flush or not to flush

[paulfischer]

somewhere I was reading the debate of to flush the tranny or do old school and drop pan and change filter add new fluid.
My burb is a 2004. I called the dealer (actually 3 of them) and asked about a tranny service, all 3 of them said that GM recommends the flush, and NOT to remove the pan and change filter. I always thought you wanted to change the filter, but the GM Dealers all said that the dirt get fluished out. But wont it go back into the tranny?? They said no.

I had the flush done at a GM dealer, truck had about 50,000 on it when flush was done.
Just curious what you guys all think about the subject.

[2000CAYukon]

IMHO, not changing the filter is bad for the tranny. I guess I am old school since I won't do a flush. I drop the pan and replace the filter.

The magnet also needs to be cleaned and the only way to do that is dropping the pan.

//2000CAYukon

[j cAT]

[quote=2000CAYukon]IMHO, not changing the filter is bad for the tranny.

The magnet also needs to be cleaned and the only way to do that is dropping the pan.

my many years of trouble free transmission experience is replace filter and fluid when color changes. the 2000 sil 5.3 L requires this to be done at 30,000mi. dropping the pan is the only way to remove debris. also just one minor point, inspect whats going on in there. dealers tell you to flush because its faster and profit margin is higher ,also you will need new vehicle sooner this is good for sales........

[J-Ri]

Oh, boy... another flush debate

Almost all transmission "filters" are just screens to keep big chunks in the pan and not in the pump/valve body, so they really don't need to be replaced, as they don't get plugged. I do agree with occasionally removing the pan to clean the magnet... although if you have enough metal floating around that the magnet can't hold all of it, you have bigger problems. A simple solution would be to install an in-line magnetic filter.

Done properly, I have NEVER seen a flush damage a transmission.

[j cAT]

[quote=J-Ri]Oh, boy... another flush debate

Almost all transmission "filters" are just screens to keep big chunks in the pan


i have a 2000 5.3 silverado and 96 impala both have 4l60 transmission and the transmission filters i use have filter media simular to an oil filter my truck has deep pan so this filter is constucted differently but the area that sucks up the fluid is not a screen. now these are oem style filters. yes i have seen the type you have refered to,but these are not an oem type for use with these transmissions.....i believe fram makes the screen type that you are refering about.....my sil uses a NAPA 1-8567 this is for the deep pan the 96 impala uses TF289 an ac delco filter. if you check it out this is the proper type to use and only the smallest of particles will get through. don't use the insect screen type unless you want to rebuild your transmission next summer. i'd rather go fishing..... the first fluid change i found has the most debris at over 100,000mi the debris at pan bottom is very small....

[paulfischer]

I've always dropped the pan and filter my cars. But When I called the dealer for info, they said GM doesnt recommend the dropping the pan anymore.

Will check into the inline magnetic filter.

Thanks for all the replies!

Paul

[MT-2500]

Your dealers are feeding you people a bunch of it hook line and sinker.
Do not believe a word of it.
They proabley have new flush machines and are wanting you to help pay for it at the risk of messing up your transmission.

I have yet to see a GM repair manual or maintenance schedule that says to flush.
MT

[MT-2500]

Originally Posted by J-Ri

Oh, boy... another flush debate

Almost all transmission "filters" are just screens to keep big chunks in the pan and not in the pump/valve body, so they really don't need to be replaced, as they don't get plugged. I do agree with occasionally removing the pan to clean the magnet... although if you have enough metal floating around that the magnet can't hold all of it, you have bigger problems. A simple solution would be to install an in-line magnetic filter.

Done properly, I have NEVER seen a flush damage a transmission.

The screen type filters are from way back in the old days.
The gm 350 and several ford transmissions did use them.
All newer GM uses the cloth type filter that needs changed on a regular mileage.
MT

[wafrederick]

I know about and I hear nothing but problems after a flush.Complaints are will not shift when warmed up.The problem with the machine is that is the machine is it backflushes,uses more fluid and where does the dirt,crud and metal shavings go?In the valve body causing sticking valves requiring a valve body cleaning.I know a transmission shop in my area that does this.I replaced one transmission in a 1999 Monte Carlo,the transmission was flushed and acted up and tried fixing it once.It came back and the transmission had to be replaced.

[J-Ri]

Originally Posted by MT-2500

All newer GM uses the cloth type filter that needs changed on a regular mileage.
MT

I didn't realize those are any better. I'll have to cut open the next one I get and see what they catch.


The "dirt" in the fluid is removed 100% because every drop that goes out stays out, only 100% new fluid goes back in. I asked around, and nobody has heard of this "reverse flush" machine that keeps getting mentioned... Who makes it? I'd like to see what the manufacturer says about it.. The only flush machines I know of hook up to the lines and is basically two bags inside a cylinder that is large enough for one to be full. One starts out full of new fluid, the other one starts out empty. As the transmission pumps fluid out, the empty bag fills up and forces the new fluid out of the other bag and into the return line. Of course that's a very simplified version of the actual machine.
The only thing I cannot comment on is about the cleaner disolving the glue on older transmissions. I've never had that happen, but I do know that whoever said it knows a bit more than I do. I don;t even know if that was in this thread, I switched to advanced view to quote MT... I do remember getting a sick feeling in my stomache after reading that, and I remember it was someone whose opinion I trust.

[wafrederick]

The dirt gets stuck in the valve body during a flush with the machine and I believe this transmission shop that I know about this.The best flush is not with the machine and it is called a line flush which is better than the machine.The advantage of the line flush is you can see the condition of the fluid and you use use less fluid.You remove the bottom line of the radatior,hook up a hose and point that to a pan.Start pouring fluid in while it is running and make sure you do not run the transmission dry.Do this until the fluid comes out clear,shut the vehicle off and you are done.Reconnect the line.Get a box of ATF for the line flush.

[J-Ri]

The shop I work at has a line flush machine. It's completely idiot proof, eliminating any risk of running the transmission dry, and eliminates the need to add or drain any fluid at the end of the flush, unless it was over or underfilled when it came in. There's also no chance for a spill, aside from the small ammount that leaks when the line is removed.

Who makes this backflush machine? I really want to see what the manufacturer says about it.

[wafrederick]

The line flush is better like I mentioned and I do it this way.I seen the dirtiest fluid in some.The line flush is not messy and is a lot better knowing the dirt and crud is not in the valve body.I will not give out this transmission shop's name or thier phone number.My father even seen them clean one valve body because of a flush was done.The whole valve body was tore apart with the valves taken out,cleaned and reassamebled put back in.The vehcle shifted better after the valve body was cleaned.My father even does not recomend flushing a transmission,we have the filters,pan gaskets on hand when doing a transmission fluid and filter change.

[MT-2500]

Flushing can flush up a lot more problems than it flushes out.

No where in a factory repair manual does the factory recommend a flush.

One of the main problems with a flush is when all new high detergent transmission fluid is added it acts as a cleaner and cleans breaks lose all barnish and dirt in a transmission and drops it into the valve body.

Plus a lot of dealers and quick lubes and repair shops add cleaner to the fluid and do not service the transmission filter and even some use a one fluid fits all transmissions with a bottle of dope.

Another problem is people do not even service a transmission untill high mileage or untill there transmission is on the last leg and then think a flush is a cure for all of the no service and transmission trouble.

If a person wants to flush start with flushing it at 40-50K mileage and keep it up ever 40-50K with a pan drop and filter change and the correct transmission fluid.

Here is my answer.
To Flush or not To Flush ?
Just like Kenney Rodgers said you have got to know when to fold and when to hold.
If the fluid has high mileage 100K or over or is real dirty you had better hold.
On a trans that has had good regular service at 50K or sooner a flush is good.
But be ware of jiffie/quick/wallmart /fast lubes that offer power and fast flushes.
They have abused and over rated the trans flush.
They have a habit of using one fit all fluid out of the same barrel that fits all.
They just throw in a bottle of additive to make it fit all. Or worse they pitch in a bottle of cleaner or dope in it that can do more harm than good. And will tell you the filter does not need changing with a flush.
Just remember that all new fluid makes a high detergent cleaner that will break loose all varnish and dirt and grit in the trans and drop it in valve body and solenoids.
Always change the filter and go easy on or use no dope and cleaner.
Adjust/check the bands and linkage on the trans that have bands and adjustments.
Always use the trans fluid the trans/manf calls for. And be aware that some manf have changed the type of fluid specs since the trans was manf.
Some fords have changed the specs and a lot of cry/dodge have gone to the newer type of fluid on their trans service.
Also some fords have tsb’s and require a total complete trans flush to cure trans shifting problems. Some as low as 30K
If a person does not have a flush machine a old 5 gallon bucket and a couple of rubber hoses to connect to the cooler lines and with the other end in the bucket will make a good flush machine. Just put the hoses in the bucket and start the engine and start pouring fluid into the trans until the fluid running into the bucket gets good and clean.
It usually takes 16-20 qts. To get a good flush.
Flush or No flush always service the trans filter and trans on a good regular basic.
People that keep the serviced have a lot less trans problems.
MT

[paulfischer]

I find it very disappointing that a dealer would give us a line of BS to help their bottom line. What happened to MR. Goodwrench??? Must need to make up some money for the lost auto sales that Toyota got in 07.
I know when I had my tranny flushed, I watch the guys put in the proper dex fluid, hook it up to a trans line fitting, and run the process. My truck only has 55,000 miles on it, shifted well before and after flush. I feel fine about the flush. After all I took the guidance of 3 GM dealerships to have it flushed. Guess all these big boy auto makers really want our $$$ and dont give a crap about their service, product, customer loyality, quality products.

Love my truck, hoping to drive it till it dies many many many more miles down the road.