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sliderxc

engine rattle under load

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sliderxc
hey all I just started to mow more with my 716 alis and I noticed that when I start mowing heavier grass I hear a slight rattle coming from the right side of the motor area (when seated on tractor)motor was rebuilt ,mower deck rebuilt I run 93 octane gas so I was wondering if you guys might have an idea what it could be thanks

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MysTiK
I have had similar sounds from mine, K341s, AC716H, late 70's. It only seems to happen when things are hot, after running like an hour. And I first noticed in heavier grass. Switching to premium gas seemed to help things generally. But this knock or ping sound still happens now and then. Sometimes I think it could be carbon buildup, or perhaps a carbon buildup breaking loose - which can sound pretty 'pingy'. Lately, I noticed when mowing a ditch, climbing a bank of the ditch, the deck blades bottomed on top edge, spit some gravel, and the engine made a nasty knock, puffed some black smoke, nearly stalled, and then things were normal again. Kinda scary. That was an extreme heavy loading. What I do, is avoid full throttle mowing; but I keep a pretty good rpm, about 3/4 throttle, just not full throttle. I think that keeps the heat under control, altho the engine runs pretty hot no matter what. I was running straight SAE30 oil, as recommended in manual. Lately I am using 15w40 diesel oil. It's hard to say if that's much different; but I like to think that the "40" part helps when the engine runs hot. I haven't had problems with the 15w40 - no change in oil consumption - engine uses a little bit, add an ounce every couple weeks or so, no big deal. It's due for first oil change since the switch, as the oil is basically starting to go dark. When I got this engine, it had the worst black oil I have ever seen, and it used to noticeably smoke if it idled at all - most of that smoking after idling has ceased. It likes clean oil. And as I approach oil change time, it's kinda letting me know that it's time for oil change - just a feel thing. Also, currently getting help with bgb repairs, and discovering some trashy parts in the bgb, high wear, and probably higher friction, hence higher load on engine. I won't know until it's done (soon) but I am wondering if things will run a little freer after bgb repair. Someone was in there before, and made a bollox of it. Also discover a bearing on cone clutch - but the driven shaft in the bevel box was basically screwed, blued, worn, not nice. Fair bit of wear on the bevel gears too - lots of fun. So I don't know if that will be noticeable; but I wouldn't be surprised is things run freer; and that might translate into less load on the engine. Hard to say; but it's been getting laggy lately. Bgb was overdue - lots of play. Check gear oil is critical. Before the bgb work, the bgb was leaking oil, and I was adding an ounce of 80w90 gear oil before every mow. Timing is another thing to look into - that can make or break knocking, pinging, and retarding timing might help, if possible. Also setting high and low idle on carburetor might help. Apart from that, it's an old engine - and it keeps on running. Sharp blades and a clean underside of deck, and greased spindles can also help. With sharp blades, you can get a clean cut at less throttle. It's all connected I suppose. Al Eden commented on this a while back. I'll add that link if I can find it. HERE IT IS: http://www.simpletractors.com/club2/topic.asp?TOPIC_ID=117675 He used to grind out the combustion chamber on these engines. He also discovered differences in head gaskets as the years went by, and as the fuels available changed (esp. ethanol; possibly other changes from the fuel in play when engine first appeared). Kinda same idea as grinding the comb chamber, Al tried using 2 head gaskets, slightly lowering compression - and that apparently helped with knocks and pings. Al also said some of the later years head gaskets were actually thicker (same idea again). (and perhaps a Kohler response to the issue, or the fuel). Seems to me it's an old mystery. Add 30+ years of wear, and you might expect a few rattles. I always try to baby mine; but it has to work, or there's no point. As a nooby mechanic, I find the basics are very important; as I learn more, perhaps I can do more. So I run it easy but honest; and try to minimize the abuse. I imagine a total rebuild might be just wonderful; but I am not about to do that. Nor am I about to turn it into a 50hp pulling nightmare. I work with it; and it works for me. Anyway, that's my 2bits - hope this helps some. sm03

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GLPointon
As engines age/wear they get a "rod knock" but that is usually heard more at higher speeds than heavier load. My 7010 knocks if I rev her up too high...so I don't, It has power to spare at 3/4 throttle. Anyway if its that it can still last for many yrs (or blow tomarrow?) Like Bob, Graham & Chris said its likely a machinery noise or a combustion chamber (fuel/octane) noise... Good luck sm01

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sliderxc
ok like I said motor was rebuilt new piston ,rod ,bearings mower deck rebuilt bearings bgb rebuilt all bearings, new keyways maybe because I really never ran this tractor much mabey the noise is normal because its not really loud I will check timing again it could be that I am going to try some c-14 race gas since I have about 50 gallons of it at my shop and see if that stops it I know when I rebuilt the motor I did deck the block and head I did check the compression and in 3 turns it read 145 psi so mabey I need to drop that a little

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MysTiK
Did a test drive on fixed bgb today. One thing gone is a rattle noise that sounded like a loose bracket bouncing around under the hood, or somewhere. Another noise hopefully gone is a nasty kinda medium high-pitched whiny grindy sound like a chicken squawk. And Yes, I am suggesting that bgb can be part of some nasty noises. My bgb was a mess - somebody was in there before - parts missing, b-gears on incomplete shaft parts, and actual gears reversed on the wrong shafts. Add clutch bearing fried. Add cross-driven-shaft messed up badly. I got so lucky - my friend lead me through this - what a tour - and as garbage was discovered, he had parts in good shape from his many tractors. If I had solo'd this, I would be there still, and probably for weeks. One problem after another. My friend loves doing mechanical work - it's like Zen and the Art of Tractor Maintenance. For me, it was like a documentary, an experience, and an education - amazing. Stuff I heard here, was all visible, and discussed, there. Bgb noises can be heard MAYBE if you lift the seat deck and put an ear close. But engine noises while under load and working, it's hard to stop the world like that. And sources are often intermittent in either case. Keep watching and listening. Keep oils and greases up and clean. Keep coolers clear. And have fun - these things still run forever - it's outrageous. The Allis Manual - entire 700-series. It's different. "700 Series - GT Yard & Garden Tractors - Model # 1690211 (=716) Operator's Manual English" http://bsintek.basco.com/BriggsDocumentDisplay/default.aspx?filename=heCyEN8coK3rE3CGh54bp796Dq Kohler site has free Kohler manuals. Get the LFRM - Large Frame Repair Manual And hang out here.8D

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MysTiK
quote:
Originally posted by perry
setting the timeing correctly fixed my Kohler rattle.
How do you do that? especially the "correctly" part? Is there something unique to Kohlers for timing?

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Ronald Hribar
Think I have read that balance haft can cause problem S been suggested that using a hammer to break it and remove I had a 12hp Koehler that rattled after a complete overhaul Everything was new Work done by competent shop I sold it that way

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Brettw
I had both 12 & 14 HP Kohlers, and they rattled like there was a dozen spare parts in them. The 12 was completely rebuilt, the 14 was a partial rebuild. They both sounded just like I remember Dad's Sovereigns, so I didn't give it a whole lot of concern. I did hear what was the sweetest, quietest 12 horse Kohler in a tractor at Ken's place when I went to pick up a tiller. That tractor was in great shape and it was apparent it had very few hours on it. My thoughts would be that general age and usage, hours, etc. will lead to a bit more noise than a new engine, even if rebuilt.

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RayS
Graham, "b-gears on incomplete shaft parts, and actual gears reversed on the wrong shafts." I don`t see how that would be possible and it going forward when hydro lever was moved forward. But who knows.

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sliderxc
well checked the timing and saw that the line on the flywheel was about 1 inch below the line on the bearing housing don't know how that happened? so I made the lines meet and now seems to be quieter also seems to have more power wierd huhdOd

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MysTiK
I don't quite get the timing idea. It seems static timing is basically a check to see if there's key wear or breakage. Nothing else can change unless there is wear further up or down the line. I can see varying timing with points, since a larger gap would delay/retard timing just cos it takes longer for gap to close/fire. So if a timing ping/knock is the cause, then tweaking points is the simple solution; and rebuilding, to greater or lesser extent, complexity, expense, etc., is the difficult solution. Am I wrong in this? Apart from big wear over time, I can't see static timing even changing - and if wear is that bad, then there seems no guideline for a timing fix through static timing - since it's always the same - line up the marks on the flywheel, and it's done. ???? So what am I missing? I kinda hope I'm missing a lot, cos this seems too simplistic, and very likely all wrong. If what I am saying is correct, and I hope it isn't, then static timing is merely a measure of how messed up the engine is. Is this correct? Or is it simply an invitation to change the flywheel key. Tell me I'm wrong.

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sliderxc
quote:
Originally posted by MysTiK
I don't quite get the timing idea. It seems static timing is basically a check to see if there's key wear or breakage. Nothing else can change unless there is wear further up or down the line. I can see varying timing with points, since a larger gap would delay/retard timing just cos it takes longer for gap to close/fire. So if a timing ping/knock is the cause, then tweaking points is the simple solution; and rebuilding, to greater or lesser extent, complexity, expense, etc., is the difficult solution. Am I wrong in this? Apart from big wear over time, I can't see static timing even changing - and if wear is that bad, then there seems no guideline for a timing fix through static timing - since it's always the same - line up the marks on the flywheel, and it's done. ???? So what am I missing? I kinda hope I'm missing a lot, cos this seems too simplistic, and very likely all wrong. If what I am saying is correct, and I hope it isn't, then static timing is merely a measure of how messed up the engine is. Is this correct? Or is it simply an invitation to change the flywheel key. Tell me I'm wrong.
as it says in the manuel static timing is a starting point as for it being out that much well I have great nephews that like to watch me work on things in my shop while asking a million questions so I am thinking that could have made me skip a step or 2 after the inital run in or I could have moved the points the wrong way while tightening it who knows but atleast i found the problem with the help of you guys before any damage was done

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MysTiK
quote:
Originally posted by RayS
Graham, "b-gears on incomplete shaft parts, and actual gears reversed on the wrong shafts." I don`t see how that would be possible and it going forward when hydro lever was moved forward. But who knows.
It was hacked, Ray. Maybe double reversed? There was a spacer missing, kinda like a 1/8" thick washer, and also a clip missing, kinda like a circlip idea, (vacant groove on shaft) but more like round wire rather than flat, and also the shafts were no longer clean and shiny, but very scored, grooved, you could see and feel the wear on them - a 2" band of discoloured metal, worn in near 1/32", on the long driven shaft. (it was largely way over my head; but I know what I saw was bad news). The 2 1/2" of cone play that I measured may have been due to cone bearing shot. Needle bearings shot. Main oil leak on left side, I thought it was on front. My friend was pretty disturbed about the overall state from previous 'repair'. A lot of parts came and went in the process, as replacements were brought in from a known good bgb. I may have the details wrong; it was a serious mess. Gears were replaced, original gear teeth were 'tapered' by wear (still usable - kinda sorta). My friend saved me a lot of money. Working well now, quiet, less drag - mowed with it, no problem. Haven't checked play tho, 8) If you want, I could ask him for details. He's done a few, and works as a millright, does bearings all the time. Also restos '60's chryco muscle showcars - he's good. He loves mechanical stuff, like you. I'm just plain lucky. sm01 I gave him my parts-716-6/no motor for his collection. Time about 12 hours, a few other items included also - trans belt, gas gauge, clutch bearing, ventplug (scintered brass?). Pretty thorough. dOd Probably a fat bill at the dealer, maybe 1K. Getting it done, priceless. Guided tour, bonus. I was amazed he helped me to this extent; I feel like I owe him. Funny - I was supposed to do the work under his instruction - well, that never happened. But he showed me more than I could absorb. (also - I was adding oil and mowing with it right up to the end - last mow, there was a new bad vibration (not rpm related) and heavy drag noticeable - amazing - it never quit - and it should have). I come away from this wondering how more people aren't doing bgb repairs, or maybe we don't hear of it, or maybe mine was just worse, or maybe they get shimmed early, to offset worse later. (?) I also wonder if I could do it myself, now that I have seen it. I can say that having a parts tractor could pay for itself immediately, in this area alone. Overall, this was an amazing educational experience - and kinda like a strange dream - very strong impressions. I think it has changed me, and how I view a lot of this stuff. I still don't know much; but I learned something that might be realized later. Like some kind of growth process - I've been noticing changes happening slowly. - sorry to run this off topic sm01

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MysTiK
quote:
Originally posted by sliderxc
well checked the timing and saw that the line on the flywheel was about 1 inch below the line on the bearing housing don't know how that happened? so I made the lines meet and now seems to be quieter also seems to have more power wierd huhdOd
Wow. I'm glad you found that, and glad it helped. I also wish I had read this before shooting my mouth off. Clearly, I don't understand this yet. I need to read the manual, and I don't know what else. I tend to get intimidated real fast when I hear anything about working on a flywheel. But I am seeing this as something very similar to the idea of tweaking a distributor on an automobile; but not the same. I probably misinterpreted a post from Al Eden, where he said something like the static timing was most important, and the points adjustment could seem to be way out of spec on a worn engine. In my relative inexperience, I don't know how a flywheel can get that far off. For all I know, it might be easy to do that - and I wonder if it could be desirable, to a certain extent. I need to read more and go look at my own tractor. More feedback or guidance appreciated also. Glad you are ok, slider. Kinda glad I am all messed up here too - at least I know where I need to learn more. It's all good, somehow. :D Graham .

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Al
Hi, We always set the points on a Kohler to break on the S mark on the flywheel. I never check the point gap because wear in the cam and other issues can make .020 gap to cause the timing to be way off. If the engine is running and you hook a timing light to the plug, the S mark on the flywheel and the line on the closure plate should be in perfect alignment. If not adjust the points to make it happen. When we have a Kohler out, we wire brush the marks out and use like a tooth pick and yellow paint to enhance the marks. Often we tape some emery paper over the end of a flat screwdriver and put it through the timing hole and turn the engine over to clean the rust from the timing marks. DO NOT GET IT IN THE RING GEAR TEETH. IT MUST BE AHEAD OF THE RING GEAR!!! HAVE THE SPARK PLUG WIRE OFF AND BUMP THE STARTER AROUNG!!!! We have one of these $5.00 square 6 volt flashlights that we cut the wire from the switch to the light and put 2 electrical jacks in the body so we can plug a pair of test leads in and when they make connection and the switch is on it lights. This what we use when we set the points. When setting the timing, always turn the flywheel in the normal or clockwise direction. Set the timing marks to the S mark and adjust the points to break there. Then roll it back and then forward to see exactly when the points break, roll it back about 15 degrees and come forward very slowly again. If you don't always roll back and come forward, the slack in the timing gears will give you inaccurate results.Tweak the points and repeat. One other note. DO NOT HAVE 12 VOLTS CONNECTED TO THE COIL WHEN DOING THIS IT WILL TURN YOUR TEST LIGHT INTO A FLASHBULB. Safest way is to disconnect the points lead from the coil. Also if you run across a Kohler we have rebuilt or similar that has a flywheel screen you will see a yellow mark on the edge of the screen and a yellow S and T and matching mark on the blower housing. It is so much easier to set the timing with these marks. An automotive timing light check running is the ideal final check. Al Eden

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mtoney
While I might be a bit green at the older Briggs engines, Kohlers I know well. The "Kohler Rattle" that is common after a rebuild is the result of forgetting to check the cam shaft end play. There is a spec for it and you want it on the tighter side of the spec range. The rattle, sounds like a rod sometimes, is from the camshaft slapping back and forth in the block. We had a guy tear down a 14hp in a puller 4 times trying to find the problem. Even he forgot to check the camshaft runout with a dial indicator. Once he shimed up the shaft, it was nice and quiet! Mike

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perry
and don't forget about them pesty balancing gears. talked about here - http://www.simpletractors.com/club2/topic.asp?TOPIC_ID=119244&SearchTerms=balance,gears
[img]http://i176.photobucket.com/albums/w164/onlycubcadets/KSeriesTimingA.jpg[/img]

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MysTiK
quote:
Originally posted by mtoney
While I might be a bit green at the older Briggs engines, Kohlers I know well. The "Kohler Rattle" that is common after a rebuild is the result of forgetting to check the cam shaft end play. There is a spec for it and you want it on the tighter side of the spec range. The rattle, sounds like a rod sometimes, is from the camshaft slapping back and forth in the block. We had a guy tear down a 14hp in a puller 4 times trying to find the problem. Even he forgot to check the camshaft runout with a dial indicator. Once he shimed up the shaft, it was nice and quiet! Mike
That's interesting, Mike. and I used to get the same kind of noise from a Honda dirt bike 500 single 4-stroke thumper w 4-valve head. It did that from new, but only on extreme, near stall situations, or grunting uphill in 2nd or 3rd gear, low rpm, pure torque situation, and especially when almost stalled. I knew there was something familiar to the same sound w the Kohler; and the situation I described crawling out of a ditch, near stalling, was the same sound. Motor almost stopping and then piston hits TDC and fires, and everything gets spun - cam, valve noise. But that doesn't explain getting the rattle at higher rpm in long grass, except cam play like you mentioned would explain it. I'm kinda glad I remembered this. It's not piston noise. But I can't explain it like I can at low rpm, where the rpm changes rapidly. But there is a similarity with the engine loading up due to tall grass. And that seems to point to timing - not firing at TDC. Slack, play being taken up, causing noise in the process. if that makes sense. The sound is very distinct; almost like a hollow click, or several of them. There's a percussion instrument called 'bones' that gets close to it - basically 2 hardwood sticks about an inch thick, tapped together. In the tall grass situation, I had a thought of 'valve float'; and there was visible exhaust at the time - whitish exhaust, like a wisp of smoke, only at high rpm it was a continuous stream from the exhaust. This is the best I have ever been able to describe it, or even remember it in detail like this. I don't know if this is helpful. At the time, I backed off the throttle slightly from near full to 3/4 and things were normal again. Increasing throttle to near full, created the same problem again. Grass was thick and about 8". Speed probably 4-5 mph normal mow speed.

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Al
Hi, O think you are getting pre-ignition or "ping" This a violent explosion occurring before the spark plug firing. This will destroy pistons if it continues. Usually occurs at high temps under heavy loads. Try changing brands of fuel or buy some premium and see if it doesn't correct it. We had a lot of trouble with this in the early 80s when the real gas went away. I posted an article on reworking Kohler heads to fix it. I don't know where to look to find it. Often changing fuel, slightly richer mixture may help, be sure timing is right on 20 degrees at the sp mark. It is sometimes caused by a sharp edge or a piece of carbon glows and pre-ignites the mixture. If you pull the head and see little pock marks on the top of the piston, in particular around the edge this usually damage from pre ignition. If someone can find the head rework article, I would appreciate it. Al Eden

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