Good morning Everyone. I noticed on my TD that it will do the diesel rock when I exit after running on the freeway for an extended period. What would be the cause of this?
Thanks in advance for the feedback.

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96 Legacy LSi wagon
92 Mitsu Expo
95 525iT
1983 300TD clackclackclack sold
1972 Toyota Corolla wagon TE28 sold
1991 Galant VR4 pshhhhh non-op
1989 Montero RS pop's ride

Damper bolt out of adjustment or badly worn. Worn motor mounts may also contribute to rocking.

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Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.

Thanks Mike. So, it is the same even if it just happens after running on the freeway and when coming to a stop?

__________________
96 Legacy LSi wagon
92 Mitsu Expo
95 525iT
1983 300TD clackclackclack sold
1972 Toyota Corolla wagon TE28 sold
1991 Galant VR4 pshhhhh non-op
1989 Montero RS pop's ride

Check your fuel filters for age, fuel lines for leaks, and the tank for vaccuum after a hard run. You could have slow fuel delivery after high speed running from dirty filters or plugged screen in the tank, or fuel lines bad, sucking in air.

Most of these also produce other symptoms, like low power at speed, or failure to accelerate properly, too. If the tank is plugged and won't vent, you can fuel starve after a hard run -- this will go away as you sit and the vaccuum bleeds down on the tank. Check it by running hard, stopping and shutting the engine off, and immediately taking the filler cap off. If it hisses and sucks in, the vent line is plugged. It's buried somewhere under the car near the tank and has a filter element in it that can get clogged.

You could also have dirty injectors, try some Redline or other injector cleaner/fuel treatment.
Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Thanks Fred. I have tried the Techron and then Redline DFC. It helped some. I will try your suggestion on a plugged vent.
The filters are what my Dad suggested we do next.
Does our injection pump ever need calibration?

__________________
96 Legacy LSi wagon
92 Mitsu Expo
95 525iT
1983 300TD clackclackclack sold
1972 Toyota Corolla wagon TE28 sold
1991 Galant VR4 pshhhhh non-op
1989 Montero RS pop's ride

Hi:
This is a first-time post. after reading on the site for months. I have had a 71 200/8 for over 7 years and an 86 300E for about 3. I purchased my first diesel (1984 300D T) this spring. It had 110K on it when I bought it and now has 115K. So far I love it. I am still trying to get a handle on how it should perform. Sometimes it runs really smooth with no rocking at idle, sometimes not. Sometimes lots of white smoke on start-up and acceleration, sometimes not. The fuel I get seems to make a difference. I use Redline every fill-up now. The pump I fill up at says the CTE (?) rating is 50.

I was interested in the effects of vacuum build-up in the fuel tank. My 300D T seems to run better as the fuel level in the tank goes down. By better it seems to smoke less and doesn't rock as much at idle. Could it be because the vent is blocked and as the fuel level goes down there is more air space in the tank so the effect is mitigated?

71 200
84 300D T
86 300E

Mike:

Adjust your valves. Also, upgrade to synthetic oil if you haven't, it helps keep rings free. Cetane rating (CTE) is like octane rating. 50 is good, but diesel fuels vary much more than gasoline. I cannot use Phillips 66 in my diesels -- huge smoke issues, and very poor power. Amoco, Shell, and Busler (the local discount dealer) work fine. Try and check, then use the one that works best. For wintertime, use truck stop diesel -- they blend for prevention of waxing, and not all other stations understand what it is -- diesel fuel "gels" or waxes up when it is cold (the specification is pour point, or the temperature at which you can no longer pour a sample out of a small brass container). You won't have too much trouble in Colorado, but here in the lower midwest, we get caught once in a while. The RedLine will help.

Also, check for leaks in the suction side of the fuel system. Bad hoses will allow air to get sucked in, and air in the injection pump will cause rough running, knocking, and smoke.

A plugged vent line could cause your idle problems. See previous post for a way to check.

Wagonboy:

MB pumps rarely need calibration unless dirty fuel got in them, or water. Or gasoline (eek!) -- it happens, I almost put diesel in the work truck today at a Shell station....! You might want to have it bench tested if you rebuild the engine. About the only think that goes wrong is a broken spring on the pressure valve, or leaks around the pressure vavle retainer. Easy to fix.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Can you install a new damper bolt without lifting the injection pump? I actually haven't taken a very close look at that area of my engine, but I know that there isn't too much clearance between the back of the IP and the oil filter housing. Thanks.

Alex

__________________
1983 300D (parked for four years)
2012 VW Sportwagen TDI Manual
2001 Miata SE
1962 Chevrolet Corvair Rampside

Peter, thanks for all those tips.

__________________
96 Legacy LSi wagon
92 Mitsu Expo
95 525iT
1983 300TD clackclackclack sold
1972 Toyota Corolla wagon TE28 sold
1991 Galant VR4 pshhhhh non-op
1989 Montero RS pop's ride

DieselHead - Yes you can replace the damper bolt without removing anything else. I was able to remove mine with no trouble at all.

Phil.

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1981 300SD 164K Miles

Can someone explain in lay-terms the function of the damper bolt? I see it on the side of the injection module and have read about adjusting it to fix rough idle but don't understand what it is doing or what I would be doing by adjusting it.

My car runs perfectly, has new engine mounts/shocks, has properly adjusted valves, and has good filters everywhere. Still, on occasion, at idle the car shakes more than it should. Usually, the idle is quite smooth but not always. Could that be a bad damper bolt?

Its not a major issue with me but I'm always looking for easy improvements.

Thanks,

Nic
'85 300CD @ 145k miles

Peter
Thanks for the advice, I will adjust the valves (I am ordering the wrenches), keep experimenting with the fuel, and check the lines to and from the fuel tank. I think I will switch to synthetic oil as well. While I am at it I think I will change my thermostat and clean out the fins on the radiator. My car runs hot. It has run close to max with the air on when the outside temp is over 90+ (I had to shut the air off) and runs over 90 regularly.

later,
MikeyOh

Mike:

Check to make sure the auxillary electric fan is working -- there is a pressure switch on the high pressure side of the AC system that should swtich on about 300 psi. Should also come one when the engine temp goes up -- find the sensor and ground the wire -- if it comes on, the sensor is bad. If the fan doesn't run, especially on AC, check the low speed resistor (large ceramic block) -- they can go bad and only let the fan run at high speed when the engine gets hot.

Also, check the visco clutch on the fan. Should lock the fan at slightly above 80C, causing it to roar -- if you shut the engine off hot (90C), the fan should stop immediately (less than one turn) -- if it spins, the visco clutch is shot, replace it.

It is normal for the needle to go the the mark about 80 when the AC is on in traffic on a hot day. Higher than that, I'd check, but just to 90 isn't a problem -- gives better cooling, believe it or not!

A bad radiator cap can cause it to get too hot, too, usually with coolant loss as well.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

I agree with Mike. A bad damper bolt can cause rocking after freeway driving. To learn more about the damper bolt, check out the following link:

300SD Idle

David

Peter
Excellent suggestions, thank you. I checked the aux fan sensor switch early on based on Chiltons, I will go over it again. I will also look for an open on the resister. I didn't realize that the clutch fan should get that "stiff", I will check it too. Also, I miss-stated my running temp, it is closer to 100C (the mark between 80 and 120). So it is running pretty warm. I did try some of that water wetter, I can't tell if it helped or not.

Thanks again,
Mikey Oh