I'm wanting to completely change all the trans fluid in my '69 Camaro 350 with a TH350. Since I've owned her I've only done the usual pan drop, filter change and 4 qts. of new fluid. Is there a proper method for flushing the system without having to take it to a service garage with a flush machine?
I've always performed my own service and I don't really want a strangers hands on her if at all possible.
Anyone who owns a first gen knows exactly what I mean.......
I've read a couple write ups on the internet describing the disconnection of the trans cooler line, attaching a clear tube to the cooler line, placing the free end of the tubing in an empty container, starting the engine, letting the trans pump expell all the old fluid in the container and at the same time adding fresh fluid via the dipstick/filler tube.
Is this a feasible procedure or is there something
better?
I would appreciate any feedback.
Thanks very much! Ray.......
"GET-R-DONE"

Aside from doing it yourself, any competant trans shop should be able to do a complete flush.

we just had that done to my wifes Volvo V70R, its part of regular service. they just unhook the lines and hook it up to a machine that cycles fluid through untill it flows clean, very basic. several volvo sites i looked at describe doing it as you describe, but you have to have quite a bit of fluid handy, since if its dirty, you'll run considerably more through than its capacity to get it clean. i had volvo do it, since its still under warranty, plus you know its gotta be messy when done at home.
i've never done it to any of my performance cars, i just regularly change fluid and it stays clean, i would say thats the best way to do it, imo.

There is a method that uses the cooler lines but uses a drill pump to displace the fluid in the system. Another method is to drill a small hole in the convertor to drain it, then plug it with a small fiber washer and pop rivet, this with a complete pan oil change will get about 98% of all the fluid out of the system.

But if your not sure, I would spend the money at a tranny shop that will let you into the shop area when its being flushed to watch.

Back in the day, torque converters had drain plugs - on certain models at least. You could drain the converter by turning it over with the plug pointing down and removing the plug. Now-a-days though, most converters do not have a drain plug. So unless you pull the convertor out, you can't drain it. There are ways of draining a converter once it is removed.

Many trans shops and auto techs do not recommend this service if the trans has lots of miles on it (say, more than 50K). The old fluid has friction particles suspended into it, and keeps the clutches from slipping too much (or so I've heard). Anyway, there have been many high miliage trannys that have failed shortly after they were flushed.

Something to think about, anyway.

Originally posted by dnult:
[QBSo unless you pull the convertor out, you can't drain it. There are ways of draining a converter once it is removed. [/QB]This is ot true. The method I recomended above of draining the convertor by drilling a hole and plugging it with a pop rivet is a GM recomended method of draining a convertor, still in a vehicle. However it cannot be drilled just anywhere, or you could drill into a fin or stator.
It is also mentioned in the book "Turbo Hydra-Matic 350 Handbook" by Ron Sessions
In that book it gives you the proper location to drill and the proper type of rivet to use.

I have done this method of using the trans oil pump to exchange the oil in the t/convertor to several vehicles and it has worked well for me.

I drain the pan, change the filter, add 4 qts, and start the procedure. I use the top radiator fitting, disconnect the tube and drain from the top rad fitting, as GM fills the cooler from the bottom.

I usually go through a 12 qt case and things are fine.

As dnult suggested, OEM's did have drain plugs in t/conv's. But, the reason the plugs were removed was b/c plugs were not being tighten and the trans were burning up do to loss of oil.

Just my 2 cts.

I have to comment on this as I work in a transmission shop. Several things stick out in my mind based on replies that I am seeing.

#1. DO NOT drill a hole in your convertor! Too much of a chance that you won't be able to properly seal it when done. Also, converters are balanced so there is a slight-yes, very slight-chance that you can unbalance your converter by drilling/plugging it.

#2. If your system is so dirty that you need to flush the converter, you are probably on borrowed time and should pass on the fluid and filter change as it may worsen the condition, or most likely will be a waste of money as the trans. is on its' way out. If you are servicing your transmission at proper intervals, simply changing the filter, and replacing the fluid you drain from removing the pan is MORE than adequate!

#3. For insurance reasons, I can't/won't allow you in my shop! You can ask to watch if you like, but you will do it from a distance-meaning outside of the bay area. That is the standard answer you will get, but the real problem is this: A standard service usually takes my guys about 30-40 minutes.. With a pesky customer, who inevitably asks a thousand questions, you stretch the job out to well over an hour, and **** my employee off. For the money you are paying-MINIMAL-I can't/won't allow you in my shop to distract my employee. THAT IS THE REAL REASON WE DON'T WANT YOU IN THE SHOP! I know that may bother some of you, but for the $30 charge, and the $10 profit I *MIGHT* make, I don't need your business. You can ask me, the service manager, 1,000 questions before hand, I don't mind really, but I WON'T allow you to interact with my technicians. Sorry.

#4. Here is what I am being told is the reason that transmissions sometimes fail AFTER a fluid/filter change. I am not saying this is gospel, just what I am hearing from the "professionals", and it does make sense so I will offer this as a "hypothetical" reason.

When transmission fluid is new it has detergents and dispersing agents in it that prevent formations & varnish from forming inside the transmission. As fluid quality degrades due to heat and age (from lack of servicing at proper intervals-we always take care of this right?)deposits are allowed to form as the detergent & dispersents quit working. Now you have minute deposits that are deposited in various places throughout the valve body. They are relatively harmless at this point as they are out of the way. You then drain the old fluid out, and add fresh fluid, with fresh detergent & dispersents that then act on the deposits and begin to dislodge them. Now you have "chunks" of gook and cake moving through the transmission just looking for a small orifice, or valve to plug and "voila!" you have transmission problems!!!

Seems like a logical explanation to me.

Of course this entire issue could be avoided if we are vigilant and keep our transmissions serviced!

#5. Do not trust oil change/lube shops to check your transmission fluid level and/or condition for you! I have had 100's of people come in with problems and they relate to me that the lube guy just told them that the level & condition was fine. I then go out and check it and the fluid is black, and low several quarts (typical). A lot of these places don't even know HOW to properly check the fluid level.. Some of the new vehicles, imports specifically, don't have dipsticks and you MUST bring it to a shop to have it checked.

How To Keep Your Transmission Alive:
1. Add an after market cooler!
2. Keep the fluid and filter changed!
3. Use synthetic fluid.
4. Add an aluminum finned pan (more volume & better cooling)

Have fun with your projects!

Straight from the source. graemlins/thumbsup.gif