dcs5000 repair

[billpierce]

with a hi gauge it read 115psi with 5 pulls, perhaps i have to change the coil again!

 

ahhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh this always happens to me! hav eto remember its a learning curve.

 

thanks for all you patience and help

[Eddy_t]

with a hi gauge it read 115psi with 5 pulls, perhaps i have to change the coil again!

 

ahhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh this always happens to me! hav eto remember its a learning curve.

 

thanks for all you patience and help

 

 

That's very low compression! Have you continued to pull the saw over until the gauge stops increasing?

[spudulike]

Yup, 115psi is very low and would point to a busted ring, semi seized piston, scoring or similar.

 

I would expect 150psi from an engine in working condition.

 

Check the piston through the exhaust port if you haven't already and if you have, the clinder may need removing!

[billpierce]

my working 5000 gets 175psi! having retested with a gunson hi gauge its more like 125psi

 

this piston is very lightly scored, but have seem much worse, pot looks ok, just a tiny bit of transfer. seems pistons are impossible to get non oem ones, have ordered a caber ring, will clean everything up and hopefully this will sort.

[spudulike]

my working 5000 gets 175psi! having retested with a gunson hi gauge its more like 125psi

 

this piston is very lightly scored, but have seem much worse, pot looks ok, just a tiny bit of transfer. seems pistons are impossible to get non oem ones, have ordered a caber ring, will clean everything up and hopefully this will sort.

 

Get a pic up of the piston, you can tell if it is worn by how much it rocks in the bore!

[billpierce]

here we go

[billpierce]

borrowed a vac and pressure test kit from a pal - he says yes 125psi is v.low but the saw should run/fire.

 

whats the best way to blank off exhaust and inlet port? the kit he has fits onto hat looks like a bit brake pipe or something? how should i join this onto the blanking plates.

 

thanks

[spudulike]

borrowed a vac and pressure test kit from a pal - he says yes 125psi is v.low but the saw should run/fire.

 

whats the best way to blank off exhaust and inlet port? the kit he has fits onto hat looks like a bit brake pipe or something? how should i join this onto the blanking plates.

 

thanks

 

That piston looks toast to me and 125psi on an engine is awfully low, 175psi is good on a machine that has been run in and is low hours.......or modified:sneaky2:

 

The exhaust can be blanked off with rubber sheet between it and the cylinder, the inlet is usually the same or using rubber bungs/plastic plugs etc

 

I am assuming you are describing a pressure or vacuum tester??? You really need to do both as seals can leak under one and seal under another!

[billpierce]

That piston looks toast to me and 125psi on an engine is awfully low, 175psi is good on a machine that has been run in and is low hours.......or modified:sneaky2:

 

The exhaust can be blanked off with rubber sheet between it and the cylinder, the inlet is usually the same or using rubber bungs/plastic plugs etc

 

I am assuming you are describing a pressure or vacuum tester??? You really need to do both as seals can leak under one and seal under another!

 

so would you pump up/suck through the spark plug? - yes pressure or vac tester

 

is there any hope with just a new piston ring?

[spudulike]

so would you pump up/suck through the spark plug? - yes pressure or vac tester

 

is there any hope with just a new piston ring?

 

Personally I would fit a new piston as compression is a funny old thing, you get a certain amount of compression from the ring and another load from the fit of the piston in the bore.

 

I have found that worn pistons with decent rings will barely pull the skin from a rice pudding as it kills torque.

 

You can pull air or pressurise a saw more easily from the plug hole on most saws or impulse line on other saws..