got the 240/300D on the road Im inpressed by the power of the engine once the turbo gets spun up but it has a few problems. Here is what I have done so far, the engine had a rough idle so I did a valve adjustment, replaced the rack dampener with the updated unit, adjusted the alda, and did a diesel purge, its fairly smooth now when its out of gear, put it in gear it shackes the car a fair amount and when you drive it when you step on it it vibrates quite a bit till you get the engine spun up a ways on the highway its smooth as glass. It feels like a gas engine with a spark plug wire off but if I crack the injector lines it makes the engine miss when you open any of them so Im kinda at a loss this is the first Mercedes Ive had so Im not sure if it is normal or if there is something wrong just doesnt feel right to me any ideas would be great

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82 240D (82 300D drive train)

Did you do the swap? Did you put in the driveshaft with the big damper on the front? What flywheel do you have and was it balanced?

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

DeWhite,

When U loosen an injector line, fuel is not injected into the cylinder so it mis-fires. This is equilavalent to removing or shorting a sparkplug wire in a gasoline engine.

If there isn't a mis-fire when U loosen an injector line, then that cylinder wasn't firing.

P E H

Its an automatic, In not sure about the flywheel, and the driveshaft front half came out of a 300DT and the back half came out of a 300D, I did thet swap myself the engine mounts look pretty good but I didnt put engine shocks on it dont konw if that will make a difference, I have a habit of typing things that make sence in my head till I put them down so, the engine is not missing at idel, all cylinders are hitting, but when I going down the road i have no way of opening the injector lines to see if any of them arnt hitting so Im not sure if its a miss under load or just a drive line vibration
thank you for the responce

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82 240D (82 300D drive train)

Since you used pieces of one driveshaft (turbo) and pieces of another (non turbo), it sounds like you need to remove the whole DS assembly and have it balanced.

The dive shaft end to end was designed as if it was a single piece. That is why you have to mark relative positions when servicing the center support bearings or the flex disks.

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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 can agree that it could be a balance problem with the drive shaft but wouldnt it be a constant vibration, its smooth as silk at high way speed ? I didnt realy want to use 2 different shafts but the wonderfull junk yard I got my engien from decided it was easier to cut the shaft in half rather then take out the bolts to remove the engine and trans

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82 240D (82 300D drive train)

I'll agree with rrgrassi, about the balancing thing, also check center bearing for problems.

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83 SD

84 CD

The drive shaft isnt causing a vibration at idle. Pull the injecters and have them checked. If your ambitious pull the inj pump and have it checked also. I had this problem and it was the pump, not enough pressure to pop things off evenly until a little higher rpm.

This can be verified one way or another by reading the millivolts from each glow plug. You have to have a standard refference plug or move one plug from cylinder to cylinder as your constant calibration refference.
If the glow plugs are not very old you could do a quick scan and only investigate further if the cylinders indicated quite different voltages. The resultant voltages indicate the running temp of each cylinder. Or simply put it's general contribution to the overall engine. (power balance)
This system will also indicate a poor injector as well. Just swap injectors to determine possible pump or injector fault. Thats if the resultant initial voltages indicate a problem of course. Just a system to help localise or eliminate a problem at minumin cost. .
The gentleman I quoted that pulled his pump and took it in. He would have noticed the much lower temperatures (voltage) from the cylinders getting inadaquate fuel to burn at idle if he had done this test. Post any results if you decide to do this test. Also if you need any clarification do not hesitate to mention it.
Could of course be many other things like uneven compression. The milli volt test should also indicate any suspect cylinder or cylinders to follow up on with a compression check. It can be deadly accurate if applied properly with a little thought.
You have done the valve clearance check I see. This is always important in a case like yours before anything else. .

Barry,

How is the millivolt test done? Do U just disconnect the wire from the GP and connect a millivolt meter to the GP terminal? Or do U need an occilloscope to read dynamic voltage?

P E H

P.Haiges. All it takes is a cheap digital meter that has a millivolt range on it. Read from the glow plug harness connections on the harness plug once it is unplugged from the glow plug relay if you have one. Makes that part very simple.
If you do not have a plug in your glow plug system then you would read each plug by disconnection of the wire as you suggested. The only caution is to use the cylinder head as the ground for the meter for either approach.
Using the battery negative terminal or a chassis point for the ground will let things like the alternator mess up your voltage. The wiring resistance lets the interference develop. In fact it makes the digital meter hunt. Done properly the meter is rock stable.
Using an oscilloscope would give you no advantage. This is low tech and requires your active participation if readings are suspicious..
The primary variable in this system is to designate one plug as a calibration plug to verify the abnormal readings are being caused by something else other than the glow plugs themselves before passing that point. This is only if you have a problem and are checking with accuracy.
Now we are getting fussy though. If a cylinder has a fairly bad problem or whatever the reading will be way off as there is a major difference in voltage.(heat output from that cylinder).
Some glow plugs will generate different voltages while exposed to the same heat constant unfortunatly. So it makes for a little more work to use one plug as the calibrated refference.
All this is really doing is giving us an additional tool as used on larger diesel engines. The ability to indicate the running temperature in each cylinder compared to the others. Pyrometer?
We have had a few gentleman deal with serious knocking problems succesfully with this approach. Perhaps some of them could repost if they read this. Their injection pumps got tweeked. After the injectors were swapped I hope. Problems were gone in the majority of cases.
Even just used as a quick injector test I believe it has validity. Since it is a dynamic test as you mentioned it should be superior to any static test for quite a few things.
It is best to post any indications of a problem indicated by this method on site before dealing with it. That way nothing is overlooked. On engines with fairly recent glow plugs,smooth idles, good fuel milage, and Good performance. All the glow plugs indicated the same voltage within .2 millivolts.
The average readings from older mercedes engines will vary from 7-14millivolts depending it seems on who made the glow plugs. This in itself is not important as we are using the glow plugs for comparison purposes.
Again sorry to be a little long winded. New people who do not have your experience may read this and I want them to have a grasp of the milli volt approach as well.
If more and more people post their readings or try it this will become more mainstream I believe. . People like Sam and Yellit have read their engines I believe. Quite a few others come to mind as well.

Barry,

What is ther scientific principle tha causes the GP to generate a voltage? The filament of the GP is probably made of a nichrome like metal. I never heard of that type of material generating a voltage from heat.

Should the engine be hot when the test is being conducted?

The reason I asked about using an occiloscope was I thought maybe some of the voltage might have been generated by the pressure changes in the engine like a piezo-electric effect.

Engine should be warmed up to operating temperature so the voltages remain constant. Otherwise they would contiue to gain as engine warms causing some discrepency as you moved down the glow plugs. This is a very sensitive test.
Thermocouple action is responsible for the voltage. Heated dissimular metals generate voltage. I suspect the glow plug filament is an alloy mix and is the predominate factor.
The important thing though is the glow plug does generate a changing voltage with heat. Pizzo effect is probably not there.
It is still early to be absolutly certain of much yet. I only wish there were a detectable peak at moment of ignition. As it is an indirect injection engine it might be harder to detect but one never knows until trying. Really though I suspect not. I will have a more careful look one day though.
When this all started there were so many possibilities against it working at all it was not funny. Slowly it came together. It is not new by any means. By hearsay I think it has pattents by bosh but time has passed them by with newer diesels technology I suspect.

why hasn't anybody suggested engine shocks?

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the sooner you start... the sooner you'll get done If it ain't broke, don't fix it.. Its always simpler to tell the truth...
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tobybul,

Maybe because they are not shocks. They are dampers.

P E H