Clunking noise when accelerating

[TominMO]

Gonna look at my tranny fluid tmw. I've got ATF in there, and noticed it's leaking out of both of the driveshaft seals. Might be low, and that also might account for the clunking. Seems a lot more likely than loose inner tie rods causing it. Will switch to 20W50 motorcycle oil (like Charlie uses), which will slow down or stop the leakage due to being much thicker; and being motorcycle oil, it has all sorts of good gear additives. This is what I was running in Matthew's tranny.

Plus I'm ordering new inner tie rods for both cars.

[TominMO]

Filled the tranny with motorcycle synthetic 20W50, no change in clunking sound. I recall when I took Matthew apart, the rear tranny mount was toast, but there were no symptoms of that. So now I'm leaning towards a lower-end issue, like 2jzkilla said. Maybe a con rod bearing going out? Does this seem like a possibility? I had an MGA a long time ago, and had the same kind of clunking sound going on for a brief time (like minutes). But it was continuous, not just when accelerating. Then I heard an explosion, and found a hole in my block you could put your fist thru. In retrospect, I think that was a lower bearing giving out.

I'm having Matt D. build me a head for this motor, but sure would hate to find out the bottom end is toast. If so, I'm hoping (and expecting) he could rebuild it better than new--but major $$ involved. :-( For now, I could stick Matthew's motor into the Festy instead of the Aspire, which runs fine. Number of miles on the B6 is unknown.

I might be in the market for a good gen2 SOHC B6 block....

[bhazard]

Does it do it when revving in neutral?

[TominMO]

Does it do it when revving in neutral?

No. Maybe putting a load on it makes the difference tho. Like when getting going from a stop. That's when it's the worst.

[Movin]

Some times when the rear trans mount breaks it is really hard to see and does not rock around much. But I have seen it allow the engine - transmission assembly shift sideways under acceleration just enough for the inner cv to fully compress and the trunnions will rattle...only on acceleration.

Another time the same noise would happen with the front suspension extended. It had an aspire shaft and too much tow. The Tow in caused the front end to lift up on acceleration.

Can you get a video clip with the noise ?

[TominMO]

Some times when the rear trans mount breaks it is really hard to see and does not rock around much. But I have seen it allow the engine - transmission assembly shift sideways under acceleration just enough for the inner cv to fully compress and the trunnions will rattle...only on acceleration.

Another time the same noise would happen with the front suspension extended. It had an aspire shaft and too much tow. The Tow in caused the front end to lift up on acceleration.

Can you get a video clip with the noise ?

That would be cool if that was all it was. I plan to replace tranny mounts anyway on general principles, on both cars. If I take off easy, it won't happen (less torque), so yeah, it looks like mount movement may well be the issue here. Might get around to the video/audio clip, might not. I'll try replacing the mount first.

[TominMO]

Replaced rear tranny mount on Larry and then went on a drive. No help. The old rear mount actually looked to be in good condition; the rubber was a little softer than the new one, IDK if due to age or just a different manufacturer. The rear mount on Matthew was actually broken, i.e. the rubber itself separated, perhaps due to heavy salt exposure (that was a very rusty car). Matthew didn't have this clunking symptom.

I've ordered a front trans mount (listed under motor mounts at Rock Auto BTW), and will install that to see if it helps. Visually the current front mount looks fine tho.

I can also install the custom Dickmeyer pass-side motor mount that came with Matthew. 2jzkilla mentioned an internal bottom-end issue; hope it's not that, but......I'm thinking I should be looking for a gen2 B6 short block.....

[WmWatt]

When I had front end noise the mechanic put the front end up off the ground and tested everything with a pry bar and a big rubber hammer. Nothing. Eventually turned out to be a loose brake rotor. One thing I found useful was to put a long bar under the tire with the wheel off the ground as a lever and push it up and down simulating bumps. Tried rocking the car back and forth in gear? Good luck.

[TominMO]

When I had front end noise the mechanic put the front end up off the ground and tested everything with a pry bar and a big rubber hammer. Nothing. Eventually turned out to be a loose brake rotor. One thing I found useful was to put a long bar under the tire with the wheel off the ground as a lever and push it up and down simulating bumps. Tried rocking the car back and forth in gear? Good luck.

I have Capri rotors, which mount in back like Festy ones, so that's not it. I'll try the bar under the tire method. And the rocking in gear. Probably not until tmw.

One thing I did notice, was when going over a ripple in the road, I got the clunk. So I'm hoping that means it's a simple, non-bottom-end-related issue that I just haven't found yet.

[shadetree]

It's the steering rack .

[TominMO]

It's the steering rack .

Hope so. I have a spare. What do you base this on? How easy is it to rebuild myself? I think it just requires a bushing or two, correct?

This rack does not have a lot of miles on it tho, well under 200K; and many of them were tow miles.

[shadetree]

Sound like marbles in the heater box clunking when they hit the side ?
Ball joints or steering rack .

[TominMO]

Sound like marbles in the heater box clunking when they hit the side ?
Ball joints or steering rack.

Mainly in first gear, and less so in second, if I accelerate with any authority at all, I hear a continuous clunking until I let off. Steering seems fine at all times. I know my inner tie rod ball joints are a little loose, esp. on the driver side. Would that be sufficient to make this noise, but not exhibit any steering issues? Tie rod end ball joints are fine.

AFAIK there are no marbles in my heater box. Was this a factory option? ;-) Clunking is definitely from the other side of the firewall.

[Movin]

I must have lost my marbles

[TominMO]

I must have lost my marbles

Common occurrence with Festivites.