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bent push rod

Posted by jeeper z7 nc (My Page) on
Sat, Mar 22, 08 at 17:00

I have a 3 year old husquvarna 15 h.p.kawa engine . the problem it has bent 2 pushrods in 94 hours of use. It also surges bad. Idont think the problem is connected. warrenty is out since it is over 3years old. Dealer keep it 2 months the first time. does anyone know what would cause this.

thank you for any help
jeeper


Follow-Up Postings:

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RE: bent push rod

I would suspect a valve stem with a slight bend in it or the stem is possibly galled. The first thing I would do is replace the valve. This is not a big job, you can remove the head and replace the valve. You will need a tool to compress the valve spring. Consider taking the head off and take it to an auto repair shop with the new valve. They should be able to replace the valve if you have the head in hand.


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RE: bent push rod

I'll bet both were intake valves. If so, stale gas is sticking the valves in the guides and is also probably clogging up the carb (surging). Clean everything and never let your next fuel get over 30-days old.


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RE: bent push rod

I had a JD with a Kawasaki engine. The intake valve was stuck due to old fuel varnish. Fortunately, the push rod did not bend.

A husquvarna with a V-twin Briggs came in. The push rod was bent and the intake valve stuck. This machine only had 10 hours.

Some of the machines are assemblied, serviced and then sit 8 -9 months in front of a home improvement store. Home owners frequently have to pay for the repair.


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RE: bent push rod

A little Marvel Mystery Oil or equivalent "upper cylinder lubricant added to the gasoline will help prevent this type of damage from occurring. I think an explanation of why the "sticking valves" lead to this "bent pushrod" damage. It's not that the valves become so "stuck" in the guide that the pushrod can't open them. It is because the valve sticks "OPEN" when the camshaft lobe rotates past the lifter or cam follower (at that time the valve is supposed to start moving toward the closed position). If the valve sticks tight enough that the valve spring can't return the valve freely, the rocker arm will stall and the pushrod will fall out of the cup (or ball, as the case may be) on the rocker arm and get caught on the edge of the cup (or center of ball) and when that happens....the next revolution of the camshaft will be as if the pushrod had grown longer physically. The valve will be pushed so far down that the valve spring will be completely compressed so it can't compress any further. When this happens, the pushrod will bend. Other things that can also happen include the rocker arm breaking and or the piston striking the valve (on OHV engines).


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RE: bent push rod

I don't understand this bad fuel problem, particularly if older than 30 days. I buy fuel for the entire year (or nearly so)for my operation and have never had a problem with it. I also know that there are different fuel blends in different parts of the country and wonder if that contributes to some of the problem, but not here. My Mom's 84 Olds sat for 10 years with a 1/4 tank of gasoline in it. The car had 26,000 miles on it. A new battery and a little fresh gas in the carb and it fired up. I drove it to a gas pump and filled up the tank. After a day or two it had decreased power. The problem was diagnosed as the in-tank filter was stopped up. So we removed the filter by blowing it off (a sock type of filter in the tank) by disconnecting the line to the tank at the fuel pump and applying compressed air to the line. Fuel flowed freely then and we added a good filter in the line, at the input to the fuel pump. It has been running well ever since and has had 30,000 miles added to the car.


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RE: bent push rod

How about telling us what you found that was causing the bent push rods.


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RE: bent push rod

Well folks, chalk up another Kawasaki engine with a "sticking valve" problem and "out of place" pushrod. Early Sunday morning, a friend called me from his weekend retreat cabin out in the country. He said he fired up his Kawasaki Mule to go ride some trails and it was only running on one cylinder. Before he called he had already checked to make sure it was "sparking" on the dead cylinder and had "swapped" the plugs to to opposite cylinders to see if the misfire changed cylinders. It stayed on the same cylinder. I told him about the Kaw engines in this thread that have suffered from sticking valves and bent pushrods. I suggested that he remove the valve cover and check for a dislodged or bent pushrod. He called me back about an hour or so later and said "That's what it was, one of the pushrods was loose from its rocker arm." I asked was the pushrod bent and he said he rolled it on a flat piece of plywood and it looked OK to him. He further told me that he "Pushed the valve down with his fingers and put the pushrod back in place". He said the adjusting screw and jam nut were tight so he rolled the engine around till he detected lash between the valve and the rocker arm. He said it felt "about right" so he put the valve cover back on and fired it up and it was running on both cylinders again. I suggested he might want to add a little Marvel Mystery Oil to the fuel. He said that he had just put five gallons of fresh fuel in the tank this morning and that he did not have any Marvel Mystery Oil on hand and nowhere to buy any nearby. I asked him what kind of oil he had and he said "I have some 2 cycle oil for my string trimmer". I told him to add about 6 capfuls of that oil to his tank and go riding like he had planned. He did not say how old the gas in the tank was (before adding the new) but I'll bet it was "stale". I wonder if this is due to ethanol in the pump gas now or if it is just a case of Kawasaki using "weak" valve springs to guard against camshaft wear?????


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RE: bent push rod

This doesn't sound like "a bad gasoline" problem to me. It sounds like a too soft valve spring problem as evidenced by: he,"Pushed the valve down with his fingers and put the pushrod back in place". I have yet to see a valve that I could open by pushing down on the valve with my fingers.


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RE: bent push rod

"I have yet to see a valve that I could open by pushing down on the valve with my fingers."

That is the way I do OHV B&S Engines, don't know about Kawa. nor if this is an OHV engine.

Walt Conner


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RE: bent push rod

"...nor if this is an OHV engine."

If it had push rods, you can bet it was over an head valve engine.


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RE: bent push rod

It IS an OHV twin. My friend said he pushed down on the rocker arm at the valve and was able to depress it enough to reinsert the pushrod into place under the rocker arm. He called today to tell me that he and his wife rode all about their land the rest of the afternoon and the engine is just fine. I told him he was pretty lucky (so far).My point in wondering if Kawasaki has elected to use a "weak valve spring" is based on the presumption that (for all we know) ALL intake valve stems end up having a "sticky, resinous varnish coating" on them. Whether this results in a valve sticking in the open position (because the engine stopped in that position) when the engine is started depends on "how sticky" the varnish is and "how powerful" the valve spring is. "Sticking valves" have always been a possiblity for as long as I have been doing mechanic work (and long before that). It seems to be a "misunderstood" phenomenon in that some people infer that it means "the valve sticks while the engine is running". Actually, that's not the case. The valve sticks (due to varnish) when the engine comes to rest with an intake valve in the open position. If the engine is allowed to cool completely before restarting, and the varnish is sufficiently sticky, and the valve spring is too weak to move the valve, the camshaft will rotate away toward the base circle of the cam and the resulting increase in "valve lash" allows the pushrod to fall or jump out of its seat. Whether the pushrod gets completely free of the rocker or is caught on the edge determines whether the pushrod gets bent or just loose from the rocker arm. I can also see where a weak valve spring will lead to "floating" the valves at high RPM which can also lead to bent pushrods. The difference being that bent pushrods from weak valve springs and/or overspeed will occur WHILE the engine is running. Bent pushrods from sticking valves will occur when doing a "cold start up".


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RE: bent push rod

"If it had push rods, you can bet it was over an head valve engine."

Well that makes pretty good sense, I should have just left it that I am not familiar with Kawa.

Walt Conner


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RE: bent push rod

Me jeeper: Please tell us what you found caused your bent push rods. Please!


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RE: bent push rod

This is all related to fuel problems. The ethanol is ruining gas early. Ethanol sucks moisture out of the ari as it sits there. It get over 30 days old and it won't hardly even burn. These engines are also meant to be ran on a higher octane fule due to the ethanol in them. So every now and then put additive in your engine to keep it clean. Also a big problem that Kaw's have is poeple put puting around on them. WOT only for these engines when they are being used.


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RE: bent push rod

"...It get over 30 days old and it won't hardly even burn..."

Hey daniel - go get yourself a 30 day... heck, make it a 60 day old bucket of gas, put a match to it and see if it "hardly burns". Your comment is unfortuanetly Not True. Yes, ethanol attacts moisture, but it actually helps stabilize the gasoline. Water and pure gas causes gelling. Ethanol keeps the water molecules trapped (molecular-speak) and effectively "disolved" in the gas... for a longer time.

Unless you buy gas from a bulk-source, like farm-supply outfits, all gas comes with various additives, some of which make it last longer. Not for ever, but certainly longer than 30 days.

FYI: I winter-store my summer car for 4-5 months.... no stabilizer... just a tank full of gas (to keep the tank from breathing)... 120-150 day old gas certainly burns, and does not clog my filter. Been doing this for 18 years.

and if you still have any doubts, I do the same with my boat... it gets stored from Oct to May (7 months - 200 days), and the tanks are not full (my oh my - I'm asking for trouble)... and guess what.... been doing that for over 20 years. Not a single glitch.

Now I am not saying that fuel varnish and gelling does not happen - it does... but not in the timeframes described - unless it's bad-fuel to begin with - ie a bad formulations.

And perhaps the gas here in canada is formulated differently, but I would doubt it.

"...These engines are also meant to be ran on a higher octane fule due to the ethanol in them...."

Not sure about Kawa engines, but in general small engines are not meant to be run on higher octane.... and even if they were, it is absolutely NOT related to the ethanol. In fact, ethanol raises the octane rating of fuel... somehow you got your facts criss-crossed bud.

cheers!


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RE: bent push rod

I store my 2 and 4 cycle engines over winter with whatever is left in them, no additive, and have not had trouble with them starting or gasoline burning. Our van is only driven 2K a year and it seems to burn the gasoline from its 25 gal tank OK.

Walt Conner


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RE: bent push rod

Walt,
Same here on leaving whatever fuel is left in the tank, over winter months. I also leave the battery in the whatever. They always start in the spring or the battery is checked and replaced if necessary.
Been burning cheap gas (10% ethanol) 87 octane in all engines for many years with no problems. I do burn diesel in the 2040 add anti-gel to the last tank before storing it for winter, probably wouldn't have to since I don't use it after putting in storage - but years ago I learned the hard way on gelling of fuel - no warning just quit running, that was on a olds 350 diesel, only way to get it to run, spent overnight in the dealer garage at 60 deg F. then add anti-gel.
I think Daniel123 is not the mechanic he claims to be.


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RE: bent push rod

I agree with Wally2q's every word. Wish I could write like he does. I fill my 275 gallon gas tank every year, in late winter, when gasoline is, or should be, cheapest. Had no problem doing this for over 20 years.


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RE: bent push rod

well' I would love to tell you what the problem is but i don,t know yet. the push rod has been on order for one and half weeks now , cant belive dealers dont stock them. he said they dont have any problems with the kaw engines bending rods. will let you guys know when it gets here . ordered 2 in case.

jeeper


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RE: bent push rod

My uncle had a 345 JD mower with the Kawa motor. He had a Case 446 he liked so the JD sat a lot. He experienced the valves sticking on the JD and took it back to the dealership. Several hundred $ later he brought it home. Eventually it did the same again. I would put the push rods back in and it would last a long time with oil added to the gas. Yes, there are pretty smokey startups at times. Hey! I have even carefully hammered the push rods back straight (do not attempt this at home). After looking at this forum it certainly looks like a Kawa OHV trait. It has run good over a year until mom quit putting the oil in due to smoking at times.

My question? What is the best upper cylinder lube that smokes the least? I have thought of putting spacers under the valve springs since they do seem to push down easily. However, the push rods are pretty dainty. If memory serves me correctly, it happened to my uncle after mowing and then restarting the mower after it had cooled. it also seemed like it was worse during hotter period of the season.


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RE: bent push rod

Hey folks I agree with the whole fuel thing.one other thing that may cause issues is excessive heat due to limited airflow.check that grass clippings etc are not building up around the head area limiting cooling airflow.this can be more critical in extreme heat conditions.just a little extra. Precaution.


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