Author Topic: Siezed 394XP teardown help needed SOLVED (Read 8604 times)

Dave Shepard · « **on:** October 30, 2007, 06:25:29 pm »

I have decided to tackle the rebuild of my siezed 394XP. I took the muffler off and I can see very light scoring of the piston. I have tried to spin the flywheel to see if the piston would move at all, but no luck. How do I remove the jug without damaging it any further? I think the jug my be salvagable. I was quoted $600 to replace complete top end and crank seals.

That is out of budget, (I can get a new 24" 660 for $900), but if I can get away with a new piston, gaskets and seals and do the work myself, I'll give it a try. Any advice or suggestions would be appreciated.

Whether or not I do this depends on what is involved, and the availability of parts. I was offered a very good deal by one of our members for a porting/rebuild job, but if I can get it running in stock form for now, I need to pursue that option. Thanks.

Dave

sawguy21 · « **Reply #1 on:** October 30, 2007, 11:27:27 pm »

It sounds like the piston may not be the problem if there is only light scoring. Possibly a crank bearing has failed. Disconnect the choke and throttle linkage, remove the four cylinder hold down screws with a T-handle allen key and remove the cylinder if you can. If it is jammed you may need to stick a punch through the spark plug hole and break up the piston.

Dave Shepard · « **Reply #2 on:** October 30, 2007, 11:50:16 pm »

Thanks, I didn't try too hard to turn it over, I didn't want to make it any worse. From the dirtbikes I've worked on, I think it is the piston, but I'll know more when I take it apart. I don't have a reason yet as to why the motor failed, but from talking to a few people, I have heard that this model Husky is prone to fuel line failure, leaning out the engine. I would at least like to find a cause, the saw is very low hours, and was properly maintained/proper fuel.

Dave

CALSAW · « **Reply #3 on:** October 31, 2007, 12:51:41 am »

If you decide to rebuild it yourself Bailey's should have the parts.

Dave Shepard · « **Reply #4 on:** October 31, 2007, 03:18:58 pm »

I pulled the jug off, and the piston slid right out. The bore has a little bit of discoloration from the aluminum, but most of it wiped off with my fingers. The piston is toast, so I think I can get away with a new piston and rings. Is running a cylinder hone very lightly through the jug ok? I still have to chase the gas lines to see if they are ok, still looking for a reason for the failure. Crank bearings seem ok at a glance. More at 11:00 o'clock, as they say on the news.

Dave

sawguy21 · « **Reply #5 on:** October 31, 2007, 04:28:39 pm »

Just clean off any aluminum and check for scratches that catch a fingernail. Honing it will ruin the coating.

ladylake · « **Reply #6 on:** October 31, 2007, 08:18:13 pm »

What was keeping it from turning before if the jug slid right off? Are you sure the bearing aren't binding up ? Steve

Dave Shepard · « **Reply #7 on:** October 31, 2007, 11:30:19 pm »

I don't know why it slid apart, probably the aluminum broke free when I started pulling on the jug. Sayguy, so the nickasil is applied after the final honing of the cylinder? That may be a problem. The bore doesn't seem to have any serious damage, but there is some aluminum stuck to it, not sure how I should clean it. The bearings feel fine, the crank turns freely now. CALSAW, you mentioned Baileys, do they stock parts not listed in the catalog? If I have to spend $450 on a new top end and gaskets etc., I may reconsider the Stihl, I now have a lead on 660's with bar and chain for $800.

Dave

CALSAW · « **Reply #8 on:** October 31, 2007, 11:50:54 pm »

Dave, Bailey's has a lot more than is listed in the catalog!
394 piston kits are on sale now for 29.95, that must be for aftermarket.
You can check online, but I would recomend calling them. They are great.

I have an '89 394, still running strong, with who knows how many 100's of hours on it.
I bought it used from a logging company in Washington, so I don't think it was babyed.

Dave Shepard · « **Reply #9 on:** November 01, 2007, 12:48:31 am »

Wow, I woldn't have thought I could get this saw up and running that cheaply. I wish I had torn it apart sooner. Still the matter of the questionable jug though. $:-\$

Dave

ladylake · « **Reply #10 on:** November 01, 2007, 04:35:01 am »

Dave Muratic acid will eat the aluminum away with out harming the cylinder. Snowmobilers use it quite a bit. It's sold at hardware stores and lumber yards used for cleaning brick. Don't get it on anything else, maybe use a Q tip to apply. Steve

Dave Shepard · « **Reply #11 on:** November 01, 2007, 09:46:51 am »

Thanks, I'll give that a try. I'm excited to think I can get my favorite saw back. Any way to check the crank seals? Or do I have to put it back together and do a compression test? Thanks.

Dave

sawguy21 · « **Reply #12 on:** November 01, 2007, 10:30:59 am »

Now that you have gone this far, why not replace them anyway. You don't want a bad seal to cause a second failure.

Dave Shepard · « **Reply #13 on:** November 01, 2007, 07:21:07 pm »

I am guessing the hardest part of that is going to be getting the flywheel off, right? Any special tools needed? Thanks.

Dave

Kevin · « **Reply #14 on:** November 01, 2007, 08:04:51 pm »

Once the nut is removed you may need a set of pullers.

Dave Shepard · « **Reply #15 on:** November 01, 2007, 08:42:53 pm »

I've got lots of pullers, probably 200 pounds of them. (It's easier to quantify them in pounds than to try and count them, we've got lots.)

Dave

sawguy21 · « **Reply #16 on:** November 01, 2007, 10:56:16 pm »

Remove the nut and washer then run the nut in until it is flush with the end of the crank. Put some pressure under the edge of the flywheel in line with the key with a screwdriver then give said crank a sharp , I said SHARP boy, smack with a hammer. The taper fit should come loose without wrecking anything.

Dave Shepard · « **Reply #17 on:** November 01, 2007, 11:55:36 pm »

While I've got this thing apart, any suggestions on opening it up a little? You guys must have known this was the next step, right?

I'd like to do something with the muffler, possible polish things up, if it isn't too involved. I have time, it gets dark real quick these days.

I'm not trying to make a crazy saw, but I have heard that it will run cooler with a little work. Thanks.

Dave

leweee · « **Reply #18 on:** November 02, 2007, 10:46:40 am »

Dave you need to talk to Ed Heard (EHP) one of our fellow members.

EHP

arojay · « **Reply #19 on:** November 03, 2007, 11:24:09 am »

My 394 seized once. It was about 3 years old and I had only used it for bucking up until a couple of weeks before the seize. I had started to use it for felling and cutting stumps low in some bigger timber. Well, I made a cut and shut it down and when I tried to start again it had seized. It was just about dark, so I put it in the truck and went home. Took it in the shop and gave it a pull. Round it goes. Hmmm. Next morning I started it outside the shop, seemed OK so in the truck and off to the bush. Went to start it and it is seized. Hmmm is a little milder than what I really said. Back in the shop that night I start to take the jug off and find that the wrist pin is hanging out and hooked into a port and has gouged up the wall. No sign of keepers in the jug, the muffler or anywhere. I put it back together and took it into the dealer for their mechanic to look at because I figure it was a bit of a warranty case. They balked a bit because I had started to tear it down but I made a bit of a case for the keepers to have been missing all along and ended up with about half of the rebuild cost returned to me from Husqvarna.

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Author Topic: Siezed 394XP teardown help needed **SOLVED** (Read 8604 times)

Author Topic: Siezed 394XP teardown help needed SOLVED (Read 8604 times)