Mishimoto Thermo Bypass - Install/Thoughts

[cgunter73]

I figured i would share my experience with the MishiMoto thermo bypass valve and why i decided to buy one.

So the internet can make you do stupid things. Take for instances the hysteria about the OEM bypass valve. it will fail, shops have been replacing them right and left, blah blah.
Ive dropped some serious coin on my truck with the turbo actuator going out. Since I have 120K on the truck and didnt have 80K to plop down on a new truck (nor did i want the crazy high payment that would go with a loan), I wanted to make my truck last as long as possible. Its paid off and hasn't really given me any issues since the water pump came apart at 30K. I decided to upgrade the turbo, have some parts fall off, and tune it. I also changed out all the fluids since its been awhile.

I got to reading about this bypass valve and the "need" to replace it lest if fail at some bad time. I did some research and settled on the Mishimoto bypass valve because it has a thermostat that i could replace with a bypass if i so choose and it has a Lifetime Warranty. Supposedly it flows better than the stock valve but I havent found the numbers. I was also impressed with some users claiming how much cooler their transmission fluid was. More on that later.

Install was fairly straight forward. Watch the video if you want. There are many online. One bit of advice. Make the swap out when the transmission is cool, meeting you havent drove it. I tried to change out the valve after I got home from work and i thought i was going to drain the whole transmission. The next day i did it and drained out maybe a half a quart at the most. Make sure the O rings stay on the hard pipe fittings.

I took it out for a spin and wasnt really impressed. I was expecting a huge difference as in before the swap out my temp ran around 175. After it runs around 160 -165. I dont think converting it to full bypass is going to make much difference other than delaying the temp from getting up to whatever normal operating temperature is. It just doesnt make since that a bypass will keep your transmission fluid from reaching whatever temp is going to run at on a given day at a given outside temperature. Claims at running at 140 degrees beg the question of the outside temp and how long the truck has been running.

So all in all, was it worth the money? I dunno I think i could have used that 164.00 to buy a new front cushion for the truck vice really NEEDING to change the valve out. Was it easy to remove and replace. Sure it was. Surely someone makes some intermediate hoses to join the hard pipes at the transmission to the transmisision cooler lines and save yourself some money. Or figure out a way to remove the thermostat in the OEM valve. In the end i think its solving a problem that doesnt really exist.

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[AK Bob]

I figured i would share my experience with the MishiMoto thermo bypass valve and why i decided to buy one.

So the internet can make you do stupid things. Take for instances the hysteria about the OEM bypass valve. it will fail, shops have been replacing them right and left, blah blah.
Ive dropped some serious coin on my truck with the turbo actuator going out. Since I have 120K on the truck and didnt have 80K to plop down on a new truck (nor did i want the crazy high payment that would go with a loan), I wanted to make my truck last as long as possible. Its paid off and hasn't really given me any issues since the water pump came apart at 30K. I decided to upgrade the turbo, have some parts fall off, and tune it. I also changed out all the fluids since its been awhile.

I got to reading about this bypass valve and the "need" to replace it lest if fail at some bad time. I did some research and settled on the Mishimoto bypass valve because it has a thermostat that i could replace with a bypass if i so choose and it has a Lifetime Warranty. Supposedly it flows better than the stock valve but I havent found the numbers. I was also impressed with some users claiming how much cooler their transmission fluid was. More on that later.

Install was fairly straight forward. Watch the video if you want. There are many online. One bit of advice. Make the swap out when the transmission is cool, meeting you havent drove it. I tried to change out the valve after I got home from work and i thought i was going to drain the whole transmission. The next day i did it and drained out maybe a half a quart at the most. Make sure the O rings stay on the hard pipe fittings.

I took it out for a spin and wasnt really impressed. I was expecting a huge difference as in before the swap out my temp ran around 175. After it runs around 160 -165. I dont think converting it to full bypass is going to make much difference other than delaying the temp from getting up to whatever normal operating temperature is. It just doesnt make since that a bypass will keep your transmission fluid from reaching whatever temp is going to run at on a given day at a given outside temperature. Claims at running at 140 degrees beg the question of the outside temp and how long the truck has been running.

So all in all, was it worth the money? I dunno I think i could have used that 164.00 to buy a new front cushion for the truck vice really NEEDING to change the valve out. Was it easy to remove and replace. Sure it was. Surely someone makes some intermediate hoses to join the hard pipes at the transmission to the transmisision cooler lines and save yourself some money. Or figure out a way to remove the thermostat in the OEM valve. In the end i think its solving a problem that doesnt really exist.

My understanding is the stock transmission thermostats generally fail in the stuck closed position. This results in no transmission fluid flow through the cooler and over heats the transmission.

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[cgunter73]

Thats what I read too. And i can see that if you aernt monitoring your transmission temps then you could smoke it if the OEM valve fails. I just havent found that its a product of a defective design or that its a common occurence. The Mishimoto valve is beefy ill give it that.

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[AK Bob]

Thats what I read too. And i can see that if you aernt monitoring your transmission temps then you could smoke it if the OEM valve fails. I just havent found that its a product of a defective design or that its a common occurence. The Mishimoto valve is beefy ill give it that.

Agree, also the Mishimoto valve is rebuildable with a replaceable thermostat.

The thermostat assembly can be easily removed if necessary to give full bypass flow through the cooler should it ever stick closed.

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[Chrisn162001]

The thermostat failure rates aren’t as bad as people think, but they fail.

And yes the bypasses do keep them cooler constantly not just until they warm up.

With a bypass temps are generally 50-60 above ambient temp.


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[cgunter73]

The thermostat failures rates aren’t as bad as people make it seem. But they do fail.

And yes the bypasses do keep them cooler constantly not just until they warm up. With a bypass temps are generally 50-60 above ambient temp.


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I’ll have to convert it to full bypass and see what it does.


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[Chrisn162001]

I’ll have to convert it to full bypass and see what it does.


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I would.

It won’t hurt it at all.


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[Tankstagno]

I just did the ATS Thermal bypass, and my transmission (Aisin) has been running about 135.

The outside temp here in Tennessee has been from 85 to 95.

I was worried it was too low, but the lower, the better.

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[z28-50]

Tagging for temps after "convert it to full bypass."

Assume this means removing the thermostat.

I have one NIB (Mishimoto bypass) not installed yet.

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[That_One_Person]

@cgunter73

Do you have a Deep Pan or any other mods installed?

I installed a Revmax unit in the past few weeks.

Almost forgot an o-ring going back in.

Mine will get up to the mid 150s on my 33 mile commute in the afternoon heat.

Better than 168-172 that it was doing.

Short trips or on my morning commute, I see the magic 140 number.

No deep pan on mine.

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