timing and ksb

[swankmetal]

so, if timing has been advanced, should the ksb be disconnected? just remember reading about excessive timing causing high cylinder pressures. or is that just under load/upper rpm's?

 

[bgilbert]

Yes unplug it, you don't need it. Thats the last thing you need is that extra advance, don't know exactly how much it advances, but if you're already advanced, you can blow an o-ring in the pump or something. I'm sure someones else will chime in on this topic.

 

[Greenleaf]

It's the old, dry rotted O rings that leak. Internal pump psi ain't the problem, it's your old O rings. Get yourself the seal kit and replace all your seals/O rings. If you doubt your abilities to tear into a pump, I know somebody that can help.



GL

 

[cerberusiam]

The KSB only advances on cold start and in no way effects the overall timing the pump is going to develop. Disconnecting it only stops advance when its cold. As the rpm's come up the pump pressure increases internally and acts on the same mechanism the KSB does.



Disconnecting it just slows down the warmup and leaves unburned fuel in the cylinders.

 

[jaynes]

i'm confused

I always thought when the ksb was energized it stopped the cold advance mode. After my truck warms up, and when the ksb is "energized" or "de-energized' (i forget which is is) the idle rpms come up just a hair and the engine losses just a bit of it's growl; kind of more like a smoother sound and not so much like a flowerpoke. If I leave it unplugged, it will keep that harsher growl, the idle rpms stay down AND i notice it blows a bit more smoke. Since my pump is advanced, I leave it plugged in because of the change in sound. I thought when it growled that much that the ksb is advancing the timing a bit more for cold weather warm ups. So i guess I'm alittle confused on the subject.



jaynes

 

[Greenleaf]

I'd have to get into my manual to say how it works exactly. I don't want to steer you wrong. I can tell you that it will advance the internal pump timing by increasing the internal pump pressure. This, in tern, will serve to increase the timing by moving the timing advance piston towards the advance mode. Piston moves towards the engine.



The sensor in the intake manifold will signal when to advance and when not to. I don't recall the temps, I'd have to look it up as well.



If you have your static timing advanced a good bit you may not require as much advance when starting as one with out advanced static timing. Not all the VE pumps have an advance start mechanism. I don't use my KSB. I have experimented with it and notice no difference in engine performance. I also experiment with engine timing as well. When energized it's advancing the pump's timing. There is a resistor used in line. The solenoid needs 10 vdc.



Hope this helps you out some



GL

 

[cerberusiam]

Working from memory, when the KSB is energized it closes a spill port on the timing advance causing the bumpy disk to rotate to advance position. When it deenergizes it opens the port again drop the advance.



Some pumps don't have the KSB and some have a KSB that works opposite of what my truck does. Not sure if it works the same way on the older models. I would suspect the pumps without KSB are not subject to emissions standards as I think the main reason for advance at cold is to help the burn cycle and cut down pollution.



JMO

 

[jaynes]

Yeah, I think mine might work opposite. When I don't have it plugged in it seems to be in a permanent state of cold start advance, hence the louder growl, and when it's plugged in a warmed up, it smooths out a bit, so I think it has to be energized for that to happen, infact I read in the manual last night that when it is 59 deg or below, there should be no volts at startup and until a certain temp is reached, when at that point, it supplies voltage to the little heater to make the wax pellets expand to to open a spill port to the low pressure side to reduce the advance... . or something



jaynes

 

[swankmetal]

so once the rpm's come up, it's not really doing anything? am i understanding that correctly cerberusiam? what's going on is, my temp sensor just went out the other day and i advance the timing the day after. just wondering if i need to get a new sensor and hook that thing back up or not. oh yeah, so cylinder pressure is NOT an issue at idle? thanks, dave

 

[Greenleaf]

The Cummins manual and quite possibly our trucks FSM give very clear instructions as to how to test the KSB Cold Start Advance System. You'll find both the wax motor and the electrical solenoid style. Each is tested differently as they are not entirely the same.



I would highly suggest that all the guys who intend to perform even the most minor repairs to insist upon a FSM or the Cummins B Engine Repair Manual as a Christmas gift.



There is so much to learn by simply setting down with your favorite cup of Hazel Nut coffee and reading all about our engine.



Just do it.



GL

 

[JLEONARD]

your favorite cup of Hazel Nut coffee

:-laf :-laf

 

[cerberusiam]

your favorite cup of Hazel Nut coffee

Blechchch! Foo foo stuff! Iffn it don't melt the spoon and the horseshoe don't float its colored water.



My understanding is the KSB doesn't add to overall timing advance. Can't find anywhere that says that or disputes it so not sure.



Now if the person with VE manual in his back pocket and time on his hands would contribute we would have a solid answer.



Yoo hoo, he with all the answers, watchya got fer us.

 

[Greenleaf]

I don't have any of the manuals in my pocket, nor do I have all the anwers and not near enough time



However, I can offer what I do have...



I counted twenty pages in the Cummins manual covering the KSB as well as "several" pages in the Bosch manual. If there is someone out there that can "post" some of this info ,that would be great. I'm not very computer savy, sorry. I'd have to set down and "quote" the books.



In short. Yes, the KSB advances the pump's timing by increasing the interior pressure. It is emissions related. It is not functional after the engine warms up.



The manual(s) state specifically what the system does, how, where/when it's used and why as well as how to test each individual component.



I'd be happy to answer a specific question... . by quoting the manual(s)



Scott

 

[JLEONARD]

I have a copy of the Bosch VE manual in pdf format. Who ever wants a copy to read the surprising facts on how it functions, feel free to e mail me for a copy at:

-- email address removed --



But do it today or tomorrow or you may have to wait until next year to get it (I'm out thursday thru most of next week).

Jay