Bypassing radiator transmission cooling. (1 Viewer)

[Maynster]

I’ve read several threads on the subject, but I have not seen a total consensus as to whether or not this is detrimental to the transmission. Needing a new radiator, i’m thinking about going with an aluminum radiator minus the transmission lines. Thus going directly to the trans cooler behind the grill.
any long term issues?
thank you for your time

 

[Wyatt Pine]

That would work OK. The trans cooler lines also aid in warming up the transmission. I would think you'd be ok.

 

[jjdeneen918]

Why mess with Mr T’s engineering?
I put in a Ron Davis radiator, it comes with the radiator/trans ports.
I think it would be more work to replumb all the lines.

 

[Marco Lau]

I have thought about this when i was looking to upgrade my radiator. The automatic tranny puts out more heat and thus having a secondary cooler is important. It also acts to heat up your tranny fluid faster in colder climate as water heats up faster than oil. The only drawback might be limiting your radiator cooling for those is at the capacity of the stock radiator.

 

[Dave 2000]

Being a mechanic in an area where there are 40c on the coast and -20 a few hours drive away in the mountains where there are people skiing I have to say I would go through the engine radiator after the cooler behind the grill to help bring the trans temps up. Having said that I am not a lover of trans lines through the engine rad for a couple of reasons. The first is the biggest problem when there is a failure in the inside and the transmission gets ruined by water getting into it. And the second is there is secondary heat being added to the coolant so not good in hot climates.

If I had a free hand I would fit a decent trans cooler and thermostat, this way the trans gets to the right temperature, and the engine rad is left out of the equation.

regards

Dave

 

[ZackR]

Keep in mind the transmission needs to warm up to allow for the use of 4th gear and torque converter lockup. By having the transmission fluid warm up quickly in conjunction with the engine temps (via the radiator) both of these can happen sooner.

From my understanding high transmission temps are not a common issue on these vehicles.

1994 FSM

 

[Dave 2000]

Unfortunately there has been numerous posts about the transmissions overheating, and I have seen it here in Spain. It normally rears it's head during a long hot climb.

regards

Dave

 

[Maynster]

I’ve not had a heat problem with the transmission, but as I’m to understand, the 80’s here all got the supplemental cooler on them. I’m in need of a new radiator, as the one I have is leaking, and if I’m understanding right, the TRad 3 core brass radiators are no longer available. I’m playing with the idea of a Ron Davis, or other US aluminum radiator, however painful that is to the wallet. The cheapest, being $800 or so from Wizard Radiator. I‘d go with CSF, but as I’ve searched the board, it’s a mixed bag on quality?
thanks for the info, it’s appreciated.

 

[Marco Lau]

I’ve not had a heat problem with the transmission, but as I’m to understand, the 80’s here all got the supplemental cooler on them. I’m in need of a new radiator, as the one I have is leaking, and if I’m understanding right, the TRad 3 core brass radiators are no longer available. I’m playing with the idea of a Ron Davis, or other US aluminum radiator, however painful that is to the wallet. The cheapest, being $800 or so from Wizard Radiator. I‘d go with CSF, but as I’ve searched the board, it’s a mixed bag on quality?
thanks for the info, it’s appreciated.

I went with CSF when my stock one blew @ 220k, and had nothing but overheating with it for 3 months.....yanked it out and tossed it into the dumpster next door (literally). Luckly for me...i have a 3FE, or for most 1fz-fe owner will be crying for spending $3-5k on HG repair...for me, $1000 is a cheap insurance.

 

[cjmoon]

I only use the stock secondary cooler bypassing the radiator. In the winter anything below 45deg F I cover it other wise the trans will never warm up past 80-90. I run a stand-alone trans computer and adjusted all my temp lockup and shifts down. If the trans is below about 80 it flares and slips locku. But keep in mind I have a lot more low end torque.

so morel is the clutches when cold don’t grip as well. Modern trans use clutch material that grab better at high temps and keep trans at 160 F with the use of thermostats. That’s to hot for the a343f. It’s happy 100-130. Sluggish shifts over 150.

I haven’t found a 100-120deg thermostat yet. All aftermarket are geared toward the modern 150-160 mark manufactures require. Otherwise I’d already have one. In my system.

 

[Heckraiser]

Being a part-time participant in the 4runner world over the years, radiator failure trashing the transmission by introducing coolant is a very common failure point. The term "pink milkshake" is just as ubiquitous to 4R guys as "PHH" is to 80 guys. The radiators have a similar design, I often wonder why it's not really a thing for us. Especially given the variety of aftermarket radiators we all use. Also since the 1fz is so sensitive to heat, makes sense to devote all the radiator size (via aftermarket radiator) to water and cool the transmission separately.

But what do I know?

 

[baldilocks]

I’ve not had a heat problem with the transmission, but as I’m to understand, the 80’s here all got the supplemental cooler on them. I’m in need of a new radiator, as the one I have is leaking, and if I’m understanding right, the TRad 3 core brass radiators are no longer available. I’m playing with the idea of a Ron Davis, or other US aluminum radiator, however painful that is to the wallet. The cheapest, being $800 or so from Wizard Radiator. I‘d go with CSF, but as I’ve searched the board, it’s a mixed bag on quality?
thanks for the info, it’s appreciated.

You are over thinking this. The Trad aluminum 2 core radiator that is still available will out perform any brass/copper radiator you buy. I’m also one who ran the CSF for a couple years and had my eyes glued to my aftermarket temp gauge the whole time. I now run an oem aluminum radiator and have forgotten about my temp gauge. The two rows of larger tubes and the all aluminum design flows better (water and air) transferring heat well.
If you live in northern regions, the need for a Ron Davis is not there. I’m not sure the need is there for any 80 owner.

The water in your radiator will cool trans fluid down rapidly compared to the air cooler up front and will aid in warm up on those cold winter days. My dodge/Cummins tow vehicle has its own little radiator for the trans fluid and then it moves on to the air cooler up front just like the 80 which was designed to operate in harsh conditions of all kinds around the globe. Some things just don’t need to be “fixed” by shade tree enthusiasts.

 

[Maynster]

I’ll prolly end up with an aluminum radiator, and as for the need for a Ron Davis type... I run a supercharger, and do frequent the south west. I’m looking at the Wizard Cool radiator as well. US made and simpler hook up for the transmission lines into the radiator itself.

 

[madisonr34]

Bypass it if you want. I did in my corvette and I get around 140 ATF temps driving around town all day. I was up in the 200s with the radiator in line. cold starts around 75 degrees but goes over 100 in quick like 2 min. The being said, I got over 300k miles on the stock factory cooler inline with radiator. I would worry about extreme cold only.

 

[PeterTheBeater]

With a gauge monitoring fluid temps in the oil pan I’ve never ever ran above 150* in California.

 

[Maynster]

Good to know. You’re at an area that see temps higher than mine on average as well.

 

[asutherland]

I have some real life experience to add to this thread.

I've got a 1hdt in my LX, and the OEM LX gasser radiator was not cooling the truck well enough on hot summer days.

So I purchased a brand new OEM Toyota diesel radiator. But they don't sell them anymore for auto, so my new rad did not have the trans cooler section in the bottom. I plumbed out of the trans directly into the front mount trans cooler and back. That was last summer.

I live in a semi-dessert part of central BC.
I have an aftermarket coolant temp gauge and trans temp gauge. Last summer, even at +30C, I did not have any issues with the trans getting too hot. In fact, I didn't see any different temperatures on it at all, compared to when it ran thru the radiator first.

This winter, we have now seen -22C, and still I have not noticed any issues with the trans warming up. In fact, it warms faster than the coolant does. So I don't believe, at least in my case, that the coolant would help it warm up, especially since the thermostat would be closed/nearly closed the entire time the trans is warming to OP. temperature.

Tag @Cruisin'

 

[flintknapper]

Keep in mind the transmission needs to warm up to allow for the use of 4th gear and torque converter lockup. By having the transmission fluid warm up quickly in conjunction with the engine temps (via the radiator) both of these can happen sooner.

From my understanding high transmission temps are not a common issue on these vehicles.

1994 FSM
View attachment 2241414

An older post I know....but just to clarify (many folks misunderstand this), the transmission will not shift into overdrive (or remain there) unless the COOLANT temp (not transmission fluid) is at certain parameters.

 

[zapatius]

When I purchased my Cruiser, the radiator was already bypassed. I have not had any overheat issues with the transmission. I normally let it run for until the high idle stops until driving, if it's cold. I also routinely drain and refill my transmission with Redline D4 ATF.

 

[QuackAxel]

You are over thinking this. The Trad aluminum 2 core radiator that is still available will out perform any brass/copper radiator you buy. I’m also one who ran the CSF for a couple years and had my eyes glued to my aftermarket temp gauge the whole time. I now run an oem aluminum radiator and have forgotten about my temp gauge. The two rows of larger tubes and the all aluminum design flows better (water and air) transferring heat well.
If you live in northern regions, the need for a Ron Davis is not there. I’m not sure the need is there for any 80 owner.

The water in your radiator will cool trans fluid down rapidly compared to the air cooler up front and will aid in warm up on those cold winter days. My dodge/Cummins tow vehicle has its own little radiator for the trans fluid and then it moves on to the air cooler up front just like the 80 which was designed to operate in harsh conditions of all kinds around the globe. Some things just don’t need to be “fixed” by shade tree enthusiasts.

Do you have a PN or link to a oem aluminum radiator that fits the 80? All the ones I'm finding online are single row.

Any opinions on these?

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