I have been reading many of the post dealing with the complete changing of the transmission fluid and filter. I have talked to (2) dealers and (3) different transmission shops and they all say the same thing. It is better to do a power transmission flush and not worry about changing the filter. I tell them my truck has 150,000 miles on it and I have had the transmission flushed 3 times ( each time around 45,000 to 50,000 miles ). I have never changed the filter as they always say it's not nessasary. This goes against most of the advise I read on this and othe forums. All of the shops state the filter is magnetic and the flush washes over the filter and removes any of the particles. Any help or comments on this would be helpful along with an approx. cost to drop the pan and replace the filter. Also can this be done on my 1996 blazer myself or is this a truck where jacking up the motor or other complicated work needs to be done to make it happen.

thanks in advance for all those that help

 

WOW, I can't believe that they have been snow balling you like that for so long. If a shop did a flush and didn't change the filter out... I'd be hot! I can't really remember the flow diagram for a trans, but I believe that the oil flows from the filter, to the pump and either through the trans cooler then transmission itself (or vise-versa), then back into the pan. If it is through the cooler first, then most all of the crap would be getting dropped back down into the pan and subsequently into the filter.

Irregardless of how it flows through the transmission, the filter is still seeing all of the wasted band material and other contaminents in the system everyday that you drive it. That all adds up. There is a magnet in the pan that will catch the metal particles, but there are non-magnetic particles that come off the bands that lodge in the filter. And in no way does a flush clean the filter!

I'd be more worried about changing out the filter than getting a flush performed. I have heard a lot of people that say that they never had transmission trouble until they had it flushed. If you have been doing it all along the life of the vehicle, it shouldn't be a problem, but on higher mileage trannies, the flush could knock loose gunk that was keeping the tranny alive.

 

The transmission is a sealed system, the only dirt the filter needs to filter is crap from the tranny. If the filter gets plugged, your tranny is shot. Then you will not only need to replace the filter, you will also need to rebuild the tranny.

Heat is the number one killer of auto trannies. Heat deteriorates the lubrication qualities of the tranny fluid. In your case, having the tranny completely flushed every 50K is fine, no need to replace the filter. I used to think the same as the rest of you until I rebuilt my tranny and spent 3 hours with a guy who has been rebuilding them for over 40 years. If the tranny was subject to outside contamination, then yes you would need to replace the filter frequently, like the air filter, or oil filter. The tranny is a completely closed system, it has no influence from anything outside. The only contamination to plug up the filter would come from the tranny clutch packs, and if they are disintergrateing, your tranny needs to be rebuilt, replacing the filter won't fix it.

I have talked with several tranny pros about the best way to service them. Here is what they both said and do on their vehicles.
Install a drain pug in the tranny pan.
Drain the tranny pan at least once a year, and top off with new fluid.
If your drive in extreme conditions, add an auxilary tranny cooler. Extreme conditions would be 4wheeling, towing, live in the mountains, drag race, stop and go traffic all day long, or idle all day long (cops & taxis).
If you drive in extreme conditions, drain the pan every other oil change and top off with new fluid.

Neither recommended external filters, or replacing your current filter when you drain the pan, except maybe when you drop the pan to install the drain plug. Changing the fluid and controlling heat are the best two things you can do.

 

clutches wear, gears wear, bearings wear, all those metal particles get caught in the filter, It needs to be changed.

 

I have never thought about it in the way that Hanr3 has stated, but for the price of the filter (especially if you are dropping the pan), why not... I do agree that there shouldn't be all that much crap to clog up the filter especially considering that the magnet in the pan should catch anything that could damage the filter itself.

I must say though, I have never heard of anyone not replacing the filter, EVER. It's a weird perspective, but it is sound.

 

Changing the filter won't stop or fix that. IF they create enough debris to plug up your filter, you have a much bigger issue and the tranny needs to be rebuilt.

 

I just bought a 2000 Blazer with 75000 miles. I don't know if it's had a tranny fluid service. Should I do a change or leave well enough alone? Like the old adage, if it aint broke, don't fix it.. Thanks...

 

It's not a matter of the particles plugging the filter, it's what gets past the filter once past it's useable limit. Recirculating those particles will eat up the internals like a sandblaster. I had tracer with 75000 miles on it without a filter change, the fluid looked like silver paint with so many fine particles floating in it. When the tranny was rebuilt the guy said the inside of the tranny looked like someone had polished it. There were no sharp edges on anything and everything was worn. The passages were even out of spec.

 

If you have metal floating around in your tranny you have much bigger issues. The wear parts in a tranny are the clutch packs, gaskets, rings, and seals. All of the gears and bearings should not wear out. They should last forever. The only other thing that will wear is the vanes on the pump. But then again, if you have metal floating in your tranny fluid, you have bigger issues. Something isn't working right and the result is chewing your tranny apart.

When you buy a rebuild kit, it contains no metal parts. Not saying you cannot break the metal parts, but if you do, you have bigger issues. The most common part to break is the sun gear.
Pic of my son holding a sun gear.
http://offroadworld.tenmagazines.com...nr3/120102.jpg

 

It was a crappy tracer (same as an escort) It's a wonder it didn't fall apart into a million pieces. It went through three tranny's in the short time I had it. Talk about a turdmobile.[:'(]