Excessive Valve Train Noise? - PeachParts Mercedes-Benz Forum

lietuviai · #1 09-15-2003, 07:35 PM

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?

samiam4 · #2 09-16-2003, 01:04 PM

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

Wasuchi · #3 09-16-2003, 02:01 PM

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.

lietuviai · #4 09-16-2003, 07:44 PM

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?

Wasuchi · #5 09-16-2003, 08:54 PM

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.

lietuviai · #6 09-16-2003, 09:25 PM

Quote:

Originally posted by Wasuchi
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.

samiam4 · #7 09-16-2003, 10:40 PM

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

rmmagow · #8 09-16-2003, 11:20 PM

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.

lietuviai · #9 09-17-2003, 11:53 AM

Quote:

Originally posted by samiam4
Ok- sorry to offend.

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.

samiam4 · #10 09-18-2003, 12:49 PM

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

lietuviai · #11 09-18-2003, 05:55 PM

Quote:

Originally posted by rmmagow
These are noisy machines that smell good.

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

samiam4 · #12 09-19-2003, 12:23 AM

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

lietuviai · #13 09-19-2003, 01:31 PM

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.

Rick Miley · #14 09-19-2003, 02:15 PM

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.

lietuviai · #15 09-19-2003, 06:48 PM

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.