trans fulsh - your opinion

baldeagle · 03-04-2004, 08:33 AM

2004 2500 Suburban with 5,300 miles.

Thinking about having the transmission flushed as a preventative maintenance step.

What is your opinion?

Thanks,

Dave S.

nickcrowhurst · 03-04-2004, 08:45 AM

The fluid can be cooked by a single instance of over-heating, perhaps when backing a trailer at an angle into a campsite. I always change the fluid on a vehicle I buy used, but after that I check by color (bright red is good, brown is bad, for the fluid I use), and smell (cooked fluid is acrid). I then take out the dipstick and let a drop of the fluid fall onto a piece of clean white tissue paper. After a few minutes, the stain should be an even pink color. If there are rings of different color, with a dark ring on the outside, the fluid is burnt, and must be replaced immediately. This technique is used in chemistry laboratories to analyse mixtures of chemicals, and is known as paper chromatography. I fit a temperature sensor to the output fluid line from the tranny and attach this to a temperature gauge under the dash. I keep the temperature below 200 degrees at all times, and change fluid at the recommended intervals for towing vehicles as in the manufacturers book. Fluid is cheap, trannies are expensive. Nick.

baldeagle · 03-04-2004, 08:50 AM

Thanks Nick,

That sounds like good advice. My suburban has a built-in trans temp gague and i wil keep my eye on that.

What about other contanimates which might result from initial break-in and towing on a new unit? Any concerns there?

Dave S.

wb13798 · 03-04-2004, 08:56 AM

nick has the right idea. i would do the paper test and determine if the fluid needed to be changed. or for peace of mind change it . if you do it your self it is only $20. if you get Mr good wrench it is about $100.

smily · 03-04-2004, 08:58 AM

Seems we have some good experience here today,
I have heard many horror strories on changing tranny fluid, of course they are stories.

Can anyone dispell the myths. I have heard of people pulling into tranny shops for a fluid change and the vehicle never moves again or does not last long after the fluid change. Any truth to these stories?

Smily

baldeagle · 03-04-2004, 09:13 AM

Ken,

I have heard of such stories also. One of the reasons i am interested in getting a broad range of opinions/experiences/

Dave S.

TomW · 03-04-2004, 09:23 AM

Years ago, a buddy of mine worked in quick oil change type of place. Management's rule was that if a vehicle had over 50,000 miles, and the transmission oil had never been changed, they would strongly recommend against changing it.

Their explanation was that crud builds up in the transmission after the detergent additives in the oil wear out. Replacing the oil had a tendency to clean the insides with its new batch of detergents. Sometimes it would result simple leaks. Other times, it seems the crud was holding something internally in the proper position. Once the crud was dissolved, the transmission would not work right.

I found it believable. If nothing else, management thought strongly enough about it to lose a sale.

Tom

**jcanavera** · 03-04-2004, 09:40 AM

I have had this done on multiple vehicles and for all intents its preventative maintenance. Now the real issue is how do you change the fluid.

One theory is to drop the pan and replace the filter while draining the oil. The positive on this is that you get a good picture of the state of the transmission, metal shavings etc., and you are dealing with a clean filter. I have used this method.

The negative is that this method will not change all the fluid since some is still trapped within the transmission. The defense most shops give you is that they clean the pan, replace the filter, and that what oil is left in has minor effect once new oil is added.

The other theory is to do a fluid exchange which I also have had done. In this case they open up a line going into your transmission cooler and while the engine is running the extract the transmission oil and inject new oil. The positive on this method is that they can completely change the oil, although I'm not sure how they can do make this statement since new oil will mingle with the old.

The negative is that you have not dropped the pan to check the condition of the transmission and you have not changed the filter or cleaned the pan. The defense on this method is that transmissions filters don't get cloged like oil filters do, and that any large debris are held by the filter, and that stuff in suspension is removed in the exchange process.

So that's my take on the process. Bottom line you need to perform this maintenance. I'll change it either by color or by towing conditions.

Jack

TomW · 03-04-2004, 10:21 AM

If you are going to change the oil yourself, remember the torque converter holds a lot of oil (like maybe half of the total volume?) that I believe stays in place when the engine is off. Some torque converters have a drain plug you can remove to get the oil out.

Click and Clack of CarTalk fame seemed to think highly of the machine flush (open a line) system on one episode. As I recall, most of the old oil is removed, and replaced with some sort of flushing compound. Then that is removed, and replaced with new oil.

Porky Pig · 03-04-2004, 10:29 AM

When it comes time to changing the trans fluid ... I'll be going to the Ford dealer. My TorqShift uses a new type of fluid that I can't find anywhere ... plus the dealer has a special "sucking device" to extract the fluid trapped in the trans ... and the money in my wallet.

I don't know about the GM trucks .. but the trans temp gauge on the Ford is useless .. so I installed the X-Monitor on my a-pillar to track my pyro, boost and trans with an easy to read digital display. You can also set alarms for each and check your peaks after a run. So far so good ... the trans has remained below 200 at all times.

dtbw · 03-04-2004, 12:36 PM

Porky,
Bet your Ford tranny calls for Mercon V, which is a pure sythetic fluid made specifically to Ford standards. This stuff is not all that difficult to find, but you do have to look OR ask specifically that Mercon V be used. There are even "upgrade" fluids that claim to make other transmission fluids meet the MERCON V standard, but I am question how Ford would respond if such had been used vs true MERCON V.

I had my tranny fluid exchanged at about 20K miles as the factory fluid seemed to be just a bit off in color. No unusual odor or banding when dropped onto paper, but not quite that nice pink. My local lube shop did the fluid exchange using almost twice the total fluid capacity of the transmission, just to make sure that they got all the old fluid out. I also added a thermostatic, electric fan cooled Hayden Transcool in addition to the original factory unit. This way, I have good transmission cooling even in slow forward speeds. The fluid first goes thru the radiator cooler, then the factory external and finally thru the Hayden before returning back to the transmission. The thermostat on the Hayden fan is controlled by the temp on the return tube after the Hayden, so as to preclude it running when not needed.

david

Porky Pig · 03-04-2004, 01:10 PM

Quote:

Originally posted by dtbw
Porky,
Bet your Ford tranny calls for Mercon V, which is a pure sythetic fluid made specifically to Ford standards.

I wish it was Mercon V ... for the TorqShift the correct fluid to use is Mercon SP. So far ... only available through Ford Dealers ... but this will hopefully change in the future.

sander17 · 03-04-2004, 02:42 PM

At first glance it seems easy to drop the pan by crawling under the truck, but unless you love the smell of tranny fluid, have someone else do it. You will wind up drenched with fluid. Then comes the fun of scraping off the old gasket.....
It's worth the money to have Mr. Goodwrench get wet.

overlander64 · 03-04-2004, 03:01 PM

I have followed the general rule of having my transmission fluid and filter changed every 30,000 miles for a number of years. My current Suburban (1999 K2500) has been treated to a complete flush and new filter at the GM dealership every 30,000 miles since it was new; at 124,000 miles, all is well and the transmission behaves just as it did when the truck was new. The same maintenance schedule has been applied to my Cadillac since I purchased it in 1995 at 95,000 miles - - it will be due for its second servicing since I purchased it this summer (currently has 122,000 miles) -- my GM dealer also handles its maintenance and has used the flush and new filter process for it as well. Thus far, I haven't had any transmission failures or repairs beyond this regular service routine - - before starting this routine, the transmission in my '71 Buick Sportwagon failed at 49,000 miles.

Kevin