394XP circlip failure.

[CurSedVoyce]

I'll try the hotter plug, thanks. 100UL they were talking about for years with racing as well.. See what happens. So long as the alcohol is out of the equation, good to go. Of course all the other additives and detergents kind of suck too. Look at what happened when you mixed Echo mix with Arco gas. Don't know if they changed that additive that made what looked like fiber glass or not

 

[Burnham]

There are still questions in my mind as to the validity of this whole ethenol, today's gas doesn't keep, it's all crap, argument.

Saturday I finally got the weather break to allow me to till the veggie garden so we could plant. B&S 5hp motor on a Craftsman rear tine tiller about 20 years old. Per normal, I'd put it up a year ago with a smidge of fuel in the tank, not run out or anything special. Forth pull on the starter cord, fires right up.

You guys may be right, what do I know; but none of my saws (both my own and Uncle Sam's), air compressor, lawnmowers, and this tiller complain about today's fuel or my less than protective treatment of them. Tell me why.

 

[Jed]

Thanks for the suggestion B. I'm a grass-is-always-greener-on-the-other-side-of-the-fence type of a guy, and I've always run Stihls just because of their prevalence, so, of course, now, I'm all about a Husq. Plus, they sound really cool when they're ported. Yeah, I ran a really great 064 for a couple of months. Had a great balance with a biggish bar. I actually--despite Jerry's discouragement--(my hero-worship can't be that bad!) thought about getting an 056 because Craigslist is absolutely swarming with em in our area. Plus I thought I'd rack up more old school points with the boys.

I'm a tool.

Chevron 93 with Valvoline 2 cycle: never a hitch.

 

[CurSedVoyce]

I think some of the fault can be placed into the vendors of the fuel Burnam. The Echo mix problem was real, seen the results for myself. Mix that gas with that mix, bang.. Muffler full of black fiber glass looking crap, all clogged up. Change gas with the same mix, no problem. Some additive created it. We had a gas station that sold fuel up here that all of a sudden would not run in 4 stroke engines just like your B & S. Lawnmowers, etc., not starting. All could be traced back to the fuel station it came from. Switch gas stations/brand, no problems, start right up. Kat got some fuel in town and then filled up in the valley just recently. Her way home UPHILL she got better mileage than going Down the hill. A LOT better mileage. Stopped buying gas there. Now get better gas mileage. Couple years ago, more water in the gas and the ethanol was causing it to attract or separate. Real fun there. I forget the chemistry. Then you have the synthetic vs regular mix issue. Synthetic tends to keep the ethanol and fuel from separating, the regular does not. Not a good scenario. Just switching to a full synthetic mix oil will solve a lot of problems. But it will not cure the vendors from selling dirty fuel, additives and detergents than can also be harmful or just perform poorly, to the consumer. We are currently down to 4 fuel stations we will buy fuel for the truck, 3 (if you count the avgas) we will purchase higher grades of fuel for the equipment. We have 10 fuel stations I believe with in my service area radius. Maybe not an issue in some places, but here in my part of CA, be careful what you buy.

 

[Burnham]

I hear you, Stephen, and do not discount your reports...but how do you explain the fact that there are not different runs of fuel from the plants...the same darn fuel goes to every stinking station?

I do not mean to act like y'all are wrong...I just don't understand why I have had essentially no fuel related problems with my 2 and 4 cycle engines...not back in "the day", not back 10 years ago, not right now.

Something just doesn't add up...I run my saws so less frequently than you full-timers...run 87 octane with 10% ethenol, mostly...and send roostertails of wood chip, like to beat the band.

 

[CurSedVoyce]

There are levels of purity in the business also Burnam. There is a reason they test avgas (daily I believe) for impurities or contamination.
There are different refineries and the different companies. Some companies use an additive that others may not.. Their little secret ingredient.
Dunno.. Guess you may be lucky. Your filling stations may not buy from the lowest priced broker to sell high like our here. Our Texaco is great. Chevron was better, it went defunked. Shell ok.. We have mostly mom and pop no name stations. One guy owns both the Texaco and the Grizzly Gas (the once proud Chevron) and the Grizzly Gas fuel will make older vehicles diesel and knock. Texaco wont. Chases fleet station... you can almost get drunk on the alcohol driving buy it. It eats lawn mowers for breakfast. Ring failures. Maybe up where you are they have tighter reigns on the brokers. I can only know what goes on local here. I can only report what I see in my books when I switch products and watch my maintenance expense curve turn to my favor and drop 1-2-3000.00 a year back into my pocket by switching products.
Sorry about the derail ..
I hear what you are saying Burnam... I would be confused too if I were not experiencing what I have first hand.
Gawd I hate ethanol threads
Now I am going to get Erik, Brian and Magnus all worked up

 

[stig]

I think it is woodoo, Burnham.

My neighbour couldn't get his lawnmower started this spring. Took it to the repairshop and was told it was because he had put it away with gas still in the tank.

It is the same repairshop that I use for all my saws and small engine stuff, good people, will not BS a customer ( especially when they know he is my neighbour)

We buy fuel from the same gasstation ( only one there is, we're out in the sticks) and I left a ½ a tank in my mower when I put it away for winter, so I figured I'd have trouble.

Darn thing started right up and ate the rest of that gas with no problems!

 

[Magnus]

The wrist pin locked up and broke piston setting clip free. These cracks in piston only happen when the wrist pin is stuck.

So why do they get stuck?
99% of the time bearing fail from lack of lubrication.
This create heat and it swells from center out. Finally breaking the sides of piston pin go thru and she stops singing.

 

[Magnus]

I think it is woodoo, Burnham.

My neighbour couldn't get his lawnmower started this spring. Took it to the repairshop and was told it was because he had put it away with gas still in the tank.

It is the same repairshop that I use for all my saws and small engine stuff, good people, will not BS a customer ( especially when they know he is my neighbour)

We buy fuel from the same gasstation ( only one there is, we're out in the sticks) and I left a ½ a tank in my mower when I put it away for winter, so I figured I'd have trouble.

Darn thing started right up and ate the rest of that gas with no problems!

Gas ages faster than you think. This is very common. Dump the old in with new and out the door they go.
If you have half a tank and yours start as his didn't on gas bought in same place, say very little unless you stand beside him and fill your can at the same time.
Storage is another thing, condition of plug too. Other facts that comes to mind is what engines it is, age, hrs on them and speed of pull.

 

[Dave Shepard]

The wrist pin locked up and broke piston setting clip free. These cracks in piston only happen when the wrist pin is stuck.

So why do they get stuck?
99% of the time bearing fail from lack of lubrication.
This create heat and it swells from center out. Finally breaking the sides of piston pin go thru and she stops singing.

This makes no sense to me. The bearing is perfectly fine and the pin slides in and out smoothly, and has a thin film of lube on it. The only way I can see this failure happening is for the clip to go first.

 

[Magnus]

The bearing can lock and be free again as it cools and pin return to shape.
Pull in it and it gets oil on it too, but it does not mean much...

A clip can not cause the piston to break like this, even if you place it above piston and do your best.
Piston is softer, especially when hot and it will dig in to piston rather than break it like this.

Those cracks are not clip damage. It is something else with great force involved.

 

[Al Smith]

It's after the fact so the cause is hard to determine .However if it shot the clip at just the right time it could have been blown up the transfer tunnel and the pin snagged the transfers probabley on the way down .

It stands to reason in my mind that if it snagged going up it would either have bent the rod or broke the crankshaft .Going down the piston would be the weakest link .

 

[Magnus]

Lost Clip will set the pin free. It can go out and snag the port, but there usually is a lot of damage done prior the snag. Mostly they stop and wonder what happened before it go in to port. If so it is very easy to see were pin traveled and hit.
There is no way only a clip can do this damage.

If a clip can do that, the piston stoppers will do a lot more damage...

It can't break the piston like this unless pin change form and size the piston. Usually they are split in two so top is separated from wrist and pin. I have seen this damage with both clips and pin intact and in correct place.

 

[Dave Shepard]

The pin was hitting the port, look at the pic. I'm not saying that the clip broke the piston, the pin did when it caught on the port.

 

[Al Smith]

Well yes that's pretty obvious .The question remains ,what tossed the clip?

 

[Jed]

Hey Boys: I think that obviously Dave is right. Almost certainly, the pin broke the piston by snagging on the transfer port. I don't think that Magnus is denying this. I'm trying to imagine my difficulty in trying to translate this problem into Swedish.

Stig where you at? You gotta' know at least as much Swedish as I know Spanish!

 

[Cut4fun]

Was it a aftermarket piston and clips or at least aftermarket clips being used?

 

[Dave Shepard]

Yes, it was from Bailey's. I don't know what brand it was. I'm contemplating the OEM top end kit, at some point. I'll ask about a top end kit when I order parts for the 372 this week from my Husky dealer.

 

[Al Smith]

Aha,the rest of the story . Like I said I've had some problems before getting the Meteor clips to fit in .They seem at least to me to be a tad too thick to seat properly in the groove .

 

[CurSedVoyce]

And soft.
Even with an after market kit, I order OEM clips, wrist pin and bearings.

 

[Magnus]

There is lots of things that can happen.

If you see lots of saws you come across a lot of strange things.
It is very hard to say for sure even if you have the saw in front of you.

I see the pic, but it doesn't help much. The markings I can see in the port area is not enough to crack the piston like this.
It is usually more damage even with intact piston.

The clip itself if put in right will not be under any stress or forces. It only prevent the pin from falling out.
It is not often I have seen wrong clips in a piston set. Even the very cheep ones have clips that work if installed correct.

I put them in wrong, learned the hard way to make sure it is correct.

You only get one shot/clip. If you alter its form just a tiny bit it is very high risks involved.
they can be corrected if you know how they are supposed to look and how much tension there is, but it is quite a risk for a cheep part.
I reuse and reshape etc, but I don't rek. all to do it.

If it is mounted wrong it fails pretty quick. Not hard to see or hear when one is gone.

 

[Magnus]

Best clip is those without ear to hold it in. Not so big chance they are altered in shape and tension before they sit correct.
I have several pistons like this here and I found the tells of excessive heat on all of them.
I still think bearing failed and heat caused the piston to expand, setting the clip free.

I am wrong sometimes, this could very well be wrong, but based on what I can see and read this is what I think.
There is much more to this in order to know what happened?

Were is the clip? It will not burn easily so it is some were...
When did the sounds start? How long did it run with it? seconds, minutes, day's?
How does the crank case, cylinder top, inside of ports, shaft, pin and bearing look?

 

[Al Smith]

The question of reusing cir-clips is often a debatable subject . The method of removal I use does not compress them very much so I just reuse them .

An ice pick with a slightly bent end works very well to pry them out of the groove .Much less stress than using a thin bladed screw driver .

On the aftermarket clips I couldn't determine if the clip was actually too thick or the piston pin was slightly too long .At any rate the clips just would not seat in .It did work though using one after market clip and one OEM .You don't have much variance of length to work with .

 

[dastevoe]

Was it a aftermarket piston and clips or at least aftermarket clips being used?

Yes, it was from Bailey's. I don't know what brand it was. I'm contemplating the OEM top end kit, at some point. I'll ask about a top end kit when I order parts for the 372 this week from my Husky dealer.

Aha,the rest of the story . Like I said I've had some problems before getting the Meteor clips to fit in .They seem at least to me to be a tad too thick to seat properly in the groove .

OK.........here goes , I have done more than a few builds lately with both Meteor & NWP pistons,pins & clips and have found it not uncommon for the pins to be too long to have the clips seat in the grooves properly and have made reference to this on other sites for guys to double check that the clips actually seat into the gooves properly BEFORE final assbly.
IMO I don't think the clips are the culprit on these failures, it's most likely the pin length or secondly (not as likely IMO), the groove is not cut deep enough.
My solution has been to surface grind the pin to the correct length. If you don't have access to a SG then find someone who does.
Sorry for your bad luck Dave.

Steve

 

[Al Smith]

You could most likely even use an oil stone or just a piece of fine sandpaper to shave a tad off one end of the piston pin .They couldn't be off much over a couple thou .

A little off the subject but along the same lines .When I souped the Stihl 038 Mag I got from B I had to freeze the damned pin to get it back in alignment with the bearing and piston .That saw had so little running time on it there was almost no slop what so ever in the assembley .Of course those parts where all OEM Mahle / Stihl .