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Discussion Starter #1
This thing is driving me nuts...its on a Deere 185, mower is in good shape..

I get it in the shop, complaint is, it surges and backfires...

i crank it, it fires right up, i rev it up, iot surges and backfires loudly. So i pulled the carb, cleaned it up, it looks okay inside. i put it back on, fresh fuel...same deal.

Okay...so I check all the switches and stuff, all good, i even isilated them all, same result.

i then noticed that, the exhaust gasses are VERY hot after just..a minute of running, so hot in fact that you could easily get 3rd degree burns iof you put your hand near the outlet for just a few seconds..my other mowers DO NOT do this, its hot, but not..THAT hot.

So I said..okay, timing. The customer read online on his phone, and everyone said..igniter ignitier igniter.....So he ran up and bought an 87 dolla module from the deere store, i put it on..no change, exact same symptoms.

I did a leakdown test, under 10%...its a good motor. The valves were not out of adjustment...

I pulled the wheel, key is intact 100%...the coil is gapped at the correct spacing.

im at a loss....I have nowhere else to look, beyond...the coil itself, and possibly an internal failure, like a broken cam or something?

Anyone know what model and years had a plastic cam gear?
 

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Wow, wish I could help you RED! I have one on my 180, but never had this issue! God willing ,someone got a idea!
 

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Can't tell you what year the plastic cam gears started, but it sounds like the cam timing may have slipped. Have you had the rocker cover off and checked to see if the rocker arms do the 'dance' at TDC between the end of the exhaust and the start of the intake strokes? Its worth a quick check.

Also, there's a very rare possibility that the muffler is stopped-up, possibly not by debris but by a broken or partially-broken internal baffle. Kohler-powered Cub Cadet 2166 tractors are bad about suffering from this problem. A baffle will break in the muffler, and the EGT's will rise so much that the engine will often vapor lock. I'd pop the muffler and shake/thoroughly inspect it.
 

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10K and Climbin!
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Check for a manifold / vacuum leak.. :dunno:

Did you verify the fuel shut off was opening fully?

How about replacing the plug?? It may be bad under compression..

I don't think these engines have the plastic cams.. the FD 620's had that beauty..

I found this in another forum.. **For some reason the Kawasaki on the 265 was plagued with plugs fouling. I worked as a Deere mechanic for many years and would have machines that had just had plug replaced not start, new plug and away we go. Try a new plug even if you have a new one that has been in and running I had best success with NGK.Good luck

:goodl:
 

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Discussion Starter #5
Muffler is freely flowing.

i put a dowel down the plug hole and brought the piston up, at TDC the valves were both in the right orientation, so the cam is probably fine.

At this point, im down to "the coil"....Its about a 70 dollar swing...
 

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And you checked for play in the throttle shaft? One of the most often overlooked issue I run into. Wouldnt explain the backfire though....I assume you have already used carb cleaner/wd40/ect. to check such things though. (You are one of the few I would assume this of as thorough as you are)
 

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Red, the 265 (FC540) I have will do that most of the time when I crank it up but will clear up after a few minuets. I assumed it was the worn carb. http://www.mytractorforum.com/showthread.php?t=269006&highlight= The shaft I made didn't help. On the 265 there are 3 relays in the steering tower, one of them is an ignition relay according to the wiring diagram. I have no idea what that relay does or why it's necessary. I don't think this engine has plastic gears. When you figure it out let us know what it was.
Cannon
 

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It would be interesting to positively locate TDC and mark it on the flywheel and engine case and then see where the spark is happening with a timing light.
 

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Here's the basic about "backfire"

Possible cause.

1. valve not closing properly
2. timing off
3. overheated head due to carbon deposit (auto ignition/detonation)
4. mixture to rich/lean
5. misfire at the wrong timing (valve open)

That's what pop out of my head for now.
 

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I like rayjay's 'set up a timing light' to verify timing/advance. I would run an inline spark tester, to verify spark quality while it is missing.

But if your positive it is not the fuel, and I hope you completely removed whatever was in the gas tank(think diesel contamination) then I would suspect the valves... sticking, or loosing the sealing effect after warm up, you haven't said anything about having the head off yet.

wwxx
 

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Red,if the muffler & pipe are good,,I'd lean toward the valve train.That would cause that hot pipe,backfiring,etc.Like wwxx said,I'd knock head off & take a look.
 

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Discussion Starter #13
Customer doesnt want me going that deep into it, and its a chore to remove the head on a whim.

Ive tried 3 different new plugs, and spark quality is...difficult to gauge, the inline tester of course indicated that there was spark, but..as far as spark quality...no real way to gauge it without a tool that opens up the gap...but while misleading, spark didnt look all that impressive.
 

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You're the professional, but if I were doing the Dx, I'd be checking the carb a little more, and checking intake system for leakage. Backfire and overheat point to either retarded timing {overheat} or lean mix. Do you have another carb you can swap for a test? If the coil works, the coil works. From your reports, the spark is sparky...
tom
 

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Ok, don't take the head off on a whim

Depends on your spark tester, for sure. If your using one of those B&S, that is round and has some pointed studs with an air gap to jump, then you can usually see if the ignition is missing. (If your using a resistor type spark plug, it is very difficult to see, use a non-resistor plug if you can't see the arc) If your using the 'high tension lead with a neon tube'~type ign. tester, they really only 'show' a miss at the lower speeds, but after 2000 rpm they just show an orange blur...but they are handy!

Obviously since the $70 igniter didn't fix it, and is non-returnable the customer is going to get nervous. He may be nervous, or possibly, the customer has never had the head off, for any kind of maintenance. Which on a 20 year old engine, valve service is possibly way past due.

Sure the expense of a head gasket, any additional items, & additional testing/labor would make me nervous, and the customer may say 'don't spend any more money', but at that point then there is no point to go further with it & still get paid. If he specifically requires you do not disturb the head, then I wouldn't. I would try to settle up right then an there and load him out the door, but that is just a whim I sometimes have.

I don't think I would charge for replacing or the price of an $70 igniter, if that didn't at least fix that part of the engine problem. I would stick his old igniter back on there if possible, keep the new one and 'write it off' as a new tool on my taxes. I try to never charge for something that did not prove to be required & even demonstrable.

You could try instead of a leak down test, try a compression test cold, and then hot, that should inexpensively prove the whim I suggested. Even with compression releases, you can back the valve lash off alittle in order to get a more realistic compression value.

The problem absolutely could be a bad coil, I use the old black box 'coil tester'(basically an ohm meter) to test both primary & secondary circuits, only if it is separable from the electronic ignition. I rely on visual signs of high tension lead wear, external coil covering cracking or sometimes signs of arcing in the strangest places, and of course the ground & primary circuit.

Not sure if you can do it on a kawasaki coil, but on many magnetos, the high tension lead is sealed in glue at the coil, I rarely replace a coil just because of a bad high tension lead. I grab the lead with pliers, twist to break the glue, & rip it out of the coil, then replace the lead, often you will find a threaded stud or nail down in the hole that the conductor must be in full contact with. Seal the lead with glue.

Try to test the ignition with the blades engaged to help load the engine somewhat (it is missing already, so turn the blades on...just for fun)

wwxx
 

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Discussion Starter #16
The igniter was the customer...he was here and I was trying to DX the problem and when the carb, and base tiing failed to give any clues, he looked online and saw multiple instances where people said to replace the ignitor module, I told him in my experience they were either good, or bad...not in between. So he called on his cell and found one locally..went and got it, and I put it on...obviously...didnt help.

It seems like its not sparking on the compression stroke, but it is sparking on the exhuast stroke..my theory is, its unable to jump the gap under compression...

im going to try to sidegap the new plug to just .015"...and see if it improves.
 

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if you've confirmed good,non intermittent spark and no intake leaks,carb clean and good!just tell the guy either pay to take it apart,buy a new engine or wear earplugs!no point in losing sleep over it! if you get all the cam specs. and degree the flywheel you might be able to pin point the bent crank or cam timing problem!but it's still going to cost more to figure all this out!

Like Dave Marcus says "We done so much, for so long, with so little,we can now do anything with nothing!
 

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Discussion Starter #18
Smaller plug gap in a side gapped plug did reduce the popping considerably but it still runs very rich, and surges badly, just...doesnt pop as much.

slowly closing the choke will reduce the surging, but at the moment the surging stops, it runs pig rich...I took the carb back apart, stil spotless, no signs of debris at all, all holes are clear.

I dunno...im in it for about 5 hours at this point...
 

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This surging and popping you are describing screams lean fuel mixture, especially because the engine's running improves momentarily when the choke closes.

I Just got an off-the-wall idea here, but have you taken the Welch plug covering the idle transition passeges in the carb off and cleaned behind it? As Im sure you know, the engine only runs off the first and maybe second transition ports at high idle, and a blockage behind in this part of the fuel circuit will cause a bad surge. You can always re-seal a new plug with nail polish once done cleaning.

Also, what if the carb wasn't the source of the lean fuel mixture at all? What if you have an air leak downstream of the carb, which is leaning things out? Im wondering if the heat shield between head and carb isn't cracked, or if the gasket between the heat shield and head hasn't become damaged. 20 + years of constant thermal expansion and contraction may have caused a crack, or somebody messing with the mower before you got it could have torn the gasket and just slapped it back in place and hoped for the best.
 

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Discussion Starter #20
This surging and popping you are describing screams lean fuel mixture, especially because the engine's running improves momentarily when the choke closes.

I Just got an off-the-wall idea here, but have you taken the Welch plug covering the idle transition passeges in the carb off and cleaned behind it? As Im sure you know, the engine only runs off the first and maybe second transition ports at high idle, and a blockage behind in this part of the fuel circuit will cause a bad surge. You can always re-seal a new plug with nail polish once done cleaning.

Also, what if the carb wasn't the source of the lean fuel mixture at all? What if you have an air leak downstream of the carb, which is leaning things out? Im wondering if the heat shield between head and carb isn't cracked, or if the gasket between the heat shield and head hasn't become damaged. 20 + years of constant thermal expansion and contraction may have caused a crack, or somebody messing with the mower before you got it could have torn the gasket and just slapped it back in place and hoped for the best.
Thats what makes no sense...it pops like its lean, but smokes black...

If it was a normal up and down surge, id go to the carb or intake..but its like the engine is shut off and on, off and on...choking it slows the surging, but only until it floods out from the choking.

I dont know, Ive sprayed ether all around the head, intake, carb, etc...no change on anything at all, and all the gaskets and insulators are in place, and intact,

Also, if I manually override the governor, it still wants to surge..figure that one out...Im done with this thing, its had probably 3-4 people in it already, and I dont have any kawasakis laying around to test parts off of..wish i did.
 
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