Powermore Engine won’t start

[Jenden1]

Hi all, new here.
I have a 2013 MTD 420/38 ride on mower that runs a Powermore 420cc engine.

It was running fine then stopped. Investigated and found a blown head gasket. Would turn over with no compression.

Replaced head gasket and fired straight up. Ran for about 20 seconds then stopped and again just turns over and won’t start.

My question is: perhaps I’ve under torqued the head and when it started to heat up it’s lost compression. Does anyone know the torque specs for this ? I torqued it to 25ft/lb but am now thinking that’s light.

Any help would be appreciated.

 

[Scrubcadet10]

25 ft lbs ought to be enough.
I would spray some gas or carburetor cleaner down the plug hole, if it fires it's either valve problem or not getting fuel. No fire most likely no spark.
Then spray some through the carburetor behind the air filter, if starts then dies its a fuel issue, if doesn't start probably a valve problem

 

[ILENGINE]

Hi all, new here.
I have a 2013 MTD 420/38 ride on mower that runs a Powermore 420cc engine.

It was running fine then stopped. Investigated and found a blown head gasket. Would turn over with no compression.

Replaced head gasket and fired straight up. Ran for about 20 seconds then stopped and again just turns over and won’t start.

My question is: perhaps I’ve under torqued the head and when it started to heat up it’s lost compression. Does anyone know the torque specs for this ? I torqued it to 25ft/lb but am now thinking that’s light.

Any help would be appreciated.

Looks like the torque spec for the model P90 head is 41-44 ft/lb in step increments using a crisscross fashion with the last bolt to be torqued closest to the exhaust studs.

 

[Jenden1]

Update, thanks for the advice. Found the problem. The exhaust valve spring retainer {sits on the end of the spring and locates into the slot on the valve stem) had flogged the centre and would only stay located when not under pressure, the would pop off thus preventing any return spring pressure.

$20 for a new retainer cap and shes as good as new. Did a head gasket replace at the same time. Happy days.

Thanks again.

 

[Scrubcadet10]

Great!
Thanks for letting us know how you fixed your problem