Diesel injector timing (3000SD)

[GregZ]

Hi All,

This question is regarding my 1985 300SD. How many notches (I mean teeth) does the star coupling have which is driving the fuel injector pump? I just put my engine together and trying to set injection timing; I get a 12 degrees reading instead of the 24 degrees that my doctor prescribed Can the minus 12 degrees be adjusted just by turning the pump (it seems to be right in the middle of the adjustment possibilities)?

Thanks,

Greg

How are you aligning the pump?

[GregZ]

Did my best to align according to the manual (looking at marks, etc.). I was trying to do it carefully but I may have misaligned it by a tooth; that is my real question. Should I try to adjust it or is it exactly one tooth off (that's why the question about how many teeth the coupling has)

You know about this right?

[GregZ]

Thanks, I was aware of that. I do not think it applies to my injector (the car being a 1985), plus 3 teeth off would result in about 34 degrees off (if calculating with 64 teeth on the coupling). Plus such a mistake would advance the injection timing not delay it (if I am not mistaken).

[Diesel911]

If you have the time and money it might be best to get/rent/barrow one of those IP timing alignment pins. $28-$35 plus shipping. There may be one available in the rental program.


It goes here.


When install the pump insert it so it is mid range in the slot on the pump flange.
Install Injection Pump with locking screw:
http://www.pauldrayton.com/uploadfiles/merc/Service/W123/w123CD2/Program/Engine/617/07_1-201.pdf

[GregZ]

Thanks guys but none of them answer my questions. If you need to reply please try to answer my original questions...

[Diesel911]

Originally Posted by GregZ

Hi All,

This question is regarding my 1985 300SD. How many notches (I mean teeth) does the star coupling have which is driving the fuel injector pump? I just put my engine together and trying to set injection timing; I get a 12 degrees reading instead of the 24 degrees that my doctor prescribed Can the minus 12 degrees be adjusted just by turning the pump (it seems to be right in the middle of the adjustment possibilities)?

Thanks,

Greg

OK I will try. I think you have already counted the notches; I believe you said there was 64 (I have not done so). (Also you did not mention what method of timing you used to get the 12 degrees.)
If you are in the middle of the adjusting slots on the IP you should be able to rotate the pump housing and time it to the 24 degrees (drip method?).
However, if 3 gear teeth =32 degrees then 1 tooth is close to 10 1/2 degrees. If this is so you could be 1 tooth off; which will not make a differance if you do not have tilt the pump so far that you need to bend your IP hard lines alot after you have the correct timing.
That being said if you are 1 tooth off it should not take much rotation of the IP houseing to compensate for it.
The timing pin I suggested is not a replacement for any of the timing methods but is most likely to get your pump mounted in the area where there is a proper range of adjustment to complete the timing job.
Of couse all of the above is only my opinion.
It is also my opinion that it is very easy to install this IP with 1 or more teeth off.

[GregZ]

Exactly, that's why I need to know how many teeth (64 was a guess); my IP is still mounted and I'd rather not unmount it. BTW I used the drip method with slight pressure applied to the return line fittings (so there is a clear point when the fuel flow stops)

[Diesel911]

Originally Posted by GregZ

Exactly, that's why I need to know how many teeth (64 was a guess); my IP is still mounted and I'd rather not unmount it. BTW I used the drip method with slight pressure applied to the return line fittings (so there is a clear point when the fuel flow stops)

OK I have another pump in the garage I will count the teeth for you. How about looking in the manual and finding ou how may teeth the Flat spot on the gear takes up.

[Diesel911]

I counted 67 teeth on the drive gear and it looks like the space has 1 missing tooth making my best guess a total of 67+1 tooth = 68 teeth.

That works out to about 5.2 degrees per tooth at the Injection Pump. I don't know how much that works out to at the Crank Dampet end. You would think that 1 degree of Crankshaft rotation = 1/2 degree of pump rotation.

I deleted the sentance that was here is my conclsion was wrong!

[Brian Carlton]

Originally Posted by Diesel911

That works out to about 5.2 degrees per tooth at the Injection Pump. I don't know how much that works out to at the Crank Dampet end. You would think that 1 degree of Crankshaft rotation = 1/2 degree of pump rotation.
So it would seem you are at least 2 teeth off.

Five degrees at the IP is 10 degrees at the crankshaft. Therefore, the OP is off by almost precisely one tooth at the pump.

[GregZ]

Thanks guys, that's what I was afraid of.

[Diesel911]

Originally Posted by Brian Carlton

Five degrees at the IP is 10 degrees at the crankshaft. Therefore, the OP is off by almost precisely one tooth at the pump.

If you are 1 tooth off at the IP gear is there enough clearance to the adjustment slots to rotate the pump housing to compensate for that?

[BenzDiesel]

Originally Posted by GregZ

I just put my engine together and trying to set injection timing; I get a 12 degrees reading instead of the 24 degrees that my doctor prescribed Can the minus 12 degrees be adjusted just by turning the pump (it seems to be right in the middle of the adjustment possibilities)?

Thanks,

Greg

You might as well take the pump off and time it correctly at 24* now, rather than wait and have to fix an oil leak that will occur when you move the pump trying to get that other minus 12*. I'm assuming you rebuilt the engine and know you don't want it running poorly or have a major oil leak after all of the hard work you have done to get it to this point. Anyway, align the pump to the marks on the ring and install it at 24* BTDC on the compression stroke at #1 cylinder. It's a lot of work removing the oil filter and all and have oil dripping on you, but if everything else is ok, the little oily saturated sweat you spend is well worth it. A well timed 617 is not sluggish at all and a good one out of time is generally referred to as a dog.

BenzDiesel