette » June 20th, 2013, 1:34 pm

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adding a high rise hood allows a much larger choice in intake designs that will fit under the hood, but does little to reduce engine heat trapped under the hood, keep in mind that if you can increase the radiator fans efficiency "and thats done partially by reducing and resistance to air flow exiting the engine compartment" you can increase the air flow mass absorbing heat as air passes over the radiator fin surface.
remember the c4 corvette sucks air from under the car, so at lower travel speeds the electrical fans are responsible for the vast majority of the air flowing thru the radiator, as vehicle speeds increase a increased air pressure builds under the cars nose increasing air flow rates thru the radiator.

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http://www.carid.com/1985-chevy-corvett ... 12083.html

http://www.eharwood.com/catalog/HOODS/
adding hood vents like these pictured above are mostly for show, and in my opinion some styles just look bad! (as in CRAPPY)but any decent size vent will help lower engine heat (MARGINALLY AT LEAST ) if they are to small to be ideal
if you have a good source for vents that you think might look good please post some links, but keep in mind the panel that you cut below is limited in size to about 9" wide and 12" long on each side


http://www.hoodlouvers.com/products.html
adding a larger area hood vented panel to each rear panel area thats about 9" x 12" indicated ,increased air flow rates enough to lower engine temps a measurable amount,plus it tends too lower front end lift at high speeds, especially at high track speeds, larger vents like these will help lower engine heat and they are large enough to be closer too ideal
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the rear panels are almost placed as if designed as a good location for heat to exit the engine compartment if the proper vents are added
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IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: cooling off that c4 corvette

Postby philly » December 15th, 2013, 12:21 am

some thoughts about cooling the c4:

for what its worth and if i remember correctly lincoln mark viii fans flow in the region of 2300-2500 cfm and can be had at a junkyard for 25 bucks.

i have heard, although have never used them personally, that fans from later srt10 vipers flow 4000 cfm and can be had for less than $150.

IF you dont want to add vents to your hood to allow the heat to escape (and i personaly dont) then another alternative would be o make vents into your wheel wells, the smarter design would probably be back cut like the side vents on early c4's to prevent dirt and mud and stuff from being slung into your engine bay by the tires.

if the car is a race car, or you dont mind detailing your engine bay often, you can remove those wheel well surrounds almost completely for a very race car look with the hood up (i think its neat) and that should basically eliminate the argument of trapped air in the engine bay.

in the quest for designing a ram air intake for the callaway, we briefly considered running downward facing ducts with thin scoops in the corners of the vette (like around the radiator overflow tank) but have since ditched the idea and are deigning a system that uses the existing special hood ducting for the intercoolers and doesnt go infront of the radiator at all. however finding covert ways to channel air from the front outside of the car to the front of the radiator is probably equally promising as it is for the intake system.
-phil

There's never enough money to build it right, but there's always enough to build it twice!
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Re: cooling off that c4 corvette

Postby grumpyvette » December 15th, 2013, 10:43 am

as always, posting clear detailed pictures of any custom mods, you do to any of your cars, from several perspective angles , along with a detailed description of what you were trying to accomplish and the theory behind any mods being done would be VERY WELCOME!


BTW most early TPI corvettes had an oil cooler mounted between the engine block and oil filter that would reduce the oil temps in the engine, by circulating the engine coolant and oil thru separate,parallel passages , this had the advantage of more rapidly warming cold oil but keeping its max temp lower than without its use.
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yes they work, they easily drop the oil temps 15 plus degrees F or more, by running the oil flow alongside but separated from the engine coolant. now they are NOT as effective as a aux cooler because they can,t lower temps to quite as low as engine coolant temp levels,and if you pay attention to your gauges youll generally see oil temps tend to run 15-30 degrees over coolant temps, on most engines. while if you install the AUX oil or trans fluid coolers , with the electric fans ,those can, at least in theory lower temps to outside air temps, or at least to significantly lower levels than the coolant temps. and yes that can easily be 100F LOWER. I,d also point out that a 7-8 quart baffled oil pan, the longer length oil filters and an adding an fan cooled oil cooler can reduce oil temps very rapidly , so get a few gauges installed to help verify actually operating oil temps.
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IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Re: cooling off that c4 corvette

Postby philly » December 15th, 2013, 12:28 pm

as soon as we go thru with the custom air box i will definitely post up some pics, it kind of took a back sat to the blown out turbo seal.
-phil

There's never enough money to build it right, but there's always enough to build it twice!
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Re: cooling off that c4 corvette

Postby dfarr67 » January 30th, 2015, 11:26 am

My old 1990 TBI chev truck had coolant crossover at the rear of the intake with the heater core pulling coolant off of it- returned to the cold side of rad. Changed over to aftermarket FIRST TPI and there is no coolant crossover at the rear- the heater core is supplied off front of intake and returned to low pressure side of water pump. Any affect on towing capacity here- was thinking about putting SS T-line from rear intake to front.
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