Shindaiwa 488 Rebuild Woes

[David Young]

is there any chance that the throttle plate is hanging up?
if you shut it off and restart does it reset?
could be the linkage could be the plate itself is loose and moving around.

 

[beaglebriar]

Done it a few times, plugging muffler and intake, and testing thru the impulse line. It's held pressure and vac just fine, which is stumping me. I wondered if maybe the crank seals are on their way out, and losing pressure once there's some friction added...?

I'm converting it to a 488P, and have all the parts needed except the black plastic elbow after the carb.

Are you rollover it over while testing? Have you dunked it in a bucket of water while under pressure??

 

[eric4]

Are you rollover it over while testing? Have you dunked it in a bucket of water while under pressure??

Honestly, I hadn't considered doing either. Assuming rollover means turning the flywheel while under pressure?

 

[whybother]

Honestly, I hadn't considered doing either. Assuming rollover means turning the flywheel while under pressure?

Yes, turn the crankshaft while you are pressure/vacuum testing it. Sometimes the seals show no signs of leaking when the crank isn't turning.

 

[eric4]

It's pretty easy if you have a decent seal puller or can make one. I've made a variety of seal pulling tools with old flat head screwdrivers of different sizes. Hutzl also has an aftermarket puller that's essentially a copy of the Stihl seal puller - I've not used one though.

For installation - you'll need a sleeve for the crank so the inner lip doesn't roll. You can make a sleeve with a beer/pop can.

I've got a seal puller on order now. Tinkered with the saw again today, and thought it was settling in, but then once it started to warm up, the idle took off.

i would pressure test the carb......it cant hurt to pressure test the saw and pull it over a few times and see if it fails

I'll do a test on the carb itself. Pressure tested the fuel line, and there were no leaks, but I didn't actually test the carb.

 

[Woodwackr]

I've got a seal puller on order now. Tinkered with the saw again today, and thought it was settling in, but then once it started to warm up, the idle took off.



I'll do a test on the carb itself. Pressure tested the fuel line, and there were no leaks, but I didn't actually test the carb.

I have a spare 488 carb you can try if needed. It is an epa model with fixed H but should work for testing.

 

[backhoelover]

It's pretty easy if you have a decent seal puller or can make one. I've made a variety of seal pulling tools with old flat head screwdrivers of different sizes. Hutzl also has an aftermarket puller that's essentially a copy of the Stihl seal puller - I've not used one though.

For installation - you'll need a sleeve for the crank so the inner lip doesn't roll. You can make a sleeve with a beer/pop can.

stihl puller is ok have to tap the seal before pulling, i like the husky seal pullers they dont mess around

 

[backhoelover]

Had a saw that the seals would only leaking when in mid to high rpm when running, damn thing through me for a loop. had to use carb cleaner to find the leak, not a fan of that but sometime you have to do what you have to do.