CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Yet more flush questions

Sorry to be asking these old questions, but I feel like I don’t have time this morning to research the answers on the site.

'99 Escort, about 75K miles. Son has my car at out-of-town school, getting ready to move to another city. He asked what maintenance should be done beyond regular oil changes. I reviewed my service records, and decided that changing coolant, ATF, and brake fluid should be done. For ATF, based on several years following this site, I specifically said drop the pan and drain the fluid; do not flush (“Transmission flush = wallet flush”). (Also to inspect brakes and serpentine belt, but that’s not pertinent here.)

So, of course his trusted independent mechanic (near the urban campus) is pushing for tranny flush: “Draining only gets 1/4 of the fluid.” Do you experts still hold by drop-and-drain? What’s the rationale? “Only 1/4 of the fluid” seems low; anything unusual about the Escort?

And mechanic has said to do brake flush, rather than just replace the fluid. (What the heck is the difference???) Do you experts have any advice?

And BTW – for coolant, which do you prefer: drain-only, or flush (I’ve done both on various cars I have owned)?

Beyond that, it’s all psychological. Son has time now; the shop is very convenient; he’s leaving in two weeks and will never see this mechanic again.

Thanks.

I am personally OK with the mechanic’s recommendations. I have ATF fluid exchanges done with no negative results on my trucks. I get only about 50% of the fluid capacity when I do drain and fills on my Subaru.

The key, as I understand it, is to do the pan drop and get the filter changed before the fluid exchange is done. This method does get more old fluid out and as I noted, with no negative effects. I think the wallet flush part refers to some machines that add chemicals to flush/back flush the trans, and that is probably unnecessary and a bad idea. My mechanic has a normal fluid exchange machine and a good pan drop, filter change and fluid exchange. On my Subarus (with spin on ATF filter), I do multiple changes over a relatively short period of time, obtaining generally similar results to a fluid exchange. In this case, having the mechanic do the fluid exchange makes sense, based on age and mileage of the vehicle.

To me, brake flush = brake fluid replacement, so don’t know what the distinction is.

Flushing ATF or coolant might make sense if the change is long overdue and the old fluid is in bad shape.
With an ATF flush the pan should still be dropped and cleaned out. Otherwise the flush will just stir up the gunk.
About 1/2 the ATF comes out with a drain and refill, but if the old fluid is still in good shape that’s not so bad.

I changed the coolant in my Matrix at 5 years instead of the recommended 7.
Since the old coolant looked clear I simply got a jug of Toyota’s coolant, drained the radiator and refilled.

Agree with jayhawkroy that brake flush is the same as replacement, except maybe the mechanic is referring to his fancy new brake flush machine.

If the coolant looks clear, a simple drain-and-refill is all you need. If it looks turbid, run tap water through the system before refilling. You can do all this yourself. Resort to a power flush only if you are experiencing a related problem.

It may help to call a Ford dealer.

I called my Subaru dealer and they were able to tell me on the phone what Subaru recommended (Drain and fill without a pan drop or gasket change).

Shouldn’t hurt to do more though if you are so inclined / skilled.

The problem with a flush is some machines actually back flush under pressure and they can damage your trans, also it increases the chance to knock loose junk that is not causing any issues. If you are that concerned about getting more fluid out, it is almost better to do a few consecutive pan drops (drop pan, drive 100 miles, drop pan, drive, etc) then a flush.

Of course he’s going to push the flush, its quick easy money but your transmission is not properly serviced. DO NOT flush the transmission without first dropping the pan and changing the filter. He is looking for the easy way out. He is improperly servicing transmissions and he knows it.

transman

He’s also wrong about the fluid %. Its somewhere in the 50% neighborhood on the Escort. One of the reasons I do most of my own car work now is that I hate being in that position where I’m pissing off some mechanic b/c I’m disagreeing with them about what’s what & what ought to be done. We each end up thinking the other is just one of those idiots with no idea what they’re talking about.

Just get someone to drop the pan & change the filter. If the fluid has been neglected or shows signs of being bad then think about full fluid exchange.

“I hate being in that position where I’m pissing off some mechanic b/c I’m disagreeing with them about what’s what & what ought to be done”

Lately I find myself in that position with plumbers, carpenters, doctors etc. too.

Maybe I’ve gotten too smart, or stupid, or both!
I blame the internet.

Thanks for all the advice, especially about the tranny flush. Now all I have to do is communicate to my son and let him deal with the mechanic.

BTW, this is the son who had the adventures with the Chevy Tahoe he was ferrying to Alaska a few summers ago. We both appreciate the help we’ve gotten here, time and again.

(After I posted I had a chance to look at my Haynes, and it’s clear that dropping pan and changing filter is right way to go. Can “flush” after that. Also after posting, I realized that what I intended for the brakes is a flush – push out all the old fluid – rather than “replace”, whiuch somebody might think meant suck the fluid out of the MC reservoir and put in new.)

Not all flush machines are the kiss of death. Many use a diaphragm and the pump inside the tranmission to flush the fluid. Pump shoves 12 quarts out, diaphragm shoves 12 quarts in.

As many know I’m frequently at odds with what the so-called factory experts recommend and consider many of their recommendations ludicrous or laughable; or both.

Transman might like the following response from corporate Subaru when a customer contacted them about automatic transmission fluid change intervals.

“I researched previously with our Technical Services Department as to when these fluids needs to be replaced. They advised: The transmission fluid in your Subaru should be replaced if it is really black and smells burnt.”

:slight_smile:

I to have found that too often, mechanics, plumbers and doctors seem to have a menu of profitable options to offer and push from that menu with more concern for profit than for the specific needs of the customer. The local medical center nearly let me die as they laid a feast of tests and treatments in front of me for more than 3 years before a www search lead me to test my blood sugar.The glucose meter cost me less than $20. The useless tests and treatments cost more than $10,000.

Concur on the transmission. As for the brakes, flush=fluid replacement I don’t think is exactly true. The end results are the same, but the process might be different. If someone drains all the brake fluid out, the refills the system and bleeds it, that would qualify as a replacement. A flush uses the new fluid to push out the old so bleeding is not necessary. I prefer to not allow air into the system if possible, but sometimes that is not possible, i.e. replacing a caliper, wheel cylinder, hose etc.

I guess flush=replacement is OK, but that does not mean that replacement=flush.