Anyone had this problem before?

[jaynes]

Apparently there is an o-ring on the back side of the injection pump (against the engine block) and mine just blew out, leaking diesel all over the place. I took it to Cummins and the mech said it could just be wear and tear, or there was excessive pressure which caused it to blow . He said they could test it to see if the latter was the case, but it was expensive, and I told him to just fix the o-ring and put the pump back onto my engine. Has anyone else had this problem? What can cause excessive pressure in the pump? Was I stupid not to have it tested? Thanks!



Jaynes

 

[Philip]

Formula had this problem about a year ago on his pump. I am sure he will be along here shortly to fill in the details.



The pump had to be pulled to repair the leak. I would have had it checked while it was off.



The way I work on auto's/trucks. If a part comes off for any reason. Rebuild or replace it. Ask Case500D I have been helping him remove the previous owners fingers prints on his W350. LOL

 

[jaynes]

Well I hope formula comes along here and helps me out. I would've had it checked, had I had the cash! I'm a poor college student with only enough to have the leak repaired. I would like to have it looked at, see what kind of shape it's in.

 

[Case500D]

jaynes,



It shouldn't be too expensive to have the pump resealed and checked out. Especially if you are able to remove and install it yourself. Good luck.



Philip, see signature.



Jeremy

 

[jaynes]

too far?

I advanced my pump about a month ago. Could advancing it too far have done something like this? Is advancing it too far dangerous to the pump?

 

[BushWakr - RIP]

The mechanic was correct..... either the o-ring was weak and failed and/or there was a bit too much pressure which blew it out.

It actually happens a bit more often than it seems... .

It comes with the tweaking and cranking we do on these things.

Too much advance can do it, yes... normally severe advance and an old or weak seal contribute together when it comes to failing.



I don't know about any of the other fella's but I have had the my truck running some serious advance. . as in about 2 days advance...

This brings up a good point.....

Timing.....



I'll speak for myself here, that way no one feels dumb except me...



Over the last year I've learned a great deal from all of you here, the folks that I've spoken to over the phone and of course from Piers Harry and everyone at PDR. (ok that's not a plug, it's a fact)



Timing... we're in a rush to have the pump timing advanced so we use the 1/8" method. It is pretty accurate in most cases (which is what I'm referring to, most cases... )

Now, if you've had you pump 'Pinned' to, say, 1. 6mm plunger lift, and then you ADD the 1/8" method, you're running some pretty advanced timing... right... !!??

Ever wonder what happens when you fire up 'ole BFT on a cold morning and the KSB kicks in... ???? think about it for a second...



Spill port timing = 1. 7mm lift

Physical timing = 1/8" (equates to roughly 1. 5mm lift or roughly

15* advance, as opposed to the stock

1. 25mm lift... )

KSB function = ... ... ... ... ... ... ..... approx. 5* advance. .

Now heaven help me... if certain other factors are at or over it's "acceptable range" then you are well into the 20*+ or more range...

Now, one more..... at max rated RPM the KSB function is reduced (I think to 60% of it's value????) but at max rated RPM the timing is advanced further... . see what I mean... . NASTY !!!



Sooooo... . todays lesson is, it's all a matter of timing... . your's and engines'... ... . Hint: does your CTD sound like an older Mercedes???? TIMING??!!

Since I don't have my literature here I'll reserve the right to correct any fubar's I've made at a later date.....



Pastor b0b.

 

[hdm48]

Well slap me silly, I thought we covered this a while back.

Normaly (and I'm talking about the truck, not the driver) the "O" ring will be pushed out by too much internal pump pressure. This can be caused by the KSB sticking or the sensor on the engine sticking in the "cold"position. When the KSB is activated the internal pump pressure doubles to advance the timming and go to max fuel for cold start and at high RPM it can/will push out the "O"ring.



dave

 

[formula]

Hey,

Indeed, I had the same o-ring leak last winter. I decided to have the pump rebuilt while it was at the shop, but the tech said that most of the time it's just the o-ring getting old and shrinking or improper tightening of the bolts on the cover plate. You'll most likely be fine just replacing the o-ring.



As for timing having an effect on internal pump pressure... ... . I just don't see how that can be true. The internal pump pressure is determined by the pressure regulator and the KSB mechanism. The pump itself has no idea whatsoever where you have the timing set at. Timing is just the positioning of the start of injection relative to crank position.



Cheers,

Sean

 

[jaynes]

wow

Lot's of good info. Well here's my final question regarding my situation, and others as well:



Does timing effect the internal pump pressures so much as to blow the o-ring? I'm getting yes's and no's. I'm just alittle confused, thanks all Thanks!



jaynes

 

[hdm48]

Jaynes, I think Formula hit the nail on the head. The answer to your question about timing causing the O ring failure is,



NO



The physical location of the pump in relation to the crankshaft has no effect on the pumps internal pressure.

O ring failure, KSB failure, sensor failure, internal pump pressure regulator failure. Those are your options.



Now say 9 hail horsepowers and give Pastor Bob 7 rwhp until you're forgivin.





Dave

 

[jaynes]

ok....

hail horsepower!

hail horsepower!

hail horsepower!

hail horsepower!

hail horsepower!

hail horsepower!

hail horsepower!

hail horsepower!

hail horsepower!



rwhp!

rwhp!

rwhp!

rwhp!

rwhp!

rwhp!

rwhp!



Pastor Bob, I have committed a sin, the sin of Ignorance on Injection Pumps. Please bless me with thy knowledge of the Injetion Pump, so my truck will race straight and true. Amen.



Jaynes

 

[BushWakr - RIP]

I'd like to do some more 'hashing' on this one.

It's pretty late for me right now so I'll hold off on some thoughts till tomorrow or weekend. That way I'll have some printed material to reference that goes a bit further than the bosch pdf manual.



Lets kick this around a bit and, I think maybe we can all pick up some tips... .



Bob.

 

[phillips5]

Formula and HDM48 are correct the inside of the pump does not care what position it is bolted to the engine.

 

[jaynes]

yes

Right,I can see that now. The more I think about it, the more it makes sense. I can't see how the position of the pump relative to the crankshaft could effect the internal pressure. It's just turning it around alittle bit, nothing more. Now messing with other things like the fuel screw, starwheel and such, that could raise internal pressures, right? Or am I mistaken?



jaynes

 

[JLEONARD]

Formula and HDM48 are correct the inside of the pump does not care what position it is bolted to the engine.

Yes, I agree with that... even timed 180 * out the pump wouldn't care...

Now them thar pistonis and those valve thingymabobs???... . they would care

E C Jay

 

[jaynes]

Thats true! Never thought about that either. Man I better start thinkin' or sumptin!

 

[BushWakr - RIP]

I hope this isn't too long or rambling...

Ok guys,,, check my thinking here and let me know if you see me going to the left...



Lets assume for the conversation, that our pump is set at exactly "0" timing... . at idle, with no KSB advance, no RPM advance and no pump "pinned" advance.

Lets keep terminology simple and refer to any advance in degree's not mm plunger lift.



Ok we're at "0".....



Now if we agree that engine RPM results in the supply side pressure going up, and the supply side has a direct effect on the high pressure side we then have an "effective" increase in timing because the start of injection begins soon when pressure rises... yes/no ????

(Lets disregard the impact/effect of the 'pressure wave' for the moment)

So as RPM climbs above idle value we have an escalating timing value... lets say it caps out at, say, 5* advance at 3000 RPM.

So we have "0" at idle and 5* at 3000 RPM.



Now if we then "pin" or set the pump's inital advance at, say another 5* advance we then have... .

5* advance as the initial pump "pinned value" and another 5* at 3000 RPM, for a total advance of 10*.

Next if we bring the KSB into this mix I think we have this... . (yes/no??)



When the KSB cycles ON, it raises internal pump pressure on the supply side... we now have a starting value of the 5* initial value re: pump "pinning", another 5* re: KSB function, and finally at 3000 RPM we have the final 5* advance... . total advance 15*...



The KSB is a "physical or mechanical function" that alters the timing via the closing of a return fuel passage... a physical condition resulting in an increase in pressure which produces an "effective increase" in timing... (is this making sense so far??)



Now since the supply side pressure has risen due to the closing of the return fuel passage, this also alters the pressure of the high pressure side, which, increases the total timing at 3000 RPM.



All of this is directly connected both in the physical sense and the "hydraulic" sense resulting in timing increase..... yes/no??



Now, rotate the pump and add another 5* initial advance... . were are we now for total advance at rated RPM. . ???? 20*???



Now install the governor spring... this thing has a direct effect on the position of the control collar. This collar is also responsible for the "effective stroke" of the plunger in it's barrel...



If you increase the effective stroke you also alter timing in the reverse direction. . to some degree because, the completion of the effective stroke takes longer than it would at minimum value/distance... . another physical condition resulting in an alteration of timing...



Now I take it back... . the timing itself is not the culprit in the loss of the o-ring seal, but the increased pressure is, and so indirectly timing is in the mix... . are you guys buying this... ... . ???



It gets even worse... I think..... there are one or two other things which have an immediate and direct effect on pressure that can be done internally to the 'ole VE.....

One of course is the initial "set" value of the pressure valve on the supply side, and then there is the value of the KSB "opposing spring" which determines the relief stage of the KSB...

Why?? because there is another relief function to save us from ourselves, built into the KSB function... it opens another relief passage if the pressures climb too high, which the "book" says will result in "the failure of a seal or seals and possibly cause permanent damage to the high pressure head... " this relief "valve" is in the form of the opposing spring on the other side of the KSB solenoid... it is preset at a given value and if the pressure in the closed off return port rises too high, it opens and vents fuel back to the tank. . or was it the supply side... . ??? I think the tank. .



Ok, I'm pooped out... . did I go off course here???

One last thing... the "pressure wave" I mentioned... . it has an effect on both the build up of pressure to injector release AND on the closing of the DV, there is a "drawback" function in the DV that impacts this pressure wave. .

and we haven't even gotten to the impact of the delivery valves, the I. D. of the injector lines and resulting increase/decrease of line pressures... BTW, the velocity of sound in diesel fuel is

1500 m/sec. . that's how fast the pressure wave travels... microseconds in each direction... .

For those of you who stuck with me on this lunatic dissertation, take 5 bonus RWHP... .

Pastor Bob... .

 

[hdm48]

Bob, yer scarring me here. I understood what you said.



But,



I think I am right and you are right also. But on a different subject.

I am refering to the pumps physical location on the engine.

You are refering to the pumps internal timing.



Well?????



Now even if we concider the combustion pressure inpacting the injector tip during the injection cycle due to over advanced timing the pressure couldn't push the injector tip back open and send a shock pulse back to the pump and cause an over pressure condition internally do to the diverter valve. Even with the bleed back cut on the diverter valve it couldn't effect the pump itself. The diverter valve does a few things, it delays the pressure to the injector to allow a build up of pressure for a more controled injection, and it also protects the pump from the reverse shock pulse from the injector closing, plus it keeps a neutral pressure in the line between injection cycles to improve possitive timing control. I have modified the spring spacers in the diverter valves with no ill effects. In fact, I gained some free HP. Not sure how much, but I can feel it with my butt cheek-O-meter.

I do agree with you about over timing in the pump. But that would be a internal thing, not external. Right?



Are we thinking of two different things here?



Please correct me if I am wrong.



Your humble sevant

Dave

 

[formula]

I agree that the internal pump pressure is a function of rpm, and that the KSB solenoid does increase the internal pump pressure. However, said pressure is not controlled at all by the base timing of the pump relative to the crankshaft.



There is more to the timing advance mechanism inside the pump than just the solenoid that activates the KSB cold temp advance. It is the timing mechanism itself that is responsible for advancing the timing as rpm increases. The advance piston is attached to the cam roller ring inside the pump. The piston will move as the internal pump pressure increases. This, in turn rotates the cam roller ring against the direction of pump rotation, in effect advancing the start of injection timing. You can see that this effect is the same as what is accomplished by rotating the entire pump..... what you're really doing is rotating the cam roller ring relative to the cam plate. (the position of the cam and pump driveshaft relative to the engine crankshaft remain fixed due to the gear drive system)



The cold advance KSB solenoid activates a bypass on the pressure regulator which raises internal pump pressure. (this is accomplished via the little metal line that goes from the front of the pump near the gear down the side to the KSB solenoid) This increased pressure causes the timing advance piston to go to full advance at a much lower rpm, as well as changing the advance curve.



So, the end result is that the internal pressure of the pump is NOT dependent on the timing, but the timing (only as effected by the advance piston) is dependent on the internal pressure of the pump.



Sean

 

[hdm48]

Oh sure, use big fancy words to say the same thing I did and take all the credit.



Well, kinda.