Just thought that it could be some carbon deposits on the top of the piston causing a ~~~glowing~~~ and thus a pre-ignition condition. Igniting the air/fuel mixture too early on the low end could cause that popping effect but as the engine speeds up, the timing would be closer and thus reduce or eliminate the popping/ pre-ignition. Wouldn't hurt to check the piston and head for carbon deposits. Hope this helps.
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Strange Kohler 15.5 hp issue
- Thread starter Charlie_S
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Export threadJust thought that it could be some carbon deposits on the top of the piston causing a ~~~glowing~~~ and thus a pre-ignition condition. Igniting the air/fuel mixture too early on the low end could cause that popping effect but as the engine speeds up, the timing would be closer and thus reduce or eliminate the popping/ pre-ignition. Wouldn't hurt to check the piston and head for carbon deposits. Hope this helps.
I suppose carbon buildup could be at least part of the issue, though compression reading isnt excessivly high like it normally would be with alot of carbon on the piston.
the backfire/popping issue is at all throttle positions though not just one particular engine speed so whatever the cause its consistant when under no engine load scenerio.
The real stumper to this whole issue is everythings backwards, when problems arise they usually manifest themselves under working conditions not no load conditions.
the backfire/popping issue is at all throttle positions though not just one particular engine speed so whatever the cause its consistant when under no engine load scenerio.
The real stumper to this whole issue is everythings backwards, when problems arise they usually manifest themselves under working conditions not no load conditions.
Your engine is somewhat of a mystery. Popping and backfiring from my experience has been timing issues and valves and these were addressed on here. On older engines bad points and condensers going out could cause popping and backfiring. Just wondering what were your measurements on both intake and exhaust valves cold and hot? Other mechanics suggested a stretched exhaust valve when it warmed up. That would be enough to make the valve stay off its seat slightly and still have enough compression to fire. I know you ran a crude compression test and obviously it has enough to run. As far as my previous suggestion of carbon deposits glowing, it's a remote possibility. Most of the time glowing carbon makes one diesel and sputter on after you turn it off. I'd measure the valve clearances and possibly pull the head just to see what things look like. Let us know what you find.
When the exhaust guide moved up in mine (over time) it apparently ran (well, by the way) until insufficient mixture was being admitted and or excess burned mixture was left upon intake charge (couldn't escape) to ignite. This because the exhaust valve was only lifting about .100" The torquey engine, huge flywheel and governer really covers a host of sins in these engines IMO. As noted compression was ok even when the engine went to one cylinder (Intek 24 V) . :smile:
In my opinion, you are going to have to do one of three things to get to the bottom of this problem.
1. Perform a compression test with a gauge to get an actual reading. Your thumb can be pushed off with as little as 30psi.
2. Perform a cylinder leak down test, to see if the cylinder is actually sealed.
3. Pull the head and inspect all the parts to visually verify they are good and working properly.
Without this we are only guessing, which is going to lead to a false diagnosis, big bucks spent, wasted time and frustrated individuals.
1. Perform a compression test with a gauge to get an actual reading. Your thumb can be pushed off with as little as 30psi.
2. Perform a cylinder leak down test, to see if the cylinder is actually sealed.
3. Pull the head and inspect all the parts to visually verify they are good and working properly.
Without this we are only guessing, which is going to lead to a false diagnosis, big bucks spent, wasted time and frustrated individuals.
Lawnranger
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In my opinion, you are going to have to do one of three things to get to the bottom of this problem.
1. Perform a compression test with a gauge to get an actual reading. Your thumb can be pushed off with as little as 30psi.
2. Perform a cylinder leak down test, to see if the cylinder is actually sealed.
3. Pull the head and inspect all the parts to visually verify they are good and working properly.
Without this we are only guessing, which is going to lead to a false diagnosis, big bucks spent, wasted time and frustrated individuals.
If you've noticed, almost every test recommended has been poo-poo'ed and dismissed, won't even give it a second thought to try what's recommended. I'm finished with this one. Have fun guys.
Personally, without hearing it, I would suspect it is only unburned excess fuel contacting the hot muffler. If otherwise the performance is satisfactory, I wouldn't worry about it. If it is something that "could" become serious, you should "start" to notice changes in the engines sound and performance before any serious damage happens.
If you've noticed, almost every test recommended has been poo-poo'ed and dismissed, won't even give it a second thought to try what's recommended. I'm finished with this one. Have fun guys.
IF you'll accurately read what i wrote previously, I did mention compression was 110, and that i did a primitive leak down test holding my thumb over the plug hole BECAUSE at this point i dont have the capability to do an accurate leakdown.
Sadly, unlike some apparantly I have real farm work that needs done so i cant jump to all suggestions at everyone's beck and call.
Some suggestions i dont give a second thought to simply because several of you misread my origional post as to mean it ran bad when mowing which is not the case.
In Fact, a couple did catch on and realize its just the opposite, Thus some suggestions are not relevant, and others while they have some merit, but still dont make sense simply because it runs well when working but not well static with no load.
Still, when time allows i will check a few things suggested, but again, I dont always have the luxury of jumping to things at everyone elses schedule so for those of you who made helpful suggestions thanks. to the rest that dont get it other things do take priority sometimes go **** yourselves, i'm outa here. And herein lies the main reason i seldom do forums is the assholes that dont realize things cant always be done immediately to they're liking.
Charlie, I taught small engine repair for 30+ years to individuals for 14-65 years old. I have also worked in the field for over 25 years. During that time I have dealt with true idiots and experienced professionals. Some of these people shouldn't be allowed to change an air filter, but they think that are mechanically minded. That could be both the idiot and the "pros". You came to this forum looking for help. That means to us that you wanted our input. Most of the proffesionals here realize that people who come here don't have the money or a vast amount of time to do the work immediately. We understand that you may not have the tools we recommend using. With that being said look at it from my side of the postings. I cannot see the engine or equipment you are working on. I must use your descriptions and my past experience to visualize what you are doing and then try to give you suggestions as to how to solve your problem. I know that most people don't had all the tools I recommend using, but still hope that they might be able to borrow one. Some threads are not completed or solved for weeks and even longer, due to both sides not having the time test, research, or post back. I also make mistakes and ask people to do things more than once, because I don't reread every thread completely, to review what has been asked for or been done. Being on this forum is like a classroom, many individuals wanting help at the same time. Do you realize that many of the pros on this forum spend time looking up parts or researching manuals to help individuals solve their problems. We don't get paid, but just enjoy passing on our knowledge to those who appreciate our help. You called all of us a bunch of names and told us what we should do. How would you feel if those terms were used toward you, when someone disagrees with the knowledge you have in your chosen field. We disagree with each other all the time, but that doesn't mean that we can't learn from each other. I know that because of your comments no one is going to help you, but I do hope that you solve your problem and learn from this. Rivets
IF you'll accurately read what i wrote previously, I did mention compression was 110, and that i did a primitive leak down test holding my thumb over the plug hole BECAUSE at this point i dont have the capability to do an accurate leakdown.
Sadly, unlike some apparantly I have real farm work that needs done so i cant jump to all suggestions at everyone's beck and call.
Some suggestions i dont give a second thought to simply because several of you misread my origional post as to mean it ran bad when mowing which is not the case.
In Fact, a couple did catch on and realize its just the opposite, Thus some suggestions are not relevant, and others while they have some merit, but still dont make sense simply because it runs well when working but not well static with no load.
Still, when time allows i will check a few things suggested, but again, I dont always have the luxury of jumping to things at everyone elses schedule so for those of you who made helpful suggestions thanks. to the rest that dont get it other things do take priority sometimes go **** yourselves, i'm outa here. And herein lies the main reason i seldom do forums is the assholes that dont realize things cant always be done immediately to they're liking.
WOW!!! Now there's a real attitude of gratitude! Sheesh!