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

[barry123400]

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?

[coldwar]

Originally Posted by barry123400

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

[tomnik]

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)

[barry123400]

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.

[barry123400]

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.

[Wes Bender]

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

[punky]

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.