To flush tranny or not to flush tranny.

[DouglasReid]

Originally Posted by TitanMike

Everyone has their own ideas but just draining and refilling, even multiple times, often does not get ALL the old fluid out as it's been mixed with the new.

The method that makes the most sense involves a "Fluid Exchange" machine that isolates the old fluid from the new while replacing exactly the same amount of new as was pumped out by the old.

One machine that does this and you can actually see the difference has a trade name of "Viper". Consists of a transparent cylinder with piston that separates the old/new fluid. Pressure from the old pushes the new out in exact amounts. Flushes out the converter and valve body as good as you can get without actually tearing down, rinsing parts, and reassembling.

A lot of quick lube shops use machines like this and as long as they use the proper fluid, not just regular Dexron that the y "dope" with an aftermarket additive to make if supposedly meet the Mfr's spec, they do a good job. Other than hooking the machine inline with a cooling line, the technician is just a long for the ride with the machine doing all the intelligent work.

BTW, the term "Flush" is used which is fine as long as you don't use any Chemicals , just the proper transmission fluid for your transmission All the magic additives are a formula for transmission failure.

I FULLY agree that EVERY ONE do in fact have their own ideas. In addition to this forum I am VERY active in the Duramaxforum.

As I stated in my original post the member who goes by Mr.Transynd is a retired Allison Fluids Engineer. It is my belief that he has forgotten more about the construction, use and servicing of the Allison 1000 transmission than I could ever hope to know.

He is one of the persons suggesting he Double Drain method for switching over to Transynd from Dex VI. It is the ONLY method he recommends. Based on his training, knowledge and experience, which he so generously shares without compensation I trust his opinion. I will nearly always follow the advice of those with more knowledge of any particular subject than I have unless I suspect some ulterior motive. In this case that is not applicable.

Allison DOES NOT recommend flushing their transmissions.

There is a method, called the "Hoot" method which pumps the fluid out and you replace it quart by quart. The problem is if done slightly incorrectly it can seriously damage your transmission, resulting in a multi-thousands of dollars repair. For me, NO THANK YOU!

Do as you please, of course, it is your vehicle and your money.

[babock]

He has a 5.3 which means he has a 1/2T. Need to stop with the Transynd/Allison posts.

[bareftn]

My old 3/4 ton chev had over 275000 miles 150000 miles pulling a 24 ft stock trailer on it before the trans went. All I ever did was change the trans fluid and filter. I would NEVER EVER DO A POWER FLUSH THE OLDER the trans is the more damage it will do to o rings and other soft parts . The newer trucks will run hotter , my 2002 always ran around 200 pulling the trailer and it had a 190 degree thermostat in from the factory which I changed to a 180 and had a trans cooler installed now it runs about 180 or 185

[TitanMike]

Originally Posted by bareftn

My old 3/4 ton chev had over 275000 miles 150000 miles pulling a 24 ft stock trailer on it before the trans went. All I ever did was change the trans fluid and filter. I would NEVER EVER DO A POWER FLUSH THE OLDER the trans is the more damage it will do to o rings and other soft parts . The newer trucks will run hotter , my 2002 always ran around 200 pulling the trailer and it had a 190 degree thermostat in from the factory which I changed to a 180 and had a trans cooler installed now it runs about 180 or 185

This is a popular misconception of what it means when a mechanic hooks up a machine to "flush" a transmission. The only "Power" used is the pump inside the transmission itself and pressures are exactly the same as when you are driving down the road, maybe a lot less considering that the service is done with the engine at idle.

The term "FLUSH" is a holdover term from the 50', 60's, and 70's when chemical companies made fortunes on transmission "Flushing" additives. Add a can of our "Magic Formula", run it for 100 miles or so, then drain the old fluid. These chemicals were merely petroleum distillates that behaved like solvents to dissolve the gum that formed inside from burned or oxidized fluid. They also had a habit of softening seals and 0-rings.

The proper term today is "Fluid Exchange" when old is replaced with new and unlike the "Pan Drop" method, the exchange method also replaces the fluid trapped in the converter with new. The fluid in the converter can be twice what you find in the pan (+ or - depending on design).

Many transmissions have no filters in them anymore, merely a screen that keeps any stray pieces of friction material from entering the system and plugging valve body orifices. A Fluid Exchange won't dislodge them and if enough are caught in the screen, chances are the tranny is ready for a rebuild anyway.

Remember, "Fluid Exchange", not flush.

[dsayl1]

Worked at a GM dealer for a few years now and I've never seen a transmission fail after a flush. I've seen people bring in cars with transmission issues that want to try and fix it with a flush... 100k? Better change plugs, 4x4 fluids, brake flush, and do the trans flush. Change the oil (and check it) a little more frequently now. Those are great trucks. Own a 2012 myself.

[bareftn]

I have seen may fail after a power flush, transmissions are I think is one of the most neglected things of cars and truck when just a few bucks and always checking could prevent many costly repairs. so many people will wait to change the oil only when they reach the miles it says to in the book. ME I do it every other year no mater what the miles are

[spock123]

That’s something I have to get done next month is change all the fluids. The Silverado works hard for me. The oil I can change myself everything else is changed by someone else

[DouglasReid]

Originally Posted by spock123

That’s something I have to get done next month is change all the fluids. The Silverado works hard for me. The oil I can change myself everything else is changed by someone else

They are all very easy and MUCH less expensive if you do them yourself. If you can change your oil, you can do all of these. Here are a couple links to teach you how:

How To: Brake Fluid System Flush - Chevy and GMC Duramax Diesel Forum

How To: Power Steering/Hydro-Boost Flush - Chevy and GMC Duramax Diesel Forum

Rear Diff fluid change questions - Chevy and GMC Duramax Diesel Forum

This from a VERY knowledgeable man about Allison transmissions:

Former Allison Transmission Fluids Engineer (Mr. TranSynd) - Chevy and GMC Duramax Diesel Forum

and lastly the coolant, post #10 is from a guy you will have read in the above posts. He is a VERY knowledgeable and conservative guy regarding maintenance of our trucks:

Need to change coolant - Chevy and GMC Duramax Diesel Forum

Good Luck, Hope this is helpful

[babock]

I change my brake fluid every 2 years. I have that HF vacuum pump. I only use it to change my power steering fluid. It's worthless for doing brakes. I use a Motive pressure bleeder and have adapters for all my vehicles.

A lot of people seem to think Dexcool is bad news. I totally disagree. You just need to change it like any other coolant and don't leave it in as long as they say you can.

[DouglasReid]

Originally Posted by babock

I change my brake fluid every 2 years. I have that HF vacuum pump. I only use it to change my power steering fluid. It's worthless for doing brakes. I use a Motive pressure bleeder and have adapters for all my vehicles.

And Ive had perfect luck with the HF pump. Done mine and friend's trucks, no problems at all.

It is good for the initial drain of the PS/HB pump flush as well.

[babock]

And to really do a proper brake fluid flush, you need to have a scanner that puts the ABS in bypass mode to open all the channels in the ABS control. Most people are not aware of this.

Suction brake bleeders are hit and miss since many brake bleed screws leak around their threads. I got tired of that hassle and switched to the Motive.

And again...the OP does not have an Allison transmission!!!!!

[TitanMike]

Originally Posted by babock

And to really do a proper brake fluid flush, you need to have a scanner that puts the ABS in bypass mode to open all the channels in the ABS control. Most people are not aware of this.

Suction brake bleeders are hit and miss since many brake bleed screws leak around their threads. I got tired of that hassle and switched to the Motive.

And again...the OP does not have an Allison transmission!!!!!

A little trick we taught all our brake techs when using vacuum bleeders, bruh all the crud away from around the bleeders screws and blow clean with compressed air. Remove bleed screw and apply silicone grease to the threads only. Reinsert and go about your bleed, flush operation(starting at point farthest from master cylinder).

The silicone grease will provide enough seal to keep air from being pulled in past threads. IF any grease is sucked in it immediately is sucked back out by the vacuum unit.

Even if you do see bubbles and haven't done the above, if the color of the fluid has changed, there's no airin that line.

Lastly, do yourself a favor and use the vacuum bleeders to suck all the old fluid from the master cylinder and fill with fresh before starting your flush. It's also helpful to have an assistant monitor fluid level in master cylinder to make sure you don't suck it dry. Do that and you need to start over. 😨😈

[DouglasReid]

Originally Posted by TitanMike

A little trick we taught all our brake techs when using vacuum bleeders, bruh all the crud away from around the bleeders screws and blow clean with compressed air. Remove bleed screw and apply silicone grease to the threads only. Reinsert and go about your bleed, flush operation(starting at point farthest from master cylinder).

The silicone grease will provide enough seal to keep air from being pulled in past threads. IF any grease is sucked in it immediately is sucked back out by the vacuum unit.

Even if you do see bubbles and haven't done the above, if the color of the fluid has changed, there's no airin that line.

Lastly, do yourself a favor and use the vacuum bleeders to suck all the old fluid from the master cylinder and fill with fresh before starting your flush. It's also helpful to have an assistant monitor fluid level in master cylinder to make sure you don't suck it dry. Do that and you need to start over. ����

The HF kit comes with a bottle that you fill with brake fluid and hang on an adapter upside down after opening the ball valve. It keeps the MC from being sucked dry.

I LOVE the silicone grease trick. I will try it. I saw the bubbles and assumed they were being pulled around the threads of the bleed screw.

[DouglasReid]

Originally Posted by babock

And again...the OP does not have an Allison transmission!!!!!

Well excuuuuuuuuuse ME all to HE-- for trying to give him the requisite knowledge to feel comfortable saving some money.

Feel free to totally ignore every single post I ever make from this date forward since rather than offer concrete advice you seem to be happier denigrating the advice given by others!

[TitanMike]

Originally Posted by DouglasReid

The HF kit comes with a bottle that you fill with brake fluid and hang on an adapter upside down after opening the ball valve. It keeps the MC from being sucked dry.

I LOVE the silicone grease trick. I will try it. I saw the bubbles and assumed they were being pulled around the threads of the bleed screw.

Most of the vacuum bleeders sold come with something along the same lines as the upside down bottle. They work good as long as they remain in place. Otherwise they overflow the mc reservoir.

A lot of them spend their lives on the shelf with the mechanic just topping off when moving to different wheel or using a helper. Success really depends on the mc design.

If it works good for you that's all that matters. 👍👍

[TitanMike]

Originally Posted by DouglasReid

Well excuuuuuuuuuse ME all to HE-- for trying to give him the requisite knowledge to feel comfortable saving some money.

Feel free to totally ignore every single post I ever make from this date forward since rather than offer concrete advice you seem to be happier denigrating the advice given by others!

I believe he was merely pointing out that the advice didn't apply to the OP.

Now if an Allison tranny was involved it would have been great advice.

[babock]

Originally Posted by TitanMike

Lastly, do yourself a favor and use the vacuum bleeders to suck all the old fluid from the master cylinder and fill with fresh before starting your flush.

Yep...I do that first with the HF vacuum unit.

Depending on the vehicle, they don't always follow the old rules of farthest wheel first. Both a Lexus the and Honda that I have had didn't follow the convention. Important to consult the OEM service manual.

For the Silverado I have, the procedure is rear right first and then the rest has no sequence. Probably since the ABS unit is located mid vehicle on the left side.

[spock123]

Originally Posted by DouglasReid

They are all very easy and MUCH less expensive if you do them yourself. If you can change your oil, you can do all of these. Here are a couple links to teach you how:



How To: Brake Fluid System Flush - Chevy and GMC Duramax Diesel Forum



How To: Power Steering/Hydro-Boost Flush - Chevy and GMC Duramax Diesel Forum



Rear Diff fluid change questions - Chevy and GMC Duramax Diesel Forum



This from a VERY knowledgeable man about Allison transmissions:



Former Allison Transmission Fluids Engineer (Mr. TranSynd) - Chevy and GMC Duramax Diesel Forum



and lastly the coolant, post #10 is from a guy you will have read in the above posts. He is a VERY knowledgeable and conservative guy regarding maintenance of our trucks:



Need to change coolant - Chevy and GMC Duramax Diesel Forum



Good Luck, Hope this is helpful

I really appreciate the advice but changing the oil is about all I can do. I save when I can but most things I leave for professionals, but again thanks for the advice. Your post let me know there is a few other things that need to be changed. Like the brake fluid, power steering fluid, coolant, it's all great advice. When I get the appointment to change out the transmission fluid I'll get these other things changed. My truck has been very good, well except for def and that's been taken care of plus that wasn't the engine and drivetrain fault. Thanks again

[TitanMike]

Originally Posted by babock

Yep...I do that first with the HF vacuum unit.

Depending on the vehicle, they don't always follow the old rules of farthest wheel first. Both a Lexus the and Honda that I have had didn't follow the convention. Important to consult the OEM service manual.

For the Silverado I have, the procedure is rear right first and then the rest has no sequence. Probably since the ABS unit is located mid vehicle on the left side.

Granted. I should have written "longest line first."

FWIW, my brake bleeding days go back to when all brakes on the vehicle operated from a single master cylinder. You used a piece of windshield wiper vacuum hose and a Coke bottle when bleeding. When bubbles stopped you closed screw. Took two people but no big deal then. Minum wage was only $1.25/hr. 😂😂

[pastorlarry]

Originally Posted by Locky

I have a little over 100000 miles on my 2013 Silverado. I'm debating on if I should have the transmission flushed or drop pan and replace filter and fluid or just leave it alone. Thanks in advance.

I had a 2015 Silverado and I replaced the fluid as I was new to pulling a RV. I only had 49,000 miles on it.