2002 EZGO TXT Engine Crankcase Pressure Issue

2002 EZGO TXT golf cart will start and run briefly then cranks only. Robbins engine 295. Compression is 125 psi on both sides, carburetor and fuel pump new and clean and the spark is normal even as it shuts down. As soon as it quits running it makes a weird whistling sound that persists for a few minutes or until I open the oil cap and relieves the crankcase pressure or vacuum on the engine case. What might cause this issue?
 

HotRodCarts

Cartaholic
The compression should be 160. The first thing I would check is the valve lash the intake valves are probably to tight.
 

Nubs

Cartaholic - V.I.P.
It sounds like the breather diaphragm is stuck shut, those engines do build a lot of crankcase pressure but it bleeds off as soon as it shuts off.
 
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