Hey Guys,

My baby (82 300D) has developed the shakes, after reaching normal operating temp, she seems to miss at idle. You can see the front end of the car rocking as if she were a chevy 350 with a radical cam.

When she starts after sitting over night, the idle is smooth. After driving a while, when I come to a stop, she shakes like crazy at idle. No missing under acceleration, though. All research I have done leads me to believe I have an injector acting up or air being sucked in a hard line. I do not detect the smell of fuel when running, or shut off. The number 3 injector does not have the braided return lines. Looks like the PO used regular vacuum line instead.

I did notice that my left engine mount is torn and I know that will accentuate the shakes.

I just wanted to see if my diagnosis sounds right. Everything else seems to operating as it should.

Thanks!

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

99 W210 E300 Turbo Diesel, chipped, DPF/Converter Delete. Still needs EGR Delete, 232K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Gone and still missed...1982 w123 300D, 1991 w124 300D

I have the same exact problem with my '91 350SD. Starting cold it runs beautifully, then starts shaking once the engine warms up. If anybody has experience with this problem, I would definitely be interested!

mine was doing that pretty bad until I replaced the fuel lines under the car and to the fuel filters. She was sucking in air once warmed up, plus I was losing a good bit of diesel from the leak under the tank.

-OB

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"Ninja monkeys are meeting as we speak, plotting my demise."

1982 300D "Melba" 332k
1985 4Runner "billygoat" 204k

How high is your idle? Maybe it just needs to be set a bit higher, assuming all routine maitenance is up to date, like valve adjustment, filters, etc. The fuel lines should be replaced with the braided ones to get a proper seal. If you have the old primer pump it could be sucking in air too. You can watch the torn engine mount when the engine is shaking to see how much the mount is contributing to the shake. It's either the mount or poor combustion in one or more cylinders which can be caused by a million things or a combination of the two. You'll need to start eliminating variables one by one.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

Another thought I just had is the governor idler pin on the back of the IP. If it's too far out or it's worn out it will cause a massive shake on the OM617 engine.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

That will cause a hot vibration if it's worn or out of adjustment:

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1CQ0J3JZ41V50S5OOG&year=1982&make=MB&model=300-DT-001&category=D&part=Governor+Idler+Adj.+Pin

The idle shouldn't have to be very high to be smooth. Mine is very smooth at about 550 rpm.

The above suggestions sound good, but having gone through this with my previous MB E320 (RIP) and my current 300TDT, I offer these suggestions (FWIW):

1 Like others have said, try upping the idle speed and fix the leaking pump,
2 Replace both motor mounts, especially if you can see that 1 of them is torn.

As for the motor mount replacement - both my cars would idle okay when I started then up in the morning, but I would get Idle 'shakes' after driving a while in traffic. The Idle 'shakes' would lessen if I would take the car out of D and put it in N (say while sitting at a light). My observation - the rubber portion of the mounts gets 'softer' from the heat build up as the motor heats up.

In both cases I upped my idle by 50-100 rpm, and installed new motor mounts and then my Idle 'shakes' were gone. YMMV.

The idler pin cancels out the oscillations of the IP, but I wouldn't worry about it for now. I agree with Old Greek about first taking care of the leaking pump and the mounts.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

That is what I plan on doing. I have noticed that the shake settles down sometimes when the car is in D or R and the A/C is on. It does shake when coming to a stop. You can see the speedo needle bouncing with the shake.

__________________
RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

99 W210 E300 Turbo Diesel, chipped, DPF/Converter Delete. Still needs EGR Delete, 232K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Gone and still missed...1982 w123 300D, 1991 w124 300D

I thought my rough idle had something to do with the heat, but I think I may have determined that the heat may not be such an influence - I've been reading about the 'Italian Tune-Up' and have started trying it - albeit a 'Light Italian Tune-Up' because I'm not running it at high RPM's for a long period of time - just pushing it hard out of stop lights/signs, etc. It puffs out a little fog of black smoke and then it idles nice the next time I stop... and the longer I idle the worse it will get. Then I'm off again with another "Italian Tune-Up" and the problem seems to get a little better... I originally thought the idle was getting worse throughout the day because the car would warm up, but I now believe it has something to do with the amount of fuel that is going through the engine, especially at idle. That's when the issue really takes place.

Try a diesel purge and don't forget to replace the motor mount shock absorber when replacing the motor mount

rrgrassi,

How is your shaking problem coming along? When hunting down fuel leaks, don't forget that short piece of hose that goes between the primary fuel fitler and the lift pump (the thing the primer pump is bolted to). Its about an inch long and it gets pulled over so it has a bend in it from the weight of the primary fuel filter. I had this hose start to let air in at idle but leave no visible leak. Plus it didn't let enough air in to cause problems at cruising speed so it ran fine down the road.

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Seth

1984 300D 225K
1985 300D Donor body
1985 300D Turbo 165K. Totaled. Donor Engine. It runs!!!
1980 300SD 311K My New Baby.
1979 BMW 633csi 62K+++? Dead odo

Hey thanks for the VERY helpful tips guys...

So I've been thinking - I'm putting my 350SD in the shop this week for the GreaseCar installation (sorry, I wish I could do everything myself, but I'm a professional saxophone player - you can hear my music on my website at www.RustyBlevins.com - so I cannot risk wrecking my hands/fingers, so the installs and repairs, etc. have to be done by a pro!) and I'm thinking of asking my repair tech to replace the original fuel lines all the way through the car from the tank forward. Is that overkill? I'm convinced that my rough idle problem is somewhere in the fuel delivery because the car starts and runs BEAUTIFULLY in the morning and it only acts up intermittently with the rough idle. I'm also thinking of asking him to run a Diesel Purge, too - sounds like that is a great thing for a diesel with lots of miles on it.

Thanks again for all the helpful info - and please keep it coming! I love to read about your experiences!

Replacing all the rubber fuel lines is not overkill. In fact, its regular maintenance, I believe.

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Seth

1984 300D 225K
1985 300D Donor body
1985 300D Turbo 165K. Totaled. Donor Engine. It runs!!!
1980 300SD 311K My New Baby.
1979 BMW 633csi 62K+++? Dead odo