'83 300D intermittent missing/knocking/ticking- i feel defeated (video included) - PeachParts Mercedes-Benz Forum

dinman · #1 10-18-2017, 11:52 PM

Going to try and make a long story short. purchased this car for a mere $400 and i would love to bring it up to snuff. Here it is

No Bueno

I have done the following- yet i STILL have this ominous sounding knock/tick/misfire. Its actually 2 different noises. One is a high pitched tap, one is a nasty sounding knock, accompanied with the engine missing. Happens occasionally at running speed, but rare. Happens more when cold.

Car has unknown mileage (243k) on halfway working odometer, and unknown maintenance. ive done the following in the past 2k miles ive had it:

Valve adjustment (4 times)
Rebuilt injectors w/ Monark nozzles torqued to 58 ft lbs
water pump
alternator
both alt brackets
belts
air cleaner bracket/mounts
diesel purge
both fuel filters (twice)
return lines
oil change (twice)

and other things that wouldnt pertain to this issue such as brakes, seats, wood, wheel bearings, etc

Let me note one thing that may be essential- the #3 valve (intake on cylinder 2) will not adjust into spec. the nut seems stripped, not only on the hex portion (can only fit the wrench on one side of it) but also on the valve. No matter how much i fight it, i cant get the clearance to close. The closest i can get it is over .020, when i know it is supposed to be .004 for intake on the om617 turbo. all other valves adjust perfectly.

going to check the valves again tomorrow

could it be a fuel delivery issue? the car sat for 7+ years before i got it and i havent touched the tank.

it sounds horrible, i would say it is catastrophic engine failure, but it comes and goes. I would believe if the engine was about to pop, the noises would just get worse and worse.

Sometimes it drives great, and sometimes it does terrible.

Oh, and after installing the injectors with new nozzles, it smokes A LOT. Like before i never got any smoke. Now, it smokes pretty heavily on start up (when cold) and is puffing out a faint haze most of the time when driving. But the old injectors were for sure trashed, i couldnt even see the tips of the needles on some of them.

Of course it didnt do alot of what it normally does in this video im posting below. You can defintely hear the inconsistant high pitched tick, and the loud knock/misfire only happens once or twice. Once at 0:06, and once again at the 2:22 mark of the video, right at the end before i shut the camera off. Its a loud "knock" where the engine makes one violent shake, then goes back to normal. It does it sometimes when driving, but not often. Feels like a surge of power when it does it.

Oh by the way, my exhaust is off right now (in the process of putting it back on) so some clattering and noises can be heard because the pipe rattles pretty bad down there.

and yes i need to adjust my linkages bad. i think my idle is too high. i also need engine mounts

https://www.youtube.com/watch?v=gnAYVBcbuqY

any help would be oh so appreciated. will buy you a beer, if we ever cross paths. this car is really frustrating me. every time i fix something, two more things go wrong. but hey. "nothing more expensive than a cheap mercedes"

Junkman · #2 10-19-2017, 08:12 AM

Begin with what you see. Figure out what has to be done to adjust the valve. Is that fuel leaking at # 1 & 2?

dinman · #3 10-19-2017, 09:19 AM

Quote:

Originally Posted by Junkman

Begin with what you see. Figure out what has to be done to adjust the valve. Is that fuel leaking at # 1 & 2?

whoops, meant to explain that. i just changed oil and made a mess. spilled it all over the engine. i will say, after running the car at highway speeds for a long period of time, the #3 injector leaks a little at the halves

Maxbumpo · #4 10-19-2017, 10:17 AM

OK, I love threads like this!

My approach in a case like this is exactly what Junkman said. Begin with what you see and know to be wrong, and fix that.

Smoke after the "new" injectors: Sounds like this was a DIY job? Did you use a test stand to set the injector opening pressures? If you did not, you need to get the injectors calibrated to make sure they are set correctly for your car. If you don't want to invest in the test stand or make your own, find a local Bosch service shop that does diesel injectors, they will probably charge you $20 or so per injector to test and set the pressures.

The valve that you can't adjust properly is REALLY concerning to me, combined with the intermittent "clunk" noise in the video at about 6s and 2m:22s. I would not drive the car until that is fixed, this should be your highest priority.

On your injection pump, I see a white knurled knob for the priming pump. Replace that with a new Bosch primer pump, which is a small black cylinder, costs about $25 or so? Been a long time since I did that job. The original white primer pumps have a very bad reputation for allowing air to leak in and fuel to leak out and let the injection pump lose its prime which makes the car very hard to start and may lead to other issues, like poor running.

Maxbumpo · #5 10-19-2017, 10:20 AM

The fact that the noise and behavior is intermittent means to me that the engine is sound and is worth fixing. The repair(s) can be relatively low cost if you turn your own wrenches.

Junkman · #6 10-19-2017, 10:54 AM

Smoke may be injector related. If you didn't pop test accurately, either do them again or see whether Greazzer can be bribed out of retirement. He has all of the required stuff and has been through the learning curve.

dkr · #7 10-19-2017, 02:12 PM

I would figure out how to adjust that one valve before going through any of the other steps.

It has been mentioned before, but did you pop-test the injectors? If not, you are taking a large guess assumption that they are in spec.

Dkr.

ChrisArnt · #8 10-19-2017, 02:32 PM

I bought a car that was only driven around the block twice a year for the last 10 years.
Algae in the tank.

I can't give you advice on the mechanical technical stuff like popping the injectors or whatnot., but I would just keep pulling that secondary filter and flushing it.
Also, try 1/2 quart of marvel mystery oil in the engine oil. It may free up some stuck lifters or clear out some plugged channels.

renaissanceman · #9 10-19-2017, 02:40 PM

Quote:

Originally Posted by ChrisArnt

I bought a car that was only driven around the block twice a year for the last 10 years.
Algae in the tank.

I can't give you advice on the mechanical technical stuff like popping the injectors or whatnot., but I would just keep pulling that secondary filter and flushing it.
Also, try 1/2 quart of marvel mystery oil in the engine oil. It may free up some stuck lifters or clear out some plugged channels.

There are no lifters to stick in this old beast, right?

dinman · #10 10-19-2017, 02:58 PM

wow thanks for all the replies. i have parked the car and im not driving it until i figure this out.

I ordered the nozzles from mercsource brand new, and properly lapped and thoroughly cleaned all the surfaces. i almost believe the injectors had never been serviced they were so bad.

but no, i actually did not pop test them, 1.) being i didn't want to buy all the stuff just to do it once and 2.) no one in my area even wanted to TOUCH the injectors. all shops local to me like to say "everybody stopped wrenching on those cars ten years ago, give it up" to hell with them

im pulling the valve cover again today to check everything out.

my primer pump actually always leaks, and when i begin to pump it, it really starts pouring fuel out. This isn't normal i suppose?

Sorry for my lack of knowledge on this car. I've never owned/worked on a diesel, much less a mercedes diesel. I'm only 21 so i have never been around these cars. my interest for them sparks from my dad owning them back when they were new, and it's just such a cool car to me.

so i'd love to get it back in good reliable shape. i have hope in this engine since the noise is intermittent.

renaissanceman · #11 10-19-2017, 03:22 PM

Getting the injectors pop tested is critical for good running. As is correcting any (even slight) fuel leaks -- they introduce AIR on the suction side of the lift pump.

The rack damper can be adjusted:
http://www.peachparts.com/shopforum/diesel-discussion/309971-1985-300d-rack-damper-adjustment.html

Larry Delor · #12 10-19-2017, 04:20 PM

I see you put new braided hoses on the injectors, but what did you do with the last one? #5? I couldn't tell in the video.
She seems to shake a little at idle too, but that may straighten out when you get the valve straight.
The rack dampener adjustment as mentioned above, can help, but personally I might wait to do that - check first to see if you have an old one, or new one. I think the new ones are brass colored.

dkr · #13 10-19-2017, 04:52 PM

Quote:

I ordered the nozzles from mercsource brand new, and properly lapped and thoroughly cleaned all the surfaces. i almost believe the injectors had never been serviced they were so bad.

but no, i actually did not pop test them, 1.) being i didn't want to buy all the stuff just to do it once and 2.) no one in my area even wanted to TOUCH the injectors. all shops local to me like to say "everybody stopped wrenching on those cars ten years ago, give it up" to hell with them

The old injectors may not have been serviced, but how could you possibly know anything unless you STARTED with pressure testing them?

There is a range for pressure on the injectors and after that they need to be balanced within 50 psi of each other. If they are within spec, but not balanced you could have some funny stuff with your engine like you are mentioning. Also, you have no way of knowing the injectors are actually producing the mist they need and not just drizzling out diesel fluid.

At this point, you NEED the proper equipment or to get the injectors to someone who has the proper equipment to test and balance them.

Most of the original mushroom pumps leak. It's a cheap part and about 15 minutes of labor, so I would replace it.

Dkr.

dinman · #14 10-19-2017, 05:52 PM

Quote:

Originally Posted by renaissanceman

Getting the injectors pop tested is critical for good running. As is correcting any (even slight) fuel leaks -- they introduce AIR on the suction side of the lift pump.

The rack damper can be adjusted:
http://www.peachparts.com/shopforum/diesel-discussion/309971-1985-300d-rack-damper-adjustment.html

thank you thank you

Quote:

Originally Posted by Larry Delor

I see you put new braided hoses on the injectors, but what did you do with the last one? #5? I couldn't tell in the video.
She seems to shake a little at idle too, but that may straighten out when you get the valve straight.
The rack dampener adjustment as mentioned above, can help, but personally I might wait to do that - check first to see if you have an old one, or new one. I think the new ones are brass colored.

#5 just has the one running from #4 and then an end plug correct? at least that is how mine has been. Im going to check the valves before anything else at this point

Quote:

Originally Posted by dkr

The old injectors may not have been serviced, but how could you possibly know anything unless you STARTED with pressure testing them?

There is a range for pressure on the injectors and after that they need to be balanced within 50 psi of each other. If they are within spec, but not balanced you could have some funny stuff with your engine like you are mentioning. Also, you have no way of knowing the injectors are actually producing the mist they need and not just drizzling out diesel fluid.

At this point, you NEED the proper equipment or to get the injectors to someone who has the proper equipment to test and balance them.

Most of the original mushroom pumps leak. It's a cheap part and about 15 minutes of labor, so I would replace it.

Dkr.

thanks. i would love to test them, but where can i ship them off to? noone will touch them in the area.

Here are how bad the old ones were