Husqvarna 440 with stripped spark plug - worth rebuilding?

[flymo]

So my sister-in-law had me look at her saw, which "just quit all of a sudden." I popped the cover and the spark plug fell out in my hand, and further investigation showed the threads are stripped - not terribly surprising, since my sister-in-law has been known to gorilla things before. From a quick look at the parts diagram, it seems like that's a full cylinder replacement. So the question is whether it's worth it. The cylinder jug appears to be about $120, and I assume I'd need various gasket and such.

I've never rebuilt a chainsaw before, but it's always good to learn something. And it's a decent little saw. Alternatively, is it possible to put a helicoil in without taking it all apart anyway to get the chips out?

Thanks for thoughts, ideas, help!

 

[J D]

There was another thread about this just recently but I can't seem to find it.
In short, you can helicoil/recoil/timesert the cylinder. Best practice is to remove it to do so, but it isn't strictly necessary to.
Basically if you ensure the piston remains above the transfers, grease the tap to catch any swarf, & ensure the cylinder is properly evacuated of any swarf that escaped (blow through exhaust port etc) & it should be fine

 

[Wood Doctor]

Try an aftermarket P/C kit from HLsupply for less than $50 and rebuild the top end. I bet it will work fine. I've done that a couple of times for tree service companies and all those saws are still running after several years. Good Luck!

 

[Mad Professor]

I've done helicoil repairs without taking off the cylinder, or 4-strokes the head. You have to be careful to avoid any cuttings from the tap falling inside. Going slow and using grease to catch the cuttings helps. Have the piston high enough to seal the ports, but not get hit with the tap.

When finished lower the piston just enough to open the ex port, and blow out the cylinder through the plug hole with air. On 4-strokes I move the piston until the ex valve starts to open.

Not as safe as taking it apart, but I'd sure try it on a low end clamshell tsaw hat is more work to take the jug off.

 

[heimannm]

Heli-Coil Sav-A-Thread kits are made for just such a situation.



I also have some Time-Cert spark plug thread repair tools, but that route is more expensive to get started and the inserts are pretty spendy too.





Mark

 

[slowcar281]

Those save-a-thread kits are a nice cheap option, but the tap has to be driven straight and the insert set as the correct height.

I tried to save a Ms441 cylinder but I set the insert a tiny bit too high and the spark plug washer wouldn’t seal properly and leaked a bit.

 

[stihltech]

A new cylinder for bad threads?
Sparkplug threads are a common repair in the shop. I have used regular Helicoils and the sleeve type. Use grease on the tap to catch shavings and clean out the cylinder when done.

 

[flymo]

Thanks all! I found this video too: It looks like a fair amount of stuff to take apart, but not the worst thing I’ve ever done.

I may try the helicoil thing in the short term as it seems so much easier. Can anybody point me to the exact kit I’d need (or just confirm the pic above is the one)? Not sure about sizes. Thanks again.

 

[flymo]

I suspect that is the right kit. To help the next person, I’ll link this video too:

 

[heimannm]

The 440 would have a 14mm spark plug so that is the correct kit. Additional inserts can be found as you use them up if you search diligently.

Mark

 

[wildwes]

I've done helicoil repairs without taking off the cylinder, or 4-strokes the head. You have to be careful to avoid any cuttings from the tap falling inside. Going slow and using grease to catch the cuttings helps. Have the piston high enough to seal the ports, but not get hit with the tap.

When finished lower the piston just enough to open the ex port, and blow out the cylinder through the plug hole with air. On 4-strokes I move the piston until the ex valve starts to open.

Not as safe as taking it apart, but I'd sure try it on a low end clamshell tsaw hat is more work to take the jug off.

Same here. Those Save a thread kits work well if you take your time and do it right. I use loctite sleeve sealant with them and haven't had one leak yet. I would probably pull the cylinder for a nice, higher end cylinder, but for a budget saw probably not. I did the same thing he is instructing with a rough MS260 that I picked up for next to nothing, and it has never given a moment's trouble, at least not from the piston/cylinder/sparkplug. It is my beater saw that lives in the truck.

 

[flymo]

Thanks gents - really appreciate the assistance!

 

[wildwes]

One other thing that can help- if you have a helper, get them to hold a shop vac hose where you are cutting the threads, it can help pull chips out before the drop into the cylinder as well.

 

[flymo]

Same here. Those Save a thread kits work well if you take your time and do it right. I use loctite sleeve sealant with them and haven't had one leak yet. I would probably pull the cylinder for a nice, higher end cylinder, but for a budget saw probably not. I did the same thing he is instructing with a rough MS260 that I picked up for next to nothing, and it has never given a moment's trouble, at least not from the piston/cylinder/sparkplug. It is my beater saw that lives in the truck.

Was the Loctite product the 609 or the 640?

 

[wildwes]

I don't have the bottle in front of me, but I believe what I have is 640. Between that and the serrated insert being flared out into the cylinder, they have held very well for me.

I have had that bottle of loctite for a long time, use it all the time for various engine components. I even used it on the flywheel of a 1917 Economy hit and miss engine- the keyway was worn and the flywheel moved on the shaft. A little of that and it hasn't budged since. It's easy to remove with heat from a torch too.

 

[David Ellis]

A few years ago I purchased another Husqvarna 435 for parts. The cylinder was scored, and I... decided to experimentally rebuild it using these parts https://www.amazon.com/gp/product/B07MRHP8V5/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 . It worked, and continues to work. I think it was a few ounces heavier than OE, but also has few pounds more compression after break in than OE. So... for me this was a solid project. I was happy to discover the saw was fairly maintenance friendly.

I think the 435 / 440 is a terrific limbing saw.

 

[Wood Doctor]

This thread intrigues me. I just got a call from a tree service company asking if I could rebuild an almost new Stihl MS500i chainsaw after an employee stripped out the plug's threads using an impact wrench. He thought I could replace the whole top end with a part costing him $50. I checked and learned that aftermarket part was actually for a Stihl TS500i that he thought would fit the MS500i. In fact, the MS500i top end is several hundred dollars and must be obtained from a dealer.

I explained all that to him. Regardless, I have to wonder how many spark plug replacement kits are selling these days because really expensive top end P/C kits must be bought through dealers or repaired by dealers, such as the MS500i.

 

[flymo]

Does anyone know the head size of the 2 bolts that hold the muffler in place? Hard to see - they appear to be Torx, but they're definitely not T27. T40 is too big, and T30 seems to start to bite, but the fit is awfully sloppy - I applied a reasonable amount of torque, but they didn't pop loose and I'm trying not to strip them. It looks like there is such a thing as a Torx T35, but I've never encountered one before.

Thanks as always...

 

[David Ellis]

On my 2010 Husqvarna 435, the muffler screws are 5mm hex / allen

 

[J D]

As David said, unless someone has fitted something else they should be standard 4 or 5mm hex.