NEW RADIATOR - Expansion/ relief cuts in core frame

[bob3dsf]

Hey,
Just received my new radiator to swap into the rig. I noticed it has 2 "cuts" in the top and bottom aluminum frame. They don't look hacked in. They are equidistant from the sides, but each from the opposite side, so they are offset as you're looking at it from the front. And, they don't effect the fluid channels. It's a Denso I ordered from rock auto. I had read of people finding this before on parts ordered. A little searching found some info that they are not defects or damage, but relief cuts to allow for expansion and contraction with heating and cooling. Is this really a thing? It does make sense. My OEM doesn't have them as far as I can tell, and maybe it was the expansion and contraction that finally let to it's failure. It's got 264k on it, but I've been hunting a coolant leak and finally found it in the radiator when I pulled back the fan shroud, where it's been hiding for a while. Thx for any opinions.


**UPDATE** If you don't have dedicated radiator hose pliers, you might want to take out the old radiator with the lower hose attached, but disconnect at the thermostat housing (this is on a V6). Then transfer your hose to the new radiator so you can get the clamp on correctly. I tried to attach that stupid hose to the lower connection and I couldn't get the hose seated like I wanted, or get the clamp slid back on. I had to take it all back out and pull the lower hose off the thermostat. And those cuts aren't damage. They are totally fine

 

[<<<<]

Save yourself trouble finding defect after install. Cap lower outlet and fill this radiator with distilled water on the bench. If that notch or any other area leaks - you know there is an issue before diving into the swap.

 

[Boort]

Hey,
Just received my new radiator to swap into the rig. I noticed it has 2 "cuts" in the top and bottom aluminum frame.... A little searching found some info that they are not defects or damage, but relief cuts to allow for expansion and contraction with heating and cooling. Is this really a thing? It does make sense.

Sounds like they are accounting for the Thermal expansion coefficient of the material. Using Aluminum as an example I usually have to increase part size by 3-5% when casting to ensure that my final part is within tolerances when cooled. The previous unit may have accounted for the expansion in another way: Looser fit in the frame, expansion slots in the mounting at one or both ends, etc...

This is similar to accommodations needed for woodworking with solid woods. The reason bread board ends and sliding dovetails can't be glued full width when interfacing grain endgrain to long grain is that as the wood shrinks and grows with humidity and temp changes the trapped wide boards will tear the piece apart.

Boort

 

[bob3dsf]

Save yourself trouble finding defect after install. Cap lower outlet and fill this radiator with distilled water on the bench. If that notch or any other area leaks - you know there is an issue before diving into the swap.

Nice. I hadn't thought of that. You mean the where the lower radiator hose attaches?

 

[<<<<]

Yep. Use some plastic bag and strong rubber band to cap that.

 

[bob3dsf]

Yep. Use some plastic bag and strong rubber band to cap that.

I did and confirmed no leaks. Thanks for the tip.

 

[missionman]

I just bought the exact same Denso part off rockauto after my 2003 4runner v6 hit 290,000 miles and my radiator is sagging.

The offset relief cuts on top and bottom are normal. They allow slight clearance in the frame for flex under heat or damage (impact) preventing the cores from leaking if the frame gets damaged or heats up to high temps. Its more likely an object will hit it from the road so if you didnt have these relief cuts the frame would uniformly push on fluid cores to the max breaking point. This way the frame can fail while not taking the cores with it. Basic physics failure control.

This sagging on my 4runner radiator will eventually happen to all 4th gens (not 3rd gens due to different design) with original OEM radiators. The frame of the 4runner saves it from completely bursting open. Notice the cuts and holes do not exist on original Denso radiators and notice how the sagging takes the cores to their max breaking point. Again, this design is for easing damage and fatigue sparing the cores. My OEM radiator flexed causing minor leaks on both sides on the bottom.

It also caused the top transmission cooler inlet to fracture causing a drip of trans fluid.

If you have sagging radiator in a 4th gen YOU BETTER REPLACE IT ASAP or you're risking catastrophic failure in so many ways its insane.
Mixing of coolant and trans fluid into your trans, engine overheating, trans overheating, trans or engine hydrolock destruction (irreversible damage) of your entire engine block (camshaft broken/bent, cracked piston, etc).

Basically your engine grenades itself.