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  #1  
Old 05-15-2011, 03:28 PM
luke4's Avatar
benz-o-matic '86
 
Join Date: Mar 2011
Location: North San Diego County, CA
Posts: 60
Loud, especially at idle, what to check? Rebuilt injectors, recent fuel in oil fiasco

Before I tear into it, chasing my suspicions, please let me know what you think the problem could be and why.

Car: 1986, 300 SDL (OM603 motor) 181K miles

Situation: the worst symptoms started just after installing all rebuilt injectors (new nozzles, pop pressure adjusted). Also, on the test run after installing the injectors, I found the crankcase to be over-filled with fuel, which turned out to be due to the fuel return line sitting over the open injector hole for two weeks with fuel dribbling into the cylinder and past the rings due to warm temps and resulting pressure in the fuel tank, AKA "the incident". (Full saga here: Blew engine last night - why, oh why?) Now I've done two oil changes in 50 miles and am running Mobile 1 full synthetic for diesel.

Symptoms:
-At cold start-up, seems like it's running on 4 out 6 cylinders. Smooths out after 60 seconds. Did NOT do this before I installed the rebuilt injectors and the "incident".
-Idles LOUD, which noise 'reduces' (not gone) above 1700 RPM and whole engine is virtually SILENT when throttle lifted and slowing/coasting all the way to stop, whereupon the noise resumes. Hard to pinpoint where the noise it's coming from, but stethoscope basically says the whole top end and not one cylinder more than another. While not as loud, this noise was present before injectors/"incident" and was the reason for doing the injectors in the first place.
-At idle and fully warmed up, the car shakes like it was my old 300SD/617. Before it's fully warmed up, the idle, while loud, is fairly smooth. But not as smooth as other 603's. This symptom was present before the injectors/"incident" but not quite as pronounced.

Just fixed/replaced/checked:

-Glow plugs. Put two new ones in and tested the other before the injectors/"incident".
-New, fresh oil, as above.
-New air filter, intake clear, turbo spins fine, EGR plugged, ALDA adjusted and lines are clear.
-New fuel filters (both).
-Catalytic converter eliminated (as an issue)
-Compressions BEFORE the 'incident' were 360-385.

I 'suspect' that new injectors with increased opening pressure may be revealing late timing due to stretched timing chain or some other reason. But am also concerned that I could have caused some other unknown damage that is causing these symptoms by running the car for 1 min (less than 2K rpm) with 8 quarts of oil PLUS 8-10 quarts of fuel in the crankcase. So perhaps the next thing to check is the compression, in case poor lubrication caused scoring of the cylinder walls or valve damage(??).

Whaddya think? What should I check?

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1986 300 SDL, gray on black, #14 head, 180K miles
1982 300 CD, silver on palomino, 290K+ miles [sold]
1980 300 SD, white on palomino, 500K+ miles when retired [uncle's car - inspiration for the above]
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  #2  
Old 05-15-2011, 03:49 PM
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Posts: 120
It is my understanding that new injectors are noisy until they break in. I have read several hundred miles. I haven't done injectors yet but was reading in anticipation of doing so.
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Old 05-15-2011, 04:38 PM
Diesel911's Avatar
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Join Date: Sep 2007
Location: Long Beach,CA
Posts: 50,968
X2 on what woodboat3 said.

Also if you replaced the Nozzles with Bosio Nozzles people say they make more noise.

An Air leak can cause the Nailing noise.

I do not know what the top of your Pistons look like but if there is any sort of a recess that the Fuel pooled in you could have had some Hydraulic lock going on. Unless before you installed the Injectors you cranked the Engine and blew it out.

As you said a higher opening/pop pressure would make the timing later/retarded and if that was added to other conditions that would make the Fuel Injection Pump Timing late you may need to retime the Fuel Injection Pump.

When step on it is the Power ok?
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Old 05-15-2011, 04:45 PM
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I seriously doubt that the mixture of oil and diesel run for that short a period of time would have done any damage.
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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
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Old 05-15-2011, 04:47 PM
luke4's Avatar
benz-o-matic '86
 
Join Date: Mar 2011
Location: North San Diego County, CA
Posts: 60
Power is fine for mileage. 13-14 seconds for 0-60 mph.
Don't think they're bosio. Sean C / Hessian Import did the rebuilt and he said they can be noisy for a few hundred miles OR they can also reveal late timing.

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1986 300 SDL, gray on black, #14 head, 180K miles
1982 300 CD, silver on palomino, 290K+ miles [sold]
1980 300 SD, white on palomino, 500K+ miles when retired [uncle's car - inspiration for the above]

Last edited by luke4; 05-15-2011 at 05:23 PM.
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