I have isolated a clacking noise that appears between 1000-2000 rpm to under the mercedes star (cylinder #5 or #4) on the valve cover using a stethoscope.

I am about to pull the valve cover hunting....what can I / should I look for that would do something like this?

this is for the '85.

Thanks,
dd

***UPDATE***

The problem is solved, the issue was a worn valve spring having excessive play between the valve keeper and rotocap. jt20 hypothesized that the worn spring was caused by the car sitting for two years (before i bought it) with the cam pressing that valve down the entire time. To save some time, here is a summary of what I did:

- pulled valve cover
- adjusted valves - they were fine
- removed injectors and had them pop tested - they were fine - left injectors out for rest of job
- checked cam timing using 2mm lift method, 4-4.5 degrees total, decided not to add woodruff key
- pulled on each valve spring to check for looseness. discovered i could move spring #10 (most rear valve, intake of cylinder #5) by hand enough to make an audible 'click' and 'clack', rocking it back and forth
- went in and replaced spring following the FSM procedure
- **took extra caution to make sure i did not drop a valve into the engine**
- had some trouble removing the rocker arm group, had to really finesse the cam position and gently tapping the rocker group's base
- installed new spring from dealer ($9.80), put all back together
- reinstalled injectors with new crush washers
- started and put 200 miles on it, noise under valve cover is gone now.

you can hear the noise in a youtube video i made here:
http://www.youtube.com/watch?v=9p0Z1SeMHSI

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

I have a similar clacking noise with mine i was told it was the lifters by a few people on here and my grandfather had it on one of his old cars, When i change my oil it will stop for a while.

No lifters on these diesel engines. Poorly adjusted valves perhaps.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Adjust your valves, and make sure that all the stuff bolted to the valve cover is properly secured.

Also, Mobil Delvac is supposed to be magic and fix stuff like blowby and weird noises.

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$60 OM617 Blank Exhaust Flanges
$110 OM606 Blank Exhaust Flanges
No merc at the moment

could be misadjusted valves
could be a bad injector nailing
could be a failing combustion chamber
could be a failing rod bearing
could be foreign objects in the cyl


happy hunting

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http://www.youtube.com/watch?v=d-Z8X_r_l_M

79 300d "baby blue nose" (sold)
87 e300d (om603) "billy" (sold)
94 e300d (om606) "mcrae" (sold)
84 300td (om617) "mom"
82 300cd (om617) "whitey"
84 300sd (om617) "benzo valdez"
87 300sdl (om603) "chip"
90 e300d (om 602) "bev"
69 280c (om603 swap) "rommel"
74 internationl scout II (om617) "scout"
64 impala (4bt) "homie"
57 chevy apache (7.3 psd) "goldie"

thank you for the ideas.

valves adjusted 700 miles ago. will re-check.

if it was a rod knock, wouldn't it only get louder with increasing rpm?

if it was a rod bearing, wouldn't I hear it lower in the engine block too?

about to go hunting under the valve cover...
dd

__________________
-------------------------------
'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

valve cover off...

-valves on cylinder #4 and 5 adjusted correctly
-no sort of funny looking things under the cover indicating anything strange

sort of looking around scratching head, about to put cover back on and take injectors out.

is it bad to take the fuel away from a cylinder by loosening the injector line and then reving the motor on 4 cylinders?

dd

__________________
-------------------------------
'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

Crack the fuel line to relieve pressure on injectors 1 by 1. If the noise goes away, you've identified the nailing injector.

I think it *may* indeed by a nailing injector on #5. I cracked the fuel line on #5 to turn off combustion, revved, and no noise. I did get a diesel shower though.

Did a diesel purge - no change.

Will remove injector and take to the Bosch shop ASAP. will also check the prechamber area. going to do a compression check when I have the injectors out for the heck of it since itll be 30 minutes of work.

Thanks again, ill keep updating, hopefully will the resolution of the injector in #5 having a fault.

dd

__________________
-------------------------------
'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

Will be interested to know the outcome of your issue.
I have a very similar noise, and have bought a set of rebuilt injectors, hoping that'd fix the issue. But it's been too cold out for me to get out there and swap them out...
My engine has the same clacking at 1500-2000 under load. Sounds just like a bad lifter.

__________________

Injectors checked at a Bosch shop today - all good.

What should I do next?

Does a compression and/or leak down make any sense to do?

dd

__________________
-------------------------------
'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

What does "All good" mean. Personally I would have asked for spray pattern results and breaking pressure numbers. If they just handed them back to you and said all good I would not rule out the bad injector theory.

they visually check the spray pattern and make sure they pop at or near the 135 bar spec. i have gone back with them before (not today) and seen the same tech do the pop/spray test, so I am pretty confident in the results. when i see a repair shop come back and say 'no work needs to be done', I am much more apt to believe it than the 'umm they're bad and need to be rebuilt, $25 an injector see you Friday' result.

the same guys rebuilt another set of 617 injectors for me and they are great.

i guess i could seek out a second opinion, but I don't know of any Bosch diesel injection shops in the area :-/

__________________
-------------------------------
'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

can't an injector still make noise but function properly?


how does this sound change with increased RPM?

when warm or cold?

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jt20,

noise is not there at idle for the most part. at about 1000-2000rpm it is present, with a sweet spot being around 1700 or so where its the loudest. it seems to be louder under load, but I can also hear it revving in neutral.

It is basically the same all the time, but worst when its cold.

I can hear this in the cabin while driving. But, if I turn the blower on high I cannot hear it anymore, if that is any indication of loudness.

Im going to try again to post a video somewhere.

dd

__________________
-------------------------------
'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car