71LS5

Hi,
I am trying to figure out if my radiator I just pulled (its leaking pretty bad) is original and or the correct type. It does have a filler neck and an overfill nipple to the copper expansion tank (the only marking is T08 – 77 stamped tag).

My car is a 1971 LS5 BB with AC manual transmission.

1. Does the 1971 LS5 BB with AC manual transmission radiator have a filler neck?
2. What is the difference in the radiator if its manual or auto?
3. What is the difference in the radiator if its AC or non-AC?
4. Does any one have any pictures of a 1971 BB AC manual transmission that I can get or see?

Thanks,

Ron

BarryK

Ron

this is what a correct '71 BB radiator looks like (except the stock factory unit was black). You can order the DeWitts unit painted black also
http://www.dewitts.com/pages/product...asp?ProdID=275

the difference between a manual trans or auto trans unit is that cars with an auto trans will have the trans cooler line connections on the rad as seen here:
http://www.dewitts.com/pages/product...asp?ProdID=283


there is no difference in the radiator between AC or non-AC cars.

71LS5

Thanks Barry for the info! Looks like I had the wrong radiator in there.

So I assume to fill up the main radiator tank one uses the overflow/expansion tank?

zwede

Correct. the factory setup had the (only) rad cap on the expansion tank. A crappy setup, IMO. I don't like the idea of a big pressurized air bubble in my cooling system, which is what the expansion tank is (it is only supposed to be filled half way).

So on my 71 I used a becool radiator that does have a filler neck w/ cap. I ditched the expansion tank and used a late C3 overflow tank instead. Now I have an air-free cooling system which let me switch to the modern long-life coolant. The new coolant does not like air, it forms sludge.

Maybe dewitt also offers a 71 BB radiator with filler neck? Or just the stock style?

71LS5

Hey Zwede,

I had a filler neck (with nipple) on my last set up with the expansion tank connected to the nipple. Are you saying that this set up inherently has air in it? Or by having the filler neck AND the expansion tank the tank served more of an overflow tank? They both are presureized in my old set up. I did used to have to "burp" the air out of the system. I am sure I had some but never had cooling problems.

Hey Kalaway,

Thanks for the info. This subject on who to buy from has been covered in my last thread. I am afraid it got very out of hand.



Maybe I should use a unit that does have a filler neck like my ogiinal set up since it seemed to be working. If I use one without it I am not sure how things will end up. with my old set up I used any type of raditor fluid and it kept the block at 195 degrees F which seems reasonable.

Still open to your opions.....

Kalway

As far as fluids go, only use the green stuff mixed with water 50/50 and change it every other year.

71LS5

Funny the Bible I use for correctness has a picture Vette Vues P24 of a 71 BB radiator WITH a filler neck on the radiator. Now I understand that these had part numbers and stampings on the top and mine does not. I assume its not original but not sure.

Does ANYONE have a 71 BB LS5 with the original radiator? If so can you send me a picture. I am very curious about this.

Often the build info is not correct or changes were made with the right documents. for example my 71 LS5 has stock original chrome valvue covers. It was not supossed to but there were excess from the 70's modle that was cut short to I bbelive a strike??? So they used the leftover valve covers until they depelted the stock.

This might be a NCRS question.......

0Tom@Dewitt

All 69-72 BB rads had no filler neck and used a separate surge tank...

The surge tank was aluminum with non AC cars
The surge tank was brass with AC cars.

The pressurized surge tank is the best way to go, with only one cap. This allows you to fill the radiator completly and let the expansion happen in the tank.

But, if you decide you want to eliminate the tank then you can simply use the 73 radiator. It is exactly the same as the 69-72 BB except it has a filler neck.

0Tom@Dewitt

I don't have a complete radiator photo, but here's an old right hand tank. The 3/8" tube is broken off, the drain is ripped out, and it's for the automatic trans. The tank for the manual is exactly the same except the two tranny holes are not there.



Here's the 1973

Kalway

Ey Tom, just looking at the picture of the '73 there, what's the difference between the '73 radiator and the '77 - '82 radiator anyways? The only difference I can see is the upper hose attachment.

71LS5

Ahhhhh now I get it.

Thanks Tom!

It looks like I had no presure in my origianl copper surge tank since I had the filler neck on my old radiator. This means that the "excess" overflow coolent was flowing into the surge tank from the radiator. Was this a one way trip only? Now I wonder if it was acting like an overflow tank or was the purge just going one way ... into the surge tank.

Dont mean to beat a dead horse but I am learning here about my cooling system...its not all obvious to me....

Tom what do you think was going on with my set up? Is the single presurized cap at the surge realy better? If so why? It looks like I have a choice.....

Thanks in advance for your resaonce (all resonces welcome!)

0Tom@Dewitt

There are "Expansion Tanks" which are pressurized and then you have "Recovery Tanks" which are not. The easiest way to answer this is to just say "Keep it stock". I not one of these purest that want everything original, I just think GM did this stuff for a reason with a lot more research than our backyard tests.

If your set up had the heater hoses plumbed in, then it was still pressurized. You could leave it that way by using one 18# cap and one 13# cap. The 18# would never blow.

I like the single cap, presssurized system because it:
1.keeps the radiator 100% full
2.provides a "high point" for air to seek
3.makes it easier to fill because of the location

zwede

The expansion tank goes inline with the heater hose so yours was still (mostly) working. The smaller hose to the filler neck is so that air can get out of the radiator and go into the tank. This part was not working right on yours as the radiator cap stopped it.

0Tom@Dewitt

The 69-72 BB & the 73-76 unit use a 27.5" core
The upper is a 90 degree
the lower tube is mounted higher up the tank and it's a 1 3/4"
the right tank is 2.5" deep

The 77-82 core is 26.2
the upper is straight
the lower tube in mounted at the bottom and it's 1 1/2"
the right tank is 3.0"deep