Well located the 0-30 pound fluid filled gauge yesterday. Standard 1/4 imch male pipe thread. Makes hooking up straightforward, cheap and easy.

Fourteen dollars and change up here in Canada at princess auto. They had restocked since I was there a week earlier. Probably 9.95 when in their monthly sale flyer.

Does glycerine freeze? Anyone know or remember? I wanted to do a permanent installation. No sense if it is going to freeze though.

Since I want to check all my cars I will probably install tees in them all with a provison to close them off after a gauge pressure check. That means I can quickly hook up periodically to make sure all is still well on the cars I do not want to permantly install a gauge on. They all should have a check in my opinion.

My oil pressure gauge has been down to -15*f without freezing.

well an interesting thought came into my mind, if you wanted more fuel economy you could just adjust the ADA (even with the full load adjusted) so that it leans out the total fuel injected. I tried this and it worked quite well the acceleration was much slower like i had a clogged fuel filter or air filter, but im sure that im saving alot of fuel without having to worry about throttle play.

__________________
Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac?

As long as they would add one additional commandment for you to keep thy religion to thyself.
George Carlin (Wonder where he is now..)

1981 240d (engine donor 1983 240d) recently rebuilt engine hurray! - No more.. fought a tree and the tree won.

pearl black 1983 240d 4speed (Converted!@$$%) atleast the tranny was rebuilt.

The same thing can be done by not pressing the throttle as much.

fwiw I stretched the spring on my TD tonight- it does feel a bit peppier now 20mm to about 28 now. Seems like its not smoking as much now? maybe my imagination.

__________________


1980 500SE/AMG Euro
1981 500SEL Euro
1982 380SEL
1983 300TD
1983 500SEC/AMG Euro
1984 500SEC
1984 300TD Euro
1986 190E 2.3-16
1986 190E 2.3
1987 300D
1997 C36 AMG
2003 C320T 4matic

past: 1969 280SE 4.5 | 1978 240D | 1978 300D | 1981 300SD | 1981 300SD | 1982 300CD | 1983 300CD | 1983 300SD | 1983 380SEC | 1984 300D | 1984 300D | 1984 300TD | 1984 500SEL | 1984 300SD | 1985 300D | 1986 300E | 1986 560SEL | 1986 560SEL/Carat | 1987 560SEC | 1991 300D 2.5 | 2006 R350

The less smoke is not your imagination. The fuel burn is better or more complete and hotter. Reflecting the increased efficiency. What was the aditional smoke is now additional energy. You should get better milage as long as you drive as you did pre stretch.

I am having some difficulty with so many not inserting a gauge. Not only does it provide good current information but indicates fuel supply problems if they exist or occur as Yellit experienced.

The most important additional function of having a gauge to me is letting you know when fuel filter change is required for milage reasons alone. For this a gauge should be installed in a permanent fashion. Not a lot of money and what it does will pay for itself so it is basically free.. Not many things like that anymore. .Also an invaluable aid for establishing where troubles may exist with time.

Since the additional power is not blowing your socks off you are probably in the high teens low twenty pound area. This is pretty safe. Listen to your engine for any change in knocking sound. You have advanced the effective injection pump timing from your pre spring stretch setting.

At some point a refference will have to be worked up by dynamic checking of the change in degrees in relation to the balancer scale by someone. At certain pressures a suggestion will develop of where to set your drip point to. It will be different depending upon the fuel supply pressure developed. Up to twenty pounds or slightly higher I suspect the old drip setting is okay. Above that things will change. Common sense.
I still await milage increase indicators or reports other than less smoke. If new fuel supply pressure is not above very low 20 pound setting I expect the increased milage to be there. It almost has to be. Common sense again.

Even above low twenty pound fuel supply pressures I expect a possibility of less higher milage per gallon exists..Yet still some. There may be a risk to the engine though if the effective timing is too far ahead.

Last but not least is why no one to my knowledge has thought about respringing the timing device in front of the injection pump for our low celane north american diesel fuel. The mechanical advance curve is tailored for a much higher celane fuel I believe. Investigating all these little areas time has come with the cost of fuel increasing beyond pocket change. My limited knowledge does not allow for mercedes doing this for north american export cars when new. Somehow I doubt it.

Fuel was too cheap when these cars where new to concern them. The manufactures were not trying for every last mile per gallon then. In fact since this model was succesful they might have not have had or taken the time to meet the needs of various fuel celanes used worldwide. If the part number for the timing device is the same for the north american and european mechanical timing advances we have our answer.

Perhas they are as confused as I am? If you haven't done this before the directions are a bit on the vague side. It is essentially "attach a pressure gauge to a line on the fuel fiter assembply." Well, OK.

At least there are pictures shown on post 106. That helps. Now, the following would help some more:

1) What kind of pressure gauge? Does it have to be specifically for diesel fuels? Will any kind that measures up to 30psi work?

2) How exactly do you attach it? One person mentioned a "T" fitting but the pictures show just a 90 degree elbow. What are you "t-ing" into? What are the threads necessary?

3) Are you measuring only peak pressure at each RPM?

If you help me past my ignorance I'll take better pictures and do an idiot's step-by-step instruction on how to do this.

They are teeing into the line that goes from the output of the primary (spin-on) fuel filter to the input of the injection pump. This means it is reading, more or less, the fuel pressure inside the IP. They are plumbing hydraulic fluid pressure gauges there, and finding that some dampening in the gauge readout might be needed (hence fluid-filled gauges).

__________________
'83 300DTurbo http://badges.fuelly.com/images/smallsig-us/318559.png

Broadband: more lies faster.

You are right of course there has been little guidance to gauge installation and interpretation. It was my bad so thanks for pointing it out. I guess basically it could be three hose barbs inserted into a tee fitting and installed in the line as the last post mentioned. The leftover barb in the tee to a hose to your gauge.

Since the gauge end is a male 1/4 pipe thread a coupling with a barb on one end takes care of the gauge end of things. I have to assume all the cheap liquid filled gauges are all made in the same oriental plant with many distributors labels on the boxes.

Zero to thirty pounds is an ideal gauge range for interpretation in my thinking as well. Small variences are quite noticeable. Small hose clamps on the fuel hose connections with the barbs are practical and reliable at the operational pressures we are dealing with.

I would like to see a diesel fuel rated hose between the third barb and the gauge myself. This also has a tremendous upside when communicating with each other. All our gauges will be more or less a constant. Yes do the guide to installation. It will aid others confidence.

It means a lot to me if I am allowed to try to contribute to areas we have not investigated. Others like yourself kicking out random thoughts are a wealth of information. Ar some point hopefully assorted ideals will jell and produce something totally unexpected by cross polination.

Members posts make me reflect in a serious fashion what may be going on. A few minutes ago I responded to a post on why a members car runs better with a low fuel levels in the tank than higher levels.

During my reponse it occured to me. What is the probable effect if indeed the cigar hose hardens with age? Right or wrong at this point it would be reflected by larger than normal pressure swings in the injection pump fuel supply pressure. Since we all will have the same basic gauge setup in place normal will become quickly understood.

Again as part of our learning experience he described what his cars smoking was like if that cigar hose was harder than when it was new. His cigar hose was eliminated hence his problem in my opinion. Became my inspiration by expansion on his problem. More jewels are going to come down the pike I suspect.

Some sembalance of the problem would occur if the cigar hose lost it's flexability with age to some extent. I have been mentally toying with several modifactions to the injection pump supply system already but far too early to go there. They might be of some benifit and are simple and cheap. Basically things like is there an upside in getting rid of the pulse totally from the lift pump present at the injection pump? Or further reducing it?

To give proper credit Yellit did mention or ask if I thought there might be any benifit in feeding the injection pump with an electric pump. My only first instinct was the reliability of the mechanical lift pump is quite good. But as it turns out there might be some advantage to a constant non pulsating feed. Also for future consideration a variable feed pressure at some point might be benificial. Thats a long way into the future to even consider this at present. At least Kevin was thinking.

So now we pick up a probably accurate picture of a complaint that has been widespread with no solution ever posted to my knowledge. It is one of those items that the cause may be thought of as faulty injectors quite easily. One now current possibility is either a restricted return line or the cigar hose hardening up with age and not able to preform its function properly. Again affecting milage and smoking to some extent. As of yet I am unaware if this hose can go hard with age as a general rule. For example it might take the elevated temperatures of the south to do it.

More and more information is coming forward if you read between the lines. The condition of the injector pumps primary fuel supply is really important. Or at least far more influential than though only a week or so ago. There have to be many other bonuses we have not even considered lurking there as well.

Part of your questions is basically what rpm do I read the gauge at? The best answer is at various rpms with the engine loaded and not loaded. So it is important to have the gauge hose long enough to get the gauge into the passenger compartment. That way when you get the base injection pump pressure in the proper range at idle in your driveway for example. You should be getting about the same operational pressure at 70 miles per hour on the highway under load if all is well.

This goes a long way towards getting the fuel milage your car should deliver in my opinion. Yellits post on his experience is a real eye opener if you read it. He at first had an operational pressure of 0-2 pounds at highway speeds.

How he rectified this is in his post . Knowing him I think you can count on very accurate posts from him as time goes along. His actual benifit was immediate by the way. His fuel milage has to be better than it was. Car is also smoking less to some degree.

As time goes on and people post their actual experiences in numbers almost all will be positive if they just follow simple rules. We can easily complicate things down the line if thats what people want. Cervans original post in this thread that is rightfully his illustrated this well. It really made my day as well. when he stretched his spring and started this thread.

I checked the spring length in my 83 300D, about 20mm. Also checked the spring from a spare injection pump from an 83 300TD, about 21.5mm. I stretched one to 27mm and installed and noticed that the bypass would no longer open when I pumped the primer pump.

__________________
1983 300D 280,000
1983 300TD 125,000 Killed by oak tree.
1983 240D Sold
1986 Ford F250 Diesel 6.9l 169,000

Could it be a tired primer pump? It does takes a little more pressure now to open that relief valve.

You are the first to mention this. Perhaps you are the first to try the primer pump after a spring stretch? Primer pump leaking out when pumping? If so it should be changed even if you had not changed the spring length.

Engine did start right up after the spring stretch ? Just an observation or was there another reason you tried the primer pump?

Maybe another spring stretching member can check and see if he has a simular situation going. If vou have an alternative fuel in the system I would consider the viscosity issue with the fuel cold and the new demand.

Is engine is running any different? For example if other things are marginal in your fuel supply the pressure release increase by the spring stretch may have no benifit to a running engine. That is because there was really no change. . For example lets say the engine at speed developes five pounds fuel pressure in the injection pump. That in itself is very substandard..

Actually the pump fuel volume wise would be getting just enough fuel to run at speed with little going if any out the relief valve. This senario us almost gauranteed to hurt fuel milage. So an indivudual stretches his spring.

You have not basically changed anything. On the highway at a simular speed. You will still have only five pounds fuel pressure available to the injection pump. Simply because of pre existing limitations only a certain amount or volume of fuel can flow. Without even further dropping of pressure.

Without a pressure gauge installed and observed at speed a person will have little information. Actually none except perhaps some seat of the pants feeling.

So as soon as a person says he has stretched his spring and there is no or very little difference that will be the reason why. Now a new fliud filled gauge cost me 14.00 and change up here in Canada. From what I understand of the American market a person should be able to source the same 0-30 pound gauge for about ten dollars. The additional fittings to hook it up properly will drive my cost to slightly less than 20.00.

Then if the fuel supply to the pump is found to be flowing properly I can custom set my operating pressure to exactly where I want it. If not flowing properly the gauge will indicate that as well. These cars are old many will have fuel volume flow issues to deal with.

These are the ones that will benifit the most of all from cleaning up the problems. I can think of no expensive parts that will cause this type of problem. So we are still dealing in basically a cost effective area here. In every case that is found to be substandard and rectified the fuel savings will pay the nominal cost of straightening things out in less than no time with increased miles per gallon. Perhaps less than the savings on one tank of fuel when properly functional.

As time goes on all sorts of clues will be posted. Lets start with a very simple senario. My car seems to get only a couple of more miles per gallon on the highway than around town.

What is likely happening here is a volume flow problem at speed. At low town speeds the engines reduced fuel flow requirement is not creating as much fuel pressure drop. So The engine is somewhat more efficient. On a higher fuel volume requirement out on the highway at 70 miles per hour as an example. The pressure sags in the pump. Elements load fuel less evenly.
Less quantity of fuel as well.

So the first casualty is the injection pumps effective timing rolls backwards. This condition is created by the elements intaking less fuel. The elements piston has to travel further to hit the injector opening pressure. The amount it does is unknown right now and thats okay for the present.

Now I also suspect the element loading without enough available feed pressure starts to become a little erratic. Those individual elements that now underload the current average cause that individual cylinder to fire later than the now generally retarded principal timing for the other elements. These general conditions existing kill off any heavy increase in fuel milage made possible by the highway driving.

You sit behind the wheel blissfully unaware as at the elevated rpms the engine sounds the same as it would if normal pressure was being supplied to the injection pump. The loss of actual power is made up by your holding the fuel pedal a little or a lot lower . You have scrapped general efficiency in this senario to some extent. The car is also unable to reach its top potential speed as well. Ability to acellerate for passing is comprimised as well.

This could even be why some 123s top out at different miles per hour. Especially 240ds. If your car wants nothing to do with what the reported average high end of it's type is this is a place to look. The higher the fuel demand at high load revolutions the worse any existing low pressure effects become.

It is really all there in Yellit or Kevins early post if you think about it. Just too early to give it performance loss numbers. Again we were very lucky Kevin decided to do tests under real load conditions. Initially the results staggered him I believe. The results were just so bad with the car still runnable.

I replaced my lift pump about 50K miles ago. The reason I used the primer pump after the spring stretch was because it wouldn't start, tried the primer pump to purge air and noticed I didn't hear the bypass opening. I decreased the stretch to about 24.5mm and tried the primer pump again to find it would open the bypass, although it seemed a little harder to open than when the spring was untouched. FWIW, my idle seems much improved, smoother overall. Will wait and see what, if any, power increase there is when I road test it. I do agree that a gauge should be installed.

Also, from Forced Inductions posts showing the Mercedes specs for measuring and adjusting the pump pressure I'm not sure that Mercedes is specifying that the spring length should be set to 26-27mm. I read it as saying that if the pump pressure is too low then one should stretch the spring UP TO 26-27mm to achieve proper pressure.

__________________
1983 300D 280,000
1983 300TD 125,000 Killed by oak tree.
1983 240D Sold
1986 Ford F250 Diesel 6.9l 169,000

Good going. You are on the money about the spring stretch. I believe Forced Induction found out quite quickly and mentioned the service information was in error. He was recovering springs that were consistantly about 20-20.5 mm long I believe.
What mercedes do specify pretty clearly is the normal operative pressure range of the fuel provided after the secondary filter. Eleven to nineteen pounds. It seems at least one pump repair guy exceeds this by a couple of pounds as a regular component of rebuilding these pumps. I suspect this was a later update by the pump manufacturer at some point so should be completely safe. Or word of mouth carried this higher end setting to perhaps many rebuilders as the preffered regulator setting.

People are now or should be aware that without a gauge many minor items can interfere with or even defeat the improvement. There is no other way really to know the information required at loaded engine speeds.

Either way to be at the upper end of the recommended setting or slightly higher makes good sense to me. The results are the more positive quantity loading of the elements. I have not totally decided yet if an additional benifit is the longer duration timewise spray of the injectors. I guess a better way of describing this mighr be. The injector is open over more actual degrees of engine rotation. It is reasonable to assume that more fuel is also released as well. A very small additional amount in context though. At the same time the additional increased running advance of the injection pump timing increases the efficiency more than any additional fuel quantity penalty.

This directly introduces the fuel quality loading of the elememnts suspicion as a component of the overall equation. At lower pump feed pressures there have been lots of indicators over time those elements at substandard feed pressures each load almost random amounts of fuel. No two elements intaking equal amounts of fuel as an extreme. You basically loose the regular designed sequential timing between elements. This factor alone is the greater suspect for the smoother idle and less smoking. The semi proof is if the idle speed is not increasing with reasonable high fuel pressures in the recomended range.
As items involved with this area get straightened out in everyones mind including my own. We all will make progress. Since your idle is improved it is reasonable to say you have increased the pressure. If there is no restriction that affects pressure in load situations negatively your power and fuel milage will be better. How much depends on a lot of factors that are easy to deal with. I wish we knew what your loaded pre stretch pressure was and what it is now.

So if your system is not otherwise restricted power under load will be greater. An important item right now is for people like yourself to really carefully estimate if the idle speed is the same or slightly higher.

Besides your ears you might have a working tachometer. Another possible helping indicator item is your hot oil pressure. I believe it will be very idle speed sensitive. If rpms are up the idle reading on a hot engine would be higher. I am not sure if transmission engagement would be noticeably different though.

The results of getting the answers to the above questions as soon as reasonably possible by many are very important. If the idle revs are pretty identical to what they were and much smoother. It can be almost be assumed the actual quality or even rate of element loading has been improved. If this is so it will tend to be much better at higher revolutions. A more demanding operational enviroment then exists.

Basically if your load operating pressure is about 22 lbs or slightly less this change has to be benificial. If higher fuel pressure is desired the dynamic running timing advance of the pump should be checked. The indicated degrees past the drip position should be recorded. You then subtract the noticed dynamic degrees from the pumps current recommended drip setting and static drip time the pump to that new location for safety. Of course like all simple things variious calibrations between indicated dynamic and static positions will have to be worked up. So it will not turn out to be a simple exercise for the first guy.

This in my opinion adds protection from running timing too far advanced and all the uglys that it can create. This area I personally want to stay away from for the present till all the issues with milder tweaking are known and dwelt with. I threw in the pump timing issue for those that are further ahead of the majority of us or for people that want really strong acceleration increases to know the risks of too much pump base pressure without other changes.

As midlwolf pointed out and I personally believe a gauge is an intergral part of this proccedure. You have to know where you are and if other problems are present. These other minor problems may be undoing all or more likely part of your change.

Just explain to your bank manager that a loan of 15-20 dollars for a gauge installation might result in fuel savings of hundreds of dollars. That should satisfy the bank manager enough to grant the loan. Hurry though while they still have funds.

well i just fought my 240d for three hours today, The fuel line clogged with something from the fuel tank solid, even compressed air wouldnt remove this crap. So i was stranded on the side of the road for about ten minutes, got it to run again by pumping the primer a ton. And drove to a local parking lot.

Thats when it hit me that i couldnt restart my car again after i shut it down.. somehow my battery had shorted and wouldnt start the car (i checked all connections all good, bad battery) Full of water too. So i remembered 1-800-for-mercedes. within 30mins i had a guy in a mercedes suv come and jump my car for free!

After he jumped my battery, my car once again ran "dry" because of the plugged tank filter and he came back and jumped me again (since it didnt run long enough to charge the battery). Awesome service if you ask me.

__________________
Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac?

As long as they would add one additional commandment for you to keep thy religion to thyself.
George Carlin (Wonder where he is now..)

1981 240d (engine donor 1983 240d) recently rebuilt engine hurray! - No more.. fought a tree and the tree won.

pearl black 1983 240d 4speed (Converted!@$$%) atleast the tranny was rebuilt.

One other area has come to my attention. I just mention it in passing. The lift pump cycles in a synchrous fashion with the injection pump. The pressure spike delivered is brutal. If there is anything not functioning right after the regulator output the pump is forced to deal with the pulse. Or a much larger pressure swing each cycle.

Since this is basically a hydralic situation all changes are considered instantainious for our purposes. The loading pressures will be completely unequal for each element being charged. Engine will smoke and other effects.


Another members post on another thread got me thinking. Does the cigar hose get soft and rot with time? Or do some start to harden with time like old rubber? It is almost certainly detrimental if they harden significantly. This flexable chamber works hand in hand with the regulator to moderate the pressure swings. So if anyone has ever noticed their cigar hose was signifigantly harder than a new one could you post it?

This could be considered a maintenance item in my opinion. Its proper function is important. I have to assume and assumptions are dangerous that if faulty it might be displayed on our gauges. On the otherhand being fluid filled they might buffer the heavy swings as well as the lighter swings present when it is working properly. So the needle would remain pretty well constant either way and not be helpful.