7.4L Running Rough After Overheat

V

vaboatdoc

Cadet
Joined
Dec 29, 2007
Messages
21
1997 Big Block 7.4L Carb overheated. Replaced impeller and cured overheat problem. Now boat idles very rough and has a slight miss at higher rpms. Checked plugs and compression and both looked good. Checked for water in fuel and found none. Engine has a engine mounted belt driven sea water pump with fuel pump mounted to the top. Wondering if anyone could give me any guidance or any hints on what to look for. Did notice when removing both rear plugs to check compression seemed like had alot of air escaping out of plug holes.
 
Fireman431

Fireman431

Rear Admiral
Joined
Sep 17, 2007
Messages
4,292
Re: 7.4L Running Rough After Overheat

First, replace the plugs. Overheating has a tendency to eat sparkplugs. But, the air escaping would have me worried that you lost a head gasket. Check the oil for water...it'll look like a chocolate milkshake if it's there.
 
Philster

Philster

Captain
Joined
Sep 15, 2009
Messages
3,344
Re: 7.4L Running Rough After Overheat

Warped head blown head gasket.
 
Brentathon

Brentathon

Petty Officer 1st Class
Joined
Dec 29, 2009
Messages
397
Re: 7.4L Running Rough After Overheat

Heads don't like overheating.
Not too long after I overheated majorly, my engine got hydrolocked........starter ripped the teeth off the flywheel...those starter sure have power.
 
You must log in or register to reply here.
Top