350 Rancher Engine problems

[JsheII3]

Air coming back through the carb = intake valve. Exhaust = exhaust valve. Oil fill cap = Piston and/or rings.

I've saw valves stick open from lack of oil and heat. The little valve springs are pretty soft and it doesn't take much for them to stick in the guide.

how hard would it be to stop the piston at the top of the stroke just using the electric start?

 

[Deleted member 3748]

What would this indicate?
And also, how hard would it be to stop the piston at the top of the stroke just using the electric start?

Very difficult to stop the piston at the top with electric start.

 

[snuffnwhisky]

Doesn't it have a pull start also?

 

[JsheII3]

Doesn't it have a pull start also?

Yes sir

 

[JsheII3]

Air coming back through the carb = intake valve. Exhaust = exhaust valve. Oil fill cap = Piston and/or rings.

I've saw valves stick open from lack of oil and heat. The little valve springs are pretty soft and it doesn't take much for them to stick in the guide.

So you’re telling me... that if I take a ball peen hammer and hit the sides of that engine enough times and in enough places, that this problem will go away?

 

[DG Rider]

What would this indicate?
And also, how hard would it be to stop the piston at the top of the stroke just using the electric start?

It's like a leak down test without the flow gauge, but it will tell you what you need to know.

I've seen pics of my own colonoscopy. They were s***ty.

 

[ByronM]

Before you take it somewhere check the valve clearance and look at the cam, running it low on oil may have wiped out the cam.

 

[JsheII3]

Alright guys.
1. Took pin light and watched until top stroke of piston. (Using recoil pull)
2. Hooked up compression test hoses to air compressor.

No leaks. @100psi. I let it hold for 10 minutes.

I pulled the air box and put my ear and face down to the carb intake.

I put my ear to the exhaust pipe. Didn’t feel or hear any air escaping.

I even went as far as to spray the entire engine w soapy water I use to find holes in tires.


Why will it hold 100psi, but not crank out but 20 ?!?


Also, I RETESTED the compression gauge against my air compressor’s gauge. It matched.

Idk

 

[Deleted member 3748]

Alright guys.
1. Took pin light and watched until top stroke of piston. (Using recoil pull)
2. Hooked up compression test hoses to air compressor.

No leaks. @100psi. I let it hold for 10 minutes.

I pulled the air box and put my ear and face down to the carb intake.

I put my ear to the exhaust pipe. Didn’t feel or hear any air escaping.

I even went as far as to spray the entire engine w soapy water I use to find holes in tires.


Why will it hold 100psi, but not crank out but 20 ?!?


Also, I RETESTED the compression gauge against my air compressor’s gauge. It matched.

Idk

Hmmmm... did you test the compression again using the compression tester by itself?

 

[DG Rider]

Alright guys.
1. Took pin light and watched until top stroke of piston. (Using recoil pull)
2. Hooked up compression test hoses to air compressor.

No leaks. @100psi. I let it hold for 10 minutes.

I pulled the air box and put my ear and face down to the carb intake.

I put my ear to the exhaust pipe. Didn’t feel or hear any air escaping.

I even went as far as to spray the entire engine w soapy water I use to find holes in tires.


Why will it hold 100psi, but not crank out but 20 ?!?


Also, I RETESTED the compression gauge against my air compressor’s gauge. It matched.

Idk

Is it cranking over at what you'd consider a normal speed?
Pull the breather tube off the crankcase and listen there. You should have heard this through where it enters the airbox/air filter, but maybe the filter hid the noise. Keep in mind that we're not talking about huge rushes of air unless you had major engine damage. A subtle hiss most likely.

 

[Deleted member 3748]

Alright guys.
1. Took pin light and watched until top stroke of piston. (Using recoil pull)
2. Hooked up compression test hoses to air compressor.

No leaks. @100psi. I let it hold for 10 minutes.

I pulled the air box and put my ear and face down to the carb intake.

I put my ear to the exhaust pipe. Didn’t feel or hear any air escaping.

I even went as far as to spray the entire engine w soapy water I use to find holes in tires.


Why will it hold 100psi, but not crank out but 20 ?!?


Also, I RETESTED the compression gauge against my air compressor’s gauge. It matched.

Idk

I'd try it again with the cylinder at the bottom. If it holds compression again, I'll be surprised.

 

[JsheII3]

Hmmmm... did you test the compression again using the compression tester by itself?

Yes. Immediately after. It held only at 20psi again. using electric start and 100 % throttle.

 

[Deleted member 3748]

I'd try it again with the cylinder at the bottom. If it holds compression again, I'll be surprised.

But you'll have to catch it on the compression stroke (when both valves are closed). On the intake stroke, the intake valve will be open, and on the exhaust stroke, the exhaust valve will be open and letting air out.

I found a cool graphic.

 

[JsheII3]

I'd try it again with the cylinder at the bottom. If it holds compression again, I'll be surprised.

Well, that’s the thing... since after a few mins it didn’t leak, and still while hooked to air compressor, I slowly pulled the start rope to see if something, somewhere gushed out. I pulled really slow and deliberately. And a full revolution. Nothing.

 

[Deleted member 3748]

Well, that’s the thing... since after a few mins it didn’t leak, and still while hooked to air compressor, I slowly pulled the start rope to see if something, somewhere gushed out. I pulled really slow and deliberately. And a full revolution. Nothing.

At one point it should have shot out of the exhaust.

 

[JsheII3]

At one point it should have shot out of the exhaust.

View attachment 142783

I agree.
And I’m not aware of any oversight.
I understand the basic theory of the test.

Could the piston have dropped? So that compression is low at top of stroke, since top of stoke isn’t high and tight?

 

[snuffnwhisky]

Makes me think timing chain or the cam is shot. Need to pull the valve cover off and see what the rocker/valve clearance is.

 

[JsheII3]

Also, worth noting...
With my pin light I could see the piston going up and down as I pulled the recoil.

It was all grimy on top.

 

[Deleted member 3748]

I agree.
And I’m not aware of any oversight.
I understand the basic theory of the test.

Could the piston have dropped? So that compression is low at top of stroke, since top of stoke isn’t high and tight?

I guess a bent rod could do that. I'm wondering if we ignore the compression test results and check for both valves closed all the time and the camshaft is smoked like @ByronM mentioned above.

 

[snuffnwhisky]

If it wiped a cam lobe you'll have a lot of rocker to valve clearance.