Please help, impulse line keeps melting and coming off.

[Hoosier]

I have a solo 694 running as a power head on my Alpine Magnum stump grinder. This thing worked great for years but two seasons ago I had issues with it running and replaced the base gasket, for some reason it failed.

While I was changing it I learned that the pulse line was failing, and I also learned what it did. It runs from the base of the cylinder directly to the carb.It's a smooth line with no pleats.
Anyway the saw head runs good, for a short while, but I cannot finish a single small stump and then the pulse line falls off / gets gooey at the cylinder nipple.

It got so bad that as a last resort I removed some fins off the cylinder so I could get the line put back on in the field instead of leaving the job to come home and pull all the covers and remove the carb to replace it only to have it happen again...nearly immediately. I am guessing that the saw might be running hot now, since I reduced the fin mass and left the covers off to gain access at the job-site.

What am I missing? I am running a cool plug, I might be able to run cooler. I mix at 32-1, I could go thicker I guess. My carb is adjusted to let it eat pretty good since it is asked to run a stumper at WOT, but it ran that way for the first 3-4 years without issue.

Do they make a high temp hose that would live longer? I have tried both the clear "Tygon" style and the grey rubber hose that is available at the local Stihl dealer / service center, both melt right away.

I have seriously considered soldering a piece of small diameter copper line to the nipple so I can move the connecting point up and away from the heat and use a shorter bit of line, but I don't know if the solder would just melt away?

I would change brands in a second if I knew of another big saw head with the same mount points, Alpine wants real money to modify the machine to go to a Stihl. (I wish I had spent the money on that head when it was new)

Any guidance would be appreciated!

 

[Stihl-Pioneer]

Don't use Tygon, it won't hold up. I would try to find a silicone based rubber hose myself.


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[ChoppyChoppy]

A hot or cold plug affects plug temp, not engine temp.

 

[backhoelover]

I have a solo 694 running as a power head on my Alpine Magnum stump grinder. This thing worked great for years but two seasons ago I had issues with it running and replaced the base gasket, for some reason it failed.

While I was changing it I learned that the pulse line was failing, and I also learned what it did. It runs from the base of the cylinder directly to the carb.It's a smooth line with no pleats.
Anyway the saw head runs good, for a short while, but I cannot finish a single small stump and then the pulse line falls off / gets gooey at the cylinder nipple.

It got so bad that as a last resort I removed some fins off the cylinder so I could get the line put back on in the field instead of leaving the job to come home and pull all the covers and remove the carb to replace it only to have it happen again...nearly immediately. I am guessing that the saw might be running hot now, since I reduced the fin mass and left the covers off to gain access at the job-site.

What am I missing? I am running a cool plug, I might be able to run cooler. I mix at 32-1, I could go thicker I guess. My carb is adjusted to let it eat pretty good since it is asked to run a stumper at WOT, but it ran that way for the first 3-4 years without issue.

Do they make a high temp hose that would live longer? I have tried both the clear "Tygon" style and the grey rubber hose that is available at the local Stihl dealer / service center, both melt right away.

I have seriously considered soldering a piece of small diameter copper line to the nipple so I can move the connecting point up and away from the heat and use a shorter bit of line, but I don't know if the solder would just melt away?

I would change brands in a second if I knew of another big saw head with the same mount points, Alpine wants real money to modify the machine to go to a Stihl. (I wish I had spent the money on that head when it was new)

Any guidance would be appreciated!

What's yours address, what length do you need I have some line you can try to see if it holds up better. Do you have a temp gun so we can get a idea of how hot it is running

 

[Hoosier]

I do have a temp gun, but I would need to work the machine to get that to temp. I had one stray job for a buddy last week and it turned into a huge ordeal that reminded me to be pro-active and get this right before mt season starts in April.

I was thinking about that the temp gun other day when I was pondering making a braze joint at the nipple to extend the hard line portion. But right now I don't have a temp number.

Backhoelover, PM incoming.

 

[backhoelover]

K no big deal we'll get this grinder right again

 

[smokey7]

I dont know the engine you speak of. But I know they must have the cover on over the topbof the jug for airflow from the fan. Without that it surely will overheat.

 

[Hoosier]

Agreed. I am in a trick box right now, I hope a higher quality line will stay on long enough to let me use the machine long enough to finish one job with the cover on. If not I am going to pull the jug and braze a length of hard line to the nipple to get it outside the cover for ease of inspection.

 

[hotshot]

https://www.mcmaster.com/#51135K615

Measure your case nipple barb OD & also the carb nipple, as this is 1/8" ID and is 400°F rated.

The problem w/Mcmaster Carr is that shipping is way more than a foot of tubing...

 

[67L36Driver]

No way in hell would I run a saw under load without the covers.

Use Stihl or Echo rubber hose.

 

[backhoelover]

No way in hell would I run a saw under load without the covers.

Use Stihl or Echo rubber hose.

i going to send him a foot of the stihl fuel line wiffy forgot to ship it today

 

[schmauster]

I'd be more worried about the engine temps. Might want to bring the non contact thermometer to work.

What temps do they normally run?

 

[backhoelover]

Around 250

 

[backhoelover]

If I can remember correctly

 

[Okie]

I'd be more worried about the engine temps. Might want to bring the non contact thermometer to work.

What temps do they normally run?

Around 250

Not sure about your engine, but the chainsaw engines I have tested when in a full bar length cut and loaded heavy with the infrared thermometer average around 300-350F and if the engine was getting too hot it would go to 350 fast headed towards 400, especially if the carb was mis-adjusted and the engine running too lean. (lean on gas= too much air intake) gas hitting the piston is what keep the piston/cylinder cool on a 2 cycle chainsaw engine.

Regular 60/40 rosin core solder should be ok on the joint, melting point is around 460-500 degrees. If engine block gets hot enough to melt 60/40 rosin core solder the engine is headed for a melt down.

I think you are probably use wrong type of pulse line. (If oil is getting into a rubber line plus heat it will get soft fast)

You need to check the engine block temp at the cylinder jug.

 

[schmauster]

Ambient temperature should make a big difference on an air cooled motor.

Obviously if it is a hose not rated for fuel it would definitely fall apart quickly at any temp.

 

[Okie]

Ambient temperature should make a big difference on an air cooled motor.[/COLOR][/B]

Obviously if it is a hose not rated for fuel it would definitely fall apart quickly at any temp.

Not really when running at higher rpms on a chainsaw.
If cooling fins are clean and good air flow across the jug.

If engine is running lean on gas and under a load she will overheat and head for a melt down very fast.

If you do not believe such take a infrared thermometer and a tachometer and purposely lean out the carb and place the chainsaw engine under load with a full bar cut and the rpm's can be below (or will be below) rated rpms due to the engine being loaded and the temp will head for self destruct at a fast rate (above 400F) with 30 sec's.
Really surprising how fast they will overheat when running lean.

 

[backhoelover]

Not sure about your engine, but the chainsaw engines I have tested when in a full bar length cut and loaded heavy with the infrared thermometer average around 300-350F and if the engine was getting too hot it would go to 350 fast headed towards 400, especially if the carb was mis-adjusted and the engine running too lean. (lean on gas= too much air intake) gas hitting the piston is what keep the piston/cylinder cool on a 2 cycle chainsaw engine.

Regular 60/40 rosin core solder should be ok on the joint, melting point is around 460-500 degrees. If engine block gets hot enough to melt 60/40 rosin core solder the engine is headed for a melt down.

I think you are probably use wrong type of pulse line. (If oil is getting into a rubber line plus heat it will get soft fast)

You need to check the engine block temp at the cylinder jug.

he is right the temp i gave you is for a mower engine etc sorry about that.

 

[backhoelover]

if stihl line will not work i bet vac line for a car would

 

[Okie]

OEM parts or parts lists not easily found for the solo 694? this link might help

http://www.solousa.com/kb_pdfs/694.pdf

You might check with these people to get the correct pulse part! and read this also.
http://www.lilredbarn.net/Solo-694-Fuel-Filter-Fuel-Line-s/40185.htm
The solo fuel line is made of either rubber, pvc formulated compounds, or viton material. A Solo 694 fuel line that lets permits air can cause poor saw performance or result in a lean fuel mixture which could cause internal engine failure.

You do need to check the running temp of your solo 694 ASAP.
Might be running lean and or overheating. If it is and you are going to need more than a pulse line for the saw and stump grinder. You will be needing to check your pulse and temperature if she blows.

Here is a link to solo 694 parts lists
Item 174 part number 965 452 060 impulse line 160mm


http://www.solousa.com/kb_pdfs/694.pdf

You also say you adjusted the carb so as to run at WOT. You might want to also review how to adjust a chainsaw carb for 4 cycling at WOT. You can find you tube videos of such and listen to the sound she makes when 4 cycling.
Proper 4 cycling carb adjusting makes them run rich (not leaning out) so as to keep her cooler at WOT.