Bypass radiotor instead of replacing? - Toyota 4Runner Forum

Boudin · 11-12-2019, 10:07 AM

Just wondering on everyones input. 99 with 144k miles, original radiator. Was trying to replace it but after buying and returning 4 of them for broken overflow nipples and crushed cores I'm ready to give up on getting a good one and just bypass the trans cooler to an external one. The stock radiator isn't leaking and I did a couple flushes to clean it up. I should be OK as long as I bypass the trans cooler right?

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BoomerBob · 11-12-2019, 11:14 AM

I bypassed my radiator with a Hayden 678 trans cooler with great results so far but on my 01 I don't do heavy duty 4 wheeling. I did pull a mountain dirt road during a 90 deg day and saw the trans cooler temp (Ultragauge) get up to 204. It normally runs in the 150-165 deg range.

I'd definitely replace the radiator anyway when you can. I recently replaced an engine because the upper hose blew off the radiator. Not sure why you're getting damaged parts. Have tried ordering from Amazon? I got this one in great shape shipped to my place.

PS: If you live in cold country; it sucks to have to do emergency repairs in the Winter. Also; nice looking rig! I might be a little biased. ;)

brillo_76 · 11-12-2019, 11:20 AM

Did you purchase from Rock Auto Denso?

The after market sadly seems to suck for radiators especially the chain auto parts stores. :[

You can bypass like others have suggested. However, nothing would stop a hole from developing and loosing all your coolant through the empty trans cooler tube.

Liquid to Liquid heat transfer is extremely efficient. Where air to liquid isnt as efficient However, lots of folks bypass. I just replace radiators every 10 years to prevent the milkshake. ;)

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calimobber · 11-12-2019, 11:43 AM

I just bypassed mine about 6+ years ago. I capped radiator ends so if a hole does happen it will stay in the radiator.

The main downside I can see is on very cold mornings the transmission is slow to warm up without the engine coolant to help but its been working fine so far. 240k miles on original motor/tranny.

Boudin · 11-12-2019, 11:51 AM

Yea I do really want to replace radiator but tired of returning one after another. All from Amazon, 2 Spectre, 1 Mishimoto, 1 Denso. I thought about just getting a Denso from the dealership. There all the same exact radiator, just rebranded I assume.

I live in the southeast, don't do any towing or offroading, that's why I'm tempted just to do the bypass.

3 years ago all other components were replaced, water pump, thermostat and upper/lower hoses.

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AntleredRuin · 11-12-2019, 12:40 PM

Bypass is fine in your situation.
I bypassed mine and I live in Houston and don't tow and the tranny has never seen over 170.
Just cap or connect tranny nipples on the radiator together. Do pay attention to the age of the radiator, though. If the top is brown and seems brittle, replace it anyways.
I got my radiator from a seller on eBay (when my top split) and he had it shipped to my porch that night (seriously) and it was in perfect condition.

phattyduck · 11-12-2019, 01:02 PM

I'd worry just as much about the plastic tanks leaking/cracking as much as a pink milkshake. If the top tank is turning brown, it should be replaced - whether or not you get a trans cooler. I even opened up my original radiator when I replaced it a few years back to check for corrosion - my trans cooler was still in perfect shape in the bottom tank (no rust or anything).

Try ordering from RockAuto, I think the put a second box around radiators when they send them out...

-Charlie

DK327 · 11-12-2019, 01:09 PM

Radiator is something you'll replace once every decade or so, so I would bite the bullet and get it from the dealer or a place like Camelback Toyota. If you order online, you can write in comments section to the seller to pack it really good so there is no damage to the product, pointing out the nipple issue you've had in the past. BTW, when i replaced mine, it was still the OEM with 233K miles on it. So long as there is no corrosion and it's been maintained regularly, flushed every 30K for example, it should be in good shape. But then again, it IS 20 years old, so I would replace it for peace of mind and as a preventative maintenance.

Mighty Buffalo · 11-12-2019, 01:32 PM

I added a trans cooler in series for added cooling capacity. The B&M 70264 will mount up using the parts in the kit using stock mounting holes, but you'll have to relocate one of the horns.

I ordered a replacement radiator on Amazon, and it came kind of beat up. Maybe try a local parts store, not sure how many carry Denso.

Sarki · 11-12-2019, 02:25 PM

Ordering a radiator online seems to be hit or miss as I purchased a Denso from Amazon a few months back and received it at my door in 2 days with zero issues......not even a single bent fin!
You may want to take a look at Timmy the Toolmans video on adding a trans cooler as I found it really helpful.

T4R2014 · 11-12-2019, 02:34 PM

Quote:

Originally Posted by DK327

Radiator is something you'll replace once every decade or so, so I would bite the bullet and get it from the dealer or a place like Camelback Toyota. If you order online, you can write in comments section to the seller to pack it really good so there is no damage to the product, pointing out the nipple issue you've had in the past. BTW, when i replaced mine, it was still the OEM with 233K miles on it. So long as there is no corrosion and it's been maintained regularly, flushed every 30K for example, it should be in good shape. But then again, it IS 20 years old, so I would replace it for peace of mind and as a preventative maintenance.

The dealer sells the same Chinese made POS you would buy at autozone. You can buy an legitimate OEM for $600 shipped from Partsouq, at that money you could have a Koyo aluminum with an external cooler! But maybe $600 is a steal since it lasts 20 years when maintained.

absalom · 11-12-2019, 02:34 PM

I wouldn’t bypass as your quick-to-warm ATF plays a vital role in bringing coolant temps up ASAP upon cold start.

T4R2014 · 11-12-2019, 02:51 PM

Quote:

Originally Posted by absalom

I wouldn’t bypass as your quick-to-warm ATF plays a vital role in bringing coolant temps up ASAP upon cold start.

Does it really? Both take more time than you'd think to warm up. Even with driving around for twenty minutes on a cold winter day the coolant will be lukewarm at best. I would think the coolant warms up the ATF faster and then maintains the temps.

twitchee2 · 11-12-2019, 03:33 PM

Bypass it, Bigger is better and then make sure you install a oil thermostat to keep it at the right temp.

I have this: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

has 10% flow at all time, starts to open at 160* and full open at 180*. I run it in both my 4runners works great, highly recommend it!

DK327 · 11-12-2019, 05:40 PM

Quote:

Originally Posted by T4R2014

The dealer sells the same Chinese made POS you would buy at autozone. You can buy an legitimate OEM for $600 shipped from Partsouq, at that money you could have a Koyo aluminum with an external cooler! But maybe $600 is a steal since it lasts 20 years when maintained.

Right on, when I replaced mine I went with Koyorad from Amazon and I guess got lucky that it wasn't damaged during shipping. It's been going strong for 30K so far and I've already flushed the coolant once, at 15K miles. I also have an inline trans cooler, I opted to NOT bypass, since the rad is new.

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