BACKFIRES!!! D15 II

Carbon build up or timing slightly off. Need to fix it, might break your crank. Tracy

No greater gift than healthy grandkids!

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!

also, a bad condensor can cause backfires...

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.

NewToMe wrote:

Thanks Tracy, where abouts would i find the carbon build up (location) and ill check the timing

Start her up, get her at high RPMS, spray some Seaform directly in carb. This should help with carbon buildup. Some people use spray water, it atomizesas steak and can clean them too. Have to be careful or you will kill it with water. HTH Tracy

No greater gift than healthy grandkids!

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...

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?

Edited by NewToMe - 29 Aug 2018 at 8:48pm

The only way we can buy ethanol free gas in our area is to purchase premium.

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.

Chech the valves sometimes if they are loose it will cause similar problems

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.

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.

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.

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.

Edited by DSeries4 - 30 Aug 2018 at 9:13pm

'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

	This site is not affiliated with AGCO Inc., Duluth GA., Allis-Chalmers Co., Milwaukee, WI., or any surviving or related corporate entity. All trademarks remain the property of their respective owners. All information presented herein should be considered the result of an un-moderated public forum with no responsibility for its accuracy or usability assumed by the users and sponsors of this site or any corporate entity.
	The Forum	Parts and Services	Unofficial Allis Store	Tractor Shows	Serial Numbers	History