Where's the GLOW??

[ERMiles]

Here's a possibly dumb question - but I'm an old time diesel guy. My Mercedes 190 and Kubota both have glow plugs. What is providing the glow in the Cummins? What, exactly happens during the preheat? I ask because I recently changed injectors (Bosch factory spec. ) and it runs great except when it's starting on a cold morning. It idles very rough for a minute or so which it didn't with the old injectors.

 

[Lil' Dog]

First off , there are no dumb questions. . Hopefully we can help.



In the pre-heat cycle the Cummins uses a "grid heater" in the intake manifold to heat the incoming air and aid in starting. The Cummins engines do not require glowplugs as they are direct injection engines unlike early Frods, and Shuffys. Also the pump timing is altered to allow easy starting with the KSB Solenoid.



As for the rough start, timing is the issue. Now that can be the actual pump timing or that the KSB is not properly functioning.



I have the same problem with rough running until warm, I believe mine to be absolute timing as it has never been adjusted and my old 89 was out by 5° at 180,000 Km. After the tuneup it ran like a top.



Also the rough idle might get smoother with a valve adjustment. Helped mine a bit.



Hope that helps. .



J-eh

 

[BushWakr - RIP]

Ya, what Lil Dog said...

Also when the grid/fuel heaters cycle they will draw down quite a bit of juice. You'll notice the alt. gauge cycling quite drastically, accompanied by a clicking noise. This will slowly decrease in intensity and duration as things warm up. Mine starts kicking in around oooohh 55*F or so. At this temp it only cycles on for about 4-5 seconds(accompanied by 'wait to start' light), 3 or 4 times then stops.

The more tired your battery the more of a swing i've noticed in the draw down on the gauge.

FWIW



Merry Christmas !



Bob

 

[ERMiles]

Thanks, Dog and Whacker for the enlightenment. I'm gonna check the timing since I had the valves adjusted last spring. Is that something a Cummins shop would do or the Bosch facility? (I'm trying to avoid the local Dodge dealer) One other question - what ignites the fuel inside the cyllinder? Pressure?



Happy holidays to all!

Smiles

 

[Lil' Dog]

Does anyone have the URL of that diesel site??? There is a site that will run you through the diesel history and process.





Anyhow the diesel fires with a combo of pressure and temperature. With the high compression pressure the internal temperature is also quite high. Typical compression #'s for a new CTD are around 400 psi I think. The diesel is sprayed in and ignites immediately just before TDC, around 10°.



The site I was talking about was great for all this kind of stuff. I'll see if I can find it...



Merry Christmas



J-eh

 

[AlK]

Hi Jason,

Is this the site that you are looking for?

http://www.howstuffworks.com/diesel1.htm

---

Al

 

[Lil' Dog]

Thats one, but no, not quite. I haven't had a chance to look very hard. The one I was looking at had more stuff related to Cummins with some general knowledge thrown in.



Thanks Al!!



J-eh



(edit) as for the timing, get a good shop to do it as there are very specialized tools required for this.

 

[BushWakr - RIP]

How about this link on the Diesel Injection Service web page...

http://www.dieselpage.com/tipshis.htm



Merry Christmas !



Regards, Bob

 

[TxDieselKid]

had to do a double take...

When I first saw the title of this thread I thought it was refering to the old GLOW-Gorgeous Ladies Of Wrestling.



Great links though.



Andrew

 

[DieselBuzz]

Talk about glow

Have you ever been driving at night when the the grid/fuel heaters kick in? I've seen brighter candles, that's why I let my truck warm up.

Art