I have a question for those of you out there that pop test your own injectors. I read on here or maybe on dieselstop that when you go to change the shims to change pop-off pressure, a .002" change equates to a 100psi change in pop off pressure, is this right?

Also, where do you get different shims to change the spring preload? Do they sell shim assortments for these injectors, or do you have to make shims, or what? Could you stretch the spring to make it pop higher if required?

Thanks,
Arthur

 

I found the .002 made about 100 psi differance through try it an see method. My injectors had several .002 shims in them from the factory, so when I put in new nozzels I wanted to balance things upon all eight injectors. I made shims from brass shim stock, and installed them between the heavier washers. The springs are relatively heavy, I don't think they would take to stretching very well, and would likely never work right again if you tried. .002 is almost nothing, so it is a very close tolerance spring.

 

Ok, I ran the GP balance test and a compression test and found my problem. Every cylinder was 1.0-1.1mv @ idle except for #3 which was 0.6mv. Compression was within +/-10psi from lowest to highest. #3 injector must have came loose at some point, the bottom section was partially unscrewed and had allowed carbon/heat to stick the pintle (and pretty much everything else inside the injector). I pumped it up to 3200psi and got not a drop of fuel out of it on the pop tester.

I have a question now...the injectors in the truck are code BB. I have another set of injectors out of a van that are code AA. Will these have the same size nozzle and pintle as the BBs, that I could just set one of these AAs to match the pop-off pressure of the rest of my BBs?

 

Well, here are the results after cleaning and resetting pop-off on my injectors. I ended up using 3 of the AA injectors, one to replace the one that was burnt up, and two more because the original injectors just did not atomize the fuel to my satisfaction. The remaining originals aren't exactly stellar either, I'll probably invest in a new set of injectors on down the road. They don't leak down, but they don't seem to atomize as fine as the AAs do. I'm assuming this is from age/abuse, not design. The AAs I have look to be in much better condition than the BBs out of the truck.

Reset Pop PSI New GP mv
1750 (AA) 0.7-0.8
1800 (BB) 0.8-0.9
1800 (AA) 0.9-1.0
1825 (BB) 0.7
1850 (AA) 1
1750 (BB) 0.8-0.9
1800 (BB) 0.9-1.0
1850 (BB) 0.9-1.0

I was shooting for 1800 psi because my turbo doesn't seem to build that 10psi of boost that would make cylinder pressure sufficient to require 1900psi pop-off. This is a larger spread than I had before (except for the dead injector). I struggled quite a bit to get the pressures even that close with the shim assortment I had, I know they should have been held to a tighter tolerance. The results were good, the miss at idle is gone of course, and power is improved. Surprisingly it's not making any more boost, I thought that it would since it should now be generating more exhaust gas. Next step is to get some new on-road numbers.

Oh, almost forgot. I did pressure test the return system using a hand-held pump. I could get it as high as about 4psi if I pumped as rapidly as I could, but it'd quickly drop back to zero if I quit pumping, and I could hear it gurgling in the fuel tank. I did find that the line had about a half kink in it where it turns toward the back of the engine. Straightening this kink with channellocks took me down to a max of about 3psi when pumping rapidly. Pumping slow and even kept it between 1 and 2psi. Does that sound about normal?

 

Arthurgoboom..........fantastic work and results...............just out of curiosity , measure the hole in the AA and BB nozzles with numbered drills and compare the pintles to see what you find out...................

Arthur noted something that we all should remember............if you ever have the need to drop the fuel tank............fix the return line so the exit of the line is Not under the fuel level.......................this will drop the restriction back pressure on the return circuit ............

keep up the good work,
crossbones

 

I don't see why anyone would have to resort to messing with the pump timing to cure overheating.

If your truck (working properly) can pull a heavy load and not overheat, you have issues that have to be verified and corrected before messing with the fuel.

I just don't see a fuel or timing issue adding all that much heat to a Diesel, and if they were that far off I'd think it would be an engine running issue before a heat issue.


Be sure to check, and/or check again as you might have missed something.

1: thermostat operation


2: the air flow through the radiator for things like Bent fins or mud between the AC condensor and radiator.

I had a huge mud dauber wasp nest in there on this truck!


3: check the coolant flow through the radiator and block as someone might have sealed off too many tubes during a radiator repair, or might have dumped a bunch of that radiator stop leak, mineral build up from hard tap water, or god knows what in there.

And even someone replacing a 4 core radiator with a 2 core because it was cheaper (my 72 F100 had that "repair" done to it long before I purchased it, and 1/2 of THOSE tubes were soldered shut.

I also rebuilt an engine that had over 4 cups of that stop leak crap in there once!
I found it while pulling the core plugs to hot tank the block!

When the coolant got low, he would add a tube with the water rather than fix the leak!


4: the radiator fan clutch operation.


5: Transmission fluid temp as a swolen torque converter will cause internal leakage and heat thing up quick causing the radiator cooler to add too much heat to the engine (#1 cause of engine over heating with a heavy loads while climbing hills).


6: any combination of them all can combine to heat things up.

 

To put this in perspective we must get very "deep" into the long lost secrets of engines and the fuel that they use.............gas or diesel...no matter................the "heart" of a engine is heating the air charge taken in through the intake .......................in a "perfect diesel world" 56% of the heat would be converted to mechanical energy.................about 10% is expelled as radiant heat and about 20% is expelled as exhaust heat and about 20% into water jacket temperature........now, all of this equates to about 150°F water jacket temperature......................to put this further in perspective this temperature of 150°F does not provide much "cold feet" heat in the winter when it goes through a heater core.........so, the "invention" of a thermostat................holds the water in the block until it is "heated"......."warm feet"..............modern "coolant systems" are designed to "cool" this higher temperature water to a average of 150°F engine core temperature................. the "thermostat" not only "warmed cold feet", it allowed the fuel company's to "dump" more and more of there "waste" under the pretenses of "fuel additives".............all of which needed upper cylinder temperature to "burn" the waste junk they call fuel................

To put this further into perspective, timing of the auto ignition of the fuel charge on a diesel has "everything" to do with the percentage converted to mechanical energy verses what goes into the water jacket or exhaust.......................

basicly, "cold feet" equals a "damn good running engine"
crossbones

 

I have read data that shows that's a bad idea. There was a book I had called "How to fix your Ford V8 & 6" That was published in the mid 1970's I lost. It had a wealth of research and theory in addition to just being a repair guide. One of the graphs in the book showed cylinder wall wear vs. water jacket temperature. 230º to 180º, the curve was flat, then wear increased slightly at 170º. Below that, it turned into an exponential curve turning sharply upward at 160º. I can't cite a source other than personal experience, but I know engines that have been run cool have a lot of oil sludge buildup because the engine isn't warm enough to keep all the solids in suspension. The earliest engine I have worked on is a 9N Ford tractor which started production in 1939, when gasoline had plenty of tetraethyl lead and obviously no cold feet issues, and it still specified a 160º thermostat.

Does this mean at 150º the engine runs more efficiently while wearing faster?

Forum tip: To make the º symbol, hold down the ALT key then type 167.

 

j-redsjeep.............I have found studying very old patents and lab test performed at Langley in the 1900-1930's to be the most informing ...........

sign_man...........there were a lot of older engines that used a 160°F thermostat............I agree that oil sludge was a major problem in the old days..............but, in my opinion, the biggest factor was the use of non detergent motor oils and motor oils that did not have the better detergents used today..........some engines did not have oil filters from the factory..........

My experience (40+years) with engines and parts replacement leads me to believe that excessive heat is the "leading factor in engine wear"

You mentioned the Ford Tractor................do some research on the Ford tractor engine used about 1924-1927 when it was equiped the "Holley carb and intake system" and then "think what was Henry trying to tell us about gasoline and tetraethyl lead".....................the harmful effects of using gasoline as fuel were well known in those years........................Not even counting adding "poison" to gasoline.............they even realized the "balance of trade problem" with Middle Eastern Countries..............................99.9% of what "they knew then" has come to pass......

crossbones

 

Well here is my ALT key and the top row.
1=¡
2=™
3=£
4=¢
5=?
6=§
7=¶
8=•
9=ª
0=º
- is nothing, but
= is ?

The other keys are here
;=…
'=æ
<=?
>=?
?=÷
\=«
]=‘
[=“
~=`


but the letters also do strange things

a=å
b=?
c=ç
d=?
e=´
f=ƒ
g=©
h=?
i=ˆ
j=?
k=?
l=¬
m=µ
n=˜
o=ø
p=?
q=œ
r=®
s=ß
t=†
u=¨
v=?
w=?
x=?
y=¥
z=?

DAMN, who knew?

 

Ok, as promised, some more glowplug reading data! I'll try to format this so it's readable. (edit: seems to be removing extra spaces and there's no way to insert tabs in the text window...sorry it's hard to read...)

Condition RPM GP mv EGT Boost
Hot Idle 700 1.0 250 0
Hard Accel 0-60mph 700-2500 1.7 500 3
Steady Cruise @ 60mph 2450 1.4 425 0.5

Air Temp was around 70 F, engine temp finally leveled out at around 185 F but it took awhile to get there with my direct drive fan clutch. (Just tried to use the Alt-167 to no avail..hrm).

When I reshimmed my injectors, I also advanced the pump a bit (3-4 degrees estimated) to try to cancel out the retarding effect of the higher pop-off pressure, but I think I went too far because I noticed I was back to applying alot of throttle to maintain speed, so after this trip we retarded the pump again maybe 2 degrees, so that from where the IP was set when I got the truck, I am retarded about 4 degrees right now. I tried it out down the street and it seemed to require less throttle position to maintain 60mph. The next day we took it out again, but this time with tractors and trailer in tow (approx 2500 lbs.) Air temp was a bit cooler, and it seemed to maintain about the same glowplug readings as observed above. I have to think that this shows net improvement since the load increased but the temps as observed by GPs are the same, correct? Also, it is smoking much less now, I really have to mash the throttle to get any smoke out of it. I think it's pretty close...

Also, I got a chance to measure the nozzles and pintles from AA and BB injectors. As I would have expected, all of the critical dimensions are identical except for the nozzle bore and the pintle diameter (I am calling the pintle the smallest-diameter point on the end of the needle...is that correct?)

AA BB
Pintle OD .022 .020
Nozzle ID .040 .043

Doesn't seem like much, but if you go through and calculate the cross sectional area of the bores and subtract the cross sectional area of the pintles and compare the resulting "flow area" as I like to call this when working on carbs and ports, the BB has 29% greater flow area...

 

ok,...on some computers Alt 1 6 7 produces the º and on others Alt 2 4 8 produces the °.....................

now, engine temperature and how it is effected by engine tune and Then how we "tune engine heat" to further "fine tune" the engine............

As Arthur is noting the cooling system is: A......over cooling..........B.....the engine is not "wasting" as much heat into the water jacket...........

At this point, it does not matter which.........................when I talk about engine "core temperature of 150°F" I am talking about the cylinder wall temperature in the lower part of the cylinder....................to get this lower part of the cylinder wall to this temperature, you must think of the average temperature of the top radiator hose and the lower radiator hose.......................perfect world example................top radiator hose temperature of 195°F..........lower radiator hose at 105°F = average of 150°F..............

Typically , what I find when I have a "good working cooling system" and I start tuning is the water temperatures start decreasing as well as taking longer to reach operating temperature...............this is a good thing.......its telling you that the engine efficiency is going up............................BUT.............to further increase engine efficiency we Must Maintain the engine core temperature in the 150°F range...........

I hope I am making my point clear on this.....................(on a diesel).......we want to start out with a cooling system that Can Maintain a Max top radiator hose temperature of 190-195°F (with hopeful core temp of 150°F) and as we tune the engine and notice water temperatures decreasing.............that we do things to maintain the core temperature ........example would be a radiator bib................

A nice test of this would be if now Arthur will raise his water temperature some (without making any other changes) to see any effect on engine performance.................................

the real objective here is to tune the engine to decrease "waste heat going into the water jacket" and at the same time "tune the water temperature of maintain core temperature "

on some of my engines, I have had to block air flow through the radiator over 50% to maintain engine temperature in the summer time........90-95% in the winter........................

Arthur, we will get to the nozzle information shortly.......................
crossbones

 

just happened on this site and thread and im wondering if it works for myself heres my specs waht you recomend
88 f250 7.3 idi
new fuel filter
stock as i know fuel system a bit rusty
2 tanks
3.73 rear
4x4
c6 tranny no od jasper rebuild
anywhere from 11 to 13 mpg roughly
stock intake removed to aircleaner and plate in air cleaner removed
flow through muffler letting out just after axle

i can find out any other info you need when i get a volt meter later here im going to do the gp thing

 

CB2, wow just what I was looking for. Stayed up until 3 am reading this and still had to finish it up this am. I know very little about these deisels and their mechanics and parts/pieces even though I've owned them for 10+ years. Please bare with me.

I have (2) 1988 F-250 XLT 7.3L 5-speed trans. N/A one w/ 286,000 m and one w/144,000.

I intend to STw/GP the 144,000. She is stock w/ K&N air filter. Unkown RA (will find out). Unknown GP and INJ Make and Model. Averaging 16 MPG HWY. Have a better estimate Thursday.

She is a cold starter.Run the GP cycle 3 or more times to get her to fire off quickly w/out griinding the starter too much. When I say GP Cycle, the light turns off and it cycles (clicks) and the amp gauge fluxuates for 30+ seconds. Little bit of white smoke but clears up fast.

Tommorow I drive 500 miles home. What should I do before I leave? I am at work (tugboat captain) and can not tinker with her before I leave. I intend to put injector cleaner x2 thru her on the way home.

Parts store is 50+ miles from home, what tools/items should I pick up an my way thru? 1. Multimeter/Voltimeter 2.Thermometer to check upper/lower hose temps. 3.Compression Tester. Anything else?

Just changed oil and have a new new fuel filter. Just ordered Chilton's shop manual to help me find my way around the engine compartment.

I am off work for 8 weeks and should be able to input readings regularly (after moose hunting).

Anything you guys can teach me is appreciated, the learning curve will be steep. I have no idea wher the Cold Advance is located, how to advance or retard the timing, fuel adjustment screw, or what a soup bowl is. PM me if anyone can clue me in.

Eero

ok after preview how do I add the sig line to list my project specs?

 

heres a site to check out
http://webpages.charter.net/idi_diesel/index.htm

and soup bowl is on the top of the air cleaner just take it off like ur going to change air cleaner and flip it over ull see it