Excessive Valve Train Noise?
 

The valve noise of my '85 300D turbo appears to be excessive. I pulled the valve cover and checked the valve clearances but they were within spec. I did measure in the correct area. Maybe the amount of noise is normal? There is some "ticking" that is constant with the amount of revs the engine is making. Less revs less ticking, more revs more ticking.
It seems to be more noticeable than when I bought the car last Spring. The oil pressure is normal and I change the oil every 3000 miles using a diesel grade oil just as the previous owners had.
I know no of you will be able to hear it but how much valve noise is normal?

Sounds like they need adjustment. If the valves are loose or tight, they make noise.

Did you have the check camshaft lobe rotated toward 1-2 o clock when checking the measurment? Accurate measurement can only be done COLD.


Michael

Did you check all the adjustment nuts when you checked the clearances? Sounds like on of them might be coming loose and that ain't good! When was the last time they were adjusted also.... like samiam4 said it does sound like they could be out of adjustment, I would check them all again just to be safe.

I appreciate the advice on the nuts & checking it cold & cam lobe position. I made sure I did everything exactly as the MB factory shop manual instructed before writing this post. After reading other posts in this, I'm beginning to think it could be one of the injectors.
Would a noisy injector sound like a valve needing adjustment?

You could start opening the injector lines one at a time and if it stops then you're right. If you think it's injectors then that's the next step.

Thanks for the tip, I'll give it a try.

Ok- sorry to offend.

you can always run your feeler gauge through a micrometer to see how much drag is appropriate. Personally, for me, it I've got to watch checking the adjustments. The airfilter and intake prevent a straight line on the feeler gauge and gap. So, especially on the exhaust, I've got to make sure it's straigt in line.

Another observation. I've had at times noises I couldn't trace down which worried me. Many times changing the oil has cured the problems- I've tested the old oil and it tested fine. So, cannot explain it. I have not had this problem with Chevron Delo or the Mobil Delvac.
Is the idle speed correct? Any loping of the engine? A good valve adjustment and clean filters- the engine should idle very smooth.

Reminds me where are my wrenches Loo!!

Michael

Mine's been noisy too and that with a two times valve clearance check. I use the go, no-go method for checking/adjusting the valves. The car's always been noisy to me BUT it is especially noisy in the morning. By the time I get to work, it sounds only regular noisy. As long as you're confident about the adjustment don't worry much about it as long as the beast runs well. These are noisy machines that smell good.

Don't worry there's been none taken nor felt.

I had no trouble getting at the valves from the back since my car is a California model and the filter housing is in the area behind the passenger headlight. The car idles fine and smoothly, It's just a little hesitant to start easily in the mornings, even with new glow plugs and letting them glow after the light goes out and waiting for the loud thunk from the relay. It usually takes a couple of glowing periods to start well enough to get going or I keep my foot on the pedal to keep the idle up until it warms up.
Once it warms up, it runs good.
I never thought about miking the feeler gauges, but that's only because I don't have a micrometer.

Not that my 81 is a good example.

The car had regular oil changes(5k to 100,000 then 3k changes) got to where it was very hard to start cold. Valve adjustments got noisy after a short time.

I ran a hot compression test at 250k. The numbers were solidly in the 400-425psi range. Ended up doing a valve job, the seats were hammered pretty badly and replaced the adjusters. Now it starts better and is quite.

I would have never done it-but it was a stress relief from a work enviroment with constant incompetence coupled with quarterly lay-offs.


Michael

I'll take the sweet smell of diesel exhaust over any foul rich running gas powered car anyday!

Actually,

You know hard starting can be as easy as a loose fan belt or dirty battery cable. Slower cranking speed=hard to start. IP timing too effects it.


M

Sorry you misunderstood me. I ment rough starting. The engine cranks at a normal speed. It's just when it starts, it usually runs rough or sputters out and dies. I need to keep my foot on the accelerator pedal to keep it from dying initially. Once it warms up, it runs great and restarts good everytime the rest of the day.

Isn't there a mechanism on the 300D to raise the idle speed when cold? Of course my 240D has the adjustment knob on the dash, but the 300D doesn't have that. I thought there was something in/on the injection pump to handle that.

You would think that there should be some sort of solenoid to raise the idle speed when the engine is cold but there isn't. I had a Diesel Datsun pick-up and even it had a throttle adjustment knob to raise the idle when it was cold. I don't know why MB didn't think that there should be such a manual adjuster on the 300D. It's a bit of a pain. I have to drive the car with both feet until it warms up. I'm seriously thinking about installing a manual throttle cable just like the 240D has.

Diesel Idle speed adjustment
 

When you mention the manual idle speed adjustment knob on the 240D's dash, do you mean the small flat knob on the left side of the instrument binnacle under the dials that you twist either right or left? If so The 300D's I've test driven both had this and I recall my cousin's two 300D's in Australia also had them. Or is there another "knob" of which I'm unfamilliar?

- Peter.

pj67coll

That is the item. On US spec cars the 300D's had this knob on the dash until the turbo's were applied. After that they don't seem to have the knob. My '83 (with Turbo) does not have the knob, but even in cold weather it does not seem to need it.

My 81 300SD always will stumble and stall in the first 30 seconds after a cold start if the RPMs are not increased slightly. After that it idles smoothly all day. I thought that this was air in fuel, but it restarts too easily.

yes,and......
 

lietuvai, my 300d had alot of nailing when cold to warm and sometimes on high acceleration when hot.Sometimes hard starts like yours.
It was the injectors.
They were replaced and it is quiet now.

Whatever
;)

Re: yes,and......
 

How much did it cost for new injectors and how much of a job was it?
I somehow didn't think the injectors could be wearing out at 218K miles but this is the first Mercedes I have ever owned.

Bosch
 

Well, assuming you really need injectors, my rebuilt BOSCH injectors were about $56-60 each and the labor to replace all of them was about $75.
Fastlane sells them for maybe less. Some people claim that the rebuilt Bosch injectors can sometimes be defective. See archives. I've had no problems.
My injectors were replaced under factory warranty when the car had about 5K miles or thereabouts. Because of noise.This last time they were replaced at about 145K miles.

Re: Bosch
 

Right, assuming it is the injectors. Right now I'm keeping my fingers crossed that it's the valve adjustment. I checked and readjusted the valves to be exactly at spec yesterday. I won't know for sure if this will make a difference until after I have driven the car for a while and give the adjustment a chance to wear in. The noise was most noticeable after the car had been thoroughly warmed up. The noise occurring after warming up tends to make me think that it might not be the injectors but I could be wrong. I've even thought about a worse case scenario, a rod bearing going out. I had an old Cadillac many years ago that had a loud tap when it was warmed up and it was a rod bearing. The Benz on the other hand does not make a loud tapping sound. It's more of a tick (but way louder) that sounds like an old wind up alarm clock.

update on the valve noise
 

Well after driving the 300D for a few hours today the "valve" noise is still as noticeable as ever. The noise was just as obvious cold as it was hot. It seems to runs fine but the tapping bugs me. I guess I'll just have to stop by a garage that works on these things and have them listen to it.

Why don't you check around your area and see if there are any nice parks or places to hold a get together? Let some others hear it... and compare it to their cars....

Sounds like a great idea, but I rarely ever see any other cars like mine around here. I might pass one by going the other way maybe once a week.

not valve noise
 

I have now ruled out that it is valve train noise. I adjusted the exhaust valves slightly on the tight side but the ticking sound still persists. Interestingly you can't hear it with the hood open but it can be heard while sitting in the car. At idle it is barely noticeable but when you give it some throttle it gets a louder. Also when driving, when you let off the accelerator it goes away but the sound reappears when you step on the accelerator.
I am totally baffled by this and am to the point if it is something truly serious such as something internal, I'm not going to worry about it since it will cost more to tear into the engine than what I could probably find another one for.
But if it's something simple I wish there was someone who can steer me in the right direction.

As someone suggested it could be an injector 'nailing' (I think that's the right term for this condition). Have you tried a Diesel Purge ? Before replacing injectors try running a can or two through the engine.Search Diesel purge for complete instructions,good luck.

lietuviai,

Based on your description, it seems throttle position, which controls exhaust flow, is a key to the volume of the noise. If this is the case, the exhaust and /or intake manifolds may be loose.

Check the condition of the intake and exhaust manifold fasteners. I am not familiar with a California set up, or the turbocharger support system, so this may not be of a great deal of value to you. These fasteners, a stud driven into the head and a copper nut, get a lot of cyclic loading from the roughness and general engine motion in normal operation. Part of the loading comes from the exhaust system being located by the body of the car and the engine being sort of floated on the mounts (at least that is the case on a 240D) resulting in significant relative motion .

The design makes the copper nut the sacrificial element of the system and it can become deformed. As a result the manifold can become loose over time and make quite a racket as it allows exhaust noise, unmuffled, to fill the engine compartment, and there is a knocking of the manifold against the head that goes along with it. One way to check is to get your hand near the manifold to head joint and have someone else rev up the engine. If you feel gasses escaping, you will have all the evidence you need.

There are other sources of noise under the hood that "go with engine speed" and another that is a frequent complaint comes from the air cleaner housing mounts failing. These little rubber mounts with embedded threaded rods fail when the rubber gets old and fails, which leaves the air cleaner housing free to bang into adjacent surfaces.

If these are not your problem, I would be inclined to use a stethescope while someone revs the engine, and poke around until you find the source. These engines are not really quiet, but they generally do not have loud metallic clanking or mechanically alarming noises. When running correctly they sound "perfect" meaning the noises are mechanically timed and regular, repeatable and even. Good luck and I hope this helps. Jim

Kyle, I haven't tried any sort of diesel purge in the system while owning the car but it is a start. I am hoping that the noise is no more than a bad injector. The car idles and runs well and seems to have enough power and I have not noticed any excessive smoking. It only has some occasional missing during start up while cold.

Jim, your suggestions of checking the manifold to head joints sound relevant as well, the turbo and oxidation catalyst were replaced about 40K miles ago and some of the studs were replaced. The manifolds are not too different from the federal models. I have looked the engine over in the past while performing various maintenance items and I haven't noticed any soot on that side of the engine. I have stethoscoped the engine while running and revving it up, but since there is so much noise coming from the engine, it's difficult to really tell if the noises I have heard are out of the norm. Interestingly enough the "ticking" noise appears to be coming from the passenger side of the engine from listening from inside of the car. I haven't been really able to hear the sound from listening in the engine bay. This sound is not unlike the sound a loose rocker arm makes hitting a valve.
The air filter housing is the only thing that entirely different on the CA model. It sits in the area just behind the passenger side headlamp.
I sincerely appreciate these suggestions from the both of you and I will carefully check them out before I give up and try to find a knowledgable MB mechanic look at it. The closest one to me is about 50 miles away.
~DJ

Noise
 

Another way to listen for noise is to drive along a wall.
For example, try a wall that divides two split level streets.

As you drive close along it, open your driver side window and stick your ear out.
The engine noise is amplified. (drive along the wall, not into it!!!-DOH)

My 300D engine ticks sometmes. I have had the valves adjusted and new injectors recently.

Only heard if I really listen for it. This is not nailing noise, however.

By the way, check your trans fliuid level. It may be at mini-minimum.
While refilling a trans on these cars( After service-topping off), I heard a slight 'ticking'
until I got that pint of fluid in to mark the minimum level.
(car idling and in PARK)

Re: Noise
 

This is an interesting suggestion since my transmission oil level is at the bare minimum mark. The only thing is the "ticking" noise gets louder on acceleration and the sound it makes is like the sound of one valve rocker loose but I am beyond certain that it is not that due to the checking and rechecking of the valve clearances I have done.
Would a low transmission oil level imitate this sort of tick or click?
BTW, what sort of transmission fluid would you suggest using?

I think a cold start miss will go away after purging , mine did and I'm sure my engine is a lot more tired than yours (415,000 km ). If not and the compression is adequate then time to replace injectors :( .

The last time the compression was checked the car had 173K miles and they were at 380, 380, 380, 340 and 295. I do have a little concern about the 295 result though.

Any REPUTABLE Dexron III trans fluid.

My observation of the tick with low trans fluid is an anecdote which may or may not hold up to true mechanical fact.It happened for me.

1 pint will bring the fluid level up one marker-level.

2 pints in a quart.

OK, I tried this but unfortunately it wasn't the problem. I beginning to more and more think that it is an injector (I hope). As soon as I am able to find some diesel purge that I have read about in some of the other threads, I will try cleaning out the injectors that way before tackling the job of removing each one, disassembling and cleaning them as is suggested in the Pindelski site.
One more thing, is it possible for an injector to wear out? Pendelski's site makes me believe that all you have to do is clean them and you only part that you really need to replace is the heat shield. Nothing seems to need to be checked for wear.

I think you can find Diesel purge or Diesel Rx on Ebay.... if you're having a hard time locating some try there.

Ebay...my first choice for parts! As far as the diesel purge, I'm going to try checking some of the local parts stores as there are lots of diesel pick-ups in my area