Engine Clicking - PeachParts Mercedes-Benz Forum

tallgrass · #1 10-24-2007, 06:31 PM

I'm on the road, bringing my 1981 300D (non-turbo) back from PA, after spending a few weeks in a crash-course Diesel 101 (and a lot of time here reading threads...you guys are great!).

It's been running pretty well, though using a lot of oil, but at this point I just want to keep it running without hurting the engine, so I can work on it at home.

Yesterday I heard a new noise, a clicking that isn't rythmic. It seems to happen mostly when I'm between 20 and 30 mph, and then again at 45 to 55. Above that I don't hear it at all.

It goes click. clickclickclick, click click, click, clickclickclickclick, , , , click click, etc. It sounds like something is loose. Air filter housing mounts seem fine. Not like metal pinging against metal. More like if there were a loose pair of scissors made out of a cheap potmetal. Kind of dry-sounding.

The engine seems to purr along pretty evenly. I get no loss of power when the clicking happens.

Any ideas?

My big concern is hurting the car if I drive it home...about 800 more miles.

Oh: the only other thing that's changed is that the odometer and trip meter has started working...it takes a little rest when changing from 99 to 00, but eventually moves, after about 5 miles. After that it keeps exact and accurate mileage (compared to highway mileposts).

1981 300D non-turbo

Hatterasguy · #2 10-24-2007, 06:49 PM

What year?

For future reference putting the year and model of MB you have in your sig really helps.

Is the sound engine RPM related or more speed related?

tallgrass · #3 10-25-2007, 12:00 AM

Thanks Hatterasguy: I added the info above.

It's a 1981 300D, non-turbo.

I'm not sure if it's RPM related or speed. I don't have a tach, only a speedometer. The speed of the clicking is pretty much the same no matter what speed I'm going. It seems to be gone when I'm higher than 55 mph.

Thanks for helping a newbie!

1981 300D non-turbo

vstech · #4 10-25-2007, 12:15 AM

is it by chance turn related? can you make the clicking go away by accelerating? it could be transmission mounts, center driveshaft bearing pay attention to exactly when and what causes the noise, and if anything you do can alter it.

t walgamuth · #5 10-25-2007, 04:34 AM

It could be also a loose air cleaner housing. The three mounts are rubber in the center and if one goes bad it makes a lof of racket. They are easily changed, a ten mm bolt comes up inside the air cleaner in three places, the base of it takes a large wrench, 19mm or perhaps even larger. They don't cost much and you will learn to keep a couple of extras around if you keep the car.

Tom W

tallgrass · #6 10-25-2007, 11:37 AM

Thanks for your help:

It doesn't seem to be affected at all by turning or accelerating or braking. It seems to come and go in those speeds I mentioned, whether accelerating or holding a steady speed. The air housing mounts were fine (seemed in good shape and new) when I looked a couple of days ago. I'll check them again this morning.

Oil pressure and temp consistently good.

For what it's worth: Yesterday morning I drove it after sitting all night and it was doing the same thing. After my errand (45 minutes off) it drove without the noises for about ten minutes, then they gradually started again.

Could it be some sort of sympathetic vibration in a fan? I lubricated them about 600 (mostly highway) miles before the noise started.

Also, I found that the PO had not driven the car very much for the four years or so he owned it, so I've been replacing a lot of dry/cracked fuel lines, vacuum connectors, tires. The belts looked pretty good. Not sure if they need to be tightened...?

1981 300D non-turbo