jfrankhash
Member
Trying to solve my "fouling" issues with the starting plugs. What plugs do you guys use? Anyone tried the anti fouling adapters talked about here several days ago? Thanks, John
- Thread starter jfrankhash
- Start date
The MD uses a Champion D89 D plug. I suppose other plug makers have something similar. This is a special plug with a very long electrode. I've had these plugs in my MD for years and have never had a fouling problem. Are you switching back to gasoline mode to shut down??? Doing that burns out any diesel left in there and should reduce fouling. To shut down, switch to gas, then turn off the gas to the carb and let the engine run until it dies. Then move the switch over lever back to diesel to set the decompression valves on their seats to prevent warping.
Anonymous-0
Well-known Member
Champion's D89D number turned into 543, but still the same plug. Brillman has them, and I've gotten NAPA to order them for me (after they quit laughing). Salty - $6-8 a pop last time. Never had one foul in 50 years of being around those gas start diesels if they're gapped correctly. Also, never shut one off and let it run out of gas, but always made sure to run it through the gas side before shutting down to make for easier start next time. Good luck.
Hello John: Sorry to read that you have more sparkplug fouling.. yet again. I thought more on your plug problem from several weeks ago when it started but quit very soon after starting on gas. Cleaning the plugs seemed to cure it back then but not now again.. I wonder if the rest of the ignition system is giving a good strong spark?? A good strong spark ( somewhat light blue?) will fire a not so clean plug.. if I remember right. Also, your coil is old and maybe getting weak and not generating enough voltage to provide a real good strong spark? Just trying to generate some comments that might help you... agpilot..
Anonymous-0
Well-known Member
Poor explanation on my part - sorry about that. OK, running on diesel, ready to shut down. Increase engine speed, then, as simultaneously as possible, move diesel speed control lever to "full off" position, and move gas/diesel lever to gas position. After engine switches to running on gas and exhaust clears up. leave diesel gov lever in off position and move gas/diesel lever to diesel position. Engine stops with starting valves on their seats to cool as desired. I hope this makes sense now - sorry about the previous failed attempt.
sflem: After allowing engine to cool off for 5 minutes or so, if it was hot, we would switch back to gas for a minute or so and then shut off the ignition switch. Leave the gas line on. a little gas on the cylinders made cranking easier the next morning if it was cold weather. After engine stopped turning we'd pull the switch-over lever back to diesel mode. My father was a diesel mechanic and it was his s-md and I ran that s-md just as he wanted it run. He had read the operators manuel. Never had any cracked head problems. It always started and run better then the gas s-m we also had. ag
Red Mercury
Member
I have a few of the gas start diesels with D89 plugs and have never had fouling problems. You may have another problem. As for shutting down on gas or diesel, I have tried both ways and not really noticed a diffrence (This could start an arguement). If everything is in good shape and adjusted properly, they seem to start just as well after being shut down on diesel. Just my 2 cents.....
rustred
Well-known Member
thats is total crock. no such thing as diesel on the plugs or having to switch to gas to burn it out. the gas is for starting the diesel engine and absolutly no sense to switch it to gas for shut down. diesel never ever see the spark plugs. idle for ten minutes and and shut down on diesel as a diesel should be shut down. and if you dont believe me then start it and get it running on diesel and romove the spark plugs and you will see there is no diesel compressoin getting to the plugs. if there is then you have a problem with the little valves.
How do you know it doesn't get contaminate the plugs when you switch to diesel? The manual says to increse throttle until diesel starts being injected. Then increase throttle and throw lever. That could be a source for contamination. Just trying to add discussion, not really sure it would matter.
Yes, I wondered how diesel could get to the plugs?? However, the manual says to switch to gas, turn off the gas at the tank and let the gas run out of the carb so that the engine stops. Then move the switch over lever back to diesel after the engine stops. This is not a direct quote from the manual, but it's basically what it says. I suppose the engineers at IH had a reason for doing it this way.
rustred
Well-known Member
i know this because there is absolutly no diesel engine combustion that takes place at the spark plugs. it is a separate chamber that when the little valves are open it decreases the compression to allow gas running. as i said the only way is to get diesel contamination on the plugs would be if the small gas valves where leaking. i have not seen a manual that states to increase throttle first , but then i have never looked for starting instructions. but that dont seem right to me. i switch the decompression lever to diesel first, and then give it a little throttle. but if thats what your doing is filling the cyl"s with diesel first then yes you will foul plugs. i really dont think that is correct though. this is the way i have always done it and no problem with plugs or starting cause i am isolating the plugs before diesel reaches them.
rustred
Well-known Member
also ment to say that when your bleeding the system after fuel filter change then you would do the throttle thing first to bleed the system, but that is the only time . if you dont want plugs fouling then run on gas longer like for 4-5 min on start up and let the plugs self clean and then move the decompression first before throttle. shut down on deisel . then you remove a plug and check for fouling before your next start up. i am sure this will answer and fix your problem.
You are correct, not the you doubted it. Here is the quote from the manual. I thought it mentioned moving the throttle before you pulled the decompression lever but that is not so.
The bottom note more than solidifies your comment that the plugs will never see diesel if the system is functioning properly.
The bottom note more than solidifies your comment that the plugs will never see diesel if the system is functioning properly.
There may be some truth in running on gas for shut down might make it start easier, BUT, what are you doing to those comb chambers? You are heating them back up and you just ran it (hopefully) on a cool down cycle. Those decompression valves are getting the full treatment of heat just when you want them cooling. You will get by doing this if you then put it on diesel so they cool on their seats but just plain better to shut down on diesel. You have to remember something about manufacturer recommendations. It is not usually set in stone situation. They sit down at the table like the supreme court does and decide . Not all agree, majority rules or higher up rules, and then they do change their minds as things show up over the years. We rarely went a day without a service bulletin coming in changing something on some piece of equipment.
If the injection pump is not shutting down completely it will foul plugs fairly quickly with dribbling fuel.
Raising the throttle is not supposed to be doable, but the linkage is old and not all that special in the first place and lets it happen. I never overlap them at all. Just isn't necessary.
Leaving the choke on more than absolutely necessary is a problem as well. They load up the manifold way too easy with full choke so I never leave it on for more than 4 or 5 pulses while cranking. 3 is usually the correct number.
Janicholson
Well-known Member
I agree in all regards. I oned one for several years and worked it pretty hard at times. In my mind the instructions are balony. A diesel idling to cool down is far far far less "hot" than a gasoling engine. The idling diesel will thus reasonably allow the coolant temp and iron components of the head to reach equalibrium. Shutting it down by merely reducing the speed control keeps the starting valves shut, and cool.
The engines do not run at all well on gasoline. They are rich in mix, and the total combustion chamber design, with the compression relief chamber and spark plug (of unbelievable electrode length to get into the ratty mixture far enough to fire)is hideous. That little valve is flame drenched in the extreme when running on gasoline, and never seats until running on diesel, or stopped in the diesel mode.
Beyond a reasonable doubt, Jim
The engines do not run at all well on gasoline. They are rich in mix, and the total combustion chamber design, with the compression relief chamber and spark plug (of unbelievable electrode length to get into the ratty mixture far enough to fire)is hideous. That little valve is flame drenched in the extreme when running on gasoline, and never seats until running on diesel, or stopped in the diesel mode.
Beyond a reasonable doubt, Jim
Nothing really, if allowed to run dry. The little valves are not given that final heat up, although it isn't really all that much. Combustion temps are pretty cold considering. I don't set my ignition as retarded as the book says though.
Killing it on gas is different. That leaves fuel in the intake system and they will kick off faster on restart. Have measured it more than once. Given enough time the effect dissipates.
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