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.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

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.

Idle appears to be about 600-650 according to the tach, when I hold the idle to 1000 then it smooths out. I have the new style Bosch primer pump, and noticed when I press it, it leaks.

Looks like I have some things to check out. Thanks for the info so far, and please keep it coming!

Dang, that pin is expensive! What does it do anyways? Looks like brass and stainless steel. I could see paying that much if it was platinum. Looks like I'll be replacing the nickel and dime stuff first.

__________________
RRGrassi


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

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

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

It sounds like the primer pump needs to be replaced anyway, so I would start with that.

Just ordered new primer pump from Phil. I wonder what causes the new style to leak. When I press the old one, I get a good tablespoon of fuel to leak.

__________________
RRGrassi


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

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

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Ok, I looked at the position of the goverot idler pin. It is nearly in the IP all the way. There is a 1-2 mm gap between the head and the adjuster.

What does that pin do, anyway? I cannot find a reference to it in my Haynes, or my MB CD manual.

Thanks!

__________________
RRGrassi


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

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

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

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.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

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