Crank seals going?

[Pioneer]

I Have a 257 Husqvarna and I suspect the crank seals are going. Symptoms, excessive low speed needle setting, and slight change in RPM (goes lean) when tilted on its side.
There's a big discrepancy in the high and low needle settings, the high only needs three quarters turn, while the low needs two turns.
Thoughts?

 

[Chevboy0167]

Can you spray a little carb and choke cleaner around both seals to pinpoint?

 

[Vintage Engine Repairs]

I Have a 257 Husqvarna and I suspect the crank seals are going. Symptoms, excessive low speed needle setting, and slight change in RPM (goes lean) when tilted on its side.
There's a big discrepancy in the high and low needle settings, the high only needs three quarters turn, while the low needs two turns.
Thoughts?

Pioneer, I’m sure you’re a nice bloke and I say this in a mostly jovial way, but what have you been up to on this forum for the last 17 years if you don’t know to do a p&v test on suspected seal issues?!?!

 

[Pioneer]

Of course, a p/v test is the best way to confirm it, BUT that means I have to make special plates to block off intake and exhaust on this model, take the carb and muffler off, make fittings for a plate, etc etc. Get my drift?
I have already sprayed around the gaskets with no results. I'm wondering if someone has had the same symptoms, usually the bad seals I have seen show much more obvious and drastic running conditions to what I have, the reason for the title of the post.
Its a lot easier to check the simpler things first before you start tearing the saw apart. There's no harm in asking other peoples opinions, it might save me needless work simply because I missed something someone else might think of.

 

[Evan]

17 years **** ohhh wait.

I had my 440 do the same finally tore it down to do seals and then fixed the weird inconsiszent tunning issues.
I never did pressure test it.

 

[ChillyB]

Don’t need to get all fancy. I rented an air conditioning system pressure tester from Autozone. Unscrews the QD fitting from one of the plastic caps then screwed fuel tubing onto that. Attached that to a spark plug adapter port. Covered exhaust with two layers of masking tape and the muffler (because that’s what I had nearby). Covered intake boot (carb removed) with a wet thumb, which was a bit of a trick since the Husqvarna 350 has a little impulse port near the intake hole. It worked well enough to confirm no leak. Would be tricky to add spraying soapy water without another set of hands.

 

[Vintage Engine Repairs]

Of course, a p/v test is the best way to confirm it, BUT that means I have to make special plates to block off intake and exhaust on this model, take the carb and muffler off, make fittings for a plate, etc etc. Get my drift?
I have already sprayed around the gaskets with no results. I'm wondering if someone has had the same symptoms, usually the bad seals I have seen show much more obvious and drastic running conditions to what I have, the reason for the title of the post.
Its a lot easier to check the simpler things first before you start tearing the saw apart. There's no harm in asking other peoples opinions, it might save me needless work simply because I missed something someone else might think of.

I don’t get your drift, because it’s 2 pieces of inner tube and 5 minutes of your time. I think you’re being lazy.

 

[ChillyB]

Another thought: you have symptoms of bad seals. How old is saw? Significant use? If it’s due for seals maybe just change them “because”? Almost everyone will say you must pressure test after that work too. A scarce few might dare to suggest that if your needle settings become normal and stops surging when to tip the saw then you can’t have much of a remaining leak. I’m too new to have a valid opinion.

 

[Pioneer]

Yup tom I'm being lazy. 5 minutes of my time to do all that? Don't think so, when I pressure test I make proper plates, I don't do things halfway. However, I don't live to work on saws, 17 years on this site means little, my involvement with the hobby is long, not obsessive. You can tell by the number of posts compared to the years. Easier to type this than to tear the saw apart. Work smarter not harder right?
Well, working smarter got me some results. Instead of tilting the saw on the side for a couple of seconds like you would normally do to check for air leaks from bad seals, I laid it on its side while It was running and held it there. This time instead of a small change the saw slowly continued to lean out and then finally die. So yeah, it confirms the seals are going bad and I saved myself the trouble of pressure testing it. Learned another diagnostic trick today.
The flywheel, clutch, and oil pump have to come off in any case, you have to take them off to expose the seals before you pressure test, so you might as well just replace them while you are at that point.
According to a couple of videos I found it's fairly easy on this saw, so new seals are on the way. Should have done it in the first place, as people pointed out it's an old saw, and with an old saw you never know what you get.
As far as pressure testing it after you install new seals I question the necessity. It's a pretty straightforward procedure and you have to do something pretty wrong for them to leak again. Pretty easy just to throw the flywheel on and run it instead, because you never took the carb and muffler off in the first place. If it continues to behave badly then its time to make plates and do the P/V test.

 

[lone wolf]

Yup tom I'm being lazy. 5 minutes of my time to do all that? Don't think so, when I pressure test I make proper plates, I don't do things halfway. However, I don't live to work on saws, 17 years on this site means little, my involvement with the hobby is long, not obsessive. You can tell by the number of posts compared to the years. Easier to type this than to tear the saw apart. Work smarter not harder right?
Well, working smarter got me some results. Instead of tilting the saw on the side for a couple of seconds like you would normally do to check for air leaks from bad seals, I laid it on its side while It was running and held it there. This time instead of a small change the saw slowly continued to lean out and then finally die. So yeah, it confirms the seals are going bad and I saved myself the trouble of pressure testing it. Learned another diagnostic trick today.
The flywheel, clutch, and oil pump have to come off in any case, you have to take them off to expose the seals before you pressure test, so you might as well just replace them while you are at that point.
According to a couple of videos I found it's fairly easy on this saw, so new seals are on the way. Should have done it in the first place, as people pointed out it's an old saw, and with an old saw you never know what you get.
As far as pressure testing it after you install new seals I question the necessity. It's a pretty straightforward procedure and you have to do something pretty wrong for them to leak again. Pretty easy just to throw the flywheel on and run it instead, because you never took the carb and muffler off in the first place. If it continues to behave badly then its time to make plates and do the P/V test.

Yes it is important to pressure test it !

 

[Vintage Engine Repairs]

Yup tom I'm being lazy. 5 minutes of my time to do all that? Don't think so, when I pressure test I make proper plates, I don't do things halfway. However, I don't live to work on saws, 17 years on this site means little, my involvement with the hobby is long, not obsessive. You can tell by the number of posts compared to the years. Easier to type this than to tear the saw apart. Work smarter not harder right?
Well, working smarter got me some results. Instead of tilting the saw on the side for a couple of seconds like you would normally do to check for air leaks from bad seals, I laid it on its side while It was running and held it there. This time instead of a small change the saw slowly continued to lean out and then finally die. So yeah, it confirms the seals are going bad and I saved myself the trouble of pressure testing it. Learned another diagnostic trick today.
The flywheel, clutch, and oil pump have to come off in any case, you have to take them off to expose the seals before you pressure test, so you might as well just replace them while you are at that point.
According to a couple of videos I found it's fairly easy on this saw, so new seals are on the way. Should have done it in the first place, as people pointed out it's an old saw, and with an old saw you never know what you get.
As far as pressure testing it after you install new seals I question the necessity. It's a pretty straightforward procedure and you have to do something pretty wrong for them to leak again. Pretty easy just to throw the flywheel on and run it instead, because you never took the carb and muffler off in the first place. If it continues to behave badly then its time to make plates and do the P/V test.

We don’t see eye to eye here, but best of luck with your repair none the less.

 

[grizz55chev]

Yup tom I'm being lazy. 5 minutes of my time to do all that? Don't think so, when I pressure test I make proper plates, I don't do things halfway. However, I don't live to work on saws, 17 years on this site means little, my involvement with the hobby is long, not obsessive. You can tell by the number of posts compared to the years. Easier to type this than to tear the saw apart. Work smarter not harder right?
Well, working smarter got me some results. Instead of tilting the saw on the side for a couple of seconds like you would normally do to check for air leaks from bad seals, I laid it on its side while It was running and held it there. This time instead of a small change the saw slowly continued to lean out and then finally die. So yeah, it confirms the seals are going bad and I saved myself the trouble of pressure testing it. Learned another diagnostic trick today.
The flywheel, clutch, and oil pump have to come off in any case, you have to take them off to expose the seals before you pressure test, so you might as well just replace them while you are at that point.
According to a couple of videos I found it's fairly easy on this saw, so new seals are on the way. Should have done it in the first place, as people pointed out it's an old saw, and with an old saw you never know what you get.
As far as pressure testing it after you install new seals I question the necessity. It's a pretty straightforward procedure and you have to do something pretty wrong for them to leak again. Pretty easy just to throw the flywheel on and run it instead, because you never took the carb and muffler off in the first place. If it continues to behave badly then its time to make plates and do the P/V test.

It's your saw and your time, what you do to test the results are going to get you the results necessary to get your saw up and running without issue. Doing the seals is cheap insurance on an old saw, so why not? You may end up having to do the p/v test later but you may not! You can ask 5 different people about a problem and get 5 different opinions, that's just how it is. Please keep us updated on the progress.

 

[Pioneer]

Well, the flywheel side seal is the definition of easy, it mounts in a screw down plate and is easy to push out of this housing with a couple of appropriate sized sockets. You can see some carbon stains that have made their way past the bearing onto the side of the housing and in the seal, probably the result of blowby.

The other side is conventional, I understand you can use a screwdriver modified into a hook shape to pull it out. Just found this excellent video explaining the method.



The screw in remover looks really slick, a good investment if you do a lot of saw work.

The flywheel side seal and mounting plate.

 

[Pioneer]

Clutch side seal out. Used a different approach, made a mini slide extractor out of some scrap and piano wire I had laying around. Hook end is wire wheel buffed smooth to prevent scratches and the stop end is brazed on. Worked well, several taps of the weight and the seal popped out.
Clutch side seal is the same size but looks very different and inferior to the flywheel side.

 

[grizz55chev]

Clutch side seal out. Used a different approach, made a mini slide extractor out of some scrap and piano wire I had laying around. Hook end is wire wheel buffed smooth to prevent scratches and the stop end is brazed on. Worked well, several taps of the weight and the seal popped out.
Clutch side seal is the same size but looks very different and inferior to the flywheel side.

View attachment 987944

Better get a patent on that! You should know soon if that was your problem.

 

[Vintage Engine Repairs]

Hey Pioneer, I have had a bit of time to think about my messages earlier, I just want to apologise for coming across a bit abrupt.

Sometimes I need to consider the bigger picture of what others choose to do, how they do it and why they do so rather than narrow in and think that my one way is the best and primary solution. It’s something I’m working on, but yet to get it right every time!

Best of luck with the repair and apologies once again.

 

[grizz55chev]

Hey Pioneer, I have had a bit of time to think about my messages earlier, I just want to apologise for coming across a bit abrupt.

Sometimes I need to consider the bigger picture of what others choose to do, how they do it and why they do so rather than narrow in and think that my one way is the best and primary solution. It’s something I’m working on, but yet to get it right every time!

Best of luck with the repair and apologies once again.

More than one way to skin a cat, as they say.

 

[Pioneer]

No sweat Tom, I don't take offense. If someone disagrees with what I do, I try to explain my though process to give meaning to my actions. "There's more than one way to skin a cat".
I think that's a pretty good philosophy when facing a task, and I always try to think out of the box.
Saw repair is just one of my hobbies, my approach to it can change day by day. I try not to take it too seriously, there are enough things in this world to stress about as it is.

That being said, I've been trying to keep this hobby under control but I think I'm slowly losing! I've got 14 running saws right now with another couple potential runners. Should I go and buy those three advertised non-running Poulans for $50? LOL! Parts of the basement are littered with saws, and I even started working on them on the dining room table. Found out how hard it is to get bar and chain oil out of a shag carpet! CAD is insidious as some of you may well know, it can make you look like a bit of a nut job to your friends who don't understand the draw of working on and using them.

 

[grizz55chev]

No sweat Tom, I don't take offense. If someone disagrees with what I do, I try to explain my though process to give meaning to my actions. "There's more than one way to skin a cat".
I think that's a pretty good philosophy when facing a task, and I always try to think out of the box.
Saw repair is just one of my hobbies, my approach to it can change day by day. I try not to take it too seriously, there are enough things in this world to stress about as it is.

That being said, I've been trying to keep this hobby under control but I think I'm slowly losing! I've got 14 running saws right now with another couple potential runners. Should I go and buy those three advertised non-running Poulans for $50? LOL! Parts of the basement are littered with saws, and I even started working on them on the dining room table. Found out how hard it is to get bar and chain oil out of a shag carpet! CAD is insidious as some of you may well know, it can make you look like a bit of a nut job to your friends who don't understand the draw of working on and using them.

Those poulans are easy enough to find for almost nothing, been given and found at the dump at least 4 in the last 2 months. They sell for around $50+ in running condition around here. Your milage may vary. They are easy and cheap learning tools, so judge accordingly.