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#1
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Grinding noise while turning and under high throttle
The car is a 1986 300 SDL.
Today my car developed a 'grinding' noise while turning and when the accelerator is pushed down to the floor. I also tried putting it in neutral and revving the engine, and the same noise starts at about 4,000 rpm. Think it could be a bad transmission mount? Or could it be two or more seperate problems(unlikely, considering all of this started at the same time)? |
#2
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Check the crank damper. Does it wobble with the engine running? Remove the belt and check all the pulleys.
Sixto 87 300D |
#3
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first off, NEVER rev in neutral to 4K!!! especially if you have a strange GRINDING noise! get a chunk of garden hose, and start listening to the various parts of the motor at idle.
if nothing is found this way, shut it down, pull the belt, and check the tensioner, and the vacuum pump. with the belt off, grab each pully and feel for any movement/grinding feel. safety first!
__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread "as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do! My drivers: 1987 190D 2.5Turbo 1987 190D 2.5Turbo 1987 190D 2.5-5SPEED!!! 1987 300TD 1987 300TD 1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere! |
#4
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Thanks for the advice. Today, I'm going to follow the steps both of you have listed and see if I can locate the problem. I have not driven the car since the noise started. I hope it's nothing expensive. It does have more than 200k on it, and I imagine that the timing chain can go at any time.
Quote:
I do need new CV joint boots. They are torn. The car has spent a lot of its life under my ownership in excess of 100 mph. |
#5
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I took it for a drive today. It makes the noise while turning; I tried revving it again once more and it didn't make the noise then, but it still makes the noise while turning. It sounds like it is coming from the middle or rear of the car.
I did try jacking it up and taking the rear wheels off. When I try to move the rotors by hand, I hear a very light "clunck" noise that, under very gentle spinning, prevents the rotors from spinning further. also, the noise is much louder when making left turns than right turns. I am thinking I could have a bad transmission mount(s), bad CV joints, bad bearings, or any combination thereof. It does not wobble. This damper was also replaced last year. The entire engine itself wobbles slightly at idle(< 2 mm), but the motor mounts were also replaced last year. Quote:
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#6
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Just a thought, are the rear wheel bearings OK?
__________________
Muleears '07 E320 Bluetec 133K my DD '04 Jaguar XJ8 VDP, 34K '10 Hyundai Accent 60K Grocery Getter '02 VW Golf soon to be on the road again '97 E300 Diesel Son's DD '61 VERY tolerant wife Hampton Roads, VA USA Gone but not forgotten: '67 250S 95K '86 300SDL '87 300D Turbo, 364K! R.I.P. '98 E300 Turbodiesel, 213K '02 S420, 164K '01 Prius 138K |
#7
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Wheel bearing is a possibility as you have the problem with side load.
Does the noise occur with your foot on the throttle, off the throttle or just maintaining speed? Does it occur turning when in neutral?
__________________
Grumpy Old Diesel Owners Club group I no longer question authority, I annoy authority. More effect, less effort.... 1967 230-6 auto parts car. rust bucket. 1980 300D now parts car 800k miles 1984 300D 500k miles 1987 250td 160k miles English import 2001 jeep turbo diesel 130k miles 1998 jeep tdi ~ followed me home. Needs a turbo. 1968 Ford F750 truck. 6-354 diesel conversion. Other toys ~J.D.,Cat & GM ~ mainly earth moving |
#8
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I don't know; I suspect they may not be. The car has probably never had them changed in its entire life. The good news is they aren't expensive to fix, unless they weld themselves in place post failure.
The noise occurs only under heavy throttle when in a straight line(> 70% with kick down engaged). I can coast in a straight line in neutral(a common practice to save fuel when not 'playing' with the car) without the noise being noticed. When cornering, the noise occurs even at no throttle with drive engaged. I have not tried turning in neutral and will do so tonight. |
#9
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While turning in neutral, coasting with the engine off, the noise is still present.
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#10
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My money is on a rear wheel bearing.
__________________
Grumpy Old Diesel Owners Club group I no longer question authority, I annoy authority. More effect, less effort.... 1967 230-6 auto parts car. rust bucket. 1980 300D now parts car 800k miles 1984 300D 500k miles 1987 250td 160k miles English import 2001 jeep turbo diesel 130k miles 1998 jeep tdi ~ followed me home. Needs a turbo. 1968 Ford F750 truck. 6-354 diesel conversion. Other toys ~J.D.,Cat & GM ~ mainly earth moving |
#11
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I'm going to have to fix it then. I think it would be a good idea to replace both of them, given the age and mileage of the car.
Is $300 in parts plus tools a good estimate? There's a DIY guide here on this site for the W126 and I'm intent on doing this job myself. |
#12
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When the cv joints begin to fail they will sometimes make a rumble when loaded a bit. This could be with a load in the back or on turning. Did you check for play in the half shafts? To do this put the car on a level place, in neutral with the parking brake set or wheels chocked and grab the half shaft and see if it will wiggle up and down.
Good luck!
__________________
[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. |
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