For several days I have been testing and refining my tests of the IP timing of several diesel MBZ(s) and will now call my latest method the:

“ Karoly MBZ Diesel Injection Pump Timing Check / Test ”

My use of “ Karoly ” in the title is to give credit and respect for my independent MBZ mechanic friend Karl [Hungarian born] who’s 30+ years of experience working with these vintage diesels has been invaluable! Here are the latest steps in our procedure which attempts to squeeze out the most accuracy possible using ordinary tools most of us have:

(1) Disconnect the #1 fuel injection line running from the IP pump element to the injector.

(2) Disconnect the wire to the #1 glow plug and remove the plug. This is to remove the compression on the cylinder and improve the ease of turning over the engine, particularly as you approach the engine/IP timing pulse you are trying to detect.

(3) IF only 1 person is conducting this test, use the bolt on the power steering pump to turn the engine over [to the right as you face the engine]. NOTE – IF the V-belt slips, you will need to tighten the steering pump’s belt tension and then readjust to your liking after the test is finished. Turn the #1 cylinder until it is approaching its compression stroke which you can judge by looking inside the valve cover and see the intake and exhaust cam lobes rising up to the top. Rotate the engine until it is at ~60 deg. BTDC as indicated on the timing marks on the front of the crankshaft.

IF 2 people work together and coordinate closely, one can turn the engine from below using a 27 mm socket and long ratchet [the longer the better] and the other can coordinate verbally from above to accomplish the same as written above in this step (3).

(4) at this point give the priming pump 2 to 4 stokes to raise the fuel pressure inside the IP... and then immediately shut off the priming pump IF it is the old style that often leaks when left open… for such leaking would probably void any advantage you achieve by such pumping ! This should leave the IP’s exposed #1 element fuel outlet fitting full of diesel fuel which is actually too much fuel but we will now remove.

(5) By whatever means you desire, you need to “wick-up” or blow away excess fuel which usually forms as a “meniscus” or “bubble” in the top of the #1 element’s outlet fitting. What you are trying to do is remove the top of the “meniscus” but leave the narrow throat of the fitting full. This is another step to help improve the accuracy of this check/test. I like to use one of those computer aerosol cans that have a “swizzle-stick” nozzle. These are normally used to blow dust out computers. IF you hold the nozzle just right, you can easily blow away the top of the “meniscus” but leave fuel in the throat of the element’s fitting.

(6) As you turn the engine through it’s final few degrees seeking to detect that illusive pulse from the #1 IP element, it is IMPORTANT to use a tool with as long a handle as possible. For instance I switch over and put my longest ½ inch breaker-bar with the socket being used [ 22 mm on the power steering pump or 27 mm on the crankshaft pulley]. This extra length increases the control, thus accuracy of your check/test as you are intently watching for movement of the fuel in the IP element that indicates the IP’s timing !

And so its time to let out a “Eureka” or “voila” when you see the fuel move up in the throat of the IP’s fitting, for you will have found as accurate an indication of the IP’s timing as I can conjure up ! My completely biased opinion is that with a little practice you too can be accurate to within one degree.

So give me your thoughts as we are open to further refinements... and better yet, give this a try and see what you get for your vintage MBZ's timing. I have thus far found our 1980 240D at 20 deg. BTDC and the 1980 300D at 17 deg. BTDC. Soon I'll be working with tow 1985 300SD(s) to see exactly where they are set.

I think that most of us on this FORUM now agree that these engine will not only run, but perform well over a wide range of IP timing settings so why worry about the timing so much. Well for me I'm hopeful that fine tuning the timing on these cars' engines will give us improved fuel economy... and the first giant step in fine tuning for economy is to get the timing close to the 24 deg. BTDC most of these engines are "spec'd" at.

Then I will begin to seriously experiment with the notion that we can use the miliVolt output of the glow plugs to make that final bit of fine tuning that will allow me to give this topic some rest.

P.S. - Armed with new piezoElectric clamp sensors, our used Kent-Moore "Tach-N-Time" meter is giving fine results and with this new accuracy in manually checking the IP's timing, we are finding that 11 to 13 degrees appears to be the proper correction factor for these K-M meters... in other words when the meter/stobe light show the timing to be 13 deg. BTDC, it is actually 24 deg. BTDC.

PLEASE voice your opinion and/or share your experience IF you try this method of checking your IP's timing!
Regards,

I'm with you here.
This is pretty much the only way I have ever set my timing.

Danny

__________________
1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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My Only issue, is the fact that the Pumping Element as it rises, and closes the spill-port inside the IP, Must now travel even More Past this 'Correct' timing point, to raise sufficient pressure to open the Delivery Valve BEFORE you actually see any change in the level at the outlet...

The correct methoid outlined by M.B. is to remove the Delivery-Valve from the outlet fitting onto which the fuel-line attaches, and using a spill-pipe (Old injector line cut and bent to shape works brill!) accurately determine the point at which you get 1 drip Per Second on regular Diesel fuel with the crank lined up to the correct timing mark. At this point, The Plunger Inside the element is JUST closing off the spill-port of the element, but Has Not Yet risen to the point where it would deliver any pressure as would be the case using your method....

Setting by your method would therefore advance the timing by ??x?? number of degrees, in comparason to the recommended M.B method....

Personally, I'll stick to M.B. proceedures for setting something as Vital as Point Of Injection-Timing. There is Zero guess-work and No straining of eyes looking at tiny 'cups' of fluid down in the engine-bay!--Dead easy to see a dripping spill-pipe from 10 foot away, or even while under the car turning the crank that tiny last bit to confirm the setting after adjusting the I.P !

__________________
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Alastair AKA H.C.II South Wales, U.K. based member

W123, 1985 300TD Wagon, 256K,
-Most recent M.B. purchase, Cost-a-plenty, Gulps BioDiesel extravagantly, and I love it like an old dog.

W114, 1975 280E Custard Yellow,
-Great above decks needs chassis welding--Really will do it this year....

Samuel... Nice work but I cant quite figure out, why not just use the "drip" or "bubble" method. I'm as hooked on the bubble method as Alastair is on the drip method . The old German MB mechanic that taught me the bubble method swears its MORE accurate than it needs to be and you don't make a mess on the shop floor. I keep a banjo fitting and a couple lengths of hose in a zip lock and can check timing pretty fast, no muss or fuss

__________________


1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

I believe ForcedInduction or BGKast stated 26degrees was optimal for his car. And someone else agreed. Just what I have heard.

__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

I got the little "Diesel Performance Tuning and Repair" booklet from **************, and this is the method he gives. It would be interesting t do it that way and then check it against the drip tube method given in the FSM. Maybe it produces the 26 degrees(using the drip method) that some on this board claim gives best performance.

__________________
Sedecrem

82 300SD 290k(needs engine swap)
79 240D 354k with new heart transplant w/220k
82 240D w/auto tranny soon to be manual 4 speed

This confirms our previous results with a the strobe light and the piezo sensor on the #1 line. We found a reading of 13.5 deg. BTDC for the SD which was set to 15ATDC with the RIV lights.

Call me stupid but 15+13.5=27.5 degrees. 24-13=11 degrees. Am I missing something here?

__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

Can we just say that you are not good with numbers?

Lol ok oops. But still they are talking about drastically differences here. I think someone mistyped. One is saying 28.5 variance and the other is 11 variance. Sounds a bit drastic to me.

__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

We're discussing three different ways of measuring the IP timing:

1) Drip method: 24BTDC
2) RIV method: 15ATDC
3) Pulse method: 13.5 BTDC.

Understood?

... but this is exactly what I think I wanted!?

As the originator of this THREAD, let me confess that I do NOT understand the inner workings of these IP(s), not even the output element portion.

So Alastair you have me at a disadvantage. I also do not understand how the fuel is pushed past what I see as that spring-loaded check valve that our method leaves in the element's " pipe " fitting [ I see that the MB manual calls this a "pressure valve" ]. I will re-read your explanation and try again to understand. Maybe my friend "Yellit" on this FORUM can translate your British English to American English for me [just "funnin"!].

IF anyone who shares my keen interest in this subject of IP timing and is proficient with the heralded MB drip method or the "bubble" method... I would love for you to do a direct comparison between your best method and this new one on your car. Maybe "sedecrem" was right in his POST above, maybe using our method will cause the IP to be set with an additional two [2] degrees of advance... and maybe that's good !??

Yes, trust me that I have tried the official MB manual's drip method and the "well-up" method and was never able to feel at ease with either despite my one-time successful setting of the IP on my 240D. But this method we are now toying with... well it seems more logical to leave the "pressure valve" in the IP's element fitting... and to look for fuel being pushed up out of the fitting... it just makes more sense to my sometimes slow brain. Maybe something gets lost in the German-to-English translted drip method that is throwing me off!?

Tomorrow I will be trying our method once again, and this time will be my first time to remove either the #1 glow plug or to loosen the injector as a means of destroying the compression that one has to fight as you are trying to gently turn the engine/IP and sneak up on the timing pulse of fuel... and detect the fuel movement at the element's fitting. I'm hopeful that this will further refine what we have thus far seen as an 11 deg. adjustment for our Kent-Moore "Tach-N-Time" meter/strobe meter!

In closing, some food for thought - whoever said that everyone must see something exactly the same way to be right? IF that were so, as soon as Einstein came up with his E=mcxc, every physicist would have immediately said "... yeh, why didn't I see that first" !
Regards,

It just dawned on me... this THREAD has identified:
(1) the MB drip method,
(2) the MB RIV tool method,
(3) the Pulse method referred to by Carl,
(4) the Bubble method [author unknown],
(5) the Well-Up method [author unknown],
(6) piezoElectric clamp sensor/timing strobe method, and now
(7) this method I'm hawking as the: “ Karoly MBZ Diesel Injection Pump Timing Check / Test ”

Can anyone think of one I have missed!!
Regards,

That is what my head is doing after reading all this stuff that I simply will never understand until I SEE IT HAPPEN!!
Having said that, I would love to have a GTG where we have somebody demonstrate this procedure, and could maybe even check out a couple of attendees vehicles while we crow-neck over their shoulder.

__________________
Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

That 'Check-Valve' in diesel-parlence, rather than British /American/German language is called a 'Delivery-Valve'--Thats what BOSCH and all the other I.P makers call these devices. yes, it IS a check-valve, but of a specialised type--

If you were to remove and examine one, you will see the central 'plunger' part has a tapered sealing face, which mates up to a corrisponding face of the 'body' part. Just below this on the central part, there is a 'rim' about 1mm below the sealing face, and is a good close fit in the bore of the body part.

The Purpose of the delivery-valve, is to maintain Residual-pressure in the H.P. line, and control the way the Injector ends the fuel delivery and to prevent 'oscillations'.

When 'End-Of-Delivery' has been reached, the pressure below the delivery-valve inside the pumping-element of the I.P falls suddenly to 'gallery-pressure'-(Same as lift-pump pressure)- as the spill-port is opened by the still rising plunger of the pumping-element.

As the delivery valve was open during delivery of fuel, with the rim above the face of the body part, it now snaps shut under the influence of the return-spring and the pressure of the fuel in the H.P line, acting on it. As the 'rim' portion acts like a tiny piston, the effect is to withdraw a controlled amount of fuel from the H.P. line, lowering the pressure within the line and injector well under the opening-pressure of the injector, but keeping a controlled amount of pressure within the H.P. line and injector, ready for the next firing-stroke.

This is done to prevent 'Dribble'--where the last small amount of diesel injected would merely 'dribble' in and cause poor combustion. The Injector needs to close as quickly as possible and in a controlled way at the end of the injection phase or higher smoke emissions can result.

This is another reason I personally feel that could make the described test at the start of this thread inaccurate, as the pumping-element must move some amount before it will lift the delivery-valve off its seat AND to get the 'rim' portion above the sealing-face to allow ANY fuel rise to be seen in the pump outlet union...

__________________
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Alastair AKA H.C.II South Wales, U.K. based member

W123, 1985 300TD Wagon, 256K,
-Most recent M.B. purchase, Cost-a-plenty, Gulps BioDiesel extravagantly, and I love it like an old dog.

W114, 1975 280E Custard Yellow,
-Great above decks needs chassis welding--Really will do it this year....