OK. Here's a follow-up report (and a question or two).

After several tankfuls of #2 diesel (including the new LSD) it appears that my mileage is marginally better, on the order of 2-3%. The power is up slightly also. (Bear in mind that this engine is in otherwise good shape, hence I wouldn't expect a drastic increase in power.)

Unfortunately, there is still a slight vibration in the 1500 - 2000 rpm range, as alluded to earlier. It isn't as bad, but it is still there.

In looking over the IP carefully, I notice that the spacers under elements 1 thru 4 are marked "13". The spacers under element 5 are marked "09". It follows that these were put in place on a bench to make the timing of each element equal. Why would one be different from the rest? I would be interested in learning what spacer markings exist on other pumps and if there are variations in spacers on individual pumps. I suspect that the numbers indicate the thickness of the spacers, but I haven't removed any to mic them.

I am also beginning to suspect that there may have been some anomoly in the #5 element position on this IP and the tech building the pump inserted a thinner spacer to compensate. To test this theory, I made several test runs at 1700 rpm under load and got a feel for the amount of vibration. I then loosened and rotated the element counter-clockwise slightly and tightened it again. (IMPORTANT NOTE: This should not have changed the timing of that element, but instead reduce the amount of fuel in order to see if that had a minimizing effect on an element that was possibly injecting too early.)

I then did a couple more test runs exactly as before and the vibration was noticeably reduced.

This vibration problem started to become noticeable after approximately 30,000 miles on the factory-rebuilt IP. At first, I was the only one who could detect it. As it progressed, my wife was able to notice it too (or was merely humoring me....).

My theory is that whatever was causing the #5 element to be late in the calibration during rebuild has now gradually cured itself with the net result that the thinner spacers now allow the element to inject too early.

Sorry for the long post. What do you others have for spacers? Do any of you have a handle on what the markings actually represent? If what I suspect turns out to be the case, I'll be looking for a couple "13" spacers. I'll bet no dealer will sell them to me either.....

Cheers,
Wes

Apparently no one wanted to check their spacer markings while this post was near the top of the diesel forum and then it faded down the list..........so, I'll proceed by myself.

I put about 600 miles on the car yesterday, mostly in 100 degree plus temps. The vibration is still there and I'm going to have to find it. It only occurs under load and is definitely engine related. Smoothes out at higher rpms, but that is typical of minor vibration issues.

It is difficult to measure the thickness of the spacers without removing them, but the "09" spacers appear to be about .010" thinner than the "13" spacers. I'm going to shim the number 5 element spacers with an additional .010" shim stock and see what results.

Onward and upward. This will probably be my last post on this issue. :rolleyes:

Cheers,
Wes

A couple of years ago when attempting a IP time I stripped the threads on top of the element. I went to the junkers and took a whole element out of an Ip on a junk car there and installed it on mine. Immediate nailing. I torqued it down as much as I could and the nailing diminished but was always there. I lived with it. After reading your recent posts I decided this weekend to remove the spacers from offending element and grind them down. They were marked 18 by the way. I just eyeballed it, no micrometer. Reinstalled and nailing is gone. Smoother idle, more power with less throttle movement.
Besides the fact that I screwed up my IP to begin with, I'll bet alot of IP's out there are out of spec. from new and could do with a tune up. Nailing problems may not always be injector fault.

I am just curious to know what type of meter you all are using that is accurate and repeatalbe enough to measure voltages in the millivolt range and differences in the microvolt range. I don't know of many meters, that one would want to use to work on a car, capable of making these measurements. Most meters, of the handheld variety, have a floor spec greater than what you all are trying to measure. Please enlighten me on this one.

When I replaced my IP, my intermittent nailing disappeared. :D

I've been using a Metex 3800 digital multimeter for a long time. They've proven to be very accurate, even when directly compared to bench (fluke, if I remember correctly) that go down to the 6th decimal place. In my experience accuracy is great and repeatability is dead on. You can get one for about 40$ plus tax/shipping from Jameco, and Digikey might carry them, I haven't really looked all over for the best price since I order from those two places a lot anyways.

Edit: Here's a link to it on Jameco's website and a picture. http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=27115

I have a couple of Fluke meters...I have access to them as I run an electronic calibration and repair lab. From time to time customers decide to throw away their broken meters and buy new ones. I repaired a couple for myself years ago. I was just kind of curious what you guys were using. For what you guys are doing, accuracy really doesn't come into play...repeatability on the other hand is what you are looking for. I have been sitting in the background reading all of this. I am almost at the point where i want to give this a shot on the wife's car. I have done about all I know to do to her car to get it running smoother. Don't get me wrong, her car, in my opinion, is about an 8 out of ten but runs a little rougher than I care for.

Name brand VoltOhmMeters [VOM] are not necessary...
 

for I have used two cheap digital meters now and both perform quite adequately for these MV tests. Remember, as Barry said, we are only looking at the voltages relative to one another... not their accuracy.

Barry - I'm happy to see you started a separate THREAD with a different slant on the MV/thermocouple concept. I just picked up new glow plugs and will intall a new set in my 240D to see if the MV imbalance is still there on #4 cylinder. If it's still there, then I'll follow your suggestion and swap out or move a couple of injectors around.

On the diesel timing light issue, I think I have discovered that our fancy SnapOn inductive timing light might just be the cause of our intermitent/inconsistent results... so I will try a very basic light soon.

Regards,
Sam

When you get your new glow plugs, measure their resistance straight from the box. If they're really close to eachother, that will give you a good idea of how close they will be when used as a thermo-couple in the car. I've had new glow plugs that varried quite a bit on resistance but worked fine on the car. I'd immagine that would throw off your heat reading, and require you to move plugs around to measure different cylinders.

I have a new set of MV readings...
 

that were taken today after I installed the new Bosch glow plugs... but first let me report that out of the box 3 of the new plugs had 0.8 ohms and the 4th had 0.7 ohms of cold resistance. Now here are the MV readings:
#1.... 11.7 mv
#2.... 13.5 mv
#3.... 10.9 mv
#4.... 11.8 mv
Well #4 does not appear to be the odd one out as before. # 2 appears to be odd cylinder out. Should I switch the GPs in... #2 and #3 to confirm what I think is the case... namely that GPs can perform differently when you get them up to a higher operating temperature. I'm not ready for MV diagnostics yet.

Let me see if I can now go back and compile my previous MV readings for you here for reference... yes here is what I POSTED
on 5/19/06:
#1= 9.9
#2=10.3
#3= 9.9
#4=8.6
And on 7/19/06
I posted MV reading for the 240D after I reset the IP's timing:
#1 - 12.7
#2 - 13.2
#3 - 13.0
#4 - 10.5
So there you have them all.
Regards,
Sam

The cold resistance reading of a glow plug itself is not signifigant I believe. As the output voltage is generated from the reaction under heat between the dissimular metals. Yet there will be still be slight to major natural output variations from plug to plug compared to each other under identical situations. Some glow plug sets have also showed no measurable voltage output variation or very little. It does appear from Sams most recent posting that we will always have to move at least one standard refference glow plug we choose around to different cylinders to use as a measuring standard. Or check the injectors out by moving them all one by one to one cylinder for output voltage comparison. Sam is also quite right about even the cheapest of meters that can read milli volts are more than adaquate. I believe this has been verified by another participant with a pretty extensive electronic background as well. In most cases it is my hope that any major initial difference will just turn out to be a difference between cylinders of voltage output of the individual glow plugs because of manufacturing tollerences or aging of the plugs. Or injectors that are out of calibration, dirty, or worn once one plug and cylinder is used as a standard refference in testing them. Pretty well foolproof then. This wil be easy to verify by swapping injectors and just reading the meter. Beats sending them out for service or replacing them on just speculation in my opinion. Up to the above stage it is pretty straightforward. Also although it is hard to be positive with Sams reading of glow plugs over a fairly extended period of time it somewhat appears that by retiming his pump he has an advanced timing compared to his old setting . That is reflected possibly by higher voltqages in general perhaps. But then again he is also on another set of glow plugs and that itself is a major unknown variable and could be the singular cause of the general voltage increase amoungst other things. Anyways always eliminate the simple stuff when using the milli volt system first. Make sure you are eliminating the effects of variables as you go along. If not sure do ask questions on this site before proceeding. That way logic should prevail and the voltages will lead you if not to a conclusion at least to what is really causing the problem . Never resist any indication to check your valve settings and compression before or after checking those injectors out. As was also previously posted on some occasions after elimination of everything else it will be indicated the injection pump is out of calabration in some fashion. At this stage it is a learning curve as to what can be accomplished at home and what cannot with the injection pump. At least if the pump does become indicated as a fault we have localised the problem by other than guess work. The pump perhaps then could be sent out for a tune up rather than a total rebuild. In the cases where the problem is confined to one element basically we might develop proceedures over time to deal with it effectively. People are trying. A lot to learn and observe. Sam, if for example you land up moving injectors around in your 240d and the voltages change in refference to each other you will have used the milli volt system to identify the basic problem I believe. On the otherhand by using one glow plug as a standard reference by moving it from cylinder to cylinder you may also determine that all is really well before resorting to that. It is all upside gentlemen with a little reasoning in my opinion or at least I hope so. This milli volt system is slowly coming into use now. Basically I believe because it not only can locate and indicate problems but is cost effective by eliminating guesswork approaches. We still continue to learn from every new post. Oh, I almost forgot Sam. Sure interchange cylinders #2&3 glow plugs for the time it takes it will tell you a lot one way or another and also let us know.

I have over a period of time tried to consider the injection pump calabration problems mentioned in posts. It is indicated to me from several posts that perhaps we will have to use a system like volkswagon used to recommend for their service shops. Perhaps they still do. It is in my bently manual. That is to measure the quantity of fuel output from each element by direct output comparison from the injectors. I believe they use four calibrated containers and just let the injectors spray into them. After a certain interval you just examine the fuel level in each container of course. It is too difficult to test sequential timing at home unless you have an excessive and not really required generally ton of specialized equipment. At a minumin you would need a pizzo sensor device and a small degree wheel temporarily fastened to the crank pully by small magnets for example plus of course a timing light. You would move the sensor from injector line to injector line recording the degrees indicated. The volume test alone should enable you to decide what is indicated for correction. But you may need both measurements to really get it right. Without a test to establish which component of the equation is at fault it is almost a roll of the dice when you adjust one or the other in my opinion. It is almost common sense that there is an overlap effect that affects element timing a little or causes a simular effect when you adjust element volume for example. But that may not be so. At present it is just my opinion that a usable comprimise is being obtained by some in spite of the unknown component factors involved. In some cases that will be more than adaquate but in others not good enough. Perhaps my perspective will change a little more over time. At present it seems that if you can run the fault down to the injection pump at home with modest equipment . It is a large improvement over what we had previously. Also with modest equipment running it down to the individual element creating the problem is also another move ahead. Once you are that far along is when the real thinking begins. A small adjustment of one element is worthwhile to attempt then as otherwise the pump should be pulled and shop serviced. I suspect to see a higher pecentage of this type of problem as these cars continue to age. Just changing your fuel filter at reasonable recommended milages alone may help a lot to deffer this potential problem area. It is a precission mechanical assembley after all and the less dirt fed through it over time the less resultant wear.

Barry - I am all but convinced that our 240D(s) are particularly prone...
 

to exhibiting symptoms that demonstrate the need to " Power Balance " the engine... this because there are only 4 cylinders and they produce so little power without a turbocharger [most of them]. If their power balance is off they are more likely to shake, rattle and roll [as it were]... telling us when something is not right... and as you say with many 240D(s) the fuel mileage is not up there where it should be... near 30mpg. I am amazed at how much smoother the 300D's engine is by comparison.
I just hope that this and your other MV related THREAD will eventually lead us to serious and effective DIYer solutions for correcting the "Power Balance" of these vintage MBZ diesel engines.

SideBar- Regarding our purchase and continuing use of the diesel accessory that allows the use of an inductive timing light... well I think the occassional inconsistent result whe have had might be due to the overly complicated "SnapOn" timing light we have used. It appears to "flip out" and give results that are 180 degrees off... so I'm probably going to invest in a very basic light [~$6] and see how it performs with the Kent-Moore piezo/pulse "Tach-N-Time" meter. In a profit driven shop business, I see the need to readily detect when these engines' IP(s) are out of time!
Sam

Correction... that was meant to be ~$60.00 !

Sam

Sorry Barry, I can't read your run-on novelettes. Try putting a few carridge returns in your post to seperate your thoughts. So I don't know what you said...

Be that as it may, I don't think anyone can read much into the difference in readings between glow plugs as they are not calibrated. Now if you moved one glow plug from one cylinder to the next, then you can compare the numbers as you moved it through the order.