Still chasing vibrations... feeling hopeless (1997 R129)

[Funny Bunny]

My 1997 M119 in my R129 shakes like this in idle

I spoke to the owner of this car in the video and he said he also changed all his mounts and parts of his ignition system and it had no effect. He drove it for 23k miles with this shake and had no problems. It still shakes.

I have all new mercedes OEM engine and transmission mounts, new spark plugs, and only 70k miles on the clock. No CEL.
Perfectly smooth idle at 600rpm and no issues with performance at any RPM. Vibration does not change in P, N, D, or R. It does not increase with RPMs. Appears to be unaffected by revs while in park.

It manifests in the cabin as a rumble in the seat and door that follows the motion of the engine.

Other people's opinions who have seen the car say to just ignore it and drive it, but clearly something's not right.

Since I have a lot of time to kill chasing this as my current biggest hobby, can someone provide me a checklist of every single thing I should go through and replace in order of what's most likely to fix the problem?

I was going to do a smoke test for vacuum leaks, but I'm not sure if that will help because wouldn't a vacuum leak affect the performance and cause a rough idle RPM gauge? I do not have those symptoms, just wobbling.

Thank you

 

[Draginev]

I would definitely looking at the engine mounts. Was the engine mount OEM?

 

[Funny Bunny]

I would definitely looking at the engine mounts. Was the engine mount OEM?

Yes I bought the mercedes OEM mounts that start with 140 part number from pelican parts. They have been in for less than 100 miles. I also changed the transmission mount with lemforder.

What I noticed after changing the mounts is: vibration is gone, but now the rumble is more pronounced. I had felt it before too before changing my mounts and I thought it was because of my old collapsed mounts.

I can tell the new mounts are working because sometimes the engine stops shaking for a second and you can feel absolute stillness in the cabin for a brief moment where as before there was always vibration in the car at all times including the steering wheel.

 

[Draginev]

Yes I bought the mercedes OEM mounts that start with 140 part number from pelican parts. They have been in for less than 100 miles. I also changed the transmission mount with lemforder.

What I noticed after changing the mounts is: vibration is gone, but now the rumble is more pronounced. I had felt it before too before changing my mounts and I thought it was because of my old collapsed mounts.

I can tell the new mounts are working because sometimes the engine stops shaking for a second and you can feel absolute stillness in the cabin for a brief moment where as before there was always vibration in the car at all times including the steering wheel.

1997 E420 engine shaking | Off-Topic Discussions

Hey GSXR: Do you know what the current Champignon spark plug part number is for the M119, equivalent to the Bosch and NGK non-resistor plugs? :?: Cheers, Gerry Hello im new to this forum, i have a 97 e420 and the engine is shaking but acceleration is good, no check engine light, i put brand...

www.500eboard.co

Could you check the cylinders of any misfires? It could be that, according to GSXR post #23

 

[Funny Bunny]

1997 E420 engine shaking | Off-Topic Discussions

Hey GSXR: Do you know what the current Champignon spark plug part number is for the M119, equivalent to the Bosch and NGK non-resistor plugs? :?: Cheers, Gerry Hello im new to this forum, i have a 97 e420 and the engine is shaking but acceleration is good, no check engine light, i put brand...

www.500eboard.co

Could you check the cylinders of any misfires? It could be that, according to GSXR post #23

If my engine has the same problem as that guy I'm going to cry. I have just over 1/3 of the mileage.
I should do a compression test then?
Anything else I can try before I do that? My M119 is so clean and runs so well. I would hate to imagine that it's toast.

 

[Draginev]

If my engine has the same problem as that guy I'm going to cry. I have just over 1/3 of the mileage.
I should do a compression test then?
Anything else I can try before I do that? My M119 is so clean and runs so well. I would hate to imagine that it's toast.

I think the more test we do, the better we can pinpoint the issue. If you have a OEM engine mounts that's not made by crap brand and new spark plugs. Then you have vacuum, compressions test etc.

What about wiring harness?

 

[nocfn]

Have you looked downstream like the flex disks, center bearing, driveshaft balancing? Vacuum modulation to tranny, loose tranny casing, bent or deformed connections. Torque converter issue might throw you some vibration at the seat. Feeling it at the seat puts the vibration somewhere in that area. Hard to diagnose at the PC...

 

[Jlaa]

This software was invaluable in my quest to chase down heeby jeeby shakes some time ago - Vibration Diagnosis for Cars and Trucks with the NVH App (NVH app). The accelerometer functions help isolate the vibes as related to engine/trans/speed etc.

 

[gsxr]

My 1997 M119 in my R129 shakes like this in idle

It manifests in the cabin as a rumble in the seat and door that follows the motion of the engine.

Does the vibration/shake only occur at idle with the car stopped, or does it also shake when driving at any speed?

I should do a compression test then?
Anything else I can try before I do that? My M119 is so clean and runs so well. I would hate to imagine that it's toast.

A comrpession test is relatively cheap and easy, I would do this next to rule out mechanical issues. The engine isn't necessarily "toast"... that term would be reserved for motors that no longer run.

Do you have access to SDS with HHT-Win?

 

[Alphasud40]

Looking at the video it looks like a primary imbalance which could be caused by unequal cylinder contribution or a mechanical imbalance in the engine. I prefer the cylinder leak down method over compression which allows you to better determine what the source of the leak down. A good engine will be under 6%. Could be valves not seating which will cause an imbalance. Now if like gsxr asked the vibration is felt at different speeds that could be something else but from what I see in the video thats all engine. Changing mounts or any other driveline repairs will not solve this. Hard to believe Mercedes would assemble an engine that had this from scratch but with other manufacturers it happens.

 

[gsxr]

Note the video is of someone else's car, but the OP says his engine looks the same.

A leakdown would be ideal, but not everyone has a leakdown tester & compressor. (Which reminds me, *I* need to get a leakdown tester!) A problem large enough to cause this much movement should appear in a compression test, but if one or more problem cylinders are identified, then a leakdown test would be needed to help figure out the root cause (rings or valves).

I agree this appears to be all engine, and it's NOT normal.

 

[Funny Bunny]

What about wiring harness?

It's a 97 so no biodegradable wiring harness. Are there any other modes of failure for the later models?

Does the vibration/shake only occur at idle with the car stopped, or does it also shake when driving at any speed?

Vibration occurs at idle in all gears P, N, D, R with no difference between them and it does not shake at speed. But if you drive really slow: 5-10km/hr or just let the car roll you can feel the same vibration that you felt at idle (not better or worse).

Do you have access to SDS with HHT-Win?

No I do not but I can always take it to a shop as well.

From what I gather right now this is most likely all engine, and since there's no change or worsening of the shake when driving and it doesn't go away in neutral or park, it's not the transmission or other driveline components like the flex discs.

Can you guys recommend a good compression tester I can buy? Any random one at car parts store will suffice?

 

[Funny Bunny]

Have you looked downstream like the flex disks, center bearing, driveshaft balancing? Vacuum modulation to tranny, loose tranny casing, bent or deformed connections. Torque converter issue might throw you some vibration at the seat. Feeling it at the seat puts the vibration somewhere in that area. Hard to diagnose at the PC...

How can I start checking for torque converter issues? I don't have much experience with transmission problems yet. The torque converter is still active in neutral/park and can cause the shaking, in the engine too?

 

[gsxr]

A torque converter issue would be extremely unlikely, IMO... and if it were causing shaking that bad at idle, I'd expect it to get worse at higher RPM.

Any generic compression tester for M14x1.25 threads will suffice. Note it's often a PITA to get the threads started if you have the common "rubber hose" type that is directly attached to the gauge, especially on the rear cylinders. Be super careful not to cross-thread anything, and only tighten just enough to seal the O-ring (a hair beyond 'snug'). A gauge with a rigid extension pipe, or even a rubber hose extension, may be easier to thread into the holes. Some auto part stores may offer a free "rental", worth checking into if you don't want to buy the gauge.

If you do this yourself, test with the engine fully hot, and remove the fuel pump relay/fuse/whatever so no fuel is injected while cranking with the key. If you can rig up a starter switch that bypasses the ignition/key that's the preferred method, but I don't know how to do it on an R129. Crank until the needle stops going up, typically 6-8 compression strokes per cylinder. I like to do all cylinders at least twice, maybe a 3rd time if I see any oddities in the measurements. Spec is maximum 1.5 bar / 22psi between highest and lowest cylinder. To see that much shaking, I'd expect one or more cylinders to be well out of this limit.

 

[Funny Bunny]

A torque converter issue would be extremely unlikely, IMO... and if it were causing shaking that bad at idle, I'd expect it to get worse at higher RPM.

Any generic compression tester for M14x1.25 threads will suffice. Note it's often a PITA to get the threads started if you have the common "rubber hose" type that is directly attached to the gauge, especially on the rear cylinders. Be super careful not to cross-thread anything, and only tighten just enough to seal the O-ring (a hair beyond 'snug'). A gauge with a rigid extension pipe, or even a rubber hose extension, may be easier to thread into the holes. Some auto part stores may offer a free "rental", worth checking into if you don't want to buy the gauge.

If you do this yourself, test with the engine fully hot, and remove the fuel pump relay/fuse/whatever so no fuel is injected while cranking with the key. If you can rig up a starter switch that bypasses the ignition/key that's the preferred method, but I don't know how to do it on an R129. Crank until the needle stops going up, typically 6-8 compression strokes per cylinder. I like to do all cylinders at least twice, maybe a 3rd time if I see any oddities in the measurements. Spec is maximum 1.5 bar / 22psi between highest and lowest cylinder. To see that much shaking, I'd expect one or more cylinders to be well out of this limit.

Thank you gsxr you're a saint
I will report back tonight or tomorrow on the compression test results

 

[Funny Bunny]

Here are the compression test results with throttle open each time and engine hot after 30 minute drive

What’s the verdict here? All cylinders are within the 22 psi range at around 200-210 psi for all of them except one is 195. But isn't 200+ psi extremely high? Is this abnormal for M119?

Next up is vacuum testing with a smoke machine? I'm scratching my head here.

 

[Funny Bunny]

Here are my 100 mile spark plugs changed last week

 

[Alphasud40]

I was mulling over your problem today and one thing I thought of if the compression results didn’t reveal anything would be injector imbalance. LH doesn’t know cylinder to cylinder mixture but more globally bank to bank. So if you have some injectors spraying poorly that could be enough to cause roughness in the idle. These injectors are very reliable unlike the old CIS injectors but it is possible. Reach out in your area to see if there is a company who cleans and checks injectors for balance. Not saying this will fix your issue just offering suggestions.

 

[Funny Bunny]

I was mulling over your problem today and one thing I thought of if the compression results didn’t reveal anything would be injector imbalance. LH doesn’t know cylinder to cylinder mixture but more globally bank to bank. So if you have some injectors spraying poorly that could be enough to cause roughness in the idle. These injectors are very reliable unlike the old CIS injectors but it is possible. Reach out in your area to see if there is a company who cleans and checks injectors for balance. Not saying this will fix your issue just offering suggestions.

I will do that next, after I vacuum leak test it. Redline SI-1 isn't good enough? I ran it a month ago.
There is a local company that does that. I have to take the injectors off the car and take it to them. But....
How likely are dirty injectors considering the low mileage and the fact that I and the previous owner always used 93 octane top tier fuel?
The car has 2 fuel filters I believe.

 

[Funny Bunny]

Here are my 100 mile spark plugs changed last week

The threads look really oily and cruddy just like the last ones. Is my valve cover seated incorrectly? and could that contribute to any of the shaking?

 

[Alphasud40]

Like I said. We are kind of grasping at ideas. Those injectors have a good track record but we are dealing with a car that is 25 years old. As a technician I have seen my share of pattern failures with specific brands and models over the years. What I came to realize is after the vehicle ages past 10 years sometimes new patterns develop but most of the time what I saw was new sporadic failures of components that had no history of failures. Like for instance one of my fuel pumps started leaking between the aluminum shell and the pump body. I have been under hood of cars since the late 80’s and I have never seen a Bosch fuel pump fail in this manner. If it’s not a vacuum leak and it’s not injectors then it’s something internal.

 

[Jlaa]

Do you have access to SDS with HHT-Win?

No I do not but I can always take it to a shop as well.

I think the idea with the SDS w HHT-Win is that it allows you to look at real time data for the ignition and possibly rule out any ignition issues. In this manner you could rule out coil / wires / plugs / wiring harness etc etc …. which would then allow you to focus specifically on mechanical issues.

SDS w HHT-Win is not that expensive if you buy a clone - there’s a big long thread here about buying an SDS C4 …

 

[TerryA]

@Benzy Boy,
The compression looks great to me. If the smoke test doesn’t reveal anything. With new motor and transmission mounts theres not much left to check.

I would again take a real serious look at the ignition system. Check everything in the distributors-caps, rotors, insulators and cam oil seals. It may also be a bad plug wire or spark plug connector or even one of the new plugs. In the past 18 years and 50K miles I’ve done a lot of work on my 500E but every once in a while I would recognize my limits and ask for help. You may have to pay a tech to analyze your motor with the proper equipment before you tear your hair out.

Just Saying

lol

 

[gsxr]

Here are the compression test results with throttle open each time and engine hot after 30 minute drive. What’s the verdict here? All cylinders are within the 22 psi range at around 200-210 psi for all of them except one is 195.

I'm seeing 13.5 bar as the lowest and 14.5 bar as the highest. That's normal and within spec.

But isn't 200+ psi extremely high? Is this abnormal for M119?

Remember your 119.982 engine has 11:1 compression ratio. Assuming you are near sea level, those pressures are normal.

Here are my 100 mile spark plugs changed last week. The threads look really oily and cruddy just like the last ones. Is my valve cover seated incorrectly? and could that contribute to any of the shaking?

The oily threads are normal. If you had a valve cover leak, there would be a pool of oil at the base of the porcelain insulator and the hex flats. This is not related to the shaking.

Like I said. We are kind of grasping at ideas. Those injectors have a good track record but we are dealing with a car that is 25 years old.

+1... totally grasping at straws here. Top Tier fuel and SI-1 normally should keep the injectors in top shape, but when you're dealing with weirdness... the bad news is there may be no change after a professional cleaning, other than your wallet being lighter.

As a technician I have seen my share of pattern failures ... for instance one of my fuel pumps started leaking between the aluminum shell and the pump body. I have been under hood of cars since the late 80’s and I have never seen a Bosch fuel pump fail in this manner.

I've never heard of this fuel pump leakage ever, then it happened to me TWICE on two different cars in less than 1 year. The only correlation was that both cars had original (early 1990's) pumps and both were switched to using non-ethanol fuel about 1 year prior. (Note - this was on the dual Bosch pumps used through late 1995 USA model year, not the single Pierburg pump phased in afterwards.)

I think the idea with the SDS w HHT-Win is that it allows you to look at real time data for the ignition and possibly rule out any ignition issues. In this manner you could rule out coil / wires / plugs / wiring harness etc etc …. which would then allow you to focus specifically on mechanical issues.

SDS w HHT-Win is not that expensive if you buy a clone - there’s a big long thread here about buying an SDS C4 …

Yep... the HHT-Win may show something that is otherwise being missed. But like the injectors, there's no guarantee. On the bright side the $600-$750 outlay will be useful for any future Mercedes diagnostics. Do your homework before buying, the kit MUST support HHT-Win and also MUST have a fully-populated 38-pin cable (some vendors ship cheap cables that are missing half the wires).

 

[Funny Bunny]

Update: Today when I opened my hood and looked at my engine, it wasn't shaking anymore. How is that possible? I'm not complaining but curious. But the vibration in the seat and floor and door is still there. Maybe 25-50% less. The only difference is that when I put my spark plugs back I torqued them to 28nm instead of 27.5nm, and I tightened the MAF clamp by 1 rotation, so basically no difference.

I will still do a vacuum leak smoke test and report back.

I am going to the entire top end "RESTO PROJECT: M119 / W124 / E500 Engine Top-End Refresh" by gerry too. Including changing the airbox seal. Fingers crossed this fixes the vibration inside.

Sometimes when I press on the gas pedal I hear a very slight whining air noise, kind of like how turbocharged cars sound but a lot more subtle. Is that just my intake doing its job or is there a seal failing somewhere?

Thanks again everyone for the help

 

[TerryA]

@Benzy Boy,
I went back through this thread to see if anyone mentioned that you should gap the spark plugs at 1mm because it helps smooth out the idle. I didn’t find it and may have missed it.

But the question is. Did you gap the plugs to 1mm?

 

[Funny Bunny]

@Benzy Boy,
I went back through this thread to see if anyone mentioned that you should gap the spark plugs at 1mm because it helps smooth out the idle. I didn’t find it and may have missed it.

But the question is. Did you gap the plugs to 1mm?

Nope they are 0.8 from the dealer. But isn't the 1mm gap only a fix for hot idle problems? My car shakes cold too.

 

[TerryA]

Nope they are 0.8 from the dealer. But isn't the 1mm gap only a fix for hot idle problems? My car shakes cold too.

I think it helps to smooth out the idle but Dave is the go to guy on this issue.

@gsxr,
I haven’t changed my plugs in years. I don’t remember what I gapped them at. In fact I have a new set to install when I get around to it. At this time my car is running great w/no detectable missing. When i install the next set I will be gapping to 1mm on general principles.

Dave I’m hoping that can you explain the 1mm plug gapping a little more in depth?

 

[gsxr]

@gsxr,
I haven’t changed my plugs in years. I don’t remember what I gapped them at. In fact I have a new set to install when I get around to it. At this time my car is running great w/no detectable missing. When i install the next set I will be gapping to 1mm on general principles.

Dave I’m hoping that can you explain the 1mm plug gapping a little more in depth?

Klink explained this in depth in a post years ago, but the short version is, when the engine is hot sometimes the narrow 0.8mm gap isn't wide enough to produce a spark large enough to fully ignite a slightly lean mixture. The larger 1.0mm gap can, sometimes, help with this scenario. IIRC there were stories about some cars coming into the dealer for service in the 80's/90's and customers complaining the engine ran "worse" with the new spark plugs (gapped at 0.8mm) due to this, so Klink and other savvy techs figured out the root cause and started gapping the plugs to 1.0mm instead.

I don't expect 1.0mm gapping would cure the engine "rocking" syndrome shown here.

 

[Draginev]

Do you also have this Issue?

 

[Funny Bunny]

Do you also have this Issue?

Nope

 

[gsxr]

The old caps in that video look fine... and, new caps aren't the long-term solution. Tsk...

New cap on left, old/nasty (lol) cap on the right:

 

[tham]

Any updates? I'm having this exact same issue - replaced my engine mounts today which were shot, and am still having this vibration. I was leaning towards something fuel related, but wondering if you've had any luck before I start throwing money at it

 

[Funny Bunny]

Any updates? I'm having this exact same issue - replaced my engine mounts today which were shot, and am still having this vibration. I was leaning towards something fuel related, but wondering if you've had any luck before I start throwing money at it

Is your vibration like in the video? If so, I believe it's unsettled engine mounts. Try driving it for a week or two and mine went away. My engine does not shake anymore.
However I still get vibration I can feel in my seat. It's a long shot but I believe that is my non-stock exhaust system that's too rigidly installed. I am going to try putting in flex pipes next spring or softer rubber mounts to see if stops the vibration that is more like a deep shudder than vibration. @gsxr I was going to ask you what your opinion was about it being the exhaust system. I think one of my exhaust rubber hangers is not as soft as the stock material.

 

[tham]

Is your vibration like in the video? If so, I believe it's unsettled engine mounts. Try driving it for a week or two and mine went away. My engine does not shake anymore.
However I still get vibration I can feel in my seat. It's a long shot but I believe that is my non-stock exhaust system that's too rigidly installed. I am going to try putting in flex pipes next spring or softer rubber mounts to see if stops the vibration that is more like a deep shudder than vibration. @gsxr I was going to ask you what your opinion was about it being the exhaust system. I think one of my exhaust rubber hangers is not as soft as the stock material.

Yeah it's just like the video. Interesting I didn't realize they need time to settle, I'll give it a few weeks and see how it is. Thanks!

 

[TerryA]

@Benzy Boy,
A vibration felt in the seat while the car is moving is usually the rear tire balance or possibly an out of round tire.

 

[Funny Bunny]

@Benzy Boy,
A vibration felt in the seat while the car is moving is usually the rear tire balance or possibly an out of round tire.

At idle!

 

[TerryA]

Did you change the trans mount? It’s a lot closer to the seats.

 

[Funny Bunny]

Did you change the trans mount? It’s a lot closer to the seats.

Yup but it's lemforder.

 

[nocfn]

I did not read the whole thread, what condition are the flex disks and center bearing of the drive shaft?