Engine won't crank - Stuck on compression?

borjawil

borjawil

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Poulan Pro pp19a42 model with 19hp intek engine.

Battery and starter are good.
Engine will turn 1/8 turn approx and starter can't get it past that. So I turn by hand a bit, and starter will start the tractor up just fine.

I have set the valves - top valve exhaust at .004-.005, bottom valve intake at .006.
In my searching some say to turn the engine by hand until piston is at TDC and both rockers are loose. Some say to turn it just past TDC until your screwdriver, or whatever you're using inside the cylinder, goes back in 1/4". I've tried both. Only thing that seems to be consistent is EX valve .004-.006, and IN at .005-.007.

Is there something else that could be causing this issue? Seems a common issue due to valve lash, or decompression cam?
 
ILENGINE

ILENGINE

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With the valve gaps set correctly, and the spark plug removed for easier engine turning, turn the engine by hand while watching the intake valve. Just before TDC compression stroke you should see the intake valve get bumped open slightly. That is the compression release. If no bump then time to open it up to replace the cam and locate the 4 broken pieces of the compression release. I say 4 pieces because that is what seems to be common, but could be more or less.
 
R

Rivets

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Simple test before throwing time and money at this engine. Before opening the engine hook a VOLT meer across the battery and watch the voltage when trying to start the engine. If the battery voltage drops below 10 VDC when the engine stops turning, your battery needs to be replaced.
 
borjawil

borjawil

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Already checked for voltage drop. Brand new battery.
 
StarTech

StarTech

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Intake .003 - .005
Exhaust .005 - .007

Always set closer to the tighter clearance on OHV engines.
 
A

Auto Doc's

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Sounds like another compression relief failure issue to me. Intek engines have a well-known history of this problem.

B&S had these cams on backorder for a very long time. Hopefully they have caught up production.

Do not order and aftermarket cam unless you like the practice of taking your engine apart for repeat issues.
 
ILENGINE

ILENGINE

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Auto Doc's said:
Sounds like another compression relief failure issue to me. Intek engines have a well-known history of this problem.

B&S had these cams on backorder for a very long time. Hopefully they have caught up production.

Do not order and aftermarket cam unless you like the practice of taking your engine apart for repeat issues.
Click to expand...
Just got 4 more for the inventory a couple weeks ago for the spring stockup order, and there was no backorder or delay in shipping. That could of changed by now though.
 
S

SeniorCitizen

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borjawil said:
Poulan Pro pp19a42 model with 19hp intek engine.

Battery and starter are good.
Engine will turn 1/8 turn approx and starter can't get it past that. So I turn by hand a bit, and starter will start the tractor up just fine.

I have set the valves - top valve exhaust at .004-.005, bottom valve intake at .006.
In my searching some say to turn the engine by hand until piston is at TDC and both rockers are loose. Some say to turn it just past TDC until your screwdriver, or whatever you're using inside the cylinder, goes back in 1/4". I've tried both. Only thing that seems to be consistent is EX valve .004-.006, and IN at .005-.007.

Is there something else that could be causing this issue? Seems a common issue due to valve lash, or decompression cam?
Click to expand...
I hope you know the piston should be @ the top on the compression stroke
 
grumpyunk

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You could have a worn out starter relay. The relay has internal contacts that get a good spark every time the starter is engaged. The contacts arc and get a pitted surface that may become less conductive, and limit current fed to the starter motor. You can jumper across the two large terminals to send power directly to the starter. If the starter then works properly, a replacement relay may be helpful. If you like to fiddle, you can drill the rivets holding the relay together, and check the contacts on the moving bar and the two stationary cable conductors for wear and damage. Clean up and re-assemble as you wish.
tom
 
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RevB

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Starter and/or battery aren't "good".
 
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