Another hot shakes query... - PeachParts Mercedes-Benz Forum

Shern · #1 01-10-2019, 11:06 PM

240D

Smooth idle at startup, engine wobble/oscillation after engine reaches operating temp (The side to side type of wobble).

Valves are in spec, engine mounts are new, fuel pump is rebuilt, overflow valve spring by greazzer, rebuilt injectors ditto, diesel purge for the hell of it (came out pretty clean), no fuel leaks, air incursion or visible air bubbles in temporary clear return line.

Here's where I'm at...

I've read through the archives and found evidence to support either
a worn IP delivery valves, or worn engine shocks hypothesis. The delivery valve hypothesis, I admit, I'm not totally clear on. The engine shocks, however, seem to lose their ability to stabilize after they've been heated by a hot engine (see this post: http://www.peachparts.com/shopforum/diesel-discussion/43751-300td-hot-idle-shaking-apparently-solved-3.html). Thing is, I can't find many who've either replaced them and noticed much difference, or ever touched them at all (and one or two who have and are adamant this is the issue).

Both are about a 50$ expenditure but I'd prefer not to throw parts at the problem if it's something I haven't considered. I'd also prefer not to tear into my IP if it can be at all avoided.

Any ideas from those of you who've been there?

rocky raccoon · #2 01-11-2019, 07:13 AM

I have replaced the engine shock on my OM617 The shock was inexpensive and only about 30 minutes to change. The removed shock showed no damping action left in it.

I am told that the engine shock only comes in to play on shutdown and has little or no function during steady state running or idling. The reason I changed mine was because of the violent shutdown shake which it cured.

mabbonizio · #3 01-11-2019, 09:32 AM

^^ this, some engines do not even have engine shocks, I don't believe my W115 240D has them and it runs smoother than my 82 240D at operating temp.

I'm curious if this car is automatic and the shake is predominantly felt in D at hot idle?

Diesel911 · #4 01-11-2019, 11:45 AM

I believe after all you have done a compression check would be next and if you find Cylinder lower the spec a leak back test to see if you can hear if compressed air is leaking past the valves or Piston/cylinder.

What type of check have you done to see your timing chain stretch. It effects your valve and fuel injection pump timing.

People have disagreed with my comment on this. Deliver Valves have 2 functions. There is a color on them to try to minimize the wave that happens inside of the Fuel Injection Hard Lines when the delivery valve shuts off the fuel and when the delivery valves close they trap fuel inside of the fuel injection hard lines.

If fuel from the fuel (hot fuel is thinner) injection hard lines leaks back past the delivery valve it causes a slightly less fuel delivery. That shows up more when say one valve is worn worse then the rese.

When I worked in a fuel injection shop I would inspect the delivery valves (both parts are mated together, don't mix them with the other valves). If you see an obvious sort of cut in the sealing surface replace it.
If it just looks a little worn (I cannot describe that) they can be lapped together but you need to keep the lapping compound away from the retraction collar I spoke of.

We did not replace delivery valve springs unless broken or the Pump rebuild kit came with new springs. Nor did I have any way to test the springs.

Shern · #5 01-11-2019, 04:34 PM

Quote:

Originally Posted by mabbonizio

^^ this, some engines do not even have engine shocks, I don't believe my W115 240D has them and it runs smoother than my 82 240D at operating temp.

I'm curious if this car is automatic and the shake is predominantly felt in D at hot idle?

Manual transmission.

Quote:

Originally Posted by Diesel911

I believe after all you have done a compression check would be next and if you find Cylinder lower the spec a leak back test to see if you can hear if compressed air is leaking past the valves or Piston/cylinder.

What type of check have you done to see your timing chain stretch. It effects your valve and fuel injection pump timing.

People have disagreed with my comment on this. Deliver Valves have 2 functions. There is a color on them to try to minimize the wave that happens inside of the Fuel Injection Hard Lines when the delivery valve shuts off the fuel and when the delivery valves close they trap fuel inside of the fuel injection hard lines.

If fuel from the fuel (hot fuel is thinner) injection hard lines leaks back past the delivery valve it causes a slightly less fuel delivery. That shows up more when say one valve is worn worse then the rese.

When I worked in a fuel injection shop I would inspect the delivery valves (both parts are mated together, don't mix them with the other valves). If you see an obvious sort of cut in the sealing surface replace it.
If it just looks a little worn (I cannot describe that) they can be lapped together but you need to keep the lapping compound away from the retraction collar I spoke of.

We did not replace delivery valve springs unless broken or the Pump rebuild kit came with new springs. Nor did I have any way to test the springs.

Pump timing is something I’ve still yet to do... the last time I checked chain stretch, I believe it was around 3 degrees.

rocky raccoon · #6 01-11-2019, 09:26 PM

Unless the pump has been removed now or in the past, you are best off leaving it alone. There is no reason for pump timing to ever go awry.

Shern · #7 01-11-2019, 11:01 PM

Quote:

Originally Posted by rocky raccoon

Unless the pump has been removed now or in the past, you are best off leaving it alone. There is no reason for pump timing to ever go awry.

Is this true?

My understanding was that pump timing was a pretty run of the mill service to perform –especially when compensating for chain stretch?

tangofox007 · #8 01-20-2019, 05:41 PM

Quote:

Originally Posted by Shern

My understanding was that pump timing was a pretty run of the mill service to perform –especially when compensating for chain stretch?

I agree. My '82 300D injection was quite retarded when I first checked it. Following adjustment, the engine ran better and, most notably, started much faster.

The notion that injection timing cannot change over time is not well grounded.

rocky raccoon · #9 01-12-2019, 06:29 AM

If chain stretch is significant enough to affect running, it is time to renew the chain.

JHZR2 · #10 01-20-2019, 04:35 PM

Quote:

Originally Posted by Shern

240D

Smooth idle at startup, engine wobble/oscillation after engine reaches operating temp (The side to side type of wobble).

Valves are in spec, engine mounts are new, fuel pump is rebuilt, overflow valve spring by greazzer, rebuilt injectors ditto, diesel purge for the hell of it (came out pretty clean), no fuel leaks, air incursion or visible air bubbles in temporary clear return line.

Here's where I'm at...

I've read through the archives and found evidence to support either
a worn IP delivery valves, or worn engine shocks hypothesis. The delivery valve hypothesis, I admit, I'm not totally clear on. The engine shocks, however, seem to lose their ability to stabilize after they've been heated by a hot engine (see this post: http://www.peachparts.com/shopforum/diesel-discussion/43751-300td-hot-idle-shaking-apparently-solved-3.html). Thing is, I can't find many who've either replaced them and noticed much difference, or ever touched them at all (and one or two who have and are adamant this is the issue).

Both are about a 50$ expenditure but I'd prefer not to throw parts at the problem if it's something I haven't considered. I'd also prefer not to tear into my IP if it can be at all avoided.

Any ideas from those of you who've been there?

My 240D always has a consistent vibration thats essentially like a tractor. If I put the idle RPMs up more than Id like, its smooth as glass under any condition, hot or cold.

My 300CD is smooth as glass when I start it, and when running any condition. But Ill get a slow oscillation when idling hot, and only when quite hot (think hot day, after a decent load, etc).

I did change the shocks, shock mounts and engine mounts on the 300CD to no success.

Shern · #11 01-20-2019, 07:23 PM

Quote:

Originally Posted by JHZR2

My 240D always has a consistent vibration thats essentially like a tractor. If I put the idle RPMs up more than Id like, its smooth as glass under any condition, hot or cold.

My 300CD is smooth as glass when I start it, and when running any condition. But Ill get a slow oscillation when idling hot, and only when quite hot (think hot day, after a decent load, etc).

I did change the shocks, shock mounts and engine mounts on the 300CD to no success.

You noticed no difference at all after changing the shocks?

I noticed the oscillation (rough running) after changing my motor mounts. The engine was really wobbling, almost like jelly. After about a week the mounts seemed to settle and the wobbling mostly disappeared.

On a recent trip up north, I was able to fuel up with B20. For the week or so my tank was full, the engine was super smooth –which kind of steers me toward the IP valves and something I read about the viscosity of hot vs cold fuel. Or was it bio being more viscous and coating worn valves better? I'm not standing by that as it wasn't my thinking, but I do find something about that notion compelling.

Shern · #12 01-28-2019, 02:18 PM

Alright, it appears I've gotten to the bottom of the shakes –at least for now.

I pulled the hardlines and removed each valve assembly for inspection and cleaning.
What I found within the assembly was interesting. Unfortunately, the environment was dark and difficult to photograph. There was a bit of fine particulate in bores 2-4, but nothing too bad(?). I was able to clean them with q-tips, followed by a thorough priming.
Bore one however contained quite a bit of reddish, I'm assuming rust. That took a bit of swabbing but was eventually returned to a clean state. Injector 1 had been nailing a bit (confirmed by loosening hardline) during cold starts.

The valve holders were all a bit rusty/reddish, though valve holder 1 had the most of this stuff on the outer surface. I have no idea from where or how it came to form.

The surface of each plunger was fairly smooth. No varnish or crud. There was a thin line however that marked the spot the plunger made contact with the valve holder. I then employed Diseasel's cerium oxide method for polishing the bevelled edge of each plunger and holder. I polished until the line stopped catching on my finger nail, though I was never able to remove it entirely.

Here's a photo of each assembly (the detail on the plungers was impossible to capture).

As you can see, number three's body is very scored, I assume, from spinning within the bore.
One and two aren't terrible and four seems okay, though my assessment is arbitrary.

I reinstalled each DV along with new valve springs and crush washers.
So far so good. The side to side oscillation is gone.
It seems the issue did in fact lie somewhere within the Injection pump, though too many variables were affected to pin anything to a single cause.

Has anyone else tried this? What did you find?

PDeputy · #13 12-02-2019, 06:21 PM

Quote:

Originally Posted by Shern

Alright, it appears I've gotten to the bottom of the shakes –at least for now.

I pulled the hardlines and removed each valve assembly for inspection and cleaning.
What I found within the assembly was interesting. Unfortunately, the environment was dark and difficult to photograph. There was a bit of fine particulate in bores 2-4, but nothing too bad(?). I was able to clean them with q-tips, followed by a thorough priming.
Bore one however contained quite a bit of reddish, I'm assuming rust. That took a bit of swabbing but was eventually returned to a clean state. Injector 1 had been nailing a bit (confirmed by loosening hardline) during cold starts.

The valve holders were all a bit rusty/reddish, though valve holder 1 had the most of this stuff on the outer surface. I have no idea from where or how it came to form.

The surface of each plunger was fairly smooth. No varnish or crud. There was a thin line however that marked the spot the plunger made contact with the valve holder. I then employed Diseasel's cerium oxide method for polishing the bevelled edge of each plunger and holder. I polished until the line stopped catching on my finger nail, though I was never able to remove it entirely.

Here's a photo of each assembly (the detail on the plungers was impossible to capture).

As you can see, number three's body is very scored, I assume, from spinning within the bore.
One and two aren't terrible and four seems okay, though my assessment is arbitrary.

I reinstalled each DV along with new valve springs and crush washers.
So far so good. The side to side oscillation is gone.
It seems the issue did in fact lie somewhere within the Injection pump, though too many variables were affected to pin anything to a single cause.

Has anyone else tried this? What did you find?

I have been posting about my surging idle that only happens when engine is hot. I have already addressed virtually every cause in the last few months. See "Surging Idle" if you want to see.

I read the posts with the one I quoted above. And the one item I haven't addressed is delivery valve replacement. I have a parts car that I can pull delivery valves from. Just messaged you to see if there is anything I should look out for when removing and replacing the valves. I have ordered new crush washers.

I am asking because I read an older forum where a man used a magnet to remove his valves and turned into an rats nest to resolve.

tages · #14 01-28-2019, 06:18 PM

engine rack damper? my car only shook at hot idle. adjusted the bolt, and it's not smooth as glass, but it aint shaking the whole car anymore.

Diseasel300 · #15 01-28-2019, 08:00 PM

I'm still running the same DV's I worked with the Cerium Oxide on. I suspect it'll last a decent while, who knows. It certainly made a marked improvement on my car.