trans question....

[powerinit]

hey guys, my other car (a 88' beretta w/ auto trans, 3.1 swapped in) when I put it in reverse, I feel a VERY light engage, then it just acts like it's in neutral. Just got the car so, I don't know what work it's had. I was told to try changing the filter, what do you guys think it could be? I know this isn't a caprice (my caprice is running fine i'm glad to say), but the beretta part of the forums don't answer much of anything and you guys are always there with an answer, which is nice. So thanks for any help.

[Blue Bowtie]

I'm not sure, but is that the 4T40?

[powerinit]

it's the 3 speed, which I believe was the 3T40?

[Blue Bowtie]

I would check the line pressure at idle in park/neutral, reverse, drive, and manual Low.

Low presure might be impedeing the application of the low/reverse clutch. Low pressure could be caused by low fluid level, worn pump, or even a loose or damaged filter. It's not a bad idea to drop the pan and change the oil and filter just for agrument's sake. You never know what you might find.

[silicon212]

Originally Posted by Blue Bowtie

I would check the line pressure at idle in park/neutral, reverse, drive, and manual Low.

Low presure might be impedeing the application of the low/reverse clutch. Low pressure could be caused by low fluid level, worn pump, or even a loose or damaged filter. It's not a bad idea to drop the pan and change the oil and filter just for agrument's sake. You never know what you might find.

To expand on what Blue Bowtie is saying above, low line pressure generally manifests itself first in reverse gear. The reverse clutch generally requires higher line pressure to engage than the forward/input clutch does, so reverse is where you will notice it first.

3T40/TH125 is what your car will probably have.

[powerinit]

well, I know the fluid is actually above the mark. I really don't know about the pump. So you guys think it's an alright idea to go ahead and try changing the filter and fluid first and go from there? I was told by others to be careful because flushing these tranny's with more than 100,000 miles for the first time could cause premature failure. Neways, thanks for the help so far guys

[Blue Bowtie]

No one mentioned anything about a flush. Simply pull the pan, install a drain plug if you feel like you'll be keeping the car, remove the filter, remove the filter's pickup tube seal, and install a new seal, filter, re-use the original pan gasket if you can, and the appropriate amount of Dexron III to return the oil level to the FULL mark (with the engine running in PARK, a warm transmission, and on level ground).

If you are concerned about the theory that draining a transmission with that many miles may "kill" it, there should still be enough contamination and friction material left in the oil stuck in the converter to give you some drive. Changing the oil in a transmission will not damage it, period. The worst it will do is remove any sludge which may be masking leaks, and dilute the amount of contamination and grit in the oil which was making an already dead transmmission work just a little bit more. If it's that bad, it is already about to go, and nothing will stop that short of a repair.

The majority of the time, changing the trans oil is a beneficial procedure. We typically only hear about those few horror stories where someone has drained the oil and lost all drive. We seldom hear about the much higher number of instances where the oil was changed regularly and the transmission lasted 300,000 miles as a result - The old "squeaky wheel" syndrome.

[powerinit]

oh, alright, so not all the fluid will come out then? I was just under the impression that it all would come out, sorry about that. Should I put some sealant type stuff on the new gasket? or is it fine without it?

[silicon212]

Originally Posted by powerinit

oh, alright, so not all the fluid will come out then? I was just under the impression that it all would come out, sorry about that. Should I put some sealant type stuff on the new gasket? or is it fine without it?

No, the oil in the pan accounts for about 30-40% of total fluid. About a pint will remain within passages in the valve body, the rest (up to 60-70%) is in the torque converter and cooling system.

[powerinit]

so would it be alright if I drive it right after changing the filter to warm the tranny up and check the level? or would there be a problem with no fluid in the pan? Also what about the sealant stuff, do I need any or is the gasket good without any? Thanks for the help, sorry about all the questions.

[troy1]

125C's have been known to burn out reverse. how does it hold when it engages?

[powerinit]

you can barely even notice that it engages at all, after that you can rev all you want and it won't do anything, like neutral.

[powerinit]

Originally Posted by powerinit

so would it be alright if I drive it right after changing the filter to warm the tranny up and check the level? or would there be a problem with no fluid in the pan? Also what about the sealant stuff, do I need any or is the gasket good without any? Thanks for the help, sorry about all the questions.

any replies?

[Blue Bowtie]

When you drain the trans pan, catch all you can (you don't want a mess, anyway). After installing the new filter and closing up the pan, add a quart of fresh trans oil. Fill that emptied container with the used (drained) trans oil. Pour another quart of clean trans oil into the trans. Fill that empty container with the used oil. Repeat this until all the oil you drained is back into the emptied containers of new oil. At that point, you should have added about as much clean oil as you drained, and it should be safe to start and drive until the trans is warm and you can check the fluid level properly.

If you can, re-use the original pan gasket. Just clean the pan and flange surfaces, and both sides of the gasket before assembling it. It will seal better than the cork replacements, and requires no sealants.

[powerinit]

alright, thanks. i'll have to get around to changing it soon.