Power balancing an engine and troubleshooting with the milli volt method.
 

Power balance reffers to the equal contribution of each cylinder to the overall engine power. The principal aim is to check if you have or have not got it. If not there how to get it back or the closest comprimise. This of course insures the best possible and smoothest idle possible for your situation or is a large contributor. There is a gain in available horsepower and torque possible as well. Needless to say milage is increased too. Hopefully most engines checked will already be in good condition. It only takes a milli volt reading and possible moving of your glow plugs around into different positions to check if needed or not in most cases. This is not based on rocket science. Plus some of our engines are older and have really not had good care. If they ran not quite right they were left alone. The old senario if not broke leave it alone. In a bad power balance situation it is somewhat broke but still running. Power balance is more like a tune up.The beauty that it is a cheap proceedure to identify things that are sub standard accuratly does apply. Plus it proves the fault before you spend money on it if you wish. Can you fellows stand another dose of this stuff right now or should we wait awhile?

At least it doesn't involve special tools, jigs and pipe bending like the IP timing. I'd like to give it a go. Do you anticipate being able to check power balance across the RPM range?

Dave

There is even more:
In my case: Everything new: GPs, injectors also balanced, valves adjusted and brand new IP, timing adjusted by flow pressure method.
The compression check showed a 2 bar lower #3.
Everything well in tolerances, the engine runs pretty well.

Last week I touched the elements (individual fuel quantity for each cylinder).
Why?
The IP (brand new) is adjusted to deliver equal quantities to the cylinders, so far so good.
BUT, this pump does not fit to my engine!
(My single cylinders can not produce the identical output with identical quantity of fuel, because as you know my #3 is different in compression).
First I took the mV reading of each GP and I found GP #3 giving only 9.xx instead of 12 – 14 of the others.
I loosened the holding flanges and turned the elements according the mV reading of the corresponding cylinder. All other mV readings changed too by touching #3. But at the end of the day I had all 5 around 11.x mV with a max. difference of 0.3 mV.
Not yet road tested but the idle is smoother and response better as a first impression.
Further I noticed that “idle smoke” (not much but common with vegoil) disappeared completely.
The fact that my balanced mV value dropped compared to the max. 14 before and the range for adjustment is pretty limited took my fear of melting a piston caused by too much fuel/heat. IP internal influences among the individual quantities resulted in max. balanced values below the max. ones before adjusting. (setting of #3 holding flange is in max. position). Maybe only the full load adjustment together with max individual quantity might be able to increase heat above safety, maybe.
My personal opinion is that this fine tuning is possible if not necessary for most of the engines (except the brand new ones or those that are worn balanced), all others need (in my opinion) an adaptation of the elements to the status of the belonging cylinder.

Feel the difference.

Tom (WestCoastGermany)

I at this point see no reason you could not double check the power balance out at higher rpms. It just might mean changing a glow plug that we were using as a sensor if we got a suspicious result in voltage on one cylinder. That is only to verify there is a problem rather than just a individual glow plug indicating a strange reading because its voltage output is off value in comparison to the others at elevated temperatiures. Actually the same proccedure we would use at idle speeds. You are also quite right as there are no jigs required. At higher rpms perhaps the readings will be more accurate as well by the way since the voltage will be much greater in general. Percentage differences or spreads between individual readings will be larger. Eventually we might use a small voltage amplifier to further increase accuracy at idle readings for example. Even at this stage we will do well without amplifiers. A high roller might even buy two meters for example. Dare I say almost anything is possible with this method and a little thought? From my perspective and what has been done so far it looks very strong. Dave, back to your question. Mentally examine the diagnostic uses of reading at higher rpms. So much to learn and apply. You will become a human diagnostic machine with some practice and thiis method on these old diesels. You sub yourself for a computor basically. The meter becomes your sensor. The milli volts readings your inputs. Again we need participants to gel this. But beware as once you start using it you might be hooked for life.

Tomic, you were a pioneer. First you eliminated most if not all other variables. Then you balanced the power. You also helped greatly by correcting a supposition I held. That it was primarily the element timing that was affected by the element adjustment. I was wrong as it appears that it is the quantity of fuel instead. That important fact changed things again. If the lower milli volt reading reflected just the lower compression on your cylinder this system can be pretty sensitive and accurate in use. Your pump guy backed up your conclusions and methods as well basically. In the long haul we are going to have a lot of better running engines. What amazed me was how that lower compression cylinder appeared to be laying back so much. Indicated by the overall change in voltage after the adjustment. Plus the initial 3 milli volt difference. We are well aware that three milli volts represents quite a difference. In fuel milage alone mind the overall power and power balance of the engine. As for risk of damage from too much fuel?? I think it is not possible. You have just the same temperature indicated on all cylinders now. That low cylinder now carries its share of the load. The partial holiday for it is over.. Your explanation is great too. Should make some people think. In a way we should not have to kind of sell this system. But it is common awareness that old ideals and beliefs die hard unfortunatly. The batting average of this system is good. Almost always better than what one would expect so far. Sometimes much greater. Until Tom did this with the milli volt method I do not believe it was possible to accomplish what he did on our type of engine by any other method. Tom, just for interests sake and knowledge you might rev the engine up to about 2000 rpm and see if the voltages are staying simular to each other. Average milli volts will be higher of course we know. Good information for everybody and verifies everything is correct. If it passes this test you are absolutly correct in all your beliefs in my opinion. If in your case the only cause of the lower temperature milli volt voltage reading was a 30 pound shortfall in compression on that cylinder. I now consider some engines will not even be recognisable after going over them. Or people will complain that they lived with such a poor performance/milage/smoothness/rough idle situation so long. Tom, my hat is off to you. Still a warning for people is advisable. People should not consider going in and tweaking their pump elements until everything else has been eliminated as a cause of the mixed milli volt readings. That means absolutly nothing has been overlooked. That alone is quite a proccedure. Experience may teach us otherwise. For now this rule should be written in stone. .Too much is still unknown. But we are learning.

I have been following these "glowplugs as thermocouples" threads with a lot of interest because I have had a slight engine vibration in the 1500 to 2500 rpm range. (Definitely an engine vibration issue rather than drive train and the vibration was only noticeable under load.)

Compression checked good. Injectors were tested by a shop in Tucson (Desert Diesel) and they were excellent and needed no adjustment. Based upon these findings, I decided that the IP adjustment might be the culprit.

A month or so ago, I did a base line check of the voltages. 1, 2, 4 & 5 were very similar, although a bit lower than I would have expected @ 7.4 to 7.6 mv. #3, however, was around 9.6 mv.

Rather than mess with more than one element adjustment at a time (I'm still kind of old-school in that I'm still leery of messing with the IP too much), I adjusted #3 to bring the voltage down to about 8.5 mv or so. This seemed to smooth out the engine vibration quite a bit.

After coming up to our cabin at 8000 ft in the White Mountains for the summer, I decided to pursue the matter further. I ran several checks on the voltages and found that they all had declined very slightly, probably due to the increase in altitude.

Yesterday, I bit the bullet and did a serious adjustment of the elements. I checked and rechecked the voltages and wrote them all down. I then adjusted each of the elements to bring the voltages up. I was able to bring
1, 2, 4 & 5 up to about 8.3 - 8.4 mv. I left #3 as it was (at least for now).
The idle is a bit higher than it was. The engine is smoother and has more power. I assume the fuel mileage will be better, but the jury is still out until I run a few tankfuls through to verify it.

I can't add much more to what has already been said. One point I might add is that, after adjusting the elements, you need to loosen and then retighten the fuel lines at the element end so that they won't have any tension from possible twisting. This should only be done with the engine shut down.

My advice to others is that, unless you are really comfortable with taking this type of adjustment on, and you are sure that everythng else is in good shape, DON'T do it. I'm fairly competent in automotive maintenance, but I still waited a while, studied it carefully, and then proceeded carefully. Further, at any time I could have gone back to close to the original adjustments, based upon the voltage readings.

More as I learn more.

Thanks for the original idea Barry. We all owe you.:)

Cheers,
Wes

Can I ask exactly how you adjusted your IP elements? Do you loosen the two nuts then slide the flanges in or out. Like, flanges out lowers element and flanges in raises element. If so, these flanges would have to be wedge shaped to acheive any hight difference.

Wes bender, The effect of a two milli volt difference in readings is always high enough to justify examining the underlying cause in my opinion. I am almost to the point of thinking any reading different by more than .5 milli volt between cylinders should be examined. Any one glow plug that is a lot higher than the others is almost an emergency situation. On the otherhand a seriously low reading on only one plug is just an underactive cylinder.
A single glow plug with a high reading can and will damage the engine eventually if say 4 milli volts higher than the average. The higher it is compared to the others the better chance of damage. You are making far more heat in that cylinder plus possible shock waves. All the effects that may be produced by it are yet to be identified but these two are bad enough. In your case the additional fuel you had seems to act as a cylinder that is far too advanced. When you were putting your engine under load it further increased the compression making the situation worse I believe. Since it was getting more fuel it would have perhaps been firing the cylinder with a little more intensity too early. The initial opening of the injector was spraying more fuel than normal in the early stages of the injection in my opinion. Therefore the initiation of the burn was far more intense and earlier earlier than it should have been. Hence under load that vibration you observed is a possibility. If so it was also hard on the engine. Plus hurting it's efficiency. My early misteak that led me to believe the adjustment was sequential timing related is because adjustment of the fuel volume seemed to affect the engine simular to an element timing problem. When I learnt that it was volume I felt initially we would be on safer ground. Not necessarily so it seems. Just gives us better control perhaps. I cannot estimate your increase in fuel milage but it should be noticable. Plus in my opinion perhaps a little more power. The smoother and quieter idle is taken for granted. How about dropping a line on this thread after you have run with the correction long enough to give an opinion? Or at least your additional thoughts about it? I also hope you did swap the glow plug with another to verify you did not have an unusual reading plug somewhere before the adjustment. If you are or have been a working mechanic I know a lot of the above has already filtered through your mind. Plus other things you might want to comment on. It is to help others out down the road when you mention these things. In fact your post was helpful in itself. Every bit of information at this stage seems to have a use in gaining an understanding of many things. The other thing we are going to have to establish is the average time required as a guide for others. Although not really that important. Guys, wes bender states he has a lot of auto experience. If you notice he did the preliminary requirements and thought about it before procceeding. To try to cover up a serious injector problem for example with this approach is fundamentally wrong. For us with lower knowledge post what you are thinking of doing before doing it. We do not want to tarnish something so good so early. Plus in the response to your question something may be learnt you either were not aware of or did not comprehend. Thanks again Wes.:)

Trends
 

Gentlemen, things are obviously going to get better and better with this system. Most learning errors made will be minor in nature and far less likely to occur if questions are asked before things are done. The common knowledge will be improved by people reading the questions, answers, and common experience with the milli volt system that are posted on this thread. This milli volt thing is a very powerful tool. If I had a penny for every 100.00 it is going to save people I would be rich. At some point I visulise a rush to enter the usage of this system. Things should get pretty hot and heavy on this site at that time. If the end result of the original expectations are met I will be a happy person. They are already in sight. Not long ago the future of the milli volt system looked doubtful to put it mildly. Instead I personally am starting to think it leads a charmed existance. Applications keep growing and everything seems to pan out better than expected. Rather than project too far ahead we will just keep hopefully open minds and keep learning together. If you thought the other related thread was getting long I think this one will blow our collective minds eventually. The other thread covered one basic premise basically. I can not even count the potential amount of applications in comparison now. Of course I am going to continue to boost it as much as practical but keeping some objectivity as well. It might even turn out to be the most important individual thing to ever have been on this site other than the fellowship and good will displayed overall. I suspect it will now be a litttle slow off the mark but accelerate fast as understanding grows. It should be entertaining as well. Warp speed ahead? Now where did I leave my crystal ball?:D Come to think of it warp speed ahead might be an interesting bumper sticker for our 240ds.

Is there a voltage that is best for all cylinders? Does higher give more power? Is there a voltage limit not to go past?

Mdisav, There is no target or high voltage to seek. The use is comparison one with the other when dealing with the engine glow plugs. Higher or lower is not important only basically the voltages being the same. Higher means more heat only. Each glow plug voltage tells the temperature in that cylinder. To work properly the engine must have the same voltage on all cylinders or very close. More power is reflected in all having the same voltage. Decisions have to be made if one voltage is very low or very high in comparison with the others. Something is wrong with that cylinder. The first thing you do is change that glow plug to make sure it is just not the glow plug causing the low or high voltage. If not trade the position of two injectors and see if the voltage stays bad. If so next check the compression. In most cases one of these things will be bad. When you understand more you can go further and further. We are all learning. An important question you asked about a voltage not to go past. It is very bad if only one of the voltages is very high compared to the others. If all are very high say 20 milli volts the injection pump iis not installed on the engine properly.

punky,
I do not have a 240d IP in front of me, but the 300 turboD IP has the „holding flanges“ with the 2x 13mm nuts fixed to the IP body.
For better understanding take off one nut, you will see the range of turning the element. Turning the element within this range will change the quantity.
Underneath the flanges you can see “adjusting plates” that gives the distance between the flange and the IP body, the vertical position of the element. This changes the individual timing. NEVER CHANGE THIS.

mdisav,

as Barry said there is not voltage target to seek. The range for turning the elements is limited so you will be happy to get them close together, no matter where.

Barry, yesterday I tried to do the 2000 rpm check, but was not able to stay at the same rpm. I had nobody assisting me. (will follow).

Tom

One thing is going to lead to another. We perhaps should make a list of all the things to check in relation to a cylinder operating poorly with low voltage in comparison to others. A few that occur to me are from the most likely downward but subject to opinion and revision plus additions of course. Injector, compression, a simple check of the valves hoipefully of benifit to raise compression, or just work as intended, If not a blow down test just in case a bad valve is lingering there. In my opinion a valve job is worth the time and effort if solidly indicated. It is not going to get better itself, You might also land up localising it to a head gasket for instance, delivery valve seal, air leaks around the prechamber area, Prechamber obstructed with carbon or ball assembley missing. People will /should add more items. For a single much higher reading it will probably be the injector. Or the glow plug might be off tolerence. Gives you a bad reading.Change it and check again. Just too much fuel getting in. Or the sequential pump timing might be bad. That can be eliminated or verified by shifting the injection pump a few degrees both ways from your timing position. If the difference in voltage tracks the timing changes with each other the sequential timing is good. If the voltage does not track in comparison to the other cylinders than you have isolated the problem. The chances are more likely it is the excessive fuel amount though. If you really understand what you are doing you might fix even those items but if not you have established a fault exists and exactly where. Only you basically can decide what is or is not acceptable to you. I never thought it was going to be totally easy. The only way we really learn is by struggling with concepts. Without the struggle you either already know or are not advancing your knowledge. That is not confined to car repairs. Hopeful;ly for most people and myself most problems will not have to be dealt with at the greatest depth. There is no reason now to not get a usable sensible answer when asking about an engine miss, rough idle, poor fuel milage, poor power etc. But the input required from you might have to be a little greater. You will have to read and record your glow plug voltages and post them as well. People will quickly learn to interpret them and make suggestions for the person to consider if he has exceeded his knowledge. Or again even if not. I believe for the majority the readings obtained and suspicious ones verified by changing out the glow plug or swapping it with a neighbour will lead them along the path. Advice should always be sought before exceeding your knowledge or comfort zone. Remember we had nothing quite like this before. :)

Glow plug calibration check.
 

A quick cheap check to see if all your glow plugs are responding normally and within a usable calabration range. Start and let your engine warm up. Read the glow plug output voltages and record. Move each glow plug one hole over to the left say of course that will have you putting the front one in the last cylinder. Start and rewarm the engine. Read and record the voltage outputs again. If simular to what you read the first time then they are good to use. If you have basically just located one odd reading cylinder it is much faster to just switch the glow plug from that cylinder with the neighbour. If the readings remain identical then you know what voltage is indicated is not in error from a glow plug out of tollerence. I suspect most will be useable at this stage. Could be wrong about that too as our experience is so limited. Only sane to cover your posterior to some extent.:D

Help needed?
 

Tom, there is a very attractive lady visiting here this mornig. Perhaps she should fly over and assist you with the 2k balance test. She seems to be a hands on lady. I think you are so skilled you might even manage to work with the distraction. In any event if you do not get it right she will make you do it over again. Kind of our foreign affairs lady.:D Life can be stranger than fiction. When I was 16 and putting an axel clip back on my 1951 chev after changing the outer seal. I saw a pair of legs from under the car. Rolled out and asked if I could help. Help myself to a better view as well? Believe it or not she asked me if I would marry her. Never had laid my eyes on her before or after. . Not being gods gift to women no matter what they say. I never forgot the epiode.:D Just a little levity as this road we are on is going to be pretty dry and repedative to some extent. Hope the humour can be apprieciated. I never mean to offend anyone. Tom has been applying a lot of dry thought as well lately. There are so many details. I find when I locate a suspicion I kind of fixate on it for awhile and examine all the dimensions of it as much as my limited abilities allow. In a way that for me is the fun component. I have spent the last two days trying to get a good grasp on what I visulise as the timing change effect when fuel quantity is modified. In my mind there is an effect there to consider. In most cases it does not matter to the overall picture. Well off to repair a dwelling unit that the tennants left in a real mess. Of course got stuck for some rent as well. The upside is the tennants over the years have paid for the house many times. If it is not one thing it is another it seems. Since the repairs are not too challenging I can also consider other things related to the milli volt method at the same time.