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'81 Trans Am

 
1993_Lx
I mow my lawn and find Chevys
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Joined: 12/09
Posted: 03/13/10 04:10 PM

My Trans Am likes to get hot. I'm considering an aluminum radiator and converting to an electric fan. Anyone have any recommendations on a good brand the average guy can afford? Also, has anyone ever built their own shroud for the fan?

Thanks, -Lx Grin  
Most call me Lx, but I was born Dakota

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gettnlarge01
I mow my lawn and find Chevys
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Posted: 03/14/10 05:29 AM

I dont know of any good cheap radiators. Maybe someone on here does  
luck is when skill and opportunity meet

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idrivejunk
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Posted: 03/14/10 09:41 AM

Hey LX, I can tell you what I've done that works. Never made a shroud but it could be done. May not look as nice as a factory one though.

On my big Pontiac, and others.. I opted for a four row brass radiator. All that water still gets too hot in extended stop and go traffic because of the underdrive pulleys. So I installed a 16" electric on a thermostat on the front of the radiator and that baby stays cool now. The regular clutch fan is from an 80s Cadillac and is still in place.

On my stock 350 El Camino, I decided to try the plastic/aluminum modern replacement offered at O'Reilly's for $112 at the time. It has worked flawlessly and never runs warm or leaks. I think I have bought my last brass 4 row. Grin  
idrivejunk

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1993_Lx
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Posted: 03/14/10 11:19 AM

Thanks Id, I never even thought to look into o'reilys. I can get one for a good price and at a discount because of how much business my Pop does with 'em. Would an electric water-pump help the cooling issue also? And won't completely removing all but the water & altenator drives from the engine pick up a couple horse also?

Laugh  
Most call me Lx, but I was born Dakota

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waynep7122
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Posted: 03/14/10 12:17 PM

just curious...     use a hand held temp gun... point it at the base of the thermostat housing..

those years should have a 192F thermostat..   the engine temp will vary from 195 to 220 without problems..   with a proper radiator cap and 70/30 mix of antifreeze /water... it can run as hot as 235 without damaging anything.. other than your brain..


how is the fan clutch...    does it stop fast when you turn off the motor.. or does it spin a while.???  they do wear out.. do not install a NON thermostatic unit.. they are almost worthless..  the  thermostatic units have a spring in the front center..  i test them with a by holding a length of heater hose at the end of one blade.. and having somebody start the motor.. if you can hold the blade from spinning easily.. the fan clutch is bad..

if you have a fixed blade fan..  without the clutch.. not likely.. but does it move enough air.. will it hold a shop rag against the ac condenser when you rev the motor????

81 trans am... i cannot get an exact image.. but that one does not have a grill for cooling air to flow directly through the radiator... it uses an air dam under the core support to direct air up and through the radiator..

my sister..(rip) had an 85 TA... that would run at 265+ at any speed above 56MPH..   he air dam was bad... to the air pressure in front of the radiator was lower than the air pressure behind it..  the electric cooling fans could not keep up..

when i installed the replacement rigid air dam to the bottom of the core support.. the cooling problems went away..

i have an air conditioning gauge air flow gauge.. i measured that the pressure was lower in front than behind the radiator.. with a pair of hoses attached to this unit..


which motor do you have???

1981 Pontiac Trans Am:
Available engines
8 Cylinders H 5.0L 4BL OHV (found in 16% of 1981 Pontiac Trans Am)
8 Cylinders T 4.9L 4BL Turbo (found in 47% of 1981 Pontiac Trans Am)
8 Cylinders W 4.9L 4BL OHV (found in 37% of 1981 Pontiac Trans Am)

the pontiac motors have little rubber and steel seals that are installed in the timing cover behind the water pump plates to keep the cooling flowing directly into the motor.. when these go bad.. or the water pump plates wear out.. you will have overheating problems..   this is on pontiac built motors..  

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1993_Lx
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Posted: 03/14/10 12:43 PM

Okay, These cars are notorious for overheating because the only grill is in the lower bumper. The Trans/Am is actually running a 350sbc crate engine. The Clutch fan is and all the accessories are new on the engine. The A/C and condenser have been gone for 20 years. The car has near new 4-core in it but my main issue is air flow. While I'm in there doing the radiator and electric fans I plan on fashioning up a home ram air of some sort. Here is a pic of my car...

<a href="http://s874.photobucket.com/albums/ab310/1993_Lx/?action=view&current=021.jpg" target="_blank"><img src="http://i874.photobucket.com/albums/ab310/1993_Lx/021.jpg" border="0" alt="Photobucket"></a>]021  
Most call me Lx, but I was born Dakota

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waynep7122
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Posted: 03/14/10 01:58 PM

even with the fan new....   does it pull enough air...

is it a normal direction fan.. or a reverse direction fan...

is it a thermostatic fan clutch????      there are normal thermostatic and heavy duty ones available..  the heavy duty have much larger fins..

is the water pump and drive pulleys set up for normal rotation or reverse rotation????

does your engine have a coolant bypass from the front of the intake back to the water pump.. usually through the heater core.. ????   without a coolant bypass the heat from the heads will take forever to get to the thermostat..

and what temp is your thermostat...  or did you leave it out..  

these cars have to have one.. as the coolant has to stop in the radiator while the coolant in the block circulates and pick up heat..    without a stat.. the coolant circulates so fast the airflow through the radiator cannot take the heat out of it ..  so the engine takes forever to get warm.. and gets hotter and hotter as you drive..

one more thing... are there or were there any rubber/vinyl flaps between the bumper and the core support that most people think are to prevent splashes.. but they are actually to direct air through the radiator instead of going around it..


got a picture of the radiator fan????  

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idrivejunk
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Posted: 03/14/10 02:27 PM

+1 wayne on the air baffles alongside the radiator, and on air deflectors that are broken off and forgotten, and on teeny tiny grill openings, and thermostats and system pressure, and, well, all that.  Laugh  
idrivejunk

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idrivejunk
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Posted: 03/14/10 02:28 PM

Lx, I've never tried electric pumps Frown  
idrivejunk

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blacksheep84
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Posted: 03/14/10 03:58 PM

look at the procomp site , i think i had seen them selling some nice looking alum radiators for a good price.


http://www.store.procompelectronics.com/index.php?target=categories&category_id=852  

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1993_Lx
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Posted: 03/14/10 05:00 PM

Wayne, The fan appears to be pulling plently of air and performing as it should. The water pump pulley and drive pulleys are all set up for normal direction. The Fan is a Thermostatic Normal directional, Its not a heavy-duty. I'm running a 160 degree thermostat thats been drilled to allow more flow. I'm running an Edelbrock Air-Gap intake that has the bypass you spoke of. The hose runs from the water pump to the intake, and from the intake into the heater core. The plastic pieces behind the front bumper are still intact. I could get a pic of the setup but it will be a little while.

Thanks Wayne. And Id, I looked into the radiator you spoke about through O'reilly and had no luck finding one.

Grin  
Most call me Lx, but I was born Dakota

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1993_Lx
I mow my lawn and find Chevys
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Posted: 03/14/10 05:03 PM

Blacksheep, Thanks for the link bud. I'm gonna make a decision on what I need thn I'll look into those.

Laugh  
Most call me Lx, but I was born Dakota

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idrivejunk
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Posted: 03/14/10 05:25 PM

This is what O'Reilly's website offers on a non turbo 301 81 Trans Am. It is aluminum single row with plastic tanks. $199.99!

Ready-Rad - Radiator
Part Number: 433573

•With Heavy Duty Cooling
•27 1/2 X 17 X 2
•1 Rows  
idrivejunk

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chevelle83
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Posted: 03/14/10 08:43 PM

If you dont have a fan shroud on this car that is the problem. My 81 camaro used to overheat until I found a donor car and got the shroud from the salvage yard.  

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waynep7122
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Posted: 03/14/10 09:14 PM

change the thermostat back to a 192F ...    make sure the antifreeze is at least 70/30...   check the radiator cap...

look at the disc in the center of the rubber gasket.. if it dangles free.. get a different cap.. that the little disc is spring loaded...


with a 160 thermostat.. there is not enough temp difference between the ambient air temp and the coolant temp...
this causes the thermostat to crank wide open after only a few laps of the coolant..

if you are worried about any air bubbles and the need for the bypass hole in the stat..     if you run a bypass circuit.. so the coolant behind the thermostat is bypassed into the side of the water pump... there are fittings in most pumps for this..  you will get a most stable in engine coolant temp..    

as the engine cooling is circulating in the block up the back of the heads.. forward though the heads to the intake.. then bypassing into the pump.. again and again until it comes up to temp where the thermostat opens slightly.. this exchanged the coolant in the radiator for the hot stuff in the block.. when the cooler stuff gets into the engine.. it closes the thermostat..  allowing the hot stuff in the radiator to sit still and be cooled by the incoming air..   then it swaps again..  at speed.. it will reach equilibrium.. with the thermostat part way open..  

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