Complete Auto Trans Fluid Change

[Rich96c4ce]

I have a C4 with the 4L60E. I would like to change all the fluid and the filter. What is the best way to change all the fluid?
Thankds, Rich

 

[78SilvAnniv]

The QuickLube places use some form of power flush system but I have heard that it can cause tranny failure shortly after the power flush.

Short of dropping the tranny to get all fluid...
My Bro-in-Law (used to work for AAMCO) says the best thing to do is frequent partial changes and stay far, far away from power flushes. We have a bucket and lid rigged up with two holes several inches apart, one for the suction end of the shop vac and a smaller one for a hose to send down the tranny dipstick tube. Turn on the shop vac and it pulls the tranny fluid into the bucket. Be sure the bucket lid holes fit the hoses closely or it'll pull more outside air than fluid.
Heidi
ps...my original 1978 TH350 tranny has approx. 250k on it. ...and I don't drive gently!

 

[Vettefan87]

Mine was power flushed with no problems, and that was over a year ago. I am not sure what problems could be caused with a entire system flush but I don't know. Both my vette and my brothers had the same thing done at about the same time, and both of our cars chirp the tires going into second.

 

[Baldie88]

My daughter had a Grand Am and had Valvoline do a power flush on her trans. End result is transmission failure 2 months later. Everything worked fine prior to the flush. I'd never have this done. Car only had 45K miles at the time. It looked like the fluid they pumped in was darker color than the fluid pumped out.

Baldie88

 

[C4ME]

Filter?

I wonder if there was a problem with the filter being damaged in the flush and the media damaging the system?

 

[c4cruiser]

Most reputable auto repair shops now have equipment to do a complete fluid flush. It doesn't take very long to do. I would avoid the fast lube drive-thru places like the plague! They have a hard enough time changing oil much less messing with other components.

Some people say that chnging out the tranny fluid if the tranny has many miles on it can cause problems, but if you do tranny service (filter change) at regular intervals according to your owner's manual. you should not have any problems doing a complete flush.

 

[cfour93]

Think of it this way if you power flush and don't change the filter why bother you just filtering though a dirty filter and with power flushing you’re pushing the grime into the filter and possibly creating blockage. The only real affordable way to do this somewhat correctly is to have a shop drop the pan check and adjust what is needed and clean before assembly replacing the filter at the same time. I just had my trans done, dropped the pan clean and adjust for $110.00 the best PM cost ever for a peace of mind.

 

[BlackNBlue95]

I would do a flush, then pan off w/ filter. Flushing itself should never cause a problem, what happens is around 40K miles the fluid brakes down, sediment of wear and tear particles settle around seals, seals form to accomdate this. flushing now the particales again become suspended in the fluid, seals no longer seal, now internal leaks occur and trans slips... end word,

Maintain the trans often min every 20K miles.
-=Rick

 

[AdvancedAutoCC]

Most reputable auto repair shops now have equipment to do a complete fluid flush. It doesn't take very long to do. I would avoid the fast lube drive-thru places like the plague! They have a hard enough time changing oil much less messing with other components.

Some people say that chnging out the tranny fluid if the tranny has many miles on it can cause problems, but if you do tranny service (filter change) at regular intervals according to your owner's manual. you should not have any problems doing a complete flush.

I do not have a trans flush machine in my shop (not for the equipment salesman's lack of trying!), nor do I advocate the use of one. How often has the shop replaced the filter in the machine, for example? Did the last car "serviced" have badly contaminated fluid? Do you really want to take that chance? If you stick with a PROACTIVE regimen of fluid and filter changes (following the factory "severe service" maintenence plan), you'll be doing your trans a favor.

Any time you service the transmission over the 50,000 mile mark if it's never been done is an invitation for trouble. Most people in this situation I run across I tell the same thing... service it and roll the dice (but not in my shop), or drive it till it quits. Either way, it's going to fail. This assumes I don't know the car or the owner... YMMV.

In response to the original question:The only way to completely change the fluid is to disassemble the transmission and replace the converter. My best recommendation is if your replace the fluid for whatever reason, use a quality synthetic ATF in its place. This, of course, will take a couple of changes to accomplish.

Good luck to you!

 

[Vettelt193]

I saw a flushing machine that hooks into the tranny cooling lines... The machine is a super simple setup. All it has is a fresh supply of fluid that sits on top of a piston in a cylinder.

You hook the car up to the machine by taking off one of the tranny cooling lines and connecting it; then connecting the machine back to where the tranny line is normally hooked up. Start the engine and it pumps the old fluid below the piston that has the new fluid on top of it forcing the piston, and new fluid up, out, and into your transmission and lines. The cylinder is clear so you can tell when the fluid coming out is clean.

the question is, who has one of these... I have no idea.. so, as stated before, change your fluid often (once a year IMHO) and it will be fine.

 

[Daryllawman]

I agree with Heidi......Stay away from the complete flush.....I have heard the same horror stories..

The QuickLube places use some form of power flush system but I have heard that it can cause tranny failure shortly after the power flush.

Short of dropping the tranny to get all fluid...
My Bro-in-Law (used to work for AAMCO) says the best thing to do is frequent partial changes and stay far, far away from power flushes. We have a bucket and lid rigged up with two holes several inches apart, one for the suction end of the shop vac and a smaller one for a hose to send down the tranny dipstick tube. Turn on the shop vac and it pulls the tranny fluid into the bucket. Be sure the bucket lid holes fit the hoses closely or it'll pull more outside air than fluid.
Heidi
ps...my original 1978 TH350 tranny has approx. 250k on it. ...and I don't drive gently!

 

[BlackNBlue95]

well our machine does not require a filter as the clean and dirty fluids are kept seperate in a bladder system. as the trans pumps the old fluid to one side of the bladder, this pushes the fresh fluid out, to empty the dirty, shop air is supplied the clean side and pushes the used fluid out.
-=Rick

 

[Crucifix]

I have a C4 with the 4L60E. I would like to change all the fluid and the filter. What is the best way to change all the fluid?
Thankds, Rich

Hi,
When you do something like this take it back to the dealer to get it done. I had my 95 Suburban tranny and motor fluids flushed and she has been running great. It's been two years.
I have the fluids changed on all my vehicles sooner than the recommended service schedule.
If something does fail after the flushes are done it's my guess that because the tranny or motor is now performing a little better that it adds stress and some parts that were borderline fail sooner rather than later.
Basically it's not the process (unless the mechanic does something) it's the effect of the process on the components.

My observation.

 

[AdvancedAutoCC]

If something does fail after the flushes are done it's my guess that because the tranny or motor is now performing a little better that it adds stress and some parts that were borderline fail sooner rather than later.
Basically it's not the process (unless the mechanic does something) it's the effect of the process on the components.

My observation.

Actually, when the transmission fluid is changed in this instance, it's usually because the friction material that's worn off the clutch plates is still ciculating in the fluid. When the fluid is replaced, that same friction material is now removed, the clutch plates have a harder time maintaining friction, and thus the trans starts to slip leading to failure.

I understand the principle of how the fluid exchanger works, but unless you replace the transmission filter when exchanging fluid, you're not doing a complete job. This means dropping the trans pan (unless you have a spin on filter), to replace the filter. You don't change the engine oil only and not the oil filter, why would you do that with a transmission?

 

[JRMaroon]

Thread Hijack -

I'm going to bump this thread to see if I can get any feedback on the service I have scheduled for the '94 this week.

My car has 21K miles and as far as I know the transmission has never been serviced. I have asked the shop to replace the transmission filter, not flush. I'm not concerned about the mileage but the age of the 11 year old fluid. I do not want to let this go too long and then put myself in a situation that AdvancedAutoCC describes. The shop also said they do not like to touch a high mileage transmission that has never been serviced.

They are also going to perform a coolant flush and fill, replace thermostat and fuel filter. Oil and filter are changed regularly.

What other recommended service am I overlooking on this 21K mile vehicle?

Thanks,
Jeff

 

[Edmond]

Plugs and wires are a basic maintenance thing along with the PCV valve.

What I was told with the trans flushes are that you could dislodge things that will plug up the system. That's what I was told, don't know how true it is or whatever.

They should've made the system easy to drain and refill, like my Toyota. There's a little hex plug on the bottom of the filter. You just take the plug off and drain, then refill.

I changed the trans fluid on the 'Vette about 3 or 4 years ago. I just dropped the pan and changed the filter and then refilled. Of course, I used a new gasket, made sure to clean the old gasket off and applied some sealer to the new gasket. Tightening in a criss cross fashion but not too tight. Checked it again the next day and it's been fine every since.

 

[AdvancedAutoCC]

I'm going to bump this thread to see if I can get any feedback on the service I have scheduled for the '94 this week.

My car has 21K miles and as far as I know the transmission has never been serviced. I have asked the shop to replace the transmission filter, not flush. I'm not concerned about the mileage but the age of the 11 year old fluid. I do not want to let this go too long and then put myself in a situation that AdvancedAutoCC describes. The shop also said they do not like to touch a high mileage transmission that has never been serviced.

They are also going to perform a coolant flush and fill, replace thermostat and fuel filter. Oil and filter are changed regularly.

What other recommended service am I overlooking on this 21K mile vehicle?

Thanks,
Jeff

The mileage is fine in your case, the age of the fluid shouldn't cause the "high-mile failure syndrome".
Coolant flush and refill is a great idea (don't use any aggressive flush chemicals!) and if the shop's doing a thermostat at the same time that's even better. The plugs can be changed if you like (due at 30,000 miles anyway) and the wires aren't a bad idea as long as you use quality parts. The fuel filter should be changed religiously every 10,000 miles (your fuel pump will thank you for it). Aside from that, you could consider the hoses and serpentine belt due to age, but I'm certain your mechanic will advise you if they're necessary. It goes without saying that the crankcase gets Mobil1 on the oil change, but I'm sure you already know that.

 

[JRMaroon]

Robert,

Thanks for the detailed reply. I dropped it off this morning for the described service. Mobil 1 is being used as always. A new serpentine belt was installed 2 1/2 years ago when the Opti-spark was replaced.

I hate to pay for any of these services but currently do not have a place to work on the car myself when the draining of fluids is involved. Plugs and wires are on the list when I am ready to skin all of my knuckles. I'll struggle through that myself.

The hoses appear to be in good shape but maybe they don't give any notice of impending failure.

Thanks again for your response,
Jeff

 

[AdvancedAutoCC]

Jeff,

No problem... glad I could help...

 

[Vettelt193]

Robert,

Thanks for the detailed reply. I dropped it off this morning for the described service. Mobil 1 is being used as always. A new serpentine belt was installed 2 1/2 years ago when the Opti-spark was replaced.

I hate to pay for any of these services but currently do not have a place to work on the car myself when the draining of fluids is involved. Plugs and wires are on the list when I am ready to skin all of my knuckles. I'll struggle through that myself.

The hoses appear to be in good shape but maybe they don't give any notice of impending failure.

Thanks again for your response,
Jeff

I hate to tell ya, but the tranny is easier to deal with than the spark plugs (IMO anyway). The LT1/4 cars have plugs that are just a PITA to deal with. Good luck with everything no matter what!