flush or not to flush

Personally I hate the idea of flushing anything(except radiator). Because of what was said, it knocks stuff lose and you are not sure if it's actually out of the transmission or floating around waiting to clog something up.

Honda recommends a three part drain and fill. This may be something you might do as well. Drain and fill and later do it again and then a third time. Eventually most of the fluid in the trans will be new.

I would choose the drain/fill option. Although I will say, we had our RX330 flushed at 62K and the tranny is still going strong over a year later, but I have heard some people have experienced problems with the flush, especially on higher mileage vehicles.

I stay away from the flush sales job. Drop the pan and clean it and the screen and refill.

Steve B.

I'm with the current majority, drain/fill. May be a PITA to drop the pan, new pan gasket, etc., but it tends to be the safest route. It ALSO, repeat ALSO lets you get to your screen. A flush ignores the screen or filter. A flush also does NOT allow you to clean the bottom of the pan of any residue. {The residue, btw, as I sure you know, can be a diagnostic of the tranny's health}.

The above is the primary reason many people suggest drain/fill over flushing. After all, if you are going to do it, might as well do it to see and change or see what's in there, right?

Let me suggest two ideas~~~

1] Install a drain plug on the pan after it's pulled. Kits abound, ya just need to drill the hole, in most cases. U can also tap, if you really want to. The only thing is, even though you can easily drain the fluid out anytime ya want to, you leave any residue in the pan, and don't get to service the screen.

2] If U feel confident, disconnect the trans. out line at the trans. cooler, start the car, let the tran.s pump push the fluid out for ya. But that still leaves the residue and screen issue problematic.

It's very similar to changing the engine oil without also changing the filter, as far as a flush goes.

"Altima" wrote

You will notice that the vast majority of people knocking the "trans flush" simply give you anecdotal evidence....ie: "I've heard that it's bad".

One of the big problems is the term "flush". I've used so-called "flushing" machines now for at least 10 years and have yet to see one transmission fail that could be attibuted to "flushing" the fluid. And I work in a large dealership where the machines are used on a regular basis.

First of all, no machine that I've used or heard of, does any such thing as "backflushing" the trans. It makes absolutely no sense to perform such a service. All these machines do is what I would term a "fluid transfer". The hookup is simple, the machine is hooked into the trans cooler line in series, it's auto-sensing so it knows which line is pressure and which is the return. Using the transmissions own pressure in the line, the fluid is returned to the trans at the same rate that the trans is pushing the old fluid out the return line. Nothing changes, no high pressures are used, fluid is not forced backwards thru the filter, all that is happening is that you are using a machine to accomplish the same thing if you pulled a cooler line off, ran the trans to pump out old fluid while filling thru the dipstick tube! Which by the way, is a method you will hear espoused as "a better way to flush a trans". This is ridiculous, as it's identical.

If the car has a filter, my personal preference would be to drop the pan, change the filter and then use the machine to get all the old fluid out. I've used these machines on my own cars and have never experienced anything other then positive results.

Ian

Well there. Sounds like you agree. : )

About this machine of yours. How much would your shop charge for a fluid change? This would certainly be a nice option.

yep this looks like the option 3 for me which is kinda option 2 (drain) using the machine. will it take care of all the ATF ? also any shop (tel, address) I can go and have it done ? I live in Austin,TX. Thanks guys for all the good info on that !

Some machines seem to do more than just "change the fluid"

what about this one?

Seems to aireate or agitate the fluid to break loose gunk deposits.

It seems that on some older trannies that are full of deposits some of the residue from these flushes can end up in the valve body and cause some problems from what some people are saying.

DO you think this is not possible?

Bob

"BOB Urz" wrote

I've never heard of this one...thanks for pointing it out. I can say that there is "no way" that I would use something like this. None of the machines that I've used or seen in use do anything like what this machine does.

It's possible if you used a machine like the one that you linked to, but I see no reason why the machines that I mention would cause something like that. How could they? They do nothing more then what is being done every day in the normal operation of the trans, fluid is moving around through the transmission cooler line circuit!

Ian

If you do it on a regular schedule, long before the fluid itself starts to fail, it doesn't matter if you do the flush or just change it. The flush gives you a complete fluid exchange, but that's not critical if you still have plenty of life left in the fluid anyway.

If you're doing it on a car that has been horribly abused without proper maintenance for years, the flush may remove some of the gum that is the only thing holding the transmission together. But, you could argue that in this case it's really only a matter of time before it fails anyway. In that case it doesn't really matter either, does it?

--scott

"shiden_kai" wrote in news:SWSKh.28069$zU1.26967@pd7urf1no:

As a non-pro, I was one of those who bought into the anecdotal condemnation of "flushing".

My understanding of "flushing" was that it involved the use of solvents that might break sludge loose, only to have the crud clog valve bodies and the like before leaving the hydraulic system.

Untrue? Or is a sludged tranny on its last legs anyway?

"Tegger" wrote

You know...I can't give a definitive answer to whether "sludge" is going to break loose. Using the machines that we use, I cannot see it. Yes, there is a chemical that is used before the fluid is "exchanged". I can only tell you that we've done thousands of GM vehicles and I cannot think of one failure that you could attibute to "flushing".

I have also seen many transmissions apart, in various stages of failure, and have yet to see one that has any enormous buildup of sludge anywhere else other then the pan. What's in the pan is usually clutch material, and bushing material, and the filter is what is supposed to keep it out of the rest of the trans.

There will always be the horror stories about how some guy had a trans with black fluid that was working just fine until it got flushed. I haven't seen it, but I have little doubt that it "might" have happened somewhere, somehow. Or perhaps it was just coincidence?

This actually could turn into another whole discussion on whether preventative maintenance is actually worth anything. I've had cars myself that I've done literally nothing to, and have had many years of great trouble free service out of them.

Ian

"shiden_kai" wrote in news:mWhLh.36109$DN.33411@pd7urf2no:

Thanks for the input. I learned something today.

I had a 76 Ford E-150 van that I drove about 150,000 mi before I traded it in 1993. I never changed the trans fluid in it (a C-6) all the time I had it. I think the only time I did anything to the trans was to add a couple qts of fluid when I installed a cooler. The trans was still working fine of spite of towing boats & cars a lot with it. It also had the original water pump, PS pump, exhaust system, alternator, etc. The AZ summers had destroyed all the upholstery and plastic parts altho the dash covering was still like new. The 93 Ranger that replaced it is pretty much on the same track...

Where I live, the shop charges $125 for an oil change using the machine (for my

97 Dodge full size van).

You could drop the pan, change the filter and refill with ATF for half that amount, or less.

All of which begs the question, "Why on earth does anyone perceive any VALUE to flushing???" Transmissions do not generate "sludge" at all, because there is no combustion by-product that gets into them. They do accumulate clutch powder in the pan and filter, but when you drop the pan to do the flush you clean that out anyway. I suppose one could argue that on transmissions without a torque convertor drain plug, flushing serves to get rid of the old fluid that would stay in the convertor, but heck just doing a regular fluid/filter change will insure that the fluid is never SO bad that you have to replace 100% of it.

You can do that to a Ford C6. You can do that to a Mopar 727 (and I have). You can do that to a GM TH-400. You can even do that to a Mopar A-518 4-speed (and I have). But you CANNOT do that with electronically controlled 4- 5- and 6-speed front-drive transaxles (or many modern rear-drive transmissions for that matter) with clutch plates the size of silver dollars and partially-locking torque convertor clutches. Well, you can- but not and expect them to live, mainly because they are so dependant on the fluid having *just* the right static and dynamic coefficients of friction in order to work without tearing themselves up. The chemicals in the fluid that serve as friciton modifiers degrade over time, and have to be replaced regardless of whether the fluid is dirty or has been overheated.

Aren't the newer cars now coming with no drain plug in the torque converters?

no flush just drain it and take a magnet see if you have shavngs..you might want to do this 2 to 3 times.the last time you do it put new filter it....and you can also drain from radiater lines to see if you got much of metal shavings in it...good luck..

scrapper....