why 518 is slow to engage 1st?

[HankL]

1995 46RH automatic transmission is original and high mileage (180,000)

Upon coasting to a stop, 1st gear is now slow to re-engage when taking off again gently.

RPM seems to go a bit higher than in the past before you feel first gear catch.

When stopped, if the brake is depressed to hold the Ram pickup still and the engine given a little gas to raise the RPM's you sometimes feel 1st gear catch...and then the pickup will drive away from the stop like it used to.

2nd, 3rd and Overdrive seem to be working normally.

What would be your estimate of what the problem is?

Maintenance history:
ATF+3 last changed at 160,000 miles and changed regularly at about 30,000 miles of use.
Lubegard 'Red Bottle' additive used since about 80,000 miles.
Bands last adjusted at 130,000 miles.
There is a slow drip from the weep hole underneath the front torque converter housing...about a quarter of a quart per month.

ATF+3 was about 1/4 inch above minimum mark on dipstick hot. A quart of ATF+3 was added yesterday and now the level is about 1/8 inch over maximum when fluid is hot and checked in neutral.
At this high mileage and the slow drip out the front...should I put the money into dropping the pan, changing the filter, adjusting the bands...or should I just have the trans rebuilt now before anything real serious has failed inside?

With old age my memory is slipping but I do seem to remember reading that about 1998-1999 Chrysler significantly changed the design of a front drum seal...moved the seal off the drum? Can this revised part be fitted to my earlier 1995 design?

Do I also remember that about 1996-1997 Chrysler started buying and installing a 'D-ring' type of seal instead of those used earlier?

Can anyone recommend good Mopar transmission shops near either
Raleigh-Durham NC
Knoxville TN
or Lexington KY ?

[John Kunkel]

Check the filter first.

Assuming the filter isn't clogged, the problem is in the rear clutch. When the clutch seals get old and leak, the clutch won't stay engaged at low speed/low pressure.

[pcrmike]

Ditto, John. :-)PCRMike

[HankL]

Thank you both for those replys, John Kunkel and PCRmike!

If the filter is not clearly clogged when I drop the pan,
is it worth considering adjusting the line pressure a little bit higher on a high mileage 518?

I am not thinking a lot higher line pressure...maybe 5 psi higher when checked running 2000 rpm in 3rd gear?

I hope to drop the pan as soon as tropical storm Ernesto passes by and the rain slows down.

[HankL]

One last observation from driving yesterday....

After coasting to a stop,
if I shift into Neutral just briefly
then shift into Drive again
I feel a slight 'clunk' as 1st engages and
the transmission will pull away from the stop in the correct gear completely normally again.

Is that an indication that the old rear seals are leaking?

[JVMopar]

I had a sundance that would do that. I'd disassemble the valvebody and clean it out (usually had a valve sticking) and put it back together and it'd be good for a couple of months. But at 180,000 it's probably time for a rebuild anyways.

[451Mopar]

My guess, The rear band may be out of adjustment, or the rear band servo may not be sealing very well.

[John Kunkel]

The rear band isn't used in Drive.

The reason the rear clutch will engage when shifting to Drive is the sudden surge of fluid, it will force the clutch to engage. Low pressure is the problem whether it's from leakage or a clogged filter.

Cranking up the line pressure adjustment isn't the answer.

[pcrmike]

Agreed. Again. John, this thing of you and me agreeing is wierd. Cool, but wierd. LOL! :-)PCRMike

[HankL]

As a follow-up to my original post
two days ago I dropped the trans pan
installled an official Mopar filter
re-torqued the three small but long allen bolts on the filter to 35 inch lbs,
installed the new hard black plastic 'no leaks' gasket from Mopar,
retorqued all the pan bolts first to 6 ft-lbs, then on to 13 ft-lbs
and put in 4 quarts of ATF +4 (9602).

On the test drive after this I coasted to a stop perhaps 20 times
but never once felt 1st gear slow to engage on the subsequent take-off from the stop.

When I got back from the test drive
I inserted the suction hose of a hand transfer pump down the trans dip stick tube and pumped out 4 quarts of the mixture of ATF+3 and ATF+4 fluid. I then re-filled with 4 new quarts of ATF+4. I am guessing this changed the ATF mixture to about 50-60% ATF+4

This morning I drove another 30-40 miles and coasted to a stop at least 20 times.

The shifting was perfect...no 1st gear slow engagement at any time.
My impression was that the 1st to 2nd gear change was also a bit smoother than before.

The old filter that was replaced did not visibly look unusual...stained a dark red from the ATF. The old filter's outside surface had a few flakes of either aluminum or babbit metal that the eye could see both on the bottom and top surface.

In the pan, the circular magnet had a 'mushroom' of very fine particles attached to it, nearly all of which was very fine...like black talcum powder.

In the center of the pan bottom there was a clump of 'white metal' shavings that were not magnetic. This clump of metal shavings was bigger than a quarter coin, but not bigger than the size of two quarters.

Looking up at the valve body it looked very clean with no visible varnish.

The ATF+3 that was drained out looked dark red but not burnt.

[pcrmike]

The "white, non magnetic" is aluminum, and indicates a possible issue, but the problem MAY have been a dirty filter or something of that nature, but don't rely on it too fully yet. I agree there is likely another issue at hand. Did you have the bands adjusted? :-)PCRMike