Trans fluid flushing?

[Pipeless416]

Hey all, just wanted to get your opinions on whether or not a full trans flush is a good idea. My car has 86k with a 4L60E and its shifting really hard from 1-2 and i pretty much have it narrowed down to a few things.

1. Dirty MAF sensor..this is my guess as to the cause of the hard shifting.

2. Needs new trans fluid.. (i don't have a record of the last change.)

3. Broken trans mount.. i won't be able to check that out for a little bit, considering i can't even get my head under my car
:o .

I figured it's about time for a fluid change in the trans and the rear differential, mostly because then i have a record of everything. the trans fluid does not look burned, but it does need to be changed soon.

Thanks for any insight.

[CJM]

If the mount was broken it would vibrate like crazy in all gears when you have your foot on the skinny pedal. You would feel it in the floor, seats, steering wheel-etc.

MAF could cause shifting issues, but I doubt it. If anything it would cause it to run rough and the idle would be lopey and bad and or possible misfires. If you dont have a check engine light for it or anything related then i doubt it.

Trans probably needs to be flushed. the single best way is to go to a place that has a trans tech machine. These machines pump in new fluid while pumping out the old and it will remove all 15-20 qts. You can often do this yourself if you have some kinda trans cooler and hook up hoses to the outlet and inlet.

Also I would take the pan off and check the solenoids and the valvebody to make sure its fine.

If you have any check engine light check the codes and see what they say too.

[brian76708]

Originally posted by Pipeless416
Hey all, just wanted to get your opinions on whether or not a full trans flush is a good idea. My car has 86k with a 4L60E and its shifting really hard from 1-2 and i pretty much have it narrowed down to a few things.

1. Dirty MAF sensor..this is my guess as to the cause of the hard shifting.

2. Needs new trans fluid.. (i don't have a record of the last change.)

3. Broken trans mount.. i won't be able to check that out for a little bit, considering i can't even get my head under my car
:o .

I figured it's about time for a fluid change in the trans and the rear differential, mostly because then i have a record of everything. the trans fluid does not look burned, but it does need to be changed soon.

Thanks for any insight.



what every you do dont get your fluid power flushed by a shop. just drain replace filter and fill up with new stuff the powerflush they do pushes all the stuff that was in your old filter past it.

but the hard 1-2 shift is usually solved by a new valve body. which isn't the easiest to replace but the parts would probably be 150 to 200. If i was you I would change the fluid and check the trans mount and hope for the best.




Originally posted by CJM

Trans probably needs to be flushed. the single best way is to go to a place that has a trans tech machine. These machines pump in new fluid while pumping out the old and it will remove all 15-20 qts.

please DO NOT do that as stated above why not to. have herd way to many stories of the trans going out in the next month after a "Power Flush".

[Pipeless416]

this is exactly what i'm talking about.. very different opinions, both with valid reasoning. i've been looking a lot on LS1tech and LS1.com and a lot of people seem to have this problem. 80% of them say they cleaned the MAF and it solved the problem. i did just replace the air lid, so i'm wondering if anything got on it. i don't run an oiled air filter, but i have been using a lot of wd40 to clean up the lid, and i'm wondering if that somehow got in there. the other 20% say a flush and new fluid solved it.. in some other threads, people say it was a dry rotted bushing for the torque arm.. there's so many things, but so far none of them are saying it's a failure on it's way :macho . i'll be cleaning the MAF now and i'll report back with any changes.

[CJM]

Im a mechanic, never seen one blow up unless it was already screwed.

Power flushes are fine, I have never had one fail. Draining the pan only removes maybe half of the fluid which doesnt really help.

Your call if you want to do it. I never had issues.

[Pipeless416]

Originally posted by CJM
Im a mechanic, never seen one blow up unless it was already screwed.

Power flushes are fine, I have never had one fail. Draining the pan only removes maybe half of the fluid which doesnt really help.

Your call if you want to do it. I never had issues.

i will be having it flushed at a performance shop when the money comes around.

update- i just cleaned the MAF sensor with MAF cleaner... feels like a new car and the hard shift is completely gone, even after the car hasn't been driven in a few days. :D i also bought a gasket for the rear end, so i'll get that done eventually. i just want records of when everything has been done.

[CJM]

Interesting, but hey sometimes ya never know.

[Pipeless416]

Originally posted by CJM
Interesting, but hey sometimes ya never know.

the ls1tech guys were saying that a dirty MAF will cause the computer to increase line pressure, causing the hard shift. overall, the trans is so much smoother and the engine seems to run better than it ever has. amazing that a $6 can of cleaner did that!

[slightlybent47]

I have herd that flushing it out or even replacing the fluid will make it start slipping because after it has that many miles on it, it has gunk built up in the passages and in gapes. And by flushing it, it cleans out the gunk and fluid starts passing through places it didn’t before causing it to slip. My truck has 140k and it started shifting hard and slipping between shift points. I took it to pep boys and it showed a code for the throttle positioning switch. So I replaced it and it salved the problem. TPS was $30.00 and the diagnostic was free.

And I’m still running the original fluid from the factory, the only thing i have done is add some fluid to it a few times.

[TRX_450]

ive also been trying to decide this...my truck has 123k on it and will slip into second when its cold and also comes out of gear on occasion at stop lights. pretty sure the tranny needs flushed but i get 50/50 on people saying do it and others say dont itll blow it up.

[slightlybent47]

All I know is a 30 dollar part fixed mine and it has a lot of miles on it with the original fluid in it. And I pull a trailer a lot of the time.

[Pipeless416]

Originally posted by slightlybent47
All I know is a 30 dollar part fixed mine and it has a lot of miles on it with the original fluid in it. And I pull a trailer a lot of the time.

you have 140k on the original fluid? since it has been slipping a little, i would imagine that the fluid is long gone :eek2:

[CJM]

Originally posted by Pipeless416
the ls1tech guys were saying that a dirty MAF will cause the computer to increase line pressure, causing the hard shift. overall, the trans is so much smoother and the engine seems to run better than it ever has. amazing that a $6 can of cleaner did that!

It depends on the trans and car itself usually, some cars like yours with a dirty MAF (I didnt know this offhand either) apparently can cause problems shifting. Hey more ya know.

@Bent:
It all depends, if your still at 140k with the original fluid or it wasnt changed very often then your trans itself could take a dump. In either case you dont have much to lose.

In my book flushing the trans should be done every 20-35k and it keeps the trans in tiptop shape.

[slightlybent47]

No what I tried to say is that it was shifting hard and slipping between shift points and a TPS was all it was. It works great now and it still has the original fluid in it. It shifts good and doesn’t slip anymore.

[slightlybent47]

I know it’s hard to believe that a 30 dollar switch that mounts to the carb and took me all of five minuets to change solved my transmission problem, but it did.

[slightlybent47]

I might add that I have owned this truck from the day one so I know it is still on the original fluid.

[k4f5x0r]

I dont know much about tranny's, but my dad has had 5+ cars all pushing 200K before he sells them, running perfect on original fluid and tranny's. its probably about 70 percent highway and then 30 towing/mixed.

[slightlybent47]

Pipless I don’t know if you have one (TPS) but I just thought I would bring it up since it save me from buying a new transmission.

[slightlybent47]

It would suck big time to replace a transmission and then find out it was a 30 dollar part all along. Witch brings me to wonder if a mechanic replaced your transmission and then found out that it was just a switch if he would own up to it or just replace the switch and say nothing and still charging you for the new transmission? Or even then tell you he also found another problem and charge you for both.

[CJM]

Originally posted by k4f5x0r
I dont know much about tranny's, but my dad has had 5+ cars all pushing 200K before he sells them, running perfect on original fluid and tranny's. its probably about 70 percent highway and then 30 towing/mixed.

Not flushing your trans is a bad thing, whats keeping your dads cars together is the mud that was once trans fluid. Would you drive 100k and not change the oil ever? Whats probably saving him is the fact he mostly does highway according to what you said-in which case the trans is not subjected to shifting to much at all vs a person who is stop and go only.

I serviced fleet trucks, specifically mostly fords and chevys and they never needed trans work until they had alot of miles (250k) and sometimes none at all-secret was flushing them and cleaning the valve bodies every 20-35k. These were worked very hard and driven hundreds of miles a day too.


Its your own call what you want to do, but 206k on my toyota truck and I always flushed using the severe schedule (every 15-20) as did previous owners and no issues at all.

@Bent:

Was it a GM product? Just curious.

[k4f5x0r]

On my CRD(06 diesel jeep libby) its at 146k without any flush but all common maintenance done, and it was previously his but now does more local then highway. I've been thinking about a tranny flush but most say dont bother with it on the CRD due to it being a sealed case.

if i ever have any tranny issues that will be one of the things i will look into after the usual things.

[416racer]

Flushing the tranny fluid is a scheduled maintance thing,not a problem solver. In my time at the shop, the people trannys that went out after a flush were the ones having troubles before. BTW the flush machines use the trannys pump to flush the fluid not an outside source.

[slightlybent47]

Originally posted by CJM

@Bent:

Was it a GM product? Just curious.


It’s a 94 Silverado with a 350 - 4 speed automatic.
I had a 05 tundra work truck that had a sealed tyranny and you couldn’t even check or add fluid to it at all. Toyota seems to think it’s only nessary to be serviced at 100k.
I think the key is if you have a new one then change the fluid every 20k, but if it’s got over 50k and it’s never been changed then don’t do it.

[CJM]

Trick to not servicing them is if it smells burnt and looks like mud its probably a good idea to leave it alone. Course everyones trans is different, I flushed a few that were like that and they were fine.

Toyota uses a synthetic fluid that imho may last to 100k, Im still skeptical tho.

[slightlybent47]

If it looks like mud then a flush may be necessary because the fluid has gotten so thick it can’t flow right. But mine is dark but plenty thin so I think it will be fine. At least I’m hopping it will.
All I know is "if ant broke don’t fix it".

[Pipeless416]

Originally posted by slightlybent47
All I know is "if ant broke don’t fix it".

lol, ^does not apply to f-bodies. if its not broken, it will be soon.

[bbender85]

Originally posted by slightlybent47
I have herd that flushing it out... will make it start slipping because after it has that many miles on it, it has gunk built up in the passages and in gapes. And by flushing it, it cleans out the gunk and fluid starts passing through places it didn’t before causing it to slip..

^^that.

the "gunk" fills the areas that have worn and keeps the tolerances between mating/meshing parts tight. flush it out and now you have loose tolerances, which is not a good recipe for an auto trans.


drop the pan, replace the fuild and filter. i also had good luck with lucas trans fix when the trans in my first car started to slip.

[400ex28]

;)

http://www.gmfullsize.com/forum/showpost.php?p=3630550&postcount=1

[CJM]

Originally posted by 400ex28
;)

http://www.gmfullsize.com/forum/showpost.php?p=3630550&postcount=1

Thats pretty much the DIY method using your own trans to pump it in and out. Ive done a few that way, its messy and fun!

[Pipeless416]

that method is pretty interesting. it doesn't seem like it will be forcing fluid out like a power flush, but you'll still end up changing more than 1/3 of the transmissions capacity.

[fearlessfred]

Originally posted by Pipeless416
that method is pretty interesting. it doesn't seem like it will be forcing fluid out like a power flush, but you'll still end up changing more than 1/3 of the transmissions capacity. i have used this method and it worked well and u kinda need someone to help u .i have done it on my f 250 and i am going to do it on my t/a soon.i was told by a trans mechanic not to overdo the changing of trans oil because it is highly detergent and somewhat abrasive and then he showed me his hands with no calous on them from being in trans fluid all the time. if the fluid smells like burnt coffee than your past due for a change.and a tps can definitly cause the harsh shift and big clunk ,when u put in gear,but a ck.engine light should come on if its the tps .or it least it does on my t/a. mine does this once in a while and all i do is mess with the wire to the tps and it corrects itself ( bad connection somewere ) if your car starts to do it again ,thats another place to look.if the computer sees low voltage from the tps than it puts the tranny into save itself mode.i read that u allready correected it.just wanted to put my two cents in

[vjace]

I had that same issue don't flush I have an lt1 trans went 800 miles later I just swapped everything to a t56

[eastside 400]

if your fluid is really bad or has gone like 70-90k without a fluid change then you are better off not flushing it. If you keep up with routine flushes then your tranny will deff. have a better chance at lasting longer... As some people have said already, then trans flush machines dont actually pump the fluid out, its just "exchanges" it, old comes in the machine and pushes the new fluid back in. the reason some trannies end up getting worse isnt because of the machine doing the flush, its just that all the fluid was replaced and the trans was already to the point where it was going out.

[fearlessfred]

Originally posted by eastside 400
if your fluid is really bad or has gone like 70-90k without a fluid change then you are better off not flushing it. If you keep up with routine flushes then your tranny will deff. have a better chance at lasting longer... As some people have said already, then trans flush machines dont actually pump the fluid out, its just "exchanges" it, old comes in the machine and pushes the new fluid back in. the reason some trannies end up getting worse isnt because of the machine doing the flush, its just that all the fluid was replaced and the trans was already to the point where it was going out. x2

[vjace]

my camaro only has 70k as of today. used to be a daily driver up until 45k i had the fluid drained and filled at 30k at 60k power flush at amcco bye bye trans at 60800. just my personal experience. plus I have a ati pro charger witch probably helped blowing the trans out but it held up for 15k no slippage until the power flush. I personally would just do a drain and fill job and if you have the pan down do a shift kit just my 2 cents, what do i know im just a mechanic for toyota for 5 years and do bg trans flushes on toyotas everyday. gm never made a good a/t trans in my opinion.

[Pipeless416]

Originally posted by vjace
my camaro only has 70k as of today. used to be a daily driver up until 45k i had the fluid drained and filled at 30k at 60k power flush at amcco bye bye trans at 60800. just my personal experience. plus I have a ati pro charger witch probably helped blowing the trans out but it held up for 15k no slippage until the power flush. I personally would just do a drain and fill job and if you have the pan down do a shift kit just my 2 cents, what do i know im just a mechanic for toyota for 5 years and do bg trans flushes on toyotas everyday. gm never made a good a/t trans in my opinion.

could the same benefits of a shift kit also be seen with a tune? i'm thinking about just doing a mail order tune by "Frost" if you're familiar. also, i've heard both ways.. what does a shift kit do to the longevity of a trans?

[vjace]

not for nothing i would take the advise from the guys on z28 or what ever ls1 form your on b/c they have personal experience with that car just like im on here for my quad. Just my two cents on advice taking im not trying to say that people on here are dumb or less knowledgeable about trans. for all i know they could be a trans re builders at a shop even they dont know how that trans would adapt to a flush b/c every car is different. As per shift kit its only like 70 bucks when i did mine back in 02 or 03 i dont remember. I order mine from rk sport I think. Its a harsher shift but you have a less chance of burning out your clutch packs. If your looking for a smooth ride dont get it. but if your into fishtailing and having those tires spinning in between shifts the a **** kit is the way to go. That was like the first mod i did and my tires would break loose when it shifted 1 to 2 and chirp 3rd. As for Frost never herd of them.
good luck buddy I have my own trans issues to deal with on my quad....

[vjace]

ps
i know this sounds stupid but did you check your trans fluid level and color? And when you did this was the car on? If its off your not gonna get the right level. maybe you discussed this all ready before for i did not read everyones reply just like the fist and second page.

[Pipeless416]

Originally posted by vjace
ps
i know this sounds stupid but did you check your trans fluid level and color? And when you did this was the car on? If its off your not gonna get the right level. maybe you discussed this all ready before for i did not read everyones reply just like the fist and second page.

yep, i checked both on and off. fluid level is good and the color is good too. im wondering if the previous owner possibly had a shift kit installed already, because my shifts are very firm compared to my friends ws.6. it does chirp from 2-3 sometimes as well. i guess theres only one way to find out.. and yes, i am a member of ls1tech and ls1.com. that's where i figured out that it could have been a dirty MAF, which is what it turned out being. thanks for all the help.. next mods are an electric cutout and a tune! :devil: