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Old 01-03-2000, 02:40 AM
jrd jrd is offline
Registered Luser
Join Date: Jan 2000
Location: Oakland, CA
Posts: 52

This is my car: 1987 300D Turbo. 186.5k
miles, starts instantly, runs 2 mm above the
80 degree mark under normal driving. 27
MPG mixed driving.

This is the problem: I hear one heck of a racket coming from my engine under the following conditions:

* Start cold, let idle until warm. Slight
noise that gradually gets louder.
* Idle or drive in stop and go traffic.
Power feels fine, but I don't know if it
is less than what I should be getting.
When I floored it getting on a freeway
onramp with this noise it would not rev
much above 3000 RPM and took longer to get
to 65 MPH. Normally it revs to 4000 before

The noise can be eliminated when I:

* Shutting off the engine
* Coast in 3rd gear at 50 MPH down about 2
miles of hill. During this time coolant
temp drops to 80 due to the cool breeze
and minimal throttle.
* Take it out on the highway. Noise is gone
by the time I reach the top.

The noise is a "tick-CLACK" repeating about
3 times per second at idle and faster at
road speed. It is very slightly
distinguishable from inside the cabin. About
as loud as someone's voice when standing
outside the vehicle, and very loud with the
hood open.

Although I'm not sure, the noise at idle
seems to go coincide with oil pressure
just a shade under 2 bar. When there is
no sound it's usually right at 2 bar.

The oil is Pennzoil 20w-50 changed 1200
miles ago by Mercedes Recycling in
Watsonville, CA. I've told by some very
helpful people on the Internet that it
isn't quite the right viscocity of oil to
use on the diesel. I bought a quart at
the store for backup and later noticed
that there is no suggestion
of a CF, CD, etc raiting on the container,
so I guess that it's not designed for diesel use. The mechanic there wanted to replace
all my lifters, but I declined since the noise wasn't happening very often. Now, 1200 miles since having the oil changed, it has become more prominent.

I recently took it up to 4500-5000 RPM in
2nd gear on some hills because of this noise, in hope of cleaning everything out. Instead the car started leaving pools of oil wherever I parked it, especially on inclines. I may have caused a lot of oil to leak from somewhere and pool in the sound cover under the engine where it is dropped when I park the car. Oil level went down 2-3 mm on the dipstick after this. Transmission now seems to shift more firmly (yay!) but the clacking
noise now comes more often and is louder. Exhaust smells and looks the same, although I have an oxidation catalyst.

What I'm unclear on is whether using that non
diesel rated oil at that viscosity can cause
that specific sort of problem. Pictures
are available at where you can see the dipstick on each side (1 and 2) when first pulling it out (before) and after wiping it and reinserting it (after). Based on afterwiping1.jpg, it appears as if the oil level is halfway between Min and Max, yet there is oil coating the entire other side of the dipstick between Min and Max. What is the real oil level here? Does the oil appear to be thinned out, is this how it should look, or is it possible to tell? (This is on a cold engine.)

Will Marvel Mystery Oil and a fresh dose
of 15w-40 diesel rated oil solve this problem? Is this oil leak possibly a sign that air is getting back into the oil? It seems unlikely, considering that the oil is supposed to be under pressure. Is the non diesel rated oil causing carbon buildup or thinning of the oil? The oil pressure used to hold at 2 instead of dropping to just under 2 at warm idle... after my "italian tuneup" it is slightly lower than it used to be.

In any event, this noise doesn't sound like it can be very good. Is this noise damaging to the engine, or can I just ignore it? It doesn't make economic sense to change the oil after only 1200 miles. (I would get it done at a different independent shop that uses higher quality oil, and my last oil change at Merc. Rec. was $60) If I provide a Bosch filter, is it safe to take it to a "quick lube" place closer to home than a mechanic?

I don't believe it is injector noise. I floor it regularly and put a dose of STP in a fresh tank not long ago. It seems as if injectors would be a different sort of noise and at different times. I will try to have a WAV file available of the noise sometime tomorrow at the above URL. The noise sounds like it's coming from the center point between the front end and back end of the valve cover. I can't hear a difference in volume when I take off the oil filler cap. When I remove the filler cap there is a little oil splashed up and down and I can see the metal on the moving parts through a jacket of oil.

All thoughts on this matter will be greatly appreciated. Please feel free to browse the files at the URL I posted. (Keep the hood star pic if you like it!) I've heard there
has been an update on the lifter design
but I do not know whether the car has this
update (I've had it for 5000 miles and do not
currently have past service records.)

Thanks in advance, and happy new year!
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Old 01-03-2000, 10:34 AM
Registered User
Join Date: Jul 1999
Location: Tampa, Florida, USA
Posts: 214
Given your description below, I'd say it's NOT the injectors. Immediately before I had the injectors rebuilt on my '83 240D, 250k miles, my symptoms were:

* LOTS of clattering/pinging noise when engine is cold. Noise got significantly louder if engine was revved. Noise goes away as engine warms up to normal temperature.
* Relatively poor fuel economy. 24-26 mpg when I should be getting 28-32.
* Somewhat excessive smoke (even for a diesel).

I paid a local shop $115 to clean and rebuild all four injectors, including brand new nozzles on two of them, which cleared up all the above symptoms.

In regard to your problem, it certainly wouldn't HURT to rebuild your injectors, especially if you have never done so in your 186k miles, but the injectors are probably not the cause of all the symptoms you listed.

- Nathan
'83 240D, 250k miles
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Old 01-03-2000, 07:44 PM
Larry Delor's Avatar
What, Me Worry?
Join Date: Jun 1999
Location: Sarasota, Fl.
Posts: 3,026
For what it's worth,...
based on some research that I did a few months ago (sparked by questions regarding oil in this forum), the Pennzoil should meet or pass the "CD" specification.
Good luck with your engine, I really hope it's not serious, but if it were mine I'd bring it to the dealer or a decent shop right away.

03/83 300D
07/73 280

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Old 01-03-2000, 09:55 PM
Registered User
Join Date: Mar 1999
Location: Suwanee, GA, USA
Posts: 4,712
One thing to let you know... I had a tech spend countless hours on one of these engines for the same symptoms... We recalibrated the pump, replaced the injectors, and checked the timing chain and performed a compression test......Nothing fixed it untill I was told by MB DOC that they liked to bend the connecting rods in the engine. We pulled the cyl head and there it was, 2 bent rods. Replaced them and all was cured (about 5K dollars for alot of work)

1981 280GE SWB
1987 16V

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Old 01-04-2000, 09:08 AM
Join Date: Jun 1999
Location: Quezon City, Philippines
Posts: 79
Justin, try loosening one high pressure fuel line at a time. This are the six steel lines from your injection pump going to your injectors. If the engine quites down when you loosen a specific high pressure line, then you know that your problem is either on a bad injector, or on the injection pump.

You can have the specific injector checked, and/or also have a Bosch injection pump mechanic replace the six delivery valve copper washers on your fuel injection pump. This type of work is relatively easy, and can be done on-engine without dismounting the injection pump.

I hope this helps.

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Old 01-05-2000, 11:58 PM
jrd jrd is offline
Registered Luser
Join Date: Jan 2000
Location: Oakland, CA
Posts: 52

Thanks a bunch! I had my oil changed and
had an additive put in the oil which
is supposed to clean out the valve train.
It went quiet after about 5 miles. We'll
see how it goes!

In case that doesn't work, I may try the
injector line idea. Do I loosen these
at the block end of the line?

I'll run a dose of Techron through the
system at the next opportunity.

Thanks again!
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Old 01-06-2000, 05:19 AM
Join Date: Jun 1999
Location: Quezon City, Philippines
Posts: 79
You can loosen the line either at the injector end or at the pump end, whichever has easier access. Remember though to loosen and retighten one line at a time only, and retorque back to correct value. I don't know the specific torque at the moment.

Of course, loosening a line should temporarily result in a fuel leak and dead cylinder due to no fuel being sent to a specific cylinder.
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