[Caa5030]

I was wondering if you could give me some direction. I recently bought a 05 1500 silverado z71 5.3. It has 97k on it with a 4l60 with the deep pan. Since I just bought it I was probably hypersensitive to it but it seemed to be shifting a little funny. Against many peoples advice I decided to change the fluid and filter. First I tried the flush method of disconnecting the cooler line and failed miserably. The fitting pushed back into the radiator when I pushed on the drain hose. After leaking about three quarts on the floor I gave up and reassembled everything and refilled the transmission. I drove it for a day with no problems. The second day a felt a significant vibration in the driveline at about 50 mph when ever everything was heated up. Come to find out I had it too full. I pumped out the excess fluid from the top to achieve the correct level. Then I started to notice the tranny slipping pretty bad after it had warmed up. Recently, I went ahead and dropped the pan and did a filter/ fluid change. It still continues to slip. The fluid that I am using is castrol dex/merc which I have read should be fine. Low gears are fine and it seams fine when it's cold. When it heats up that's when I get the soft shifts and slipping especially in third and fourth. No transmission pro here but I know a fair amount about vehicles and I have put in my due diligence searching the forum. Any help is appreciated.

 

[2005_Silverado]

ur truck takes dex vi, not dex/merc

due diligence fail

 

[Caa5030]

My manual states dex iii which is no longer made and the castrol trans max dex/merc is supposed to satisfy dex iii type h requirements.

 

[2005_Silverado]

dex iii is now dex vi

 

[Caa5030]

So are you telling me that the transmax dex/ merc does not meet old dex iii requirements? I understand that dex iv is the fluid that surpassed dex iii but as it read the trans max should be fine too.

 

[06GMC5.3L]

Should have used Dex VI. Dex VI can be used in Dex III applications, but Dex III cannot be used in Dex VI applications.

 

[2005_Silverado]

So are you telling me that the transmax dex/ merc does not meet old dex iii requirements? I understand that dex iv is the fluid that surpassed dex iii but as it read the trans max should be fine too.

im telling u theres no dex iv or dex v....it went from dex iii to dex vi. iirc 05 was a changeover year from dex iii to dex vi. GM no longer endorsed dex iii and dex vi was introduced...like stated above, its backwards compatible. I don't think the manual mentions dex/merc anywhere, might be wrong but I don't think I ever read it anywhere in there.

Point is, dex/merc is not what your truck calls for....Dex VI is...ur call if you want to change it or not.

 

[beckmand78]

I was wondering if you could give me some direction. I recently bought a 05 1500 silverado z71 5.3. It has 97k on it with a 4l60 with the deep pan. Since I just bought it I was probably hypersensitive to it but it seemed to be shifting a little funny. Against many peoples advice I decided to change the fluid and filter. First I tried the flush method of disconnecting the cooler line and failed miserably. The fitting pushed back into the radiator when I pushed on the drain hose. After leaking about three quarts on the floor I gave up and reassembled everything and refilled the transmission. I drove it for a day with no problems. The second day a felt a significant vibration in the driveline at about 50 mph when ever everything was heated up. Come to find out I had it too full. I pumped out the excess fluid from the top to achieve the correct level. Then I started to notice the tranny slipping pretty bad after it had warmed up. Recently, I went ahead and dropped the pan and did a filter/ fluid change. It still continues to slip. The fluid that I am using is castrol dex/merc which I have read should be fine. Low gears are fine and it seams fine when it's cold. When it heats up that's when I get the soft shifts and slipping especially in third and fourth. No transmission pro here but I know a fair amount about vehicles and I have put in my due diligence searching the forum. Any help is appreciated.

Vibration caused by trans overfilled? Doesn't sound right..

 

[Caa5030]

Update... I purchased castrol transmax dex vi tonight and went to flush using the cooler lines. I cycled two quarts at a time until I got to 6 quarts using the lower cooler line before I realized I was doing it wrong. I then switched to the upper cooler line. After I got setup for the upper cooler line, I started the engine and only a slight trickle came out. I was getting a much heavier flow from the bottom line. What would this mean if I am not getting a decent fluid flow from the top cooler line? Keep in mind the truck has not been driven this whole time. It probably only went 10 miles with the incorrect fluid before I parked it. Truck still continues to pull in and out of the driveway fine. It was only slipping after it heated up. Is this a possible pump failure since I am not getting fluid out of the top cooler line?

 

[outlawz2004]

Were you checking the fluid level after the trans was at operating temps, or checking it cold then adjusting the level to that. It should be checked at normal operating temps. IMO, you don't really sound like you know what your doing, may want to have it done by a professional while there may be a chance of saving it.

 

[2005_Silverado]

IMO, you don't really sound like you know what your doing, may want to have it done by a professional while there may be a chance of saving it.

this

 

[Caa5030]

http://www.gmfullsize.com/forum/showthread.php?t=179148&highlight=Complete+fluid+change

I was using this method to get the dex vi in and the dex/ merc out. Very little fluid came out the top fitting on the cooler, nothing like shown in the write up. There is plenty of fluid in the trans to push out the old. Is it possible for the cooler to have a blockage this heavy that wouldn't be pushed out by the trans line pressure itself.

I check the fluid at normal operating temp, not cold.

 

[Caa5030]

It seems like the people who have responded thus far are quick to ridicule but don't really have anything outside basic knowledge themselves. My actual questions are avoided. I also have a 99 vette and a 87 iroc-z and members on those forums are much more friendly and helpful. Trying to act like a cool kid on the internet is like trying to be the tallest midget in the midget parade. I am here to learn about this specific vehicle and come up with a resolution but have been left down as far as the world of forums go.

 

[2005_Silverado]

Idk why that how to tells u to use the cold side of the cooler. All ive ever done is turned the truck on and felt for the warmest trans line. I then remove it from the radiator and slip some hose over it and pump fluod out from there. You could try blowing out the cooler with compressed air but I doubt you have a blockage.

 

[beckmand78]

It seems like the people who have responded thus far are quick to ridicule but don't really have anything outside basic knowledge themselves. My actual questions are avoided. I also have a 99 vette and a 87 iroc-z and members on those forums are much more friendly and helpful. Trying to act like a cool kid on the internet is like trying to be the tallest midget in the midget parade. I am here to learn about this specific vehicle and come up with a resolution but have been left down as far as the world of forums go.

Did you use any kind od chemical flush/additive?

 

[Travisstorma]

If you pull the line off the bottom, does it come out at a solid stream? If so and the top just trickles out, there is an issue with the cooler. If the cooler is plugged, I'd be very curious as to where the material came from to clog the radiator, likely a failing trans if so.

 

[06GMC5.3L]

I used the cited procedure and unhooked the upper cooler line and had great flow. Not sure why yours isn't flowing.

The way I think the fluid flows is from trans to radiator via lower line, out radiator and into cooler via upper line, and out cooler back into trans with the cooler outlet line. If you have good flow out the lower line (assuming you are talking radiator), it sounds like your radiator may be plugged up. Just my .02.

You can pump out the lower line or the upper line. I think the "how to" uses the upper for ease of access.

 

[Caa5030]

Bottom line had a great constant stream. Sounds like I have a failing trans which plugged up the cooler. I am going to hit it with a little compressed air and see what comes out. I haven't used any chemicals to flush. I was just attempting to run fluid through. Do you think the dex/merc fluid was the cause of the failure if I do get a bunch of junk out of the cooler or just weird timing?

 

[Mr. 960]

welcome! I had an 88 IROC with the L98 great car. Dex/Mercon is the replacement for the old Dexron III. Starting in 06 GM went to the Dexron IV. The new fluid is fully synthetic, and is backwards compatible. Using the Dex/Mercon would not hurt your trans...... it is just like the old Dex III. To me it sounds like your trans is on the way out. How does the fluid look and smell like?

Mr. 960

 

[Caa5030]

The old fluid was a darker red or maroon but not black or brown. The pan was pretty clean. The magnet did have some metal fillings on it but nothing too heavy. Thanks for the fluid explanation. I thought I was ok with the dex merc.