Auto Mechanic type question...

[Cupcake]

or anyone who has input...

About 3 months ago, I purchased a 2001 GMC Sonoma, 4 cyl, 2WD, 115K miles. It's always run/driven/shifted fine. Figuring that everyone neglects the transmission, I decided to drop the pan, change the filter and replace the amount of fluid that came out with the pan. I've done this twice on my Focus with no problems.

Since I've done it on my truck, however, I have two issues:

1. Once in a while, when I start the truck (and its in park) the truck bumps forward gently. Why is any energy being transmitted to the wheels while the truck is in park? and not all the time, usually when it happens, it's first thing in the morning.

2. I started leaking around some rubber tubing where it clamps onto metal tubing. Trans fluid was spraying onto my catalytic converter. replaced the hose clamps with fuel line type clamps yesterday and I think that has taken care of that. related? unrelated? I don't know, just giving the info.

Any idea what I screwed up? Thanks much.

[DefensiveCarry.com]

[Mr. Habib]

Did you check the fluid level after repairing the leak? If it is low could that be causing the first problem?

[SIXTO]

I'm not a mechanic by any stretch of imagination, so take this with a grain of salt;

First, I doubt you put in enough fluid. If your starting point was putting in the amount you took out, you are already starting off low. At 115k, a lot of fluid has been churned and burned so I doubt it was anywhere near the recommended about. I'd look in the owners manual, the correct amount should be listed. If you don't have one, I'm sure it can be found via our pals at Google.

Second, anytime you drop pans or bust open a pumpkin, you will have a leak or two unless you replace the gasket too. Are you sure this isn't the source of your leak?

[TucAzRider]

What is happening is the clutch packs are sticking when you starting it causing it to act like it is in gear.. What trans fluid did you add? How much did you add?

You should be putting in Dextron III,.. and I recommend using a additive Lube-Gard #60902... You should have added about 5qts if it was full when you dropped the pan.. Make sure to the engine is at operating temperture when you check it and make sure it is in PARK...

It doesn't make sense why this would happen after doing what I've read,.. But things happen,...

[Cupcake]

Thanks so far,

I added 5 qts of valvoline Max Life hi mileage. Supposed to be good for dexron and mercon. I did indeed replace the pan gasket... clutch plates sticking, hmm...

[TucAzRider]

Put the Lube-Gard additive in there and that will more then likely take care of the problem..

[rottkeeper]

On another note just dropping the pan and replacing that fluid, it does you little good, you still have all the fluid in the torque converter that is old. As soon as you run the vehicle you will effectively be contaminating the new with old fluid

It is well worth the money to have a tranny flush which will exchange all the old fluid with new including the torque converter.

[Rugergirl]

On another note just dropping the pan and replacing that fluid, it does you little good, you still have all the fluid in the torque converter that is old. As soon as you run the vehicle you will effectively be contaminating the new with old fluid

It is well worth the money to have a tranny flush which will exchange all the old fluid with new including the torque converter.

You beat me to it RK.
I would definately get it flushed if you are having problems after the filter change.
Maybe add the Lube-Gard after the flush or have the shop add it for you.

[HKinNY]

I agree with the transmission flush there are appx 16-18 quarts of fluids in the touque converter and thru the lines. Here is the catch with vehicles with high miles and the fluids never change duing the life of the vehicle, Do not be surprised that after the flush the transmission with slip and will have to be rebuilt. The new fluid washes away the dirt deposits an dcleans everything but those gumed up parts have sealed the leaks between the gaskets and pan and seals. That is why it is not recommened to put sytactic oil into an old eng it too will start to leak and burn oil.

[Stranger]

As mentioned above get it flushed!!!
I have never had a GM tranny (not including Allison units) work correctly after just changing whats in the pan. However, after a good flushing no issues.

I have found the best way to avoid any of this is with a straight drive!!! :)

[TucAzRider]

I have found the best way to avoid any of this is with a straight drive!!! :)

HAHAHAHA... Only in the east do ya hear them words... First time my ex g/f said that to me I thought she went lo-co,.. But I've heard it after that, always from those that live between SC - Virginia,.... I needed that laugh today,. Thanks..

[rottkeeper]

As mentioned above get it flushed!!!
I have never had a GM tranny (not including Allison units) work correctly after just changing whats in the pan. However, after a good flushing no issues.

I have found the best way to avoid any of this is with a straight drive!!! :)

OK I'll ask, what's a straight drive?

[GMS]

The reference is to a manual transmission, but more technically I've heard the term used to refer to the manuals without synchronized gears that required double clutching to shift gears.

[Cupcake]

I agree with the transmission flush there are appx 16-18 quarts of fluids in the touque converter and thru the lines. Here is the catch with vehicles with high miles and the fluids never change duing the life of the vehicle, Do not be surprised that after the flush the transmission with slip and will have to be rebuilt. The new fluid washes away the dirt deposits an dcleans everything but those gumed up parts have sealed the leaks between the gaskets and pan and seals. That is why it is not recommened to put sytactic oil into an old eng it too will start to leak and burn oil.

This is hi mileage flush trouble is the reason I chose to just change the filter and the 5 qts in the pan...I've heard of bad stuff happening if it's never been done and then you do it too late. I figured a new filter and some sweetening should give me a bit more life without hurting. Thanks all for the input, checked one auto store for the for the lube additive but couldn't find it. that's my next move, assuming the leaks are resolved. Failing that, maybe I'll do the flush or just have a trans shop look at it.