What causes radiator leaks

[Sayjac]

Recently had to replace radiator on 01 Tacoma 3.4L, ~155k miles. It had no visible cracks in the plastic tank. Where it started leaking was where the plastic tank sits atop the metal and the clips fold over the tank. In this case I speculate the glue that seals and holds, just got old. ~18 years to be expected and I've got zero complaints. It was an OE Harrison, good radiator ime and imo. I have read of cracks developing in some Tacoma plastic tanks.

Replaced with a Denso (made in China) and that's what I would advise you to use. I got mine from Amazon, it was less than RA with shipping considered. Also had to buy a new cap because Denso opening smaller than Harrison.

130k miles 07, not too bad imo.

 

[FCD]

Having two cars of which one has an all metal rad and the other a plastic / alu rad, i've realized both have their weaknesses.
There is no way to make a totally fail-proof radiator.

In the older metal construction radiators the solder that keeps them together is very susceptible to corrosion, ( put a coolant with 2-Eha in one of these if you want to kill them )
And in the modern plastic / alu types they always go at the clips that attach the plastic tanks to the core.

 

[Jim K]

Not that I need one ,but out of curiosity I looked up a Denso Radiator for my 2014 Corolla and found it with free shipping for $130 . Never have replaced a radiator just wonder how hard it would be?

 

[Sayjac]

Originally Posted by Jimkobb
Not that I need one ,but out of curiosity I looked up a Denso Radiator for my 2014 Corolla and found it with free shipping for $130 . Never have replaced a radiator just wonder how hard it would be?
Admittedly I'm not familiar with 14 Corolla but have replaced two radiators, as noted one very recently. What I've found in both, the prep work leading to removal is the biggest part. Actual replacement, not tough. I did have to remove Tacoma grill to get to radiator, not difficult, just meant having replacement clips on hand as they tend to break. Below is a thread for 01 Civic replacement.

Generally there's some good youtubes and vehicle specific forum threads to use as a guide. Ime, taking ones time and having proper fit radiator on hand from the get go makes it a doable diy with a minimum of tools and mechanical skill.

https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/3282728/01_Civic_Radiator_Replacement_

 

[kschachn]

Originally Posted by JHZR2
Interesting that the plastic top radiators in every older German vehicle Ive owned (81, 82, 83, 85, 2x91) have all been original, a number of them having >>200k on top of the decades old age.

Meanwhile, the radiator on my parents 94 Previa was the only thing that failed more than once on that van, which was super reliable and great until Hurricane Sandy caused its demise with >230k.

I think I'd argue Toyota (and Honda, personally encountered two integrals with hairline cracks in the radiator tops) don't make their radiators thick or robust enough.

My BMW radiators leak at the crimped tank seams regardless of the brand. The only failure I've ever had on my Asian cars was like you describe, a hairline crack in the upper tank. It just happened two weeks ago on my old Sienna. I noticed it at the first gas stop into a 1600 mile trip, fortunately it only leaked a little and didn't catastrophically fail. I replaced it immediately after returning with a Denso radiator.

This was not the original radiator, it was replaced about 10 years ago after a minor accident.

 

[PlzRepond]

When you remove the tranny cooler lines, a small amount of fluid is lost (at least from the vids I've seen). Does this need to be replaced or is the amount negligible?

 

[bionictony]

my guess is dirt gets trapped in the fins and the temp increases on the plastics/rubber and eventually they crack and leak. sometimes the coolant corrodes through the heat exchanger and contaminates the atf fluid. i'm glad i'm able to replace mine at cost if it were to ever happen to me. while you're in there you might as well replace the upper and lower hoses also. keep the toyota oem clamps. don't use the worm type clamps.