Tranny Flush?

[Robby Avery]

Just as title implies what is the interval the trans should be flushed? I did a search on here but no results. Thanks in advance

[fpgt17]

I worked at a shop and the National car care recommends every 50,000. It is a good thing to do as long as you stay on top of it. If you have high miles and your trans fluid is black.. don't do it. But i typically do it every two years or 30,000 miles and it is the best way to keep your trans running/shifting great. My trans shop told me they would go out of business if everyone flushed their trans when they are supposed to.... Its preventative maintenance. Good luck

[Fivefingerdeathpunch]

what he said.

I would never do a tranny flush tho, its possible something could get plugged up somewhere in the tranny when the flushing happens and then blow the tranny a little while later.

I'd do a pan drop and filter change every 50k miles.

[Robby Avery]

Well I might try the pan drop method first. I have two trans codes that I need to get fixed they are P0420, and P0742. I posted in another thread I was told they are trans related. I'm guessing the trans fluid is possibly black don't know when it was last changed as its a used car and my GF had long before I met her.

[JoshsGTP]

If its black and burned its to late damage has been done. Change the fluid but dont flush.

[cerick08GP]

Man if I had a nickel for everyone who has went though this cycle. Do no maintenance, break the car, and only attempt to do the very least in a vain attempt to fix it.

I feel for ya, I went through the same thing with my X abusing her car.

Good luck, but I wouldn't expect aynthing to be fixxed with fluid at this point.

Harsh shifts, P0742

[SlowNA06]

Well I might try the pan drop method first. I have two trans codes that I need to get fixed they are P0420, and P0742. I posted in another thread I was told they are trans related. I'm guessing the trans fluid is possibly black don't know when it was last changed as its a used car and my GF had long before I met her.

My advice would be to put in fresh AC Delco spark plugs, fresh spark plug wires, fresh fuel filter, clean the mass air flow sensor with MAF cleaner, clean the throttlebody with throttlebody cleaner, and replace the catalytic converter (remove the "U-bend" in the exhaust while you're at it). A trans flush to GM spec would be good as well.

Then see where you're at.


P0420 = Bad/leaky catalytic converter or oxygen sensors, or even bad wiring to the sensors. It has absolutely nothing to do with your transmission.

Usually, this it s a clogged cat, which will break all kinds of other things - I'd start here and see if it fixes your other issues.

p0300 could be fuel contamination or clogged injectors. Maybe bad spark plugs.

I'll let the TrannyMan handle the rest:

P1811
P0742

[Robby Avery]

My advice would be to put in fresh AC Delco spark plugs, fresh spark plug wires, fresh fuel filter, clean the mass air flow sensor with MAF cleaner, clean the throttlebody with throttlebody cleaner, and replace the catalytic converter (remove the "U-bend" in the exhaust while you're at it). A trans flush to GM spec would be good as well.

Then see where you're at.


P0420 = Bad/leaky catalytic converter or oxygen sensors, or even bad wiring to the sensors. It has absolutely nothing to do with your transmission.

Usually, this it s a clogged cat, which will break all kinds of other things - I'd start here and see if it fixes your other issues.

p0300 could be fuel contamination or clogged injectors. Maybe bad spark plugs.

I'll let the TrannyMan handle the rest:

P1811
P0742

Thanks for your help that gave me everything I need to start with kudos. The codes you posted are the exact four codes that I pulled from the ECM via EFI Live scan tool.

[Robby Avery]

Man if I had a nickel for everyone who has went though this cycle. Do no maintenance, break the car, and only attempt to do the very least in a vain attempt to fix it.

I feel for ya, I went through the same thing with my X abusing her car.

Good luck, but I wouldn't expect aynthing to be fixxed with fluid at this point.

Harsh shifts, P0742

Women never car about their vehicle's only thing they care about is will it start, run, and drive and their happy lol found that out the hard way.

[Robby Avery]

My advice would be to put in fresh AC Delco spark plugs, fresh spark plug wires, fresh fuel filter, clean the mass air flow sensor with MAF cleaner, clean the throttlebody with throttlebody cleaner, and replace the catalytic converter (remove the "U-bend" in the exhaust while you're at it). A trans flush to GM spec would be good as well.

Then see where you're at.


P0420 = Bad/leaky catalytic converter or oxygen sensors, or even bad wiring to the sensors. It has absolutely nothing to do with your transmission.

Usually, this it s a clogged cat, which will break all kinds of other things - I'd start here and see if it fixes your other issues.

p0300 could be fuel contamination or clogged injectors. Maybe bad spark plugs.

I'll let the TrannyMan handle the rest:

P1811
P0742

How would I go about deleting the u bend does someone make a kit? I looked at zz performance but no luck. Again thanks to all who have helped me thus far in this thread.

[SlowNA06]

How would I go about deleting the u bend does someone make a kit? I looked at zz performance but no luck. Again thanks to all who have helped me thus far in this thread.

An exhaust shop would just weld in a piece of straight pipe - if I remember correctly, it would be cheaper than buying this. Unfortunately, my car's are a generation ahead of this, and GM did not put a u-bend on the '04+, so I don't know specifics. It's a very popular subject though, so I'm sure you can find many threads on it.

[Robby Avery]

Ok guys I checked the trans fluid today and its still red with a slight dark tint to it. I can see through it but its a little darker than brand new ATF so where do I go from here? Should I change it since its well north of the 50k mark intervals the car has 130,***mi.

[Poil336]

u-bend delete is simple, remove o2 sensor, remove bent piece of pipe, insert straight piece of pipe. keep in mind it'll throw a code/SES light because of not having a rear o2 sensor. you can either ignore it, set it to "no response" or something in the pcm, or build an emulator, which ive read is pretty easy too. something about a resistor... i don't remember

[SlowNA06]

Ok guys I checked the trans fluid today and its still red with a slight dark tint to it. I can see through it but its a little darker than brand new ATF so where do I go from here? Should I change it since its well north of the 50k mark intervals the car has 130,***mi.

I recommend flushes, but there's an awful lot of superstitious folk with regards to it. As long as you comply to GM spec (ie: no solvents, just dextron VI), you'll be fine - I specify this to the shop just in case.

[Poil336]

Ok guys I checked the trans fluid today and its still red with a slight dark tint to it. I can see through it but its a little darker than brand new ATF so where do I go from here? Should I change it since its well north of the 50k mark intervals the car has 130,***mi.

i'd probably just change it without flushing it.

[Robby Avery]

u-bend delete is simple, remove o2 sensor, remove bent piece of pipe, insert straight piece of pipe. keep in mind it'll throw a code/SES light because of not having a rear o2 sensor. you can either ignore it, set it to "no response" or something in the pcm, or build an emulator, which ive read is pretty easy too. something about a resistor... i don't remember

Could you dig up that info for me so I'll know how to wire the resistor?

[Poil336]

well... i can't remember exactly where it was, but here are a couple links that look promising.

http://www.mkiv.com/techarticles/oxy...sor_simulator/
DIY O2 simulator(s) - ChevyTalk --The Social Network for Chevy Fans

looks like it would be easier to pay for it, but that's just me lol