transmission smooth, but clunks when first accelerates

[robscards]

135 K on my 1986 4wd. I have an automatic transmission and it shifts very smooth through all three gears; however, usually when I depress the gas pedal quickly after coasting the car makes a clunk sound that can be slightly felt. It's not too bad, but quite noticeable. It sometimes happens when I let off the gas pedal, but not as bad. Any ideas?

[Gottolovem]

I would take a look at your motor mounts and cv joints if there no good you could get a clunk as decribed.
Good luck

[dlb]

could be motor mounts as gottolvem mentioned. could also be just about any front end component--ball joint, tie rod, control arm bushing, strut mount (aka bearing plate). i have personally found most clunk on acceleration/deceleration/changing gears to be caused by slop in the strut mounts. only way to check the strut mounts is to remove the steering hub and then the strut. the mount at the top of the strut should not wobble at all.

[Petros]

It could be all of the things listed, but it could also be low transmission fluid too. In fact if you have not changed the ATF I would do it now, it does not cost much and it will protect the transmission so it lasts longer. I would also add some ATF long life additive with a valve body cleaner. It will flush out the system and improve improve shifting, condition the seals and make the trans last longer.

Sometimes if the car has sat around a lot, particularly when people forget to change the trans fluid, you get deposits and gumming up of the vales, so they get sticky and make irregular shifts. A good quality additive with a valve body cleaner works well for making it act like new again.

[robscards]

If I don't fix the engine mount or whatever is causing the problem for a while (3-6 months) will it damage anything?

[Gottolovem]

If your fluids are good as petros says a bad motor mount is not the end of the world.
I have driven cars with much worse front end issues than you decribe.
Petros is right replace your fluid when you can it's cheep insurance

[robscards]

Replaced fluids today--transmission fluid and differential fluid. The guy said the differential fluid was located in back; I thought it was in the front. Also, no transfer case, right?

[Gottolovem]

This car has two diff's one is inside the tranny so if your guy replaced the gear oil in the tranny the front diff has fresh oil.
There IS a tiny little transfer case on the back of the tanny that requires a verry specific bolt to be backed out 8 complete turns before fluid will flow to and from the tranny to the transfer case.
Unless your guy is familiar with this car i doubt he backed out that bolt.
I wouldn't wory about it to much you can always back out the bolt and let it "mix"with the new oil it's a small amount.
Does the car still clunk?

[robscards]

The guy said he saw the oil come out the back. It was in goos shape with no shavings in it. The clunk is still there. It doesn't seem to be coming from the transmission, cause it doesn't happen when the gears shift. It only happens when you accelerate after coasting, and when letting off the gas to start coasting. If I am careful I can prevent the small "jolt" if I ease off and on the accelerator. But under normal driving, the jolt can be felt.

[Gottolovem]

I don't understand oil comming out the back?
Oil should ONLY come out the bottom unless the driveline is removed!

I think you have a loose part like crossmember engine mount or other component

[Mark]

He has an automatic which has gear oil in the front and rear differentials and red auto trans fluid in the transmission (middle section). Do you have this clunk when the car is stationary and you shift between "reverse" and "drive" or only when it's moving? Most of the old auto trans cars I've had over the years did this during a torque reversal (drive to reverse). On mine it doesn't do it when in 4wd mode (when the torque loads the rear wheels first) which tells me the "play" or backlash isn't in the transmission itself, but somewhere in the front differential or the front suspension. I'm hoping mine isn't in my differential and when I had the differential cover off and moved the gears/shaft around I didn't feel much backlash (not enough to make a "clunk" in my opinion). My front shocks are still good (I don't know about the mounts) so I don't want to go to the trouble of removing/checking them until they need it.

[robscards]

I guess the guy meant back of the transmission. About the clunk: I was thinking engine mount also, and will probably start there, getting them all replaced. Also, the rear struts/shocks are bad. On another note, I ordered an exhaust manifold and am going to get it replaced, along with the gasket and O sensor. Is there any cross over labor for the engine mounts and the exhaust manifold?

[robscards]

There is a slighter clunk when stationary and moving from park to drive or from drive to reverse/reverse to drive, although it is sometimes not noticeable. There doesn't seem to be a correlation between the engine's idle speed and the clunk. Sometimes it's noticeable and sometimes it's not.

[Gottolovem]

Oops my bad i just gave you good advice for the wrong tranny

[dlb]

no, there is no connection between the engine mounts and exhaust manifold.

remember there is no sense in replacing the mounts if nothing is wrong with them. they're easy to check, just look at them. if you have any doubts, unbolt them and jack the engine up slightly so you can confirm the rubber is not broken. most of the other front end components are easy to check too so make sure you do that before you start buying parts.