De-Compression Valves

[G-Man!!!]

Has anyone else noticed that the Husqvarna de-comp valve (blue tip) leaks air out of the two holes in the hex nut on the valve body? I have been doing a pressure/vacuum test on a Husqvarna 181SE (up graded to a 288 with a de-comp valve) when I noticed that the de-comp valve was leaking air out of the two holes in the hex nut, so I replaced it with a new one, only to have the same problem. Next I connected the pressure gauge straight to the de-comp valve and had the same results (leaking air out of the two holes).

After some thought, I made a trip to the local Stihl dealer to get a test plug for the de-comp valve. That's when the mechanic told me the de-comp valve must be bad and he got a Stihl de-comp valve and connected his pressure gauge straight to the valve and it held the 10 psi. The difference between the Stihl and Husqvarna de-comp valves are that the Husqvarna has the two holes opposite of each other on the hex head nut on the valve body, and the Stihl has no holes.

Anyone know the purpose of the two holes, and is it common for air to leak out of the holes? Which leads me to wonder does this hurt compression in the Husqvarna's because of leaking holes in the de-comp valve, or is it that under 150-175 psi it forces the valve tip to seal better and have no air leak?

 

[Gypo Logger]

I can't say I've noticed any blow by on decomp valves, but I've often suspected it. If you see any leakage you can replace it with a plug which is a Stihl part, but not sure of the part #.

 

[05_sprcrw]

Most of them should both be the same thread size so I would just put a new whether its a stihl or husqvarna that doesn't leak in. I did have one blue capped decompression valve that leaked swapped it with a black capped one I had around it doesn't leak now.

 

[G-Man!!!]

I purchased the plug today, for testing purposes, however I really don't want to keep the test plug in the cylinder because of the compression that the 288 will make. I have already seen the blow-by (tested at 10 psi) on the Husqvarna de-comp valve, my hope is that when under higher compression (150-175 psi) the force of the higher compression will force the seal better on the de-comp valve. I don't know how you could test the de-comp valve once the saw is running.

 

[pantelis]

I purchased the plug today, for testing purposes, however I really don't want to keep the test plug in the cylinder because of the compression that the 288 will make. I have already seen the blow-by (tested at 10 psi) on the Husqvarna de-comp valve, my hope is that when under higher compression (150-175 psi) the force of the higher compression will force the seal better on the de-comp valve. I don't know how you could test the de-comp valve once the saw is running.

you have two options
1) you work the saw with the plug so dont need the decomp valve , end of story

2) you work the saw with decomp valve so you must try to find a good valve end of story

you decide

 

[HuskStihl]

I have pressure/vac tested my huskys without significant decomp leaks. Put the known good Stihl one in and go with it

 

[G-Man!!!]

I have pressure/vac tested my huskys without significant decomp leaks. Put the known good Stihl one in and go with it

This is what I was thinking, the only thing is the Stihl de-comp valve is longer than the Husqvarna one, and is on the same side as the pull start handle, which may get in the way.

 

[thumbilly]

Man up and plug it I don't even bother with using them I wish somebody would come up a way to plug the hole left in the top covers after plugging the decomp hole. How did we ever survive before decomp and easy start recoil I mean really!

 

[pantelis]

Man up and plug it I don't even bother with using them I wish somebody would come up a way to plug the hole left in the top covers after plugging the decomp hole. How did we ever survive before decomp and easy start recoil I mean really!

Yes you can go to the next town with a donkey , but you use your car i think, you can break your fingers if you want but you want a easiest and no pain starting again i think

 

[dugide]

the stihl valve has a hole. at least the one's I've seen. very small hole on one side of the nut.

 

[pantelis]

the stihl valve has a hole. at least the one's I've seen. very small hole on one side of the nut.

the blue cap husky decomps have very big holes so too much air leaving and the problems start, i have notice some 372 that cant start or die after starting for this reason , also i have notice blue decomps new that cant full close, they close half and again the problems start.
i think that the stihl are better decomps , but and there have notice same problems but not too much

 

[thumbilly]

They're chainsaws not hand crank model ts. I suppose it depends on how you start the saw.

 

[nmurph]

Man up and plug it I don't even bother with using them I wish somebody would come up a way to plug the hole left in the top covers after plugging the decomp hole. How did we ever survive before decomp and easy start recoil I mean really!

Just remember there Rambo, Father Time is unrelenting and his record is perfect. One day you will rue your machismo.

I'm 6'4", 240lbs and still fit at 51. But I can tell you that I might be as good once as I ever was, but I'm not as good as I once was. I can still rip a 125 off without the decomp if needed, but I take advantage of technology that makes life easier and makes the body last longer. I can remember hearing everyone saying their body started hurting about 40YO. I was lucky that mine lasted about 10yrs longer, but I now have those little aches and pains that lets me know that old age isn't some imaginary thing that will never happen to me.

 

[thumbilly]

I dunno maybe it doesn't work but I can't tell the difference with or with out it on that saw

 

[Adirondackstihl]

the stihl valve has a hole. at least the one's I've seen. very small hole on one side of the nut.

Old ones did.
New ones don't.

 

[ArcticOverland]

They're chainsaws not hand crank model ts. I suppose it depends on how you start the saw.

Drop starting a modern 60cc AT saw which is equipped with an 'EasyStart' setup and primer bulb in a garage/workshop where it's warm enough to just wear a long sleeved Tshirt?

Man up? Really?

More Jane Wayne than John Wayne from where I'm standing....

 

[KenJax Tree]

Easy start on a 555? Since when?

 

[ArcticOverland]

Easy start on a 555? Since when?

Sorry. Smart Start. Not the same thing but easier than a 188 or 288 either way!

 

[G-Man!!!]

the stihl valve has a hole. at least the one's I've seen. very small hole on one side of the nut.

The Stihl valve I looked at today had no holes, and the tip was not flat and round like the blue Husqvarna valve, the black tip on the Stihl valve was longer and very narrow on the end where you grab it with your fingers

 

[thumbilly]

I guess I have to need to prove anything to anyone. I was just getting at that starting a chainsaw with or with out the decomp. Is low on my list of things that destroy my body.http://tapatalk.imageshack.com/
Regardless of whether you believe me I split this tractor by hand by myself the way I do almost all of them.


v2/15/03/19/830b17d54f96a8bfc6824dd6865c9732.jpg

This was just a lot odd bull work.