My radiator cracked a few months back while i was a few hrs from home and since it was on the top and only leaked when my blazer was turned off while it was still cooling down it didnt strand me out of state. I drove it cracked for over 2 wks til it finally just blew coolant everywhere. I didnt have much money so I got a used one from a junk yard which I have gotten good parts from for years...but then....Ive had issues overheating and after replacing a couple things that didnt work (didnt consider the radiator since I had only put that one in about 7 mths ago) I was stumped. I thought at last it was my water pump but the shop said the water pump was fine and decided to pressurize my radiator just to make sure it was ok. I hadnt lost any coolant but at the same time my coolant wasnt circulating hardly at all either. As soon as the radiator had pressure it started leaking out a crack in the plastic, the same exact area as the last radiator. Why is it that these radiators can crack and cause the engine to overheat yet they show no signs of having a problem for so long? Ive never had nor heard of any radiator having a crack in it period, regardless of the location of the crack, and it not leaking coolant...until I had the problem with the ones in my blazer that is. Has anyone else had a cracked radiator that didnt show signs of a problem right off or else had a crack they knew of but was still able to drive it for a while before having to replace it?

 

Cracking seems to be an issue with the plastic tanks on the side of these radiators. How often have you flushed out your entire cooling system?

 

Ive owned it close to a year and hadnt ever flushed it until last week, then found out about the crack in my radiator yesterday. There wasnt enough circulation of the coolant to even see it moving though so when i get it back from the shop with the new radiator should I flush it again? The one that just cracked on me I also bought used so the one getn put in it now is BRAND NEW and I totally learned my lesson on a used radiator!!

 

Yeah... I drove my prev tbird about 3 months with a weeping crack below the coolant return hose .. didnt want to get a new one because I was retiring it. Got set for a 3 hour freeway trip home and found puddle. Ended up replacing with new before I left.

I think the life of those plastic tanks is about ten years. Before we moan about how they're designed to be replaced.. lemme tell you 'back in the day' -meaning the sixties- that would have been great!

Dilemma.. I have a 9 month old rad in a car I'm driving to junkyard. And a unknown age rad shop serviced one in my current car.
Swap or not!!!
Thinking not.

 

Make sure you are not tightening down the clamp too hard, as stated, plastic radiator tanks... bad Idea GM.

 

I had the driver's side plastic tank crack on my radiator, too (2000 4WD). I replaced it with a new one in August and haven't had any problems since. The crack was up near the top, on the front side, and went straight thru some of the ribs. (I have pics if you're interested.)

While I was in there I did the thermostat and - since it was about $30 and therefore relatively cheap - the water pump, too. There's enough stuff in the way there that for a nominal additional cost (in money and skinned knuckles) it was well it to do a little preventative maintenance.

I think your "mistake" was buying a used radiator, but I don't blame you for trying to save a few bucks :-P

 

Replaceing plastic tank rad with plastic tank rad bad ideal

 

Plastic tank radiators are used in likely billions of vehicles around the world without issue so I don't see the reason to bash them...

I'd start looking for reasons why the tank split instead of just blaming a design that you really can't do anything about without buying a custom radiator.

Have either of you looked into possible core support damage? Misplaced mounting supports causing undo tension in the radiator?

 

Why? How long have you continuously driven the same car with the same metal tank radiator?

Metal tanks cracked, too... very common. The main problem though was the solder joint between the tank and hose fit tubes would break Or the tank connection at the core.
Duck soup to fix for a shop back when new radiators cost 100-150 and the shop hour rate was 20-25.

When mfrs started using plastic tanks, the issue was the seal between the tank and the core would degrade and leak. That's what happened with my 84 SVO at about ten years, I think that was 1996. I took it to a radiator shop and the guy wanted $100 to fix it.
Well, a new Modine was $130 at the time. Common topic of conversation on the Ford forums... Most agreed it wasnt worth fixing.

The bottom line is the OP put a used rad in 7 months ago. He had no idea how old that radiator was.
Plastics under heat have a definite life expectancy.
Now.. you want to gripe about water passgaes in plastic intakes, I'll go there with ya. But the Mfrs learned from that, and the earliest fails out of near 100% fail over life of vehicle, cost them some bucks for going against common sense.

But metal vs plastic radiators are a different story, they failed at about ten years too.

 

It just seems as if it would be easier to crack a plastic tank over a metal one. But you would think, that metal would indeed be stronger than plastic.
But I see what you are saying.