Backfiring through intake-6.5L

[jcmyhre1522]

Brand new engine installed-Backfires through intake very forcefully-will expand air cleaner assembly. Does run but poorly. Disconnected exhaust-still does it. I have not checked out the valve train yet.

 

[simp5782]

Brand new engine installed-Backfires through intake very forcefully-will expand air cleaner assembly. Does run but poorly. Disconnected exhaust-still does it. I have not checked out the valve train yet.

Stuck valve or bent. Or a broken valve spring. Maybe a broken retainer

Pull the covers

 

[gringeltaube]

On new engines, the exhaust valves tend to get stuck from no-use, because of the very tight lip seal not allowing any oil to keep the guide and shaft wet, to avoid rust build-up.
First cranking then bends the pushrod which usually dislocates it from the rocker.

Turn the crank until that piston is way up, disassemble retainer and spring; remove that oil seal; use plenty of PB-blaster around the stem; reassemble the spring & retainer and then tap on the valve until it moves freely again.
Never attempt to straighten- and re-use a bent pushrod; replace it!

 

[jcmyhre1522]

Stuck valve or bent. Or a broken valve spring. Maybe a broken retainer

Pull the covers

Found it-Severely bent pushrod

 

[jcmyhre1522]

On new engines, the exhaust valves tend to get stuck from no-use, because of the very tight lip seal not allowing any oil to keep the guide and shaft wet, to avoid rust build-up.
First cranking then bends the pushrod which usually dislocates it from the rocker.

Turn the crank until that piston is way up, disassemble retainer and spring; remove that oil seal; use plenty of PB-blaster around the stem; reassemble the spring & retainer and then tap on the valve until it moves freely again.
Never attempt to straighten- and re-use a bent pushrod; replace it!

replaced bent pushrod