Stihl 044C crankcase Hydraulic locking ??

[bbaley]

Hi all,
I was hoping someone could help me identify the issue I am having and how to go about fixing it.
Based on reading post here and elsewhere, I suspect I am experiencing "hydrolock" or hydraulic locking in the crankcase ?

The saw was recently (three weeks ago) running well and starting quite easy (for that saw). sure lots of compression but it felt "right", no jerking or locking, etc.

This occurred when I started it, revved it a few times and was listening to it idle, then I went to make a test cut to check the chain, and it quit and sort of seized up (or just jerked when it stopped)

Now I can pull over once but very difficult, then it "locks" with very hard compression on end of that stroke.
When I pull SLOWLY I can hear sucking sound of air - which I assume must be from crankcase ?

With the spark plug out it turns over easily and just fine.
I have the muffler off and do not see anything nasty on the piston/wall
I removed the carb as well so I can see as much as possible (and hear) as I slowly pull rope and move piston up/down.
I have verified correct spark plug - not too long (WSR6F) but like I said it was running.

The clutch assy/rim sprocket/chain is moving on pull.
I removed the rope/starter cover and verified rope is wound properly and working but I expected that since with plug out it felt fine.

I turned saw upside down so plug hole down and pulled starter/rope a bunch of times and nothing came out.

So, to recap;
- spark plug removed
- gas is drained, tank cap off
- carb is removed
- removed/checked/reinstalled roper/starter
- piston/wall/ring looks ok, or at least no obvious difference fome last time I looked, is wet with fuel/oil mix
- pulls fine and easy and smooth with plug out
- VERY difficult to pull with spark plug even screwed loosly in a thread turn or two let alone seated - and only get one cycle of piston on pull before "locks" up
- saw was running well recently, started fairly easily and had fresh mix in it (non-ethanol + Stihl HP Ultra )

I have read it is possible to get bar oil in the crankcase due to failed o-rings in the oiler ???

Anyway,
Not sure how to verify the issue and if it is hydraulic locking in the crankcase what is required to fix it ?

Any help would be greatly appreciated !!!

 

[splitpost]

Sounds like you got good compression ,have you put a comp gauge on it?,my 044 has 175psi ,which isn't overly high but you do need to be committed when pulling it

Sent from my SM-N910G using Tapatalk

 

[bbaley]

Sounds like you got good compression ,have you put a comp gauge on it?,my 044 has 175psi ,which isn't overly high but you do need to be committed when pulling it

Sent from my SM-N910G using Tapatalk

No, I don't have a gauge.
As mentioned, I am familiar with how it normally feels when starting it, and this ain't that !

 

[HarleyT]

If it is wet, then the carb is flooding. But to help much, fill in a bit on what led up to the trouble.

Like:
I just rebuilt the carb..... Or I just had it rebuilt.... Or, it has been running great, and..... Or, I just bought it at a garage sale. etc.

 

[splitpost]

Pulls fine with no plug in ,no oil or fuel running out when upside down as you wrote,so when you put the plug in do you have the lead on and master in the start position

Sent from my SM-N910G using Tapatalk

 

[bbaley]

Pulls fine with no plug in ,no oil or fuel running out when upside down as you wrote,so when you put the plug in do you have the lead on and master in the start position

Sent from my SM-N910G using Tapatalk

I don't notice any difference between the plug being in and lead UNCONNECTED and with lead connected and switch in start position
seems the same to me

 

[bbaley]

If it is wet, then the carb is flooding. But to help much, fill in a bit on what led up to the trouble.

Like:
I just rebuilt the carb..... Or I just had it rebuilt.... Or, it has been running great, and..... Or, I just bought it at a garage sale. etc.

As mentioned, it was running fine a few weeks ago.
I have not rebuilt the carb as it was running fine.
I purchased it used from an old neighbor about 6 months ago. I cleaned air filter in it 6 months ago, although it was fairly clean at that time. I replaced fuel filter 6 months ago.

 

[HarleyT]

Well drain out the fuel tank, and remove the plug, and pull the rope a big bunch of times, to make sure the saw is
fully dried out. Leave like that in the sun for an hour or two, pulling the rope some more. Really dry it out.
Then reinstall the plug, with no adding any fuel, and try pulling the rope again. See if the compression problem goes away.

 

[HarleyT]

If it goes away, rebuild the carb with a full kit w/needle.

If it doesn't, pull off the cylinder and decarbon the cumbustion chamber area.

 

[HarleyT]

cumbustion sounds dirty, eh?

You know what I mean......

 

[bbaley]

If it is wet, then the carb is flooding. But to help much, fill in a bit on what led up to the trouble.

Like:
I just rebuilt the carb..... Or I just had it rebuilt.... Or, it has been running great, and..... Or, I just bought it at a garage sale. etc.

I should re-state - wet, meaning it wasn't bone dry, but obviously lubricated with mix. not dripping wet or what seemed excessive - but then I am not an expert in how much "wetness" one should see when you look at the piston/walls through the muffler/exhaust port. but I know what dry looks like, and figured I should mention it definitely wasn't dry

That being said, as mentioned, when turned upside down and rope pulled nothing is dripping out.

 

[splitpost]

I was thinking timing may have moved

Sent from my SM-N910G using Tapatalk

 

[bbaley]

If it goes away, rebuild the carb with a full kit w/needle.

If it doesn't, pull off the cylinder and decarbon the cumbustion chamber area.

Thanks - If it comes down to cylinder and "decarboning" - do you have recommendations ? (process, products)

 

[HarleyT]

Just pull off the cylinder and scrape/buff. Then pop it back together. Not that big of a job.
A thin buildup can raise the compression ratio a bunch.

 

[HarleyT]

Try the drying out thing first, might be all you have going on.

 

[HarleyT]

Or, then, maybe a bit of both...

 

[bbaley]

Or, then, maybe a bit of both...

alright - will do. thanks!

 

[bayard]

my 044 will get very hard to pull over now and then. my comp. is 185-190. i think when it is hot it can be hard to pull over? drop starting is the only way i start mine.

 

[bbaley]

my 044 will get very hard to pull over now and then. my comp. is 185-190. i think when it is hot it can be hard to pull over? drop starting is the only way i start mine.

I hear ya - but this isn't "hard to pull"
It is literally like it seizes after 1 cycle of the piston
so when "drop starting" it jerks/seizes/stops with no further turn of the crank/piston

 

[Thommo]

Your chain should not be moving when you pull on the starter cord. Something is broken on your clutch.