W115 OM616 240D Shaking at Idle - PeachParts Mercedes-Benz Forum

Screwdriva · #1 05-28-2020, 03:41 PM

Greetings!

Please see engine shaking at idle video here:

Over the course of the last year, I've replaced/ done the following:

1) Engine/ Transmission mounts OE Mercedes
2) New Engine Stabilizing shock OEM
3) New Monark Nozzles on balanced/ tested fuel injectors (Greazzer)
4) New fuel filters, Hand pump and rebuilt lift pump (Greazzer) and hoses.
5) Valve adjustment
6) Diesel purge
7) New OFV spring (Greazzer)

While these have all helped, you can see that she's still shaking below 1000 rpm, substantially more than my OM617 on my W123 300D as a direct reference.

What have I missed? Thanks in advance!

barry12345 · #2 05-28-2020, 04:52 PM

You checked and adjusted the valves of course? If needed. If so a compression test is next. If that is good than the injection pump may be either out of adjustment or the calibration or the delivery valves are not good in it.

You first establish that their is not an air in the fuel problem? Also that the fuel pressure to the injection pump is good? Not dismally too low.

This last one is to me important. As over time I still suspect low fuel supply pressure to the injection pump on the 615 and 616 engines. May damage the first cylinders rod bearing. Over a long period of time.

Also basic injection pump timing should be on the list as well as checking for chain stretch. You own a basic antique vehicle that may or may not have recieved decent care over all the years.

I have three that I have not a clue what was done or not done over the years. With their previous owners.It too me is suprising the conditions some had yet the owner obviously never tried to have them repaired.

Shortsguy1 · #3 05-28-2020, 05:06 PM

What RPM is your video? If you don't know, you can buy these cheap optical tachometers where you just put a piece of reflective tape (included) on the crank pulley and the point the tach at it. This is basically what I have: (don't know the vendor specifically)
https://www.amazon.com/AGPtek%C2%AE-Professional-Digital-Tachometer-Contact/dp/B004Q8L894/
My reason for asking is that I tried to lower my 220d to the recommended idle rpm from the FSM (I don't recall the number) and I also had shaking. So I ended up raising it above the recommended value and just living with it. My vehicle has seen a lot less care than your own though, so I know this might not be acceptable for you.

Shortsguy1 · #4 05-28-2020, 05:10 PM

I had another thought. Any chance you are getting a tiny bit of air in the fuel lines? Does it run the same if it has sat for a few days? Also, do you use the cigar shaped return line to the fuel tank? My w115 had the straight diameter return line, but I believe the cigar shaped line is supposed to suppress some pulsation issues.

Screwdriva · #5 05-28-2020, 05:14 PM

Quote:

Originally Posted by barry12345

You first establish that their is not an air in the fuel problem? Also that the fuel pressure to the injection pump is good? Not dismally too low.

This last one is to me important. As over time I still suspect low fuel supply pressure to the injection pump on the 615 and 616 engines. May damage the first cylinders rod bearing. Over a long period of time.

Cheers Barry - Valves are adjusted, chain is tight and the compression is solid. Does not consume/ leak oil and no smoke either. Car drives really well!

I have not checked injection pump timing yet and I have no idea how to check for incoming fuel pressure but I suspect this could also be the cause of the occasional vehicle shutting off when shifting to neutral while in motion, something that has improved since completing the above work but still happens rarely.

Any thoughts on how I would go about addressing this now that the life pump is renewed?

Quote:

Originally Posted by Shortsguy1

I had another thought. Any chance you are getting a tiny bit of air in the fuel lines? Does it run the same if it has sat for a few days? Also, do you use the cigar shaped return line to the fuel tank? My w115 had the straight diameter return line, but I believe the cigar shaped line is supposed to suppress some pulsation issues.

I have the OE Cigar hose installed specifically for this reason. I also had the idle setting at the lowest using the dash adjustment knob. I could increase it above recommended also but want to address this issue if I can.

Where do you believe air would enter in the fuel line if all the components I've shared have been changed?

NZScott · #6 05-29-2020, 03:22 AM

Your idle does seem too low. I would look at that before going to any other extremes

Screwdriva · #7 05-29-2020, 01:32 PM

Quote:

Originally Posted by NZScott

Your idle does seem too low. I would look at that before going to any other extremes

Here's the motor at the maximum possible idle setting. It's the only speed at which the shaking disappears almost entirely.

Here's the motor at approximately medium/ mid point idle setting. Shaking is as bad as on the lowest possible idle setting if not worse.

Still think it's the idle speed setting?

Shortsguy1 · #8 05-29-2020, 06:28 PM

Where you are on the idle adjustment doesn't really tell you your RPM since it is totally variable based on where you tightened that lock on the cable. Rather than guess, I would suggest you figure out exactly what the RPM is (with a tach). Then you can decide if you really have a problem. Just thinking out loud. Good luck.

Shortsguy1 · #9 05-29-2020, 06:30 PM

Regarding your question about air leaks, I would just suggest you check every hose clamp to make sure you didn't miss one. Did you change the flexible fuel line at the tank (an odd little tapered section)? Did you clean the tank strainer? I wasn't sure if that was included in your "fuel filters."

rocky raccoon · #10 05-29-2020, 06:38 PM

Probably less here than meets the eye. Shorts is right. Rough idle and smooth running is almost always an air incursion problem.

Diesel911 · #11 05-29-2020, 06:42 PM

I had an odd air like when I first got the Car but had a lot of shaking to begin with and as I fixed all of the other issues I was still left with a small amount of shaking.

In my case it only happened when hot. This is what I think was happening. I had all of my hose clamps on the fuel inlet hoses in the engine compartment tight but as it turned out the hoses were inelastic and the seal was not good. When the engine got hot it allowed the plastic on the see through filter to distort and leak in a bit of air. The fix was new in my case 5/16 ID Hoses and I also used they typical worm gear clamps you get at the regular auto parts store.

Do you know if you have an M type or MW Type Fuel Injection Pump?

Diesel911 · #12 05-29-2020, 06:43 PM

I had an odd air like when I first got the Car but had a lot of shaking to begin with and as I fixed all of the other issues I was still left with a small amount of shaking.

In my case it only happened when hot. This is what I think was happening. I had all of my hose clamps on the fuel inlet hoses in the engine compartment tight but as it turned out the hoses were inelastic and the seal was not good. When the engine got hot it allowed the plastic on the see through filter to distort and leak in a bit of air. The fix was new in my case 5/16 ID Hoses and I also used they typical worm gear clamps you get at the regular auto parts store.

Do you know if you have an M type or MW Type Fuel Injection Pump?

Changing the Fuel Pressure Relief/Overflow Valve does not fix an issue inside of the Fuel Supply/Lift Pump. There is kits for both the M and MW type Fuel Supply Pumps (be sure to get one that has the 5mm O-ring in it not least expensive kit that only has the valves).

Screwdriva · #13 05-29-2020, 06:56 PM

Quote:

Originally Posted by Shortsguy1

Regarding your question about air leaks, I would just suggest you check every hose clamp to make sure you didn't miss one. Did you change the flexible fuel line at the tank (an odd little tapered section)? Did you clean the tank strainer? I wasn't sure if that was included in your "fuel filters."

Yes, all of the above done. Clamps are solid stainless worm type too, nice and tight.

Quote:

Originally Posted by Diesel911

Do you know if you have an M type or MW Type Fuel Injection Pump?

Changing the Fuel Pressure Relief/Overflow Valve does not fix an issue inside of the Fuel Supply/Lift Pump. There is kits for both the M and MW type Fuel Supply Pumps (be sure to get one that has the 5mm O-ring in it not least expensive kit that only has the valves).

Lift pump is the M style 2 bolt pump and yes, it was rebuilt by Greazzer - all o-rings were replaced including the small plunger o-ring.

vwnate1 · #14 06-01-2020, 12:38 AM

Interesting .

The first video clearly shows way too low idle speed .

My '82 240D still shakes a bit at idle and it has perfect compression and gobs of power....

I hope you find the problem and share it as I too would love a silky smooth idling OM616 .

JHZR2 · #15 06-01-2020, 01:07 AM

My 81 240d is like this. It’s on my to do list to put an optical tack on and check that. Essentially, apply the slightest throttle and it’s as smooth as can be, but hav exit in drive with the ac on, with idle set low, and it rattles like mad.

My 617 engines sometimes exhibit a slight hot idle shake, only when truly hot (like after a long highway run), and that’s different from the 240D vibration.