Kohler CH 740 low compression

[Bushwhacker]

Hi all... I was looking over a friend's Toro Z500 with Kohler CH 740 ,,he said it was blowing blue smoke under load and not gaining full power,,, so I warmed it up and did compression test ... 80 psi both cylinders.. book says should be 160 psi.... so it appears it is rebuild time... anything else I should be checking before it goes to shop ?? Thanks

 

[bertsmobile1]

Most likely head gasket failure between cylinder & push rod tube
Do leak down test with rocker cover off to confirm .