Detonation maybe?

Jerry/MT · Sep 23, 2009

mrlullabye said:
I purchased a used Farmtrac 360 about 3 months ago during the hottest part of the steamy Alabama Gulf coast summer and it ran great. It did make a funny noise for maybe 5-10 taps that sounded like a ping or detonation the first time we went to test drive it and promptly stopped, the sound did not return.

that is until this weekend. It is still warm, but probably 10 degrees cooler than when we first got it. The noise I don't know how to explain it, but I will try. Basically after mowing the grass for about 2-3 hours running in the 2400 rpm range, I was done mowing and needed to do some FEL work. So I turned off the PTO lowered the RPMs and started pushing stuff around. Within a few minutes it started the tapping/pinging/detonation noise.

I have rebuilt engines before so I know what all the parts look like, but I really don't have much experience with actual engine troubleshooting I am just a take it apart and replace everything that is out of spec guy.

Anyways if I had to guess it sounds like what I would expect a collapsed lifter to sound like. A hard TAP sound. It sounds sort of like someone is whacking some part of the engine with a ball-peen hammer. Now that said it is very obvious that it does not occur every RPM. if the engine is turning 2000 rpms the tap does not happen that frequently. It happens pretty fast but I could almost snap my fingers as fast.

If I turn the engine off and check the oil, by the time I crank it back up the noise will be gone. The noise probably won't return for the duration of the work. I did notice once it started tapping when I had driven the tractor up on the brush pile and it was at an angle that made me think it may have been a lubrication problem, but I backed it off the pile and the noise continued. I turned the tractor off counted to 20, restarted and the noise was not there.

So I am wondering is this maybe caused by a hotspot in the engine causing "detonation"?

I am running street deisel, because I have gotten aggrivated with the questions I get when I try to buy offroad deisel. For some reason the clerk always gives me a snoody look and ask me what I am putting the deisel in which really just gripes me.

So I was wondering if anyone else has an idea what this problem could be?

Does it sound like fuel related detonation?

Is it ok to use street deisel or should I be buying offroad deisel?

What should I try?

I want to reitterate this problem has only occured when the engine was ran at a continuous high rpm for a while then the rpm lowered.

Your problem is not likely to be fuel related. I can think of two possibilities: a leaky injector, or a problem with the advance/****** mechanism in the injector pump. The former, in my opinion, is more likely.

If this were my tractor, I 'd start by putting in a good injector cleaner additive( something by Stanadyne possibly) in the fuel and see if that cured the problem. If it didn't, I'd pull the injectors and have them checked and repaired or rebuilt as necessary.

If your tight on funds, you could by one new or rebuilt injector and try it on #1cylinder and if that didn't improve things, move it to #2, etc and check it out that way.

You could try to find the problem cylinder by cracking the injectors one at a time when the problem occurs but that's a pretty messy deal.

You want to sort this out because if it is a leaking injector it can lead to some costly damage( burned piston crown).

Hope this helpss you.

dodge man · Sep 24, 2009

I'm trying to learn something here. What does a leaky injector mean? Does it mean that it dribbles fuel all the time and doesn't have a good spray pattern when it is suppose to? Does it mean it doens't spray at all? Or does it mean it's not tight in the engine and it leaks air?

mrlullabye · Sep 24, 2009

to Brown. I don't know why they give me a cruddy look. Maybe I look like too much of a city boy to buy the brown stuff. Or maybe they don't much round these parts. I just don't like any sort of hassle when I buy stuff, and in order to keep me from having an "civil deviation" with the person I just don't buy it.

The hardest part is that it stops when you turn the engine off. Like duh of course it stops, I mean when you start it back up after a few seconds it is gone. I would think any mechanically failed part would continue until replaced. An injector might do some weird stuff, but i mean seriously it is cured by 5 minutes of being off.

tommu56 · Sep 24, 2009

mrlullabye said:
to Brown. I don't know why they give me a cruddy look. Maybe I look like too much of a city boy to buy the brown stuff. Or maybe they don't much round these parts. I just don't like any sort of hassle when I buy stuff, and in order to keep me from having an "civil deviation" with the person I just don't buy it.

The hardest part is that it stops when you turn the engine off. Like duh of course it stops, I mean when you start it back up after a few seconds it is gone. I would think any mechanically failed part would continue until replaced. An injector might do some weird stuff, but i mean seriously it is cured by 5 minutes of being off.

Try going in to get off road fuel in an old pick up and greasy bib overalls and when they sell it to you say why did they discriminate aganist you when you tried to buy it in your Sunday go to meeting clothes. Jk

tom

mrlullabye · Oct 2, 2009

For the record, an ounce of Marvel Mystery per two gallons of street diesel cures the problem I was having. Seams to so far at least

I was leary of this at first, but the guy at the tractor shop recommended and it seems to work. I asked him why the MM and he said "It needs more lube in the fuel"

I don't know what the **** that means, but it was close to inline with the dosage on the ancient bottle of it I had on the shelf, and it made the tap tap, knock knock, go away. I did notice that the street diesel all says "Ultra low sulfer < 15 ppm) around here. I am thinking it is likely that diesel used to have more sulfer or something in it that made it lubier.