So my 99TL is now clunking into reverse when it's not fully warmed up. Any advice on what might be the problem?

Car has 260k+ miles with the original 4sp transmission. Transmission fluid always changed based on manual's interval.

Once fully warmed up, the transmission no longer clunks in reverse.

 

That's a normal Honda Trans sound its in the design of reverse, Don't Sweat it. Just let it warm up and you wont hear it.

 

or: ck the front and rear motor mounts, failure can result in trans movement and thunk into reverse

You use the Acura/honda atf DW-1 ? not some aftermarket?

what is the interval your book says, they were written without real world experience!
30 or 60kmiles is way too long between.

Many ziners do 3 qts with every oil change, or once a year do 3 or 7 qts change
not sure capacity on 99 - verify total capacity of yours before change-out of fluid

the trans will only give up about half its contents when drained, then add replacement amount of new fluid- drive 5 minutes using each gear and drain fluid again

 

The thunk is definitely not normal. I do know that Honda transmissions like to make a loud metallic grind noise when shifting into reverse. But this is a "thunk" and you can feel it move the car slightly.

Trans fluid changes have always been OEM, done at the Acura dealer. Motor mounts have all been replaced a few years ago. Note that when fully warmed up, the reverse thunk goes away.

 

Still, check your motor mounts. They are a very common fail item. Members have seen them fail within a year or so, myself included.

 

In the first comment you mentioned a clunk which is normal.. A thump when going into reverse is entirely different.

Clunk = OK
Thump = Mounts gone south

It's worse when the engine is cold since it idles higher.. That's why there is no thump when the engine is hot.

 

Mine does this and my motor mounts are shot.

 

Thanks guys. I'll get the mounts checked out. I'm just happy that the original trans has lasted this long! Trying to get the car to 300k miles!

 

Its the reliable 4 speed 99 trans
get those mounts ckd yet?

 

Not yet. I need to also probably get the cat replaced. it's been throwing the P0420 code for about 2 years, and at the last smog check I was able to reset the code and then drive for ~40 miles so the smog check equipment would pass. But now even after resetting the code, P0420 pops up almost immediately. In CA, if your car doesn't pass smog test, you can't register it.

I'll ask the shop to also check the motor mounts.

 

isn't that the insufficient lift code for egr? ggole to make sure what it says
Codes are CLUES not a diagnosis in themselves

means clean the intake manifold egr passage and port- clogs really easy on 99s, needs cleaning every 75kmiles

 

It's this code:
P0420 Catalyst System Efficiency Below Threshold (Bank 1)

BTW, I did get the EGR TSB done for 99 TL's long time ago.

 

it was a recall to clean egr system and install a smooth thing in the port to cylinder- Reduced amount of places for stuff to attach itself
BUT
still requires removal of intake manifold and cleaning of entire egr system inside manifold every 75kmiles - that's per our mega moderator with well over 600,000!!!!!! USA Miles on his 2000 TL
That's a lot of spark plug changes and egr cleanings!

 

that bank 1 code is usually the front- pre cat O2 sensor
Codes are CLUES not diagnosis!

car have a history of using 87 octane gas?
Its easy to inspect cat, and the O2 has a a spec electrical reading
The O2 is definitely cheaper than a cat!

I don't care if your mileage is ok,,doesn't mean the right things are happening in the system!


ever smell rotten eggs after driving? = cat clogged
How does the engine rev in Neutral? can you compare it to another TL near you?
ziners are everywhere!!

 

broken front or rear motor mounts also cause a mystery vac leak which will screw things up

 

I found an easy fix to that vac leak is to unplug the motor mount vac line solenoid. Its normally closed so no more leak!

 

except you are still driving around putting stress on numerous parts due to failed motor mount!!

 

Thanks for the clues. I'll be bringing the car to the shop pretty soon and ask them to look at the O2 sensor first. I do know it's only been 91 octane from day 1 (original owner). Revving in neutral seems fine, nothing abnormal that I can tell. No rotten egg smell that I've noticed so far.

 

that's good news = rotten eggs smell is cat gone bad (or battery)

on gen2 the vac mount system boost vac to the mount on acceleration to tighten them up- stiffen the mount to resist torque

gen3 went opposite and uses it to soften the idle vibrations at idle

 

So I had it all checked out. Turns out the cat was indeed bad. Got it replaced, and the CEL hasn't come on since. The smog test verified at the cat is indeed working much better than the old one.

As for the thunk going into reverse, they said it's not the motor mounts, as they all look good. They think it's the actual transmission and attribute it to old age. Their advice was to just drive the car very gently now given the age.

 

how long since atf change? that 99 has a reliable trans- just take care of it

 

Have you ever had your solenoids off the transmission and checked the tiny filters for blocked passages?

Its possible one or more passages are blocked and need cleaned.

My 99 TL (277k) also has its original transmission and it does go into reverse hard at cold temps but its because I have worn mounts. It does not do it when the car is warmed up.

 

I have the same problem in my 99 only when cold. Warm it for couple minutes and no problem.
Also, I have found this trick and it works. "When the car is cold, move the shift knob to D position and suddenly move it to R. Make sure you don't let the trans engage in D. You won't have that thunk during cold starts. Please report back if that works for you.

 

ATF was changed fairly recently as I've been doing it even more often than recommended by manual. The shop checked the color of the ATF and said it was still pink-ish, so they think the fluid is fine.

 

I assume that you're starting from P, then move it to D, then very quickly (before D can actually engage) move it back to R? I'll try it soon and report back.

 

Yup. That's what I meant.

 

I tried this procedure, and it doesn't make a difference. It still thunks going into R when cold. At the next oil change, I may do a 3x3 trans fluid change, just to see if it helps. In the meantime, I just try to avoid going into R when cold. When parking in lots, I try to back in so I don't need to reverse coming out.

 

Have a helper with you standing over the engine with hood popped. Put the car into reverse and have them watch the engine to see if it moves excessively when it engages reverse while cold. You can also rev it while firmly pressing the brake to see if they notice extreme engine movement. If yes then you need to replace your mounts. Your best bet is to get a complete kit.