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Radiator, fan, and water pump

Bills money pit

Well-known member
Joined
Mar 25, 2006
Messages
90
Location
okla
Corvette
1981 corvette Red/Red
While determining how to replace the water pump on my 81, several questions arose. I know the previous owner replaced the radiator with an Ecklers A3902. Until I checked more closely, the radiator is a standard 2 inch core radiator and not a heavy duty. The car has air and I believed it would have a HD radiator. Was the HD an option? Also, it has a five blade fan. I thought the air package would include a seven blade fan.

Please give me some advise how to remove the radiator and fan shroud, individually or as a unit. It looks like a real challange. (mess) I think while the radiator is out; I will have it recored with a thicker core. Will this cause any installation problems?

Thanks for taking the time to answer.

Bill L.:confused

P.S. Just thought of another question. The car has developed a stumble off idle. Several months ago I rebuilt the carb and it had a dead spot off idle and it proved to be that the accerator pump cup was the cause. Now it is happening again. As I open the throttle, I do not get a squirt of gas until the pump rod has been depressed 1/4 down. Is there a more lasting fix than just a few months?

Again, Thanks!;help
 
Joined
Apr 29, 2001
Messages
2,141
Location
Rio Rancho, NM
Corvette
1981 HD Suspension; ZN1 Option
Bill L.,

The HD radiator was an option with the ZN1 towing package. And the towing package could not be had without the HD suspension (FE7) which I believe it could not be had with the manual tranny.

Check ot the this link: http://www.corvetteactioncenter.com/specs/c3/1981/81prod.html

for more info.

As far as removal of the radiator, you're going to have to remove the radiator first, and then remove the shroud. At the bottom of the shroud, the bolts holding the upper "A" arms won't clear the shroud with the radiator in place.

For maintenance convenience, I use bolts/lockwashers instead of studs/nuts on the water pump drive base. With the studs, it makes it a bear to remove the shroud when the bottom part of the shroud rim nears the pump pulley.

good luck with your project.
 

minifridge1138

Well-known member
Joined
Feb 2, 2007
Messages
908
Location
USA
Corvette
1982 Black Fastback
I have some tips on how to remove the radiator, and a few questions.
How hot is your car running? I just replaced a 2 inch brass radiator with an aluminum DeWitt's radiator. I went from running 240+ to 200. If you're not running hot, i'd keep what you have. If you are running hot (and can afford it) I STRONGLY recommend DeWitt's DirectFit radiators. It is a 100% direct replacement for the stock radiator. No modifications are needed.

I don't know about 1981, but the 1982 brackets would not have a problem holding a thicker radiator if you just want to have yours re-cored. Mine is 2 inches thick, and the bracket has about an inch of space left over.

Radiator and Shroud Removal:
1) remove the upper radiator support brackets.
2) disconnect the upper and lower radiator hoses (you'll need to drain some coolant first)
3) Disconnect the transmission cooler hoses (you'll need to plug the hoses so that you don't drain your ATF)
4) Lift the radiator out of the car.
5) Remove the fan (it is a 5 blade, not 7). It is held in place with 4 bolts.
6) remove the shroud.

Removing the shroud is the only hard part. I found it was easiest to rotate the shroud and then lift it out. It will take some work, but can be done.


I'm still trying to learn about carburetors, so i can't help much. I don't know what carb your using, but most carbs have a cam that activates the accelerator pump when the throttle reaches a certain point. Different shaped carbs result in the accelerator pump activating sooner/later. You May just need to try a different cam that will activate the pump sooner (you said it wasn't working until 1/4 of the way in).

Good luck, and let us know how it turns out.
 

Bills money pit

Well-known member
Joined
Mar 25, 2006
Messages
90
Location
okla
Corvette
1981 corvette Red/Red
Thanks for your help. I am impressed how members respond to requests. I have received much valuable info on how to keep the vet running. Great site!
 

Bills money pit

Well-known member
Joined
Mar 25, 2006
Messages
90
Location
okla
Corvette
1981 corvette Red/Red
My car temp runs about 200 around town but on the highway, it climbs to around 220. Is there enough room in the shroud to run a 7 blade fan that is 18 1/2'' across?

Thanks for the replys. FYI a local radiator shop said he can order a 2 5/8'' 4 row radiator (copper/brass) for $235.00. He also said the headers (tanks) would be 3 1/2'' wide. I am tempted but wonder if the tanks would be too wide for my brackets.. He did say his book was showing the HD rad for my application. What do you think?

Regarding the carb stumble, a carb guy believes its not the acc pump cup but the float level is too low thus the amount of fuel in the bowl is not sufficiant to fill the acc pump bore. Does his opinion hold water (fuel)?

Thanks
 

L48

Well-known member
Joined
Jun 16, 2005
Messages
247
Location
Wadsworth OH
My Vette came with an 18" flex fan which was hitting the shroud when I gun it. I am not sure about the 81 - maybe the opening is a little bigger.

If the carb is a Quadrajet I suppose the low fuel level is possible. The question I have is why was it ever right after the rebuild - it should have been like this since the rebuild. I think you can just buy an accelerator pump and change that - I would get one from another supplier in hopes to get a better one. As a last resort you could always get another float or double check the float setting.

I also know you can get a little more "shot" by shaving some off the top of the pump rod. It's been too long to recall how much, maybe a 1/4". If the car is stock it should not need this treatment.
 

Bills money pit

Well-known member
Joined
Mar 25, 2006
Messages
90
Location
okla
Corvette
1981 corvette Red/Red
Another carb consideration is I have been running carb cleaner additive in the gas. Maybe it has deteriated the acc pumb cup.
 

Pirate

New member
Joined
Aug 4, 2015
Messages
2
Location
Florida
C3 water pump removal

Recently purchased 1981 C3 and may be facing a water pump removal in the near future. Does the hood have to be removed in order to gain access to the water pump?
 

minifridge1138

Well-known member
Joined
Feb 2, 2007
Messages
908
Location
USA
Corvette
1982 Black Fastback
Recently purchased 1981 C3 and may be facing a water pump removal in the near future. Does the hood have to be removed in order to gain access to the water pump?

No, you do not need to remove the hood.

You can probably leave the radiator and shroud in place, too.

Be warned: one bolt on my water pump was seized or cross threaded and snapped off flush with the block. I ended up drilling it out and re threading it. Other than that, the job was easy and could probably be done in an hour or two.
 

Pirate

New member
Joined
Aug 4, 2015
Messages
2
Location
Florida
1981 C3 water pump removal... Thanks for the words of advice.

No, you do not need to remove the hood.

You can probably leave the radiator and shroud in place, too.

Be warned: one bolt on my water pump was seized or cross threaded and snapped off flush with the block. I ended up drilling it out and re threading it. Other than that, the job was easy and could probably be done in an hour or two.

Thanks for the words of advice
 

bill81vette

Moderator
Joined
Jan 17, 2004
Messages
4,320
Location
Troy,NY
Corvette
1981 dark blue metallic
If your A.I.R. pump is still there it will have to be removed as well.
 

murphthesurf

New member
Joined
Nov 2, 2015
Messages
1
Location
Cleveland, Ohio
Corvette
1978
1978 rebuild.

Can the radiator and A/C condenser be removed together?

Thanks

Murph




Bill L.,


The HD radiator was an option with the ZN1 towing package. And the towing package could not be had without the HD suspension (FE7) which I believe it could not be had with the manual tranny.

Check ot the this link: 1981 Corvette Production and Performance Numbers - Corvette Action Center

for more info.

As far as removal of the radiator, you're going to have to remove the radiator first, and then remove the shroud. At the bottom of the shroud, the bolts holding the upper "A" arms won't clear the shroud with the radiator in place.

For maintenance convenience, I use bolts/lockwashers instead of studs/nuts on the water pump drive base. With the studs, it makes it a bear to remove the shroud when the bottom part of the shroud rim nears the pump pulley.

good luck with your project.
 

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