Clunk from reverse to park

[JMC]

Hello everyone. I’m having issues with my 2000 Lincoln LS transmission. There are so many transmission threads, but most do not seem to pertain to my exact concern.

Back in 2010, I had my original transmission replaced at a dealership with a factory Ford/Motorcraft rebuilt transmission. The car has not been a daily driver since about a year prior to that. I have put less than 5,000 miles on the new transmission over the past 11 years. I do not know if any transmission parts/electronics were moved over from my old unit, opposed to installing new, everything. I have not changed the transmission fluid on the new rebuilt unit.

The car is backed in to my garage. When shifting from reverse, to park, there is a rough clunk. Going to other gears seems to emit a slight tug on the drivetrain, but no notable clunk.

With the rebuilt factory transmission having so few miles, but now being over ten years old, could it simply be that the transmission fluid is going bad due to age, and therefore causing the issue? Could the fluid level have burned off or dissipated some? Possible that the solenoid was not replaced? Something else entirely?

Any input from those whom have had the reverse to park clunk and would care to chime in, I would greatly appreciate the input.

While looking around underneath today, I did notice what appears to be slight seepage from the driveshaft, close to where it mounts to the transmission. Could this be a cause for any concern, perhaps of another type?

Thank you in advance!

 

[04_Sport_LS]

The factory rebuilt trans would have all new intrnals installed... including a new solenoid pack. For the most part when a transmission is "rebuilt" ... the case is checked for wear, and new parts installed. Any case that ends up "out of spec" ... is rejected. I don't know for sure if Ford would "sleeve" certain areas like most "reputible" rebuild shops would... because that is "time intensive". Most likely a bad case would be discarded for "melt".

The driveshaft coupler in your pic does look questionable, and it would probably be best to replace that. However... it is part of a "balanced assembly" and should be taken to a driveshaft shop to be balanced... with the new coupler installed.

And since the driveshaft is a 2 piece design... it has a center support bearing, and over time the rubber surrounding the support bearing goes bad. If you are also getting a driveline vibration between 45mph and 60, (more noticeable in colder weather), the center support bearing needs replaced.

However... you may have some other minor issues... that you could do/check/adjust yourself.

When you get the reverse-park clunk... do you notice the engine RPM increasing? If so... the shifter cable may be out of adjustment... or the transmission range sensor may be out of adjustment or getting quirky.

I would do the cable and range sensor adjustment first... if you are noticing an RPM increase during the reverse to park shift.

Beyond that... a full driveline inspection should be done on the center support bearing. It's a bit of a pain... because the aluminum shield under the car creates a "tunnel" that doesn't give easy access.

All of the above mentioned problems/fixes... are mostly based on the age of the existing parts.

And yes... you should have the tranny fluid and filter changed... even with the low amount of miles driven.

While Mercron V, (5), is full synthetic... once contaminents get into the fluid, (from normal wear), the fluid will start to break down.

A bit of trivia I learned a few years ago:

With conventional oils... they start beaking down, (through oxidation) as soon as they are exposed to air.

Synthetic oils don't break down when exposed to air. Just through use.

 

[joegr]

Maybe it's just the picture, but that bottom bolt on the flex coupler looks loose to me. That would explain your clunk. If it's not, then I still suspect that the clunk is due to something other than the transmission itself, like the center u-joint or the center bearing. Given the 22 year age of your car, I think that the center bearing carrier is actually a really good suspect.

(That is not a leak or seepage on the coupler. That's probably a stain from assembly.)

 

[04_Sport_LS]

Yeah Joe... by the pic..
I wasn't sure if the bolt was loose or the guibo/coupler was failing.

 

[JMC]

The factory rebuilt trans would have all new intrnals installed... including a new solenoid pack. For the most part when a transmission is "rebuilt" ... the case is checked for wear, and new parts installed. Any case that ends up "out of spec" ... is rejected. I don't know for sure if Ford would "sleeve" certain areas like most "reputible" rebuild shops would... because that is "time intensive". Most likely a bad case would be discarded for "melt".

The driveshaft coupler in your pic does look questionable, and it would probably be best to replace that. However... it is part of a "balanced assembly" and should be taken to a driveshaft shop to be balanced... with the new coupler installed.

And since the driveshaft is a 2 piece design... it has a center support bearing, and over time the rubber surrounding the support bearing goes bad. If you are also getting a driveline vibration between 45mph and 60, (more noticeable in colder weather), the center support bearing needs replaced.

However... you may have some other minor issues... that you could do/check/adjust yourself.

When you get the reverse-park clunk... do you notice the engine RPM increasing? If so... the shifter cable may be out of adjustment... or the transmission range sensor may be out of adjustment or getting quirky.

I would do the cable and range sensor adjustment first... if you are noticing an RPM increase during the reverse to park shift.

Beyond that... a full driveline inspection should be done on the center support bearing. It's a bit of a pain... because the aluminum shield under the car creates a "tunnel" that doesn't give easy access.

All of the above mentioned problems/fixes... are mostly based on the age of the existing parts.

And yes... you should have the tranny fluid and filter changed... even with the low amount of miles driven.

While Mercron V, (5), is full synthetic... once contaminents get into the fluid, (from normal wear), the fluid will start to break down.

A bit of trivia I learned a few years ago:

With conventional oils... they start beaking down, (through oxidation) as soon as they are exposed to air.

Synthetic oils don't break down when exposed to air. Just through use.

Thank you for your suggestions and thoughts. I will have the driveshaft looked at and replace anything that is worn. I do not have any vibrations from it, but living in Florida, perhaps it’s never cold enough to notice.

The clunk I get when going from reverse, into park does not seem to have any other symptoms. The engine rpm’s do not rev. The physical movement of the shift knob into park is not super smooth as it is going into other gears however.
I will have the transmission fluid flushed. Any need to open it up and install a new filter?

 

[JMC]

Maybe it's just the picture, but that bottom bolt on the flex coupler looks loose to me. That would explain your clunk. If it's not, then I still suspect that the clunk is due to something other than the transmission itself, like the center u-joint or the center bearing. Given the 22 year age of your car, I think that the center bearing carrier is actually a really good suspect.

(That is not a leak or seepage on the coupler. That's probably a stain from assembly.)

It does look like their is a gap in the photo. I’m not totally sure though if it’s flush on the other side. I’ll have to get it back up to take a look.
Thank you for your suggestions. I am making notes of what you guys have said and I will bring them up to my service adviser when I take it in.

On another note, my front engine mounts look pretty bad. I have ordered two new mounts to have installed at the same time. I do not notice any vibration while at a stoplight however. They just look to be cracked and in poor condition.

 

[04_Sport_LS]

The clunk I get when going from reverse, into park does not seem to have any other symptoms. The engine rpm’s do. It rev. The physical movement of the shift knob into park is not super smooth

That sounds like you need a shifter cable adjustment...
and probably a transmission range sensor adjustment too.

Years ago I had the same symptoms as you when going from reverse to park.

With the rpms increasing... the car is thinking it's still in reverse, (and trying to maintain proper idle speed), as you shift into park... thus the rpm surge and bang/clunk.

 

[04_Sport_LS]

The shifter locks into park. If you push the button on the shifter... with no pressure on the knob... and the shifter drops back towards reverse... then the cable needs adjustment.

The thing about that is... if you adjust the cable to properly lock into park... that will change the internal alignment of the range sensor. That is why I suggest adjusting both at the same time... starting with the shifter cable... then the range sensor.

You may still have other issues with motor mounts... the center support bearing... or rear driveshaft coupler... but the adjustments should be the first step.

 

[JMC]

That sounds like you need a shifter cable adjustment...
and probably a transmission range sensor adjustment too.

Years ago I had the same symptoms as you when going from reverse to park.

With the rpms increasing... the car is thinking it's still in reverse, (and trying to maintain proper idle speed), as you shift into park... thus the rpm surge and bang/clunk.

Sorry that was a typo. My engine does not rev when moving from reverse to park. Just a hard clunk. It’s more tough to get into park from reverse compared to other gears that glide nicely in place.

 

[04_Sport_LS]

Still should probably start with cable and range sensor adjustment.

 

[SultanGris]

I will have the transmission fluid flushed. Any need to open it up and install a new filter?

Every transmission I ever flushed required a replacement transmission soon thereafter, 3 different vehicles, I would recommend opening it up changing the filter and whatever oil comes out with that and not flushing it. Power flushing is bad for transmissions in my experience and I'll never do it again, lol

 

[joegr]

Every transmission I ever flushed required a replacement transmission soon thereafter, 3 different vehicles, I would recommend opening it up changing the filter and whatever oil comes out with that and not flushing it. Power flushing is bad for transmissions in my experience and I'll never do it again, lol

As an alternate view point...
I did the full fluid exchange/flush on my 03 at about 75K miles (schedule says to do it every 150K miles), and again at 150K or so miles. The transmission was completely fine at 220K+ miles when I traded it for other reasons (a big one being that the expansion valve stuck).

 

[04_Sport_LS]

Yeah... while I never suggested flushing, (I missed that comment), Sultan is correct.

Flushing is usually only recommended as a "hail mary" attempt... AFTER the transmission is already having problems... with high miles on the transmission.

However... if done as routine maintenance, (as Joe points out), it can be a good preventative.

Decades ago... when transmissions didn't have the modern clutch materials... or use synthetic fluid... a flush would usually cause more problems.

You don't actually seem to be having transmission problems... so a drain, filter change, and refill would be best.