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#46
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A bent connecting rod such as afflicts 3.5s doesn't make noise.
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I don't know what that sounds like but you'd trail clouds of smoke if the piston rings were bad. It'd probably be more difficult to start the engine, too. Weren't you planning a compression test? Do it cold for reference. Sixto 87 300D^2 |
#47
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I also recommend having a 17mm wrench or two at the ready to crack injection lines should you have a runaway condition after initial start.
Sincerely, PE
__________________
83 240D - 4 speed manual - Manilla Beige 189K miles, Tachometer mod, cool wooden shift knob from PeachParts, CocoMats, Original factory paint, manual windows, manual sunroof. Starting to add AudioWrap to this car too! |
#48
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Latest results:
1. Belt tensioner dampener. Pushed on this between the engin and dampening body to load up the ends - it did not reduce the knock sound. It did eliminate some very minor noise coming from it though.2. Bad crank bearing question: Drove the car up the street to load the engine - no change in noise intensity. Held brakes - loaded the engine pretty good - no change in noise.3. Boroscope inspection - abort based on geometry of engine. 4. Lifter inspection - not done yet. Maybe the lifter inspection by pushing on them. But would a completely collapsed lifter produce this much noise?Not sure where to go from here - guess I'll think on it for a while. Any more ideas? I think we should had a "what's that noise library" with confirmed issue that caused it |
#49
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a "what's that noise library" would be a fabulous idea!
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#50
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Update:
1. Completely removed injector lines while running - to rule out dribble - no change - so give up on fuel causing knock from a leaking injector 2. Checked hydraulic lifters by removal of valve cover and pushing on them with a 1/4" wood dowl - unable to get any to budge (collapse), applied a good 15lb load on them, all seem to be in tight contact with the cam. 3. Listened for noise with stethoscope while engine turned over with socket on crank - no noise heard at all. 4. Close inspection of the video's, slowed down, shows the tap is twice per engine revolution. This would be a factual clue 5. PO says he never heard any knock, now he does have bad ears, so either he can't hear or perhaps my minor rotation of the engine backwards did damage something causing this noise. Any thoughts on #4 / #5? I'm really at a loss for now , though never giving up Last edited by Oldschoolgwin; 08-26-2012 at 03:58 PM. |
#51
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Once per engine rev diminishes the likelihood of valvetrain and ignition causes. Does the knock get louder if you rev in drive while resisting with the brakes; i.e. put the engine under load?
Sixto 87 300D |
#52
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Quote:
Did the load test - no change in tone or loudness. Last edited by Oldschoolgwin; 08-26-2012 at 03:59 PM. |
#53
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You are going to have to pull the rocker cover and check for a wiped cam lobe or something broken/loose.
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#54
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If its hydraulic lifters at fault you will tend to have a noisey top noise at the valve cover area.Ive owned some 190ds with the 2.5 diesel ,it was a similiar noise and just lived with it ,yours sounds a bit worse though from the video feed you made avail. ,it maybe because of the long sit.Try letting her idle 30 minutes a day for a few days in a row to see if it clears up .Are you getting any smoke out the back?
Last edited by chasinthesun; 08-26-2012 at 01:29 PM. |
#55
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Simple to check item is to make sure all the heat shields are present underneath each injector ,esp. the one making the noise ,also they can be placed upside down by accident.Stick magnet makes easy work of it.
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#56
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Quote:
Thanks. |
#57
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It's the seal between the business end of the injector and the prechamber. It's a disk about 15mm across.
Sixto 87 300D |
#58
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THanks - clear as mud now So it would not cause a mechanical intereference that i can see - but maybe some combustion anomally. But if this were the cause - wouldn't it have been eliminated by loosening and also separation of the fuel lines from the injectors? |
#59
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To make a sound of a stuck injector is kind of were I was heading with the idea of a heat shield absent in the chamber ,if it wasnt in place Im sure it would play a part in bad injector performance.To say it would make somekind of noise if absent Im not sure of ,maybe somebody else can chime in if theyve had this issue.
Last edited by chasinthesun; 08-29-2012 at 10:47 AM. |
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