DUB

Well...to start this of I am dealing with a 1978 that has a 'getting hot' issue when the A/C is on and idling at stop lights, etc. When the A/C is not on..it is OK on coolant temps. But it can get to 240+ degrees Fahrenheit when it is idling too long. When it gets moving ..it does come down... but not to where it should be..or where I want it to be.

After doing some changes to this and that..it improved slightly but it still got hot and I took out the four row copper/brass radiator and looked at it carefully and WHAM....I noticed something that I wanted to pass along.

Please keep in mind I work on Corvettes and I am NOT a professional photographer..and I TRIED my very best to get photos of what my eyes could see...but it is really hard to do that.

These first 3 photos are of the current radiator I removed and we are looking at the inside of the bottom tube. This aftermarket radiator fit perfectly...has a PROBLEM....and that is the colloer for the automatic transmission fluid that is made into the tank...is so CLOSE to the tube that feeds the water pump..I wonder how any water can get to the water pump. LITERALLY I do not think I could get a wood matchstick between the cooler and the opening in teh tank where the tube is soldered.







That little bit of solder you see is not an issue.

That little drop of coolant you can see is right at the edge of the tube...and due to the cooler getting black paint on it from the manufacturer. It is really hard to see...but regardless if you believe me or not...if you are replacing your radiator and it is like this design...take note and inspect this area.

These photos are of a factory HARRISON radiator I have and it is completely different in this area. The space between the transmission cooler and the

tube is an easy 1/4".





SO...just because you have just purchased a four row radiator or whatever it is...ASSUME NOTHING and make sure you inspect it like a HAWK!!!

DUB

OMF

that's a really good catch.....I can see how the auto trans cooler blocks off most of the coolant flow towards the waterpump, and yet you would never know it's different looking from the outside.
You really have to wonder about these aftermarket suppliers...

Street Rat

Good information DUB.

0Willcox Corvette

One issue I've found with the aftermarket radiators is that most don't have the relief in the lower hose tube for the sway bar and on the earlier big block cars the lower tube is make in a 90 instead of a sweeping curl like the original radiators. Neither of which can be installed.

Willcox

DUB

I am having the tank that has the transmission cooler removed and I will remove the tank off the HARRISON radiator I have and post photos.

All I know is that I better get the coolant temps to where I want them. I hope hat I found the problem.

DUB

C3 4ME

Wow, in an million years, something I would have never thought to look at. Thank you DUB for all that you do!

Emeightch

Good catch!

croaker

Thanks for sharing. This could spare someone a lot of grief

SharkAttack

Thanks DUB, good info. When I had my 72 radiator re-done, the tanks were fine so I had them just install a new core on the tanks. Fortunately that means I won't encounter this issue ... this time.

Ben N

Nice catch DUB!

Ben

DUB

Thanks to all of you...and TRUST ME..I am going to post the photo of what the transmission cooler looks like in the tank when it is off and you can see it compared to the Harrison one I will take off.

DUB

Red86Z51

Wow DUB...you never cease to impress! That is one check I will NEVER forget to make when replacing any radiator ever again!!

Thanks for sharing this very important information....this thread is a MUST READ for anyone and everyone who maintains their own vehicles!!

Dave

7T1vette

With that amount of restriction, I'm not sure how it cools when it's cruising down the road!

Usually, if the cooling system works when running, but not when at idle, the culprit is the thermostatic clutch on the fan. When idling, that's when that sucker is supposed to do its work.

DUB

Well it must be able to cool good enough as long as the A/C is not on. I think it is on the 'razors edge'

I do know the owner has always stated that he has had a cooling temp problem when the A/C was on ever since the put that radiator in.

I agree...but that is why I removed the fan clutch and used the 'clutch eliminator' and tried it again with NO change.

I got the old radiator back ( with the one tank removed) from my radiator guy and he stated that it flowed as it should...but I swear...that darn transmission cooler looks like it is blocking coolant flow.

I am going to try to find the time to take the tank off the Harrison radiator I have to compare it.

I got in the new aluminum radiator and installed it today and will check it out tomorrow and HOPE that this fixes this problem. I already double checked the timing and it is good to go.

DUB

DUB

Glad to read that some of my suggestions i have given you have been of some help to you.

I did not have the time to remove the tank on the Harrison radiator today.

I DID get he car that this thread is about working and cooling VERY VERY GOOD...SO ...I am super duper happy with it. The clutch fan was put back on and the temps stayed the same as when I tested it with the 'fan clutch eliminator'...so I know that was not a problem but worth checking.

The problem HAD TO be in the radiator even though my radiator guy tested the flow and said it was OK. I am glad I 'bit the bullet' and put in an aluminum radiator.

DUB

DUB

Your 'technical jargon'; was just fine and made sense to me.

Also glad to see that the thermostat you posted a photo of has a small hole in it to help 'burp' the air out of the block.

Also glad that you found the problem and fixed it...regardless of the amount of time that it takes to fix anything...when it gets repaired...it is a great feeling.

DUB

USAFVeteran

I put a Dewitt's radiator in my big block, and even on initial fire up, with no fan in front of the car, it got to 200 degrees as we were tuning the FAST. The weather has gotten hotter here since then, and driving in traffic, stop and go, the highest I've seen it is 220 degrees.


I'm looking at the gauge, and the sending unit for the gauge is in the left head. I'm very surprised with this, every big block I've built over the past 40 something years has been just on the hot side during break in.


I guess my building was right, and my son was right on the tuning (he's done a few throttle body injection systems, it's my first). Less than 100 miles till the first oil change, and then I get to turn the screws up on it!!!


And Dub, I've seen that on 1 radiator before, just one in my life.

DUB

As promised...here are the photos of the tank that was on the radiator that was in the car that this thread is all about...and the tank to teh right is off of a original Harrison radiator I had. And for any non-believers/conspiracy theorists...if I have to take photos of the 'Harrison' logo stamped in the tank... I will.

YES..as oyu will see...there is a difference ..BUT I must be honest and say that is was not as bad as what I thought it was. BUT there is still a difference. And when it comes to fluid flow....it CAN make a BIG difference. NOW...if this area is what caused the problem...who knows...but it is something to possibly consider when you can see a visible difference.



The photo BELOW is the tank off the radiator that was not working efficiently. You are looking at the gap BETWEEN the transmission oil cooler and the outlet tube.



This is the tank off the the HARRISON radiator and you can see the width difference. It is not a lot..but enough.



Below is the tank off of the bad radiator.



Below is the tank off of the HARRISON radiator.



The transmission coolers have NOT been touched in any way to alter what you see. They are EXACTLY as they are when the tanks were removed.

DUB

DUB

THANK YOU for passing that along.

Then ...this makes number two. So...trust me..I will be looking and checking this area if I have a problematic cooling issue on a Corvette with a radiator like this....OR ...if I am installing anew copper/brass radiator for someone.

DUB

USAFVeteran

Yes sir, I'll be checking every auto radiator I have anything to do with. This is a stumper, and easy to find. Well, now that we all know to look for it.....