Videos of my 240d engine. Please help me diagnose. - PeachParts Mercedes-Benz Forum

americanflyer · #1 04-01-2007, 06:53 PM

Hello. I recently purchased a 1975 240d with a engine that the owner said was blown and sounded like a cement mixer. The car had been sitting for two years and I finally got it running today so I could hear for myself the condition of the motor. It really doesn't sound that bad to my ears yet something is wrong. The priming pump as you can see in the videos is leaking but I just didn't have it tightened down enough and now it is not leaking (needs replaced though). The diesel fuel is two years old yet the tank was full and I siphoned off some and it looks OK. Now that I finally got it running it start right up easily. I jumped in it and took it down and back up my driveway (1 mile long and fairly steep) and it had a hard time getting back up and had to put it in first gear even on the areas that have little slope. Generally seems to be holding back or lacking power. At a low idle it almost sounds normal but at higher rpm and when the throttle is pulled back sharply it makes kind of a tapping or knocking sound. To my ears it sounds more in the top end but I could be entirely wrong. The previous owner said he accidentally ran it out of oil then it started making those terrible cement mixer sounds. It just doesn't sound that bad to me. Please tell me what you think could be wrong. Thanks so much. Chris

Here are the videos I just put on You Tube.

http://www.youtube.com/watch?v=hkFzy6DbhJc
http://www.youtube.com/watch?v=ejLaBWVU3pg

americanflyer · #2 04-01-2007, 06:57 PM

The second video doesnt seem to be working yet. Sometimes they take a little time for YouTube to post them up. I also forgot to mention that when you first start the engine there is ALOT of white smoke. Is this normal? Also when I remove the oil cap with the engine running there is enough blow by to spray oil drops out. Chris

TMAllison · #3 04-01-2007, 08:14 PM

Doesnt sound bad. Throttle seems very delayed?

Probably should give it a valve adjustment, new fuel filters, check for vaccum leaks and try running it off a temp tank with fresh fuel before giving up on it.

Mustang_man298 · #4 04-01-2007, 10:44 PM

When I first got my 80 going after sitting 4 yrs, I had put fresh fuel in before even trying to start it and purged it thru the lines, it ran very sluggishly with extremely poor power (30mph tops), and you'd think I was fogging mosquitos, couldn't see the road beind the car. Ran a diesel purge thru it and drove it a few days, got better each day, runs great on the road now. Did a valve adjust recently, (also found a chewed up valve capnut and rocker) runs a bit better on cold startup, and man the fuel mileage has shot up...

benzforlife · #5 04-01-2007, 10:52 PM

it just sounds cold to me...
something is definatley going on witht the throttle, try all of the thing mentioned above, includin a diesel purge, and hope for the best
-good luck

katja · #6 04-01-2007, 11:13 PM

Nice car! Looks almost identical to mine - same exterior color - but why is it that on so many of these cars, the "Diesel" and "240D" badges have been reversed?

Anyway, it sounds pretty similar to mine....I wonder if the delayed throttle response is due to the video (sound & video not matching up) and not the car. Your primer pump leaks bad! Replace that first & drive it for a while and see if it runs any better. When my primer pump and fuel lines were leaking, it would stall sometimes after a hot startup or lose power while on the road. Any air getting in the fuel system is not good.

If it ran out of oil before, that's not good, but it doesn't sound like a cement mixer. Do all the usual maintenance (adjust valves, change fuel filters, check oil in air filter & injection pump, diesel purge) and see how it goes. BTW, there is a painful video somewhere on Youtube of a 240D being purposely run without oil at full throttle and it took a LONG time to kill it...

AFAIK, mine has never been run out of oil but mine has enough blowby to make the cap dance, and I get quite a bit of nailing when cold, but after driving a while, it is very smooth. I have been using Mobil 1 15w-50 and diesel with 5-20% biodiesel blended in, and that along with new motor mounts made things quieter....but these old engines are noiser than a 617 or 603.

How's the rest of your car? Body, interior, transmission? Looks pretty good for $500 from what I can tell!

-AC

#7 04-01-2007, 11:28 PM

Sounds fine to me.

It's only got 62hp, don't expect it to take off like a rocket.

Benzcrusher · #8 04-01-2007, 11:38 PM

Dont forget to change the oil in the IP. While you are at it clean the air filter ( gasoline works fine) and the aircleaner housing, add fresh oil to the bath up to the line...

americanflyer · #9 04-02-2007, 12:21 AM

Thanks for all the post thus far. You guys are giving me hope that this engine is not toasted.

I am new to diesel engines so I am not familiar with the usual maintenance procedures for diesel engines. Like changing the oil in the injection pump. I wasn't even aware there was oil in the pump.

Can someone explain how that is done and what oil to use etc.. Also, what exactly is 'nailing'?
Maybe the sound on the video doesn't quite show how the engine sounds in reality. There does seem to be sort of a lifter type sound that shouldn't be there although this is the first Mercedes diesel I have heard. When you increase the throttle it begins to sound more like a slight knock. Again, maybe it is normal. My neighbor seemed to think the problem and sound might be an injector. Does this sound like a possibility? If so how do you check the performance of a injector without special tools?

The rest of the car is in MINT condition with no rust anywhere except in the trunk. The trunk floor is rusted pretty good. I think the antenna mount leaked for a while and the moisture got under the mat and the PO didn't notice. Bummer. But under the floors, jack points and everywhere else under the car looks almost new. Great car.

I was surprised to see that a car of this vintage has an oil bath air cleaner yet maybe that is normal for diesels. My 1942 Chevy pickup has an oil bath filter.

I love the Mercedes and cant wait to get her driving down the road. Thanks a million for your responses. Chris

JimmyL · #10 04-02-2007, 12:22 AM

Quote:

Originally Posted by katja

Replace that first & drive it for a while and see if it runs any better. When my primer pump and fuel lines were leaking, it would stall sometimes after a hot startup or lose power while on the road. Any air getting in the fuel system is not good.

I think katja is on the right track, at least as a starting point. That huge leak does have the potential to cause issues similar to what your are experiencing. Too bad the spewing fuel was out of sight when you were revving up the engine. Would have been interesting to see what was happening to it when rpm's increased.....

americanflyer · #11 04-02-2007, 12:31 AM

BTW, the delayed throttle response is the fault of the video after it was uploaded to YouTube. The original video on my computer does not have this problem.

americanflyer · #12 04-02-2007, 12:36 AM

Also, I fixed the spewing fuel just by tightening down the cap further on the priming pump. Still needs replaced though. And what would cause the extreme amounts of white smoke I am getting? Could the two year old diesel or a bad injector be to blame?

pawoSD · #13 04-02-2007, 01:17 AM

I think it just needs: valve adjustment, maybe a diesel purge, some new filters....and to be driven hard for a while. Then I bet it will be running great. It sounded like it was running fine to me....

2.5Turbo · #14 04-02-2007, 02:13 AM

Quote:

Originally Posted by pawoSD

....and to be driven hard for a while.

Hard not to do that in everyday driving with this car

diametricalbenz · #15 04-02-2007, 02:42 AM

The engine sounds somewhat normal. It does sound a little more "clackety" than mine does. I would definitely run B100 through the engine and that will help indicate whether or not the injectors are nailing.

When the revs are up and then the throttle is released is that tapping or knocking sound accompanied by a lot of exhaust smoke? I get that sound as well and presumed it was a lot of oil being sucked into the intake from the excessibe blowby from the CCV line.