Ever since my loss of radiator incident in October I’ve been getting louder body vibration, especially at idle. My best guess is that at 352k my engine’s days are numbered.

I can live with the noise - runs great at speed, good power over the entire range. The hard part to live with is wondering if I’m missing something that I could or should do in the maintenance/repair department.

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1986 300SDL, 362K
1984 300D, 138K

check your engine mounts.


the only downside to a w126 in my opinion is that they don't use hydraulic mounts and that it has no front subframe so all the vibrations go straight into the body

Go through all the components which might make an engine run rough like filters, injectors, air in lines, valve adjustments and such.

352 really isn't a line of death for your engine. If you want to eliminate that check the compression first but I don't think that's the issue. High heat can really mess up valve springs.

I don't know how to evaluate those springs on a MB diesel.

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84 300SD
85 380SE
83 528e
95 318ic

Motor mounts, broken suspension hanger, or exhaust leak. Start basic.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Sounds like excellent advice all around. My mind went to catastrophic mode because I could swear I noticed a big change the first time I started it up after it was shipped South from my near death from heat experience. This before I put in the aluminum radiator. I just filled it with distilled water, started it up, and holy crap the rumble really took me by surprise. It’s gotten a little better since then but the last couple of days it’s really back. I’ll start with the motor mounts. Not sure what sort of shipping damage might have caused it.

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1986 300SDL, 362K
1984 300D, 138K

"loss of radiator incident" If the engine overheated maybe a warped head and head gasket issue are catching up with you.

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84 300D, 82 Volvo 244Gl Diesel

Hard to figure. At speed there is no unusual noise. Power is good, no unusual smoke. No issues with coolant or oil either.

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1986 300SDL, 362K
1984 300D, 138K

There's very obvious clues associated with head gasket and/or head issues. "Enhanced rumble" is not one of them.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Peoples descriptions of things leave much to be desired.

There is different types of head gasket leaks to include between adjacent cylinders. If that happened and caused the engine to run rough and rough running can cause noise.

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84 300D, 82 Volvo 244Gl Diesel

It definitely got hot. How hot I'll never really know.

When I pulled over and popped the hood, there was major steam present. That much at least was a good sign, there was still coolant somewhere.

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1986 300SDL, 362K
1984 300D, 138K

motor mounts first imho.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I bought a couple of Lemforder mounts and Stabilus shocks. Might not have needed the latter but I figure if I'm going to go to the trouble to take them out for inspection, I may as well put in new ones. Too much labor to waste.

I swapped some mounts in my 300SD about 10 years ago. It was a chore but not over the top. I seem to recall allen bolts on top. Nothing on top here.

On the driver's side looking up into the cavity I was a tad puzzled. I could see the end of a bolt but the hex or allen part was on the other side, and I couldn't see that above. There was a larger round thingy, couldn't make it out, looked like a post or plug.

On the passenger side was new information. Looked like some sort of membrane that was falling apart. I got a narrow chisel and dug it out. Looks like a large allen bolt but a tad off center. I'm guessing when I lift the block I can shift the engine enough to get the Allen wrench into it.

I can find damn little info about this anywere. Anybody know about the shock? I'm guessing I'll take the nut off the bottom before I raise the block.

Driver's side:



Passenger:

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1986 300SDL, 362K
1984 300D, 138K

I noticed in your narrative that you refilled with "distilled water" and then gave it a go. I suggest that you drain and refill with the appropriate (50%) mixture of G05 and listen again.

Anti-freeze coolant has a lubricating component for your water pump. The pump bearings can make a racket when unlubed. Water alone will only work for a very short time without doing damage.

The motor mounts are exactly the same as the ones on your 300SD or a W123 diesel. There are 2 allen screws on top that hold the mount to the chassis and one through-bolt from below that goes into the engine mount arm. Undo both engine shocks, but do one side mount at a time to keep the engine more or less lined up. Pay attention to the installation of the heat shields, they're important if you don't want heat or diesel leaks to quickly kill your new mounts.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

That’s good advice. The only reason I filled it with distilled water was because I knew that the radiator was leaking and I needed to move it. I hate spilling antifreeze on my driveway. There are some low spots, stuff pools.

As it was, the whole system got drained pretty good when I took the radiator out and installed the new aluminum wonder radiator along with a proper mix of coolant.

In hindsight, I probably should’ve used an antifreeze mix from the get-go and then carefully collected all of it that leaked, then drained and filtered it all for re-use. Especially since I ran it for maybe five minutes to see how bad the radiator leak had been. The question presents itself: would I rather mess with a little bit of antifreeze or put in a new water pump. I know the water pump rattle you speak of and it’s not a nice sound. But that wasn’t the rumble I was hearing. It was definitely the rattle in parts of the cabin from excessive motor vibration.

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1986 300SDL, 362K
1984 300D, 138K