Hi, I am new to the site so please bear with me. I have done a search and cannot find my exact problem. Some back story, I have a 79 240D I picked it up about a year ago and have really only put about 2000 miles on it, and 1800 of those were a long road trip last fall, as soon as got it I took it to a benz only shop that is highly reputable and had the fluids changed, the valves adjusted, and whatever else needed to be fixed fixed eg, neutral safety switch, glow plug relay, starter, this car sat around for years not being driven much.

Here is my problem, since I owned it it would tick under light acceleration intermittently normally right before shifting tick tick tick shift, then repeat for the next gear, its a auto, drove about 1600 miles then I noticed the same intermittent ticking would happen at a constant rpm/speed around 45mph if I hold that speed I can get it to tick more rapidly and it will sound like pinging from a gas motor. I have not really driven it in about 6 months because I don’t want to do any damage. The car is quite and idles good, drives great, and under heavy load and acceleration there is no ticking at all, I can make it happen by revving while parked but not consistently. the noise sounds from inside like it is down lower on the back of the motor, standing outside revving it is hard to pin down where the sound is coming from?

any thoughts?

The very first thing I would do is to add some cetane booster to the fuel. If the noise goes away then you have located the problem. The older Benz can be very finicky when subjected to the ULSD (Ultra Low Sulfur Diesel) fuels currently on the market.

You might be hearing the phenomena commonly referred to as "nailing". It's pretty much the same as "spark knock" in gasoline fueled engines.

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Welcome to the Forum.

My first thought with the ticking and you hear it down low to the rear of the engine, is the Flex Plate.
The plate is bolted to the Fly Wheel, and the Torque Convertor is bolted to the Plate.
If the plate cracks, this "Could" be the ticking you hear.

This thread has some picture to give you an idea of what it is, and pictures of a broken plate. Lets hope this isn`t your problem.

To check it, from under the car on the bottom of the transmission bell housing
is a black plastic cover. pop it off and shine a light in the hole, you will be looking at the plate.
There is 3 groups of two bolts. I use a large Screw driver to pry the TC around to get to the bolts through the metal grate.

http://www.peachparts.com/shopforum/diesel-discussion/237244-pics-cracked-flex-plate.html


sent from my POS Computer
Charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

ok, first WELCOME to the forum!

second, there are a lot of noises these cars make. if INSIDE the car you hear it while sitting at a stop with the transmission in park, it's got to be an engine/trans problem... as nothing else is moving. so, the possibilities are, Vacuum pump, injectors, valve follower issues maybe from adjustment needs, starter, flex plate.

I recommend at idle, to get a garden hose section, and gingerly, hold the hose to the motor near each injector and see if you can hear the noise listening to the other end of the hose.

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My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Thanks for the replies, I did have a question about injector nailing, first is could the sound be intermittent and go away under heavy load? and second what does it sound like and is is a constant sound every time the injector pops? I feel like I should just see if I can drive this noise away but after 400 miles or so driving with it last fall its still there. I will put some diesel PS in the tank, I run the stuff in my cummins all the time and it really cuts down on the injector noise in that motor.

Yup, sure can. Kind of a rattle, like a BB being shook around in a tin can. Varies in speed and intensity depending on driving conditions. Usually not a constant noise.

__________________
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now