my car diesels when warm

[opeldean]

my car wants to keep running when I shut her down.I have to enage the clutch to stop the engine.

I guess its called dieseling.

the carb is a 32/36 weber with the california soleniod shut off.

FWIW- my idle speed screw is turned almost all the way in ...way past the recommended 2-3 turns ..so my throttle plate is opened excessively to maintain the idle.

my carb is recently rebuilt,idles at 1,000,runs good otherwise,gasmilage has been poor at 21mpg combination driving.

cam is a 1970 solid lifter. I dont know when it was last adjusted. I was told it was adjusted about 12,000 miles ago.

i will recheck for vacuum leaks tonight..any ideas on how to attack the problem?

[OrangPeEL]

Always that way or just start? ,,, maybe distributor came loose.
-Dan

[tekenaar]

Originally Posted by opeldean my car wants to keep running when I shut her down.I have to enage the clutch to stop the engine. I guess its called dieseling. the carb is a 32/36 weber with the california soleniod shut off. FWIW- my idle speed screw is turned almost all the way in ...way past the recommended 2-3 turns ..so my throttle plate is opened excessively to maintain the idle. my carb is recently rebuilt,idles at 1,000,runs good otherwise,gasmilage has been poor at 21mpg combination driving. cam is a 1970 solid lifter. I dont know when it was last adjusted. I was told it was adjusted about 12,000 miles ago. i will recheck for vacuum leaks tonight..any ideas on how to attack the problem?

Is the ICO (idle cut off) solenoid hooked up to a "switched" 12V source (right horn black-yellow wire)? I STRONGLY suspect it's NOT and this is why your carb idle settings are mal-adjusted to compensate. ICO solenoid COMPLETELY shuts off all fuel in primary idle circuit to prevent "dieseling"!

[OrangPeEL]

Wouldn't intended purpose of that solenoid be CA emissions related (stop unspent fuel from entering atmosphere from opeldeans tailpipe during wind-down) rather than controlling his run-on?

Once fuel is in opeldeans combustion chamber (regardless of potential carb mis-adjustments/passages metering it there to keep it idling key-on) how does that fuel continue to ignite w/o coil - key-off ... if not flashing from inefficient-burn-cyl-temp, or maybe carbon deposits?

So now I'm just stuck (naively ) thinking there's two separate issues... idle FUEL supply per previous tekenaar post (rqrd/adjd crack of throttle plate for idle)... & retarded->artificial->IGNITION & dieseling (starts easy, ignites fuel, but takes useable calories from rear wheels & loads'em into block). Take no mercy on me... SET ME STRAIGHT!

Thanks!- Dan

[Dmcbrass]

Several things can contribute to dieseling.
1. Incorrect timing (causes increased engine cylinder temperature)
2. Idle speed set to high. (cylinder compression will be elevated at the instant that the ignition system cuts out)
3. Engine running too rich at idle. (leaves unburnt fuel in cyllinders)
4. Engine running too lean (increases engine cylinder temperature)

These are the most common and the easiest to correct.

[tekenaar]

Paraphrasing my answer to Rüdiger in Germany and his translation of it more than 3 years ago:

Originally Posted by tekenaar -----Original Message----- On Sunday, July 01, 2001 8:49 AM Otto Bartsch wrote: > Rüdiger, > This is called an "Idle Cut Off" solenoid. It is an electric solenoid which > only allows passage of fuel in the idle circuit when powered (i.e.. key is > on). When you turn the key off, the needle returns to the seat and shuts > off fuel in the idle circuit, preventing "run on" (dieseling) of the engine. > This used to be a big problem some years ago when the auto manufacturers > leaned out the mixture for better economy and reduced pollution. > > Most modern carburetors have this device as a pollution control. Idle > mixture is still adjusted the same way, but this solenoid is now in the fuel > passage rather than just an idle jet, so it will shut the fuel off immediately > when the key is turned off. In the 32/36 carb, the ICO and idle jet holder > have the same thread and are completely interchangeable. Does that help? > Leider kann ich daß nicht mehr so gut auf Deutsch erklären. > > Otto > From: Rüdiger Cordes [mailto:ruedigercordes@t-online.de] Sent: Sunday, July 01, 2001 5:21 PM To: Otto Bartsch Subject: Re: [Opel] ICO Solenoid? Hei Otto! Ich versuche mal zu übersetzen, dann siehst Du, ob ichs verstanden habe. Also Solenoid weiß ich ja noch, daß das ne einfache Spule (Wicklung) ist. Elektromagnetisches Ventil für Leerlaufbenzinabschaltung. Deutsch ist doch ne schöne Sprache, oder? Schnelleres Absterben des Motors beim Abstellen der Zündung durch eben kein Benzin mehr. Das ist klar. Erstaunlich finde ich, daß der Leerlauf über Benzinmenge eingestellt wird. Eigentlich dreht man ja lieber an Lufteinstellschrauben. Ich überlege gerade warum. Wahrscheinlich ist die Einstellung von Luftmengen feinfühliger möglich. Da Benzin als Flüssigkeit nicht komprimierbar ist, bedeutet schon eine kleine Änderung an der Schraube eventuell eine große Wirkung. Ach ja, Luft braucht der Motor ja die 17fache Menge, somit ist ein größerer Strom auch feiner einstellbar. Gute Nacht und danke! Rüdiger

Alles Klar?

[OrangPeEL]

Dang... Sorry Otto- not quite clear yet, maybe close! (bare with me... feel I'm tilting on the edge of a "great understanding" & may need one more shove- or slap to back of my head). Also, since this is opeldeans post, I'm really feeling guilty for dredging around in it (sorry!)... I'll stop after this (& try to save face with, "ahhhh... now I understand"):

Thanks for ICO insight... all functions make good sense. Still I'm stuck on emissions vs. runability, and ICO as pertains to opeldeans rejetted, 32/36, CA-state application specd, aftermarket carb & his delivered fuel igniting w/key-off. I have same? 32/36 carb (but non-CA-spec), ;probabily jetted dfrnt for my stock eng. I idle at 950-1000 off idle passage. When I shutdown (from idle -or- P.O.T.) I don't diesel. Without an ICO... shouldn't I experience a diesel... at least once in a while?

Thanks- Dan

[opeldean]

thank you all, I have not followed up on all your carb recommendations...yet

I DID make sure I had a good connection at the idle jet solenoid. I checked for current with the key on and off. I sanded the contacts the coated with battery terminal protectant. power is good to the solenoid. I will eval and let you know. In the middle of this project ..I drove to lunch..found out my tie rod was shot... so I had to stop the diesel project and work on the tie rod.

bad wobble ..I ordered a tie rod from OGTS today..loose as a goose on the
inboard side.

PS: tekenaar..isnt the car supposed to pull to the left when I brake hard?
I thought all 33 year old cars did this somewhat.

also..when I hit a bump on the left side or sometimes turned..suspension would make a "pop" sound.

PSS: someone once asked me if I had a lot of trouble with my car, not really..
for a 33 year old daily driver..it has been quite economical.

[tekenaar]

Originally Posted by opeldean thank you all, I have not followed up on all your carb recommendations...yet I DID make sure I had a good connection at the idle jet solenoid. I checked for current with the key on and off. I sanded the contacts the coated with battery terminal protectant. power is good to the solenoid. I will eval and let you know. In the middle of this project ..I drove to lunch..found out my tie rod was shot... so I had to stop the diesel project and work on the tie rod. bad wobble ..I ordered a tie rod from OGTS today..loose as a goose on the inboard side. PS: tekenaar..isnt the car supposed to pull to the left when I brake hard? I thought all 33 year old cars did this somewhat. also..when I hit a bump on the left side or sometimes turned..suspension would make a "pop" sound. PSS: someone once asked me if I had a lot of trouble with my car, not really.. for a 33 year old daily driver..it has been quite economical.

You were kidding, right?!! Even a 30+ year old car should stop straight with suspension, steering and brakes in good repair . . . age has nothing to do with this, good repair does. To answer your question, car will pull to the side with the bad tie rod.

[tekenaar]

Originally Posted by OrangPeEL Dang... Sorry Otto- not quite clear yet, maybe close! (bear with me... feel I'm tilting on the edge of a "great understanding" & may need one more shove- or slap to back of my head). Also, since this is opeldeans post, I'm really feeling guilty for dredging around in it (sorry!)... I'll stop after this (& try to save face with, "ahhhh... now I understand"): Thanks for ICO insight... all functions make good sense. Still I'm stuck on emissions vs. runability, and ICO as pertains to opeldeans rejetted, 32/36, CA-state application specd, aftermarket carb & his delivered fuel igniting w/key-off. I have same? 32/36 carb (but non-CA-spec), ;probabily jetted dfrnt for my stock eng. I idle at 950-1000 off idle passage. When I shutdown (from idle -or- P.O.T.) I don't diesel. Without an ICO... shouldn't I experience a diesel... at least once in a while? Thanks- Dan

Originally the "lean-burn" carbs were jetted on the lean side (>14.7:1) to reduce emissions. Leaning out the carb causes the combustion temp to increase considerably, which burns more pollutants but is also likely to cause "dieseling/run-on" when turning the engine off.

"Dieseling" (auto-ignition) is not only very hard on the engine, but creates a lot of pollutants and is, of course, counterproductive to what they were trying to achieve with the "lean-burn" carbs in the first place. That's why manufacturers began using ICO solenoids to prevent "dieseling/run-on" of their "lean-burn" engines.

Manufacturers didn't want their customers to think that there were any inherent design problems with their "lean-burn" engines, which "dieseling" is of course. So they called it an anti-pollution device (the result and positive) to deflect any references to "dieseling" (the cause and negative). This is purely a marketing ploy, nothing else. It all depends on how you look at it . . . which came first, the chicken or the egg!

To answer your specific question, if your carb is correctly jetted for your engine, it will NOT be too lean or rich, for that matter, and, as long as the idle RPM is set properly, will shut down without "dieseling" as soon as the ignition is turned off . . . no more spark to ignite any mixture in the combustion chamber.

[OrangPeEL]

Originally Posted by OrangPeEL I'll stop after this (& try to save face with, "ahhhh... now I understand"):

Otto!- "ahhhh... now I understand"... really, I do- Thanks!
opeldean, I'm on edge seat pending diesel cause/source outcome!
-Dan

(PS/warning/advance sorry... I have just spotted another post to meddle in)

[opeldean]

I think it is fixed.
solenoid was wired, but the brass piece was not real snug. I checked power to the solenoid with my voltmeter .it was good and functioned with ignition on/off.

then I cleaned and bent brass in on contacts, coated with battery terminal protectant and everything is fine in the few short trips that I have used it. I think its fixed.No diesel yet.
thanks tekenaar..I was going to look at other things first.

[Old Hippie]

:o I love a happy ending!

[opeldean]

ps:oh by the way oldhippie..are you still up for the OMC newsletter? I guess you have to be put on the ballot. I would like to be your campaign manager.
Call Gill at OGTS as he is on his last newsletter. With your skills ,you will be perfect.

as soon as you confirm I will start putting up signs in the neighborhood.

[Old Hippie]

I didn't know I was! It may be something I could help with after the first of the year. As of this point in time, my wagon is pretty full:
1) prepping small house for sale
2) trying to get the QA super job at work
3) making sure it's smooth sailing with the wife (4 yr seperation!)
4) and most important ( well, second most) building my Opels a new house!
I'm not sure how my field of work (electronic tech/QA Insp) could be of use. I'm thinking someone in the editorial world would be better. Like RallyBob, who can do mech-addins (he's a wiz) on the side, I could send in things of that nature. There's a lot of intelligent folk here much more qualified. I'm just a "Old Hippie" backyard mech-in-nic that remembers cars with points.

[namba209]

Opeldean, that was Stephen, AKA OldOpelGuy, that hinted he would do the OMC Blitz. Last Saturday was the first time Gil was aware he was interested in the position of editor.

[greensmurf20]

Gil isnt part of this website is he?

[namba209]

Jared, I don't believe he is a registered member of this site, but he is aware of it. At the OMC picnic there was some interest shown in a kit to do the 60 degree V-6/T-5 mod I'm in the process of doing. We discussed this for a very short time, and included some of the pitfalls that could arise because of the various configurations of the engine. Gil is aware of my project, in fact it was he that turned me on to his contact that got me the ZF posi, and I told him he could use anything I've done that would help, if he wanted to pursue building a kit. I gave him and others this website and the directions to get to the Articles of what I have done so far. As a side note, during the rafflle, Gil was giving out a whole lot of items he sells, and I did win one of the items, but opted to not take it, because, as he said, I already bought the store.

[opeldean]

today was warmer and my trips were longer.

I am dieseling again.

all my jets are "tekanaar' except for 1! and that is the original one on the solenoid. at the start of my rebuild ,I ordered 6 tekaneaar jetes from racetep. all 5 fit, but the 6th (idle) jet wouldnt fit to the solenoid. I noticed the hole in the idle jet of the primary was bigger than the tekanaar jet of the idle jet in the secondary.the current idle jet is not labeled or numbered as to size.I just know the hole looks bigger to the eye than the secondary.

I had to reuse the existing idle jet and its solenoid as the carb it made to have a solenoid.we tried to jet use the 6th tekanaar jet w/o the solenid but it wont fit, i guess I needed a holder for the jet which I did not have.

my car runs great, but I diesel when hot and my idle speed screw is turned way,way in..almost bottomed out.

what is my order to attack problem?

[tekenaar]

When engine is at operating temp:
1. what is your idle RPM?
2. where on temp gauge is the needle?

You talk about "idle speed screw" being all the way in, is that the idle mixture (IM) screw (mounted at angle in throttle base plate) or the primary throttle stop (PTS) screw (hex head, slotted screw with spring directly underneath choke lever)?

Your mixture screw in base plate s/b about 1.5 turns out from LIGHTLY seated position. When you turned this in, did your RPM drop and the engine begin to stumble? If not, your primary throttle-stop screw is in too far holding the primary throttle open too much resulting in too high idle RPM and the mixture screw having little, if any, effect.

On your engine with my base line jetting, forget about ICO, you should be able to achieve 750-950 idle RPM easily. Sounds to me like your primary throttle stop screw is turned in too far, so I would back it off to decrease engine idle RPM.

1. Engine not running, turn in (CW) idle mixture screw until seated LIGHTLY!!
2. Turn out (CCW) idle mixture screw ~1.5 turns, start engine and bring to operating temp.
3. Engine running, adjust PTS screw CCW until engine idles ~750-800 RPM.
4. Engine running, turn IM screw CW (in, leaner) until slight RPM surge (~50 RPM higher, lean surge).
5. Engine running, turn IM screw CCW just enough to smooth out idle RPM, s/b slightly less.
6. If engine RPM increased more than 100 RPM during previous steps, adjust PTS screw CCW a bit more to lower idle RPM and repeat IM screw steps.

[opeldean]

I think I have a lean condition. Car is not idling fast, but needs the throttle plate cracked open ( by over tightening the throttle plate hex head screw)

as a last hope,I tried to adjust timing to speed the idle so I could close down the throttle plate hex head screw,this helped a little but car would ping.so i went back to the way it was.

Prior to my carb rebuild and the changing to tekannar jets, the throttle plate hex head screw was somewhat over tightened to maintain the idle. I think the tekannar jets were a little smaller as I think I had 170 /140 and 180/140 and 50+50 for idle jets.I dont recall having the dieseling problems with my old jets.Seems like i have a leaner condition than before due to some other prior problems somewhere else besides the carb.

car does run great,but It diesel's in the summer, and I know its not a good thing to have the throttle plate opened as much as it is. The idle mixture screw is not a factor in my adjustments.car will not idle without the throttle plate opened.

1-I know this is a long shot, but I have never had a car drip so much black water type condensation out the back muffler at start up.what is the chance that I am burning coolant?

2- doesnt this sound like a vacuum leak? Its too late to fire up my glass packs tonight, but maybe tomorrow I will look using the carburetor cleaner check method.

3-seems like a lean condition? yes or no?

[opeldean]

I tried to trouble shoot it

[GTJIM]

I would suspect that the anti-diesel idle jet is not openning properly or even not openning at all so you have to crank open the throttle plates to idle on the transfer passages.
Have a real good check that the electrical connection to that horrible idle jet is actually working as it should. Take the jet out and operate it off the car to see if it opens. HTH

[greensmurf20]

on my GT, also have the anti diesel solenoid. when the hood is up and you stick your head out the door a little bit, you can hear the solenoid "click" when you turn the key off or on. can you?

[tekenaar]

Originally Posted by GTJIM I would suspect that the anti-diesel idle jet is not opening properly or even not opening at all so you have to crank open the throttle plates to idle on the transfer passages. Have a real good check that the electrical connection to that horrible idle jet is actually working as it should. Take the jet out and operate it off the car to see if it opens. HTH

From your answers to my questions, I concur with the second part of GTJIM's analysis. Best way to test, unfortunately, is by replacing ICO solenoid assembly with regular idle jet holder and recommended idle jet OR another "working" ICO solenoid.

With idle circuit completely out of the picture (ICO inoperative), you're basically "idling" on your transition ports, as GTJIM said, and this is why you can't adjust your idle normally. This is also why your primary is running slightly lean at all throttle positions, because your idle port is completely blocked off.

So, overall primary lean condition causes higher combustion temperatures and, because now your "idle" gas flow is NOT shut off with the key (actually idling on transition ports), will result in near perfect conditions for dieseling.