I had just made a downward slope sharp turn at a set of lights this morning, going maybe 25-30 mph, when there was a loud and hollow BOOM from under the car, to the rear. Think empty oil drum being hit with a rubber hammer.

I pulled over, nothing obvious wrong, nothing leaking or hanging off. No debris on road to indicate I had run over something.

Rest of drive was fine. I deliberately tried to mimic the turn, and drove over bad sections of road, no more sound.

It reminds me of the sound I got once from a car where the parking brake was seized on from sitting and I drove it back and forth to force it free. Similar hollow boom when it let go.

The exhaust is brand new (10 days). We inspected the flex discs when we did the exhaust and they looked great.

I am about to replace the driveshaft center bearing, as I had a whine at cold temps last winter. But I can't imagine how that could make such a noise then continue to turn....

Thoughts anyone?

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

Revisit the last work that was done to the car.

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Greg
2012 S350 BlueTEC 4Matic
2007 ML 320 CDI
2007 Leisure Travel Serenity
2006 Sprinter 432k
2005 E320 CDI
1998 SLK230 (teal)
1998 SLK230 (silver)
1996 E300D 99k, 30k on WVO
Previous:
1983 240D, on WVO
1982 300D, on WVO
1983 300CD, on WVO
1986 300SDL 237k, 25k on WVO (Deerslayer)
1991 350SDL 249k, 56k on WVO - Retired to a car spa in Phoenix
1983 380 SEC w/603 diesel, 8k on WVO
1996 E300D 351k, 177k on WVO

If its one of the vehicles in your sig, maybe an exhaust hanger or sway bar link?

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

Only guessing because only way is to put her up on hoist or crawl under. But I once had a loud noise on my R107. One of the sway bar links had come undone and had caught on something.

Hope its nothing serious.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

fuel tank?

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Current fleet
2006 E320 CDI
1992 300D - 5speed manual swapped

former members
1984 300D "Blues Mobile"

1978 300CD "El Toro"

DOH. Sorry, it's the '85 300d.

I am wondering if either the new muffler or resonator failed internally.

Fuel tank... had not thought of that. And I seem to remember a post from someone who had a similar issue, long time ago....

Something like a sway bar link falling off would be plausible, Graham, given the noise, however if it was left on the road I missed it (I walked back to check for debris, etc.). And it handled normally rest of drive (I have to negotiate two traffic circles - roundabouts - after that point, which load the suspension, to get to my office).

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

Check your front sway bar connections and the plastic rear sway links, one of them could have blown apart. I've seen it happen on two of our cars....especially in places with winter weather.

Could also have been a spring coil snapping, does the car sit level/springs look good?

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Spring very plausible based on the sound, PawoSD. Your idea just reminded me that I had been hearing a dull rubbing sound, not loud, lately from the right rear when turning left. So far I had filed it in the "misc whassat?" folder in my brain.

However, the boom was immediately after a sharp left, downhill, and I had to go around two traffic circles in a left arc immediately after, and no sound. I would expect a broken spring to show up going round a traffic circle, no?

The car seems to be sitting fine.

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

I second phillytwotank. It's only four 8mm hex screws to remove the fuel tank partition and have a peek. Or get under there and shake the muffler to see if it comes into contact with anything since thats the last work you did. Hell, it could have been cargo sliding around in your trunk.

No, this was a BOOM not a bang or a thump from the trunk. There is nothing in the trunk remotely capable of making the sound I heard, trust me.

I was genuinely surprised the car still ran and drove after. Sounds like that tend to attract flatbeds.

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

Roadside IED?

These cars are made like tanks, after all. May have just saved your life!

__________________
1979 300D 040 Black on Black - 1985 300D Maaco job (sadly sprayed over 199 Black Pearl Metallic) on Palamino

http://i.imgur.com/LslW733.jpg

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Visit the W123 page on iFixit for over 70 helpful DIY guides!

[QUOTE=Zacharias;3326624]No, this was a BOOM not a bang or a thump from the trunk. There is nothing in the trunk remotely capable of making the sound I heard, trust me.QUOTE]

I just wanted to make sure we rule out the simple things first

Failed car bomb attempt?

Have you pissed off anyone recently?

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Would you like the list alphabetical or by nature of offense?

You and uberwasser should hit the comedy circuit ....

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

Busted!

Someone didn't read through the whole thread and he thought he was being so unique!

Sorry Uberwasser - you have it.

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!