1984 190D 2.2 Sudden Rattle While Driving, Ran Fine Otherwise - PeachParts Mercedes-Benz Forum

Baby Benz Sandra · #1 04-10-2021, 07:11 PM

I was driving my faithful 1984 190D home last week and suddenly heard a rattle noise coming from the engine - seemed to emanate from the center front area. I froze internally; she had never made a noise like this; a rattle is not good. Scanning, scanning ... other than the sudden rattle, she ran fine like she always has. Oil pressure & water temperature fine; no smoke at all from the exhaust. I pay attention to the sounds my car makes, and my first impulse was to pull over - but I was in the middle of downtown
San Jose on a Friday afternoon around 5:00 - and couldn't. I was less than one mile from home; once out of downtown I hastily thought, "should I pull over? the engine sounds fine, running fine - you've now
got two blocks to go - make it home!" So I made it home and parked her in the parking garage where I live. I shut it down and went down to check the fluids later; they were fine.
Here's the thing: I've been afraid to start it ever since. I have triple A towing so I decided I will call them for a flatbed tow and have her delivered to an elderly man who owns a shop in Fremont who has done work for me before - he knows Mercedes-Benz vehicles and is honest but I have to wait till I get some money I am expecting next week. In the meantime, do any of you fine helpful fellows have any ideas as to what it could be? Even though I'm a female, I'm fairly mechanically-inclined - I'm proud to say I replaced the serpentine belt myself last year, so I'd sincerely appreciate any input. Thank you!

psaboic · #2 04-10-2021, 09:44 PM

Not familiar with the 190D but if it is anything like my 300D, I had the exact same thing happen to me on Friday. It turned out to be the air cleaner bracket broke. Need a little more info regarding your rattle.....Did the rattle change intensity or frequency with changes in engine speed? Did it do it both in and out of gear? I would cautiously start it and look for anything loose that could be rattling. If it was severe enough to do damage I would think it would have done it within the mile or so you drove it home. But just the same be ready to shut it off if need be.

Baby Benz Sandra · #3 04-11-2021, 02:30 AM

Thank you for responding, psaboic! In the research I've been doing, just earlier today I learned about the air cleaner bracket that many 300D owners report breaking - the 190D doesn't have that big air cleaner on it -
it has a small square one on the side of the manifold - it's a totally different design - but you are spot on about the 300D!

I think you made a very good point about if my rattle was an indication of something severe that it would have gone really bad within that mile I drove home. The rattle didn't change intensity or frequency but I didn't go over 30mph the whole way home - it's an automatic transmission and I had it in 'drive' the whole way but when I parked and shifted into "park" I don't think it changed - so those were good questions you posed because now more than ever, I'm sure it is just something that has loosened up. I'll go out there tomorrow and do as you suggest. Thank you very much!

psaboic · #4 04-11-2021, 11:22 AM

Hope I was able to help and that indeed it is something minor. Just keep a close lookout when you start it

Diseasel300 · #5 04-11-2021, 11:29 AM

If it came from the center front area, take a look at the fan/clutch area on the front of the water pump to see if it's loose or wobbly. Another EXTREMELY common source of rattling noises on the OM60x engines is the belt tensioner assembly. The shock absorber wears out and the bearings in the pivot arm and idler pulley wear and fail. If the belt looks like it isn't tracking straight, it's likely the pivot bearing or idler pulley bearing have failed. If you start the engine and the belt looks like it's rapidly vibrating or you hear a "buzzing" sort of noise coming from the front of the engine near the tensioner pivot, the shock has failed.

Baby Benz Sandra · #6 04-15-2021, 07:05 PM

Diseasel300 - I appreciate your response to my post. I shall go check on those things you suggested. Thank you