BACKFIRES!!! D15 II
Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=153460
Printed Date: 11 Aug 2025 at 12:09pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: BACKFIRES!!! D15 II
Posted By: NewToMe
Subject: BACKFIRES!!! D15 II
Date Posted: 28 Aug 2018 at 9:17pm
| Hey guys i need some help. My D15 II keeps backfiring when i turn it off while running everything runs smoothly i don't know what the issue could be the muffler is a little sketchy and not taken care of it has aluminum foil and a hose clamp holding it up.....in the process of fixing it but wanting to know if this could be the cause of the backfiring. Any help would be great!!!! |
Replies:
Posted By: Tracy Martin TN
Date Posted: 28 Aug 2018 at 9:18pm
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Carbon build up or timing slightly off. Need to fix it, might break your crank. Tracy ------------- No greater gift than healthy grandkids! |
Posted By: NewToMe
Date Posted: 28 Aug 2018 at 10:21pm
| Thanks Tracy, where abouts would i find the carbon build up (location) and ill check the timing |
Posted By: Jim Hancock
Date Posted: 29 Aug 2018 at 2:57am
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The carbon buildup will be in the combustion chamber in the head. Probably some on the valve head, too. ------------- How blessed we are by HIS GRACE! |
Posted By: NewToMe
Date Posted: 29 Aug 2018 at 5:04am
| Ok thanks a lot I’ll have a look this weekend |
Posted By: DiyDave
Date Posted: 29 Aug 2018 at 5:09am
| also, a bad condensor can cause backfires... |
Posted By: jaybmiller
Date Posted: 29 Aug 2018 at 6:27am
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Yeah, I agree with Tracy, carbon buildup. I've seen a small rider with so much carbon buildup, it'd run like a diesel ! Carbon builds up from running too rich, too long, maybe bad plugs, weak coil, choke partially on. You'll need to remove head and remove the carbon. Be sure to drain the block FIRST though..... and take a few pictures ! Helps putting stuff back on the right way and always nice to see them here !! Jay ------------- 3 D-14s,A-C forklift, B-112 Kubota BX23S lil' TOOT( The Other Orange Tractor) Never burn your bridges, unless you can walk on water |
Posted By: Pete from IL
Date Posted: 29 Aug 2018 at 8:22am
| The only time my D-17 backfires after shutting it off is when I don't let it cool down and throttle all the way down first and the unburned gas will ignite in the muffler and give a loud bang. I can't see what difference timing would make once the key is shut off. There is no spark once the key is shut off. I would not go pulling the head until the idle is set low and you allow it to cool and throttle down before shutting it off. |
Posted By: Dave H
Date Posted: 29 Aug 2018 at 9:05am
|
exactly what Pete says |
Posted By: Tracy Martin TN
Date Posted: 29 Aug 2018 at 10:29am
------------- No greater gift than healthy grandkids! |
NewToMe wrote:Posted By: DrAllis
Date Posted: 29 Aug 2018 at 12:06pm
| The engine must slow idle at 400 RPM. It must be allowed to idle at this slow speed for maybe 30 seconds or more before shutting off the key. Cheap gasoline will aggravate your problem. Improper ignition timing can also add to the problem because the combustion chamber temps will be hotter. My money says you aren't idling it slowly and long enough. Pulling a cylinder head ?? Not on my watch. |
Posted By: WF owner
Date Posted: 29 Aug 2018 at 1:52pm
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Back when we were teenagers, an older lady would come to our local mechanic a few times per year for the same problem with her car. (I don't think I ever saw her drive over 30 mph.) He would "mist" the intake with water for several minutes, with it idling, then take it out and drive it hard. Problem solved!!! None of us young guys seemed to have any problem with carbon build up...
|
Posted By: NewToMe
Date Posted: 29 Aug 2018 at 7:04pm
| REALLY GOOD POINTS, ill try slowing down the RPM first before turning it off, if that doesnt work ill give-er the old sea foam from there ill check the timing. Thanks for the help ill post some pics of the progress! |
Posted By: NewToMe
Date Posted: 29 Aug 2018 at 7:14pm
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Posted By: AC720Man
Date Posted: 29 Aug 2018 at 7:56pm
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Ethanol gas is terrible for older engines, especially small engines like lawn and garden, chainsaws and so forth. Buying nonethanol fuel will help. Seafoam in the tank as specified on the can will clean the fuel system, combustion chambers. Do not pull the head. ------------- 1968 B-208, 1976 720 (2 of them)Danco brush hog, single bottom plow,52" snow thrower, belly mower,rear tine tiller, rear blade, front blade, 57"sickle bar,1983 917 hydro, 1968 7hp sno-bee, 1968 190XTD |
Posted By: NewToMe
Date Posted: 29 Aug 2018 at 8:47pm
| Thanks for the info AC720Man just seeing if i should pour it in the gas or stall it out through the carb with the spray, i literally just bought this tractor Thursday last week, the owner before said he put premium gas in it, maybe i should empty the tank and put some fresh premium in with the sea foam liquid in the tank? |
Posted By: DSeries4
Date Posted: 29 Aug 2018 at 8:54pm
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Don't use premium in these things. Just a waste of money. These things were designed to run on low grade fuel. Dr. Allis called it right. You have it idle it down low for a minute. Mine does the same thing. The carb could also be set a bit rich. ------------- '49 G, '54 WD45, '55 CA, '56 WD45D, '57 WD45, '58 D14, '59 D14, '60 D14, '61 D15D, '66 D15II, '66 D21II, '67 D17IV, '67 D17IVD, '67 190XTD, '73 620, '76 185, '77 175, '84 8030, '85 6080 |
Posted By: WF owner
Date Posted: 29 Aug 2018 at 8:56pm
| The only way we can buy ethanol free gas in our area is to purchase premium. |
Posted By: wbecker
Date Posted: 29 Aug 2018 at 9:50pm
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What Pete from Il & Dr Allis said. Also with the bad muffler on it there may be some very thin sheet metal in the muffler that gets hot and ignites the fuel air mixture that is drawn in after the ignition is off. Let it idle slow before shut down, and make sure the idle speed is not set too hi. ------------- Allis B, IB, Low B, G, D10, JD M, 8KCAB, C152 |
Posted By: HD6GTOM
Date Posted: 29 Aug 2018 at 10:03pm
|
I been using ethonal in everything since the 1970's and have never had 1 problem with it. My chain 15+ year old Echo chain saw is now running on E15. I don't think it has ever run this good. B and WD45 are still on E10. As soon as the get low they will get the E15 too. Do as DoC Allis says, need good. |
Posted By: AlexT
Date Posted: 30 Aug 2018 at 6:51am
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Chech the valves sometimes if they are loose it will cause similar problems |
Posted By: AlexT
Date Posted: 30 Aug 2018 at 6:51am
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Chech the valves sometimes if they are loose it will cause similar problems |
Posted By: DrAllis
Date Posted: 30 Aug 2018 at 7:06am
| That is NOT a series 2. |
Posted By: modirt
Date Posted: 30 Aug 2018 at 7:43am
|
This thread caught my attention, as I have been working to revive an older D15. At the conclusion of one of the test fires, she did backfire once. That caught my attention. So I"m following. My recollection of gas engines is that backfires are generally caused when the carb is set either too rich or too lean, and/or the timing is off. A dirty engine and exhaust can also be responsible, but usually that only happens when there is enough unburnt fuel in the exhaust to ignite. So where is the source of the unburnt fuel? Too rich a mix, or dirty valves that aren't closing all the way? And something in the exhaust hot enough to ignite it? Letting a hot engine cool down before shutting it off was something I was taught from birth, and is especially true of engines with a turbocharger on them. I cringe when I see the mechanics and service guys from the local lawnmower shop start the engine on my zero turn mower, run it up full throttle and leave it there when they kill it. Most of the commercial mower jockeys I've seen do the same thing. Maybe the shops encourage this so they can sell more new mowers to replace the one's with blown engines? The main benefit of ethanol is it a transportable liquid fuel you an pour into your gas tank and it will get you up and down the road. But it brings with it a host of problems. The two most notable for engines not designed for it and those that sit unused for any length of time is that ethanol is an alcohol and alcohol is hydrophilic, which means it likes water. Water is drawn to it. So over time, you tend to get water in your gas. This feature alone causes some folks fits........the worst I've heard of are folks living on offshore maritime islands in places like Maine, who have to store their fuel in jerry jugs they haul back to the island and store for weeks or months on end. The climate is humid and wet and the stored fuel is quickly contaminated with water and their engines won't run. Not good when you livelihood, health, safety and perhaps life depends on a running engine. Second issue is ethanol is a solvent and will eat some types of plastics and rubber. Almost all of my 2 cycle engines that were not designed for ethanol had to go in for service to have gaskets, diaphragms and other rubber parts replaced, as most had fallen apart. |
Posted By: SteveM C/IL
Date Posted: 30 Aug 2018 at 8:01am
| Hey Mo,The sticker on my 05 zero turn w/ Kohler engine says to kill engine at half throttle or more. The manual with the new engine said the same.Here is the reason why. Kohlers have fuel shut off solinoid in carb.If you idle down a hot engine and kill it,it pumps that last bit of fuel mixture into the muffler and you get one heck of a belayed boom in the muffler. I f you follow instructions it never does it because it flushes that last mix on through while coasting down to stop. Don't think it's hard on air cooled N/A engine. Mine takes a good bit of idle time before it wont self ignite which isn't convenient. |
Posted By: modirt
Date Posted: 30 Aug 2018 at 8:18am
|
Good to know. Mine also has a Kohler engine.....about 2016. EFI on this one. I was always worried also about the excessive heat, warped heads, etc. |
Posted By: SteveM C/IL
Date Posted: 30 Aug 2018 at 8:34am
| My guess is that unless you are bush hogging with that yard mower,you never really work the engine hard enough to create excess heat which may cause bad thinks when shut down without cool phase. I didn't engineer it so cant say for sure. |
Posted By: Bear Taylor
Date Posted: 30 Aug 2018 at 1:09pm
| I know it is old school but my dad and grandfather trained me to allow all motors to wind down a bit before shutting them off. Motorcycles, cars, trucks and my tractor get a little idle time before shutting them off. Chainsaw and log splitter motors too. |
Posted By: NewToMe
Date Posted: 30 Aug 2018 at 5:18pm
| Its not a series II DrAllis but doesnt it have the thumb guard? |
Posted By: DSeries4
Date Posted: 30 Aug 2018 at 9:13pm
|
All D15s have the thumb guard regardless of series. My 1961 Series I has it, so does my 1966 Series II. Yes, that is definitely a Series I you have there. A few less ponies, but still a great tractor. ------------- '49 G, '54 WD45, '55 CA, '56 WD45D, '57 WD45, '58 D14, '59 D14, '60 D14, '61 D15D, '66 D15II, '66 D21II, '67 D17IV, '67 D17IVD, '67 190XTD, '73 620, '76 185, '77 175, '84 8030, '85 6080 |
Posted By: NewToMe
Date Posted: 30 Aug 2018 at 9:43pm
| Just wondering how you can tell |
Posted By: DrAllis
Date Posted: 31 Aug 2018 at 7:14am
| The serial number for one thing. Series 2 models have an oval muffler and a dry air cleaner. They also have headlites on the fenders. They don't have rivet on emblems on the hood sides. |
Posted By: NewToMe
Date Posted: 03 Sep 2018 at 10:08pm
ok guy i tried a couple things over the weekend, i added a can of sea foam to the gas i was waiting for a lot of smoke but didn't happen...sounded a little better but it was running smoothly before, and then i went to the carb fiddled around with the amount of gas going to the engine turned it down a little and found out that settled the after firing to a minimum but it still happens but not like a cannon going off. 
|
Posted By: NewToMe
Date Posted: 03 Sep 2018 at 10:16pm
im not sure if this is a sensor or what else could it be, maybe some one or one of you could tell what its for or from. its located on the head of the engine right behind the manifold
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Posted By: Tracy Martin TN
Date Posted: 03 Sep 2018 at 11:14pm
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That is the heat sending unit. Goes to the temp gage. HTH Tracy ------------- No greater gift than healthy grandkids! |
Posted By: NewToMe
Date Posted: 04 Sep 2018 at 4:23pm
| Temp gauge like water temp? |
Posted By: Jim.ME
Date Posted: 04 Sep 2018 at 4:31pm
| Yes, the water (engine coolant) temperature gauge. |
Posted By: NewToMe
Date Posted: 04 Sep 2018 at 4:57pm
| great thanks i was looking for that just got all new gauges can wait to start wiring them. |
Posted By: Jim.ME
Date Posted: 04 Sep 2018 at 5:05pm
| That was a mechanical gauge, not electric. If your new gauge is mechanical be careful not to kink or otherwise damage the capillary tube as you run it from the dash panel to the engine. Have fun. |
Posted By: DSeries4
Date Posted: 04 Sep 2018 at 9:05pm
None of the gauges are electric, except for the ammeter. ------------- '49 G, '54 WD45, '55 CA, '56 WD45D, '57 WD45, '58 D14, '59 D14, '60 D14, '61 D15D, '66 D15II, '66 D21II, '67 D17IV, '67 D17IVD, '67 190XTD, '73 620, '76 185, '77 175, '84 8030, '85 6080 |
Posted By: NewToMe
Date Posted: 05 Sep 2018 at 5:18pm
| Thanks for the heads up D series just wondering how to wire it up to the solenoid? battery? |
Posted By: DrAllis
Date Posted: 08 Sep 2018 at 6:35am
| If your plan is to have electric gauges instead of OEM style, I think you'd also have to change it over to an alternator and reverse the battery to a negative ground. |