bmp01

Spud,

Thanks for that, rather encouraging. Fingers crossed then.  

I'll check the compression and pop the exhaust off - just to be sure.

Hello, 

I'm out of my depth here - are there any model specific weak points on a Husky 395XP, 2004 vintage ?

I'm told the saw runs fine,  idles ok has decent compression etc pictures show the plastics are decent.

Are there any weaknesses in the chain drive,  oil pumps,  chain brake ? Or anything else critical / expensive that wears or fails? 

Thank you. 

Was the cylinder and piston assy a genuine part - the one that failed?  Not often you see that. .... 

After market circlips and rings on the other hand are less reliable,  some builders substitute these parts with genuine ones.

Personally i don't like circlips with those extra "grab here" features on them - the extra wire mass is subject to the same accelerations as the rest on the piston and that means there more likely to move / fret / break. 

No fuel through the low speed circuit in the carb?  Has the 'new' carb been proven work properly? 

Do you manage to the saw start with the choke enabled? Will it then run briefly at low speed or not at all ?

bmp01

1 hour ago, pinhead said:

It lost all power pretty quick and sounded rough all I have done so far is pop the exhaust off and look at the piston and its scored 

I put the saw away for a few months as I have been busy but should have some time to sort it now that'

I would be tempted to pressure test the saw before you pull it apart, nothing to lose and maybe learn something useful. 

22 minutes ago, peatff said:

I did that with my 044 and replaced the piston with an ebay bargain, my thinking was if it doesn't work I'd get a Meteor piston and cylinder but it was fine. I used patio cleaner/brick acid to dissolve the aluminium transfer and rubbed it out with 240 grit and oil. There was one small pit in the Nikasil below the exhaust port not in a critical area and it's a good saw again now. It's worth spending a bit of time and money to get one running again and it gives you a warm glow when it works.

All aftermarket pistons are cheap really, even decent Meteor brand. Time and effort to clean up a genuine cylinder etc, 10 pound cheapie or a 25 pound Meteor piston....... I don't feel the need to experiment with cheap 

As per previous comments,  if you don't fix the route cause its going to happen again.  It would seem you never quite got the saw fixed in the first round of repairs so you'll be looking to dig a bit deeper this time. Air leak is favourite,  so make sure you pressure test the repaired saw or get someone to do it. 

Only useful thing to add,  if the original cylinder isn't trashed too bad it can probably be brought back to life by removing the aluminium deposits. Takes time but if you end up with a good, genuine used cylinder I'd take that over a replacement one. ... do a bit of research on here for 'how to....'

It's a good saw,  worth the effort. 

Going through a rather tired MS171 which came to me as a box of bits, nothing very exciting. Reason for posting - noisy crank bearing led me to remove and disassemble the bearing, idle curiosity.

Picture is worth a look.

Look at the ball sat on the blutak - the outer layer has disintegrated. Poor quality steel I imagine. Bearing is Chinese,  with C4 clearance, i thought these were C3 clearance so might be an aftermarket item ?

bmp01

Jeez,  that's some oil slick 

Yeah,  I can sort of see the problem,  exit in the exhaust is quite high up, higher than the exhaust port. And there's a stupidly small internal passageway inside the exhaust that would stop the oil draining even when you tip the saw forward.  Ho-hum. Easy in hind sight innit...

So, how big was that mysterious blue cloud over Heanor today then ?   

Nice one Micky, good result. 

As to your question, took the plug out and span it over with a drill ......

Did you get much oil out of it? 

Put the clutch drum back on (if you haven't already) before firing it up.

Piston's Peachy.

No problems there.

Strange exhaust port though, bit difficult to make out the shape,  not seen one like that before. ....

Is it a genuine cylinder I wonder ?

bmp01

9 hours ago, mickyblueeyes said:

I was advised by someone ,a car mechanic actually he reasoning was that in order to get it started  because it had not run for 3 years.

Ok, thanks for clarification. ... seems i misunderstood, got the wrong end of the stick, etc, etc.

As others pointed out, if it turns easily with the plug out, there is no need to be looking at clutches,  chain brake, ignition coil foulIng the flywheel - my mistake,  apologies. 

Still worth posting a picture of the piston  seen through the exhaust,  or at least confirm the piston is good. You should see the faint machining lines running around the bottom half of the piston, so below the piston ring. Any vertical lines are damage. There's a thread here just recently "Does this cylinder need replacing" with some good pictures in it.

So have you managed to get any gunk (oil) out of the saw ?

Keep us posted.

I'm close to Jn 16 on the M1,  bit of a trek but happy to help ...

bmp01

And 3 pounds of that was for the accelerator pump parts  

1 hour ago, chuck norris said:

Thanks for the reply's, but While sanding I found a considerably bigger scrape (almost 1mm deep) so I am going to replace the cylinder as well.

If that's above the exhaust port, yeah not much choice. Below the exhaust port. .... you might get away with it.  What piston are you going to fit ? That will tell us how much you value the rebuild 

bmp01

9 minutes ago, billpierce said:

 

 

Aye I was going to chime in with some ideas but the lad will be a while doing all the random tests that have been suggested already!

 

 

On the up side there's learning to be done. An appreciation of how a saw works and is put together is no bad thing. Might even help with using the saw once its fixed.

11 hours ago, mickyblueeyes said:

The oil was added three weeks ago after that i just left it but now i really need the saw for the logs.

Micky,

Ok. So what was the reasoning for the oil back then? 

5 minutes ago, billpierce said:

So many cooks! Good luck fixing yer saw pal!

Yeah,  best to have some knowledge so you can filter the offerings. Or learn quick !

2 hours ago, Mark_Skyland said:

I would check the starter system because if it is the easy start type it could be binding somewhere when it has some resistance ie when the plug is in. I think that was something to do with the bg86 I mentioned but like I say I couldn't find a faulty component so I cleaned and greased it.

I can see the logic in that. Should be the simple start mech but even so could be something that binds when it's under load  and doesn't when the plug is out (no load).

10 hours ago, mickyblueeyes said:

The oil was added three weeks ago after that i just left it but now i really need the saw for the logs.

 

Ok. So, what was the reasoning with putting oil in there in the first place?  

Just a thought on the hydraulic lock theory suggested here with loil below the piston - if the saw is held completely upside down, the piston will be like a cup holding on to the oil. To get that fluid out, place the saw on its side (either the chain side or the pull start side) and turn the engine over, this should allow the liquid to flow through the transfer ports to the top of the piston.  Then you can turn it upside down again and drain from the spark plug or if the exhaust is still off you can drain it from there.... 

Good result,  another one dragged back from the grave !

I have to say that's brilliant service,  running saw AND a detailed diagnosis report. Don't see that too often.

Did i mention I hate accelerator pumps  before now . .... I did ?..... Oh ok, I'll shut up then. ....

37 minutes ago, spudulike said:

......this could run and run

It could. ...... but then again it might never,  ever ...... run again.....

I get the feeling is either goosed or something daft.  And before long it will be more economic to just swap the engine (and carb) for some aftermarket parts.

11 minutes ago, EricBradley said:

if it pulls over easy with no plug in as stated in first post and is hard to pull with the plug in its got to be compression related, it cant be anything else, sounds slightly like hydraulic lock.

If you read the first post through he says it was hard pull over and that's why he put some thin oil down the plug hole. .... it subsequently loosened up (or he just got used to pulling it over). 

Maybe the O.P. can confirm that's true AND if the brake was on or off and if the ignition module had been gapped correctly at that stage. 

Actually just take the 5odding ignition module off, take the clutch off, and show us a picture of the piston through the exhaust port.......

bmp01

Micky,

It probably would be quicker/easier to get some one to look at it for you.  But before you do a couple of quick things to put to bed:

-Post a picture of the piston as seen through the exhaust port (now you've got exhaust off).

-Really make sure you've got the chain brake disengaged. 

-Pull the clutch drum off  ( its the thing the drive sprocket is joined to,  held on with the 'E' clip) and the bearing inside. You need the chain brake disengaged to do this as the brake band will grip the outside of the clutch drum. Do NOT attempt start the saw like this (ignition off please while you pull the cord) we're just trying to find out if the clutch was making the saw hard to turn over. 

Maybe there will be a clue in here.

By the way, not every MS181 has the Stihl easy start mech,  but it's a small displacement saw that should pull over pretty easy anyway. 

bmp01