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#1
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Engine rattling sounds when on partial throttle
My 85 300D KaliKar (California model) is making a LOT of rattling sounds when I drive at partial throttle.
What I mean by partial throttle is the situation of driving at a constant 30 MPH. You are not mashing the accelerator pedal to increase speed, just holding it constant. I hear these sounds when holding any steady speed from about 15 up to 40 MPH. The sounds are even more pronounced when I am holding the throttle slightly open and rolling down a slight incline. I have also noticed that the sounds are lessened when the engine is fully warmed-up. Please note that this is a KaliKar, so the usual air cleaner bracket issues don't exist on my car. And I changed the motor mounts about 8 months ago and they appear fine. The slight incline point I made above worries me; could this be a slack timing chain possibility--tensioner at full extension but not quite enough to take all slack out, engine being rotated by going downhill but not because of the throttle. I have no indication of any timing chain/tensioner maintenance by previous owners. Any advice appreciated.
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Mike Frederick 1986 300SDL, 240K+ miles 1985 300D KaliKar, 270K+ miles |
#2
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belts?
hi mate
did you checked your belts? .
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w126 500SEC gen II euro, powered by OM617 turbo stolen from 84 300SD 2.88 diff,EGR blinded next wish/project: w114 coupe OM603 powered |
#3
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It is true that loose belts can cause some very metallic sounding noises under the hood.
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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. |
#4
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Checking belts
I have not checked the belts, but will this morning.
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Mike Frederick 1986 300SDL, 240K+ miles 1985 300D KaliKar, 270K+ miles |
#5
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btw if you find them 9.5mm go for 10mm in case of replacement....
.
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w126 500SEC gen II euro, powered by OM617 turbo stolen from 84 300SD 2.88 diff,EGR blinded next wish/project: w114 coupe OM603 powered |
#6
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Are you familiar with injector nailing? Can't hear your problem of course but my 240d does it at partial throttle; Pretty common in mercedes diesels I hear.
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#7
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Things that cause abnormal nailing:
Bad Fuel Air leak on the suction side of the Fuel Supply/Lift Pump to include the Hand Prmer Late Fuel Injection Pump timing and I also found out that advanced timing beyond spec will also nail. Injectors that have worn out Nozzles or the Pop Pressure is low Valves out of adjustment Late Valve Timing due to Timing Chain Stretch or Timing Gear wear (maybe) Low Compression
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84 300D, 82 Volvo 244Gl Diesel |
#8
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Other things I have done
I guess I should mention what else I have done to the engine:
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Mike Frederick 1986 300SDL, 240K+ miles 1985 300D KaliKar, 270K+ miles |
#9
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since when
.
since when rattling has appear? before or after learning attempts was it sudden or it was developed from tiny noise? .
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w126 500SEC gen II euro, powered by OM617 turbo stolen from 84 300SD 2.88 diff,EGR blinded next wish/project: w114 coupe OM603 powered |
#10
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The sound has developed slowly over the last few months. I haven't adjusted the valves for several months. Maybe I should do that again for good measure.
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Mike Frederick 1986 300SDL, 240K+ miles 1985 300D KaliKar, 270K+ miles |
#11
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it has to be biiiig chain slack to produce noise..so I dont think that is the issue
while checking belts do check vac pump water pump as to my understanding those 2 things are most common front noise makers valve adjustment in such short period would have sense only if previously badly adjusted.... good luck .
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w126 500SEC gen II euro, powered by OM617 turbo stolen from 84 300SD 2.88 diff,EGR blinded next wish/project: w114 coupe OM603 powered |
#12
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Is there a belt tensioning device on that car? They tend to make noise when worn.
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