88 OMC 5.7: ID this Sound

[Chris5280]

New plugs, wires, points, set dwell, set timing. Still have this awful high pitched sound. Replaced water pump thinking it might be the source, but the whine is still there. (Video is before dwell and timing were set, so idle is much better now- but the high pitched sound is still the same...)

 

[Lou C]

Vacuum leak, gasket under carb may be leaking or the mounting bolts are loose

 

[Bt Doctur]

Remove the belt for a quick test, guessing its a alt bearing or belt. Looks a bit loose and a bit deep in the pulley

 

[Lou C]

could be that too, what is the yellow thing on the carb linkage? and I'd advise you to get rid of the wingnuts on your battery terminals, they get loose and cause low voltage issues. Better off with a nylock or a regular nut and a lock washer.

 

[Chris5280]

Installed a new gasket on the carb and torqued the bolts- no change. Anything special about a marine alternator or can I buy an alternator from Advance Auto Parts?

 

[southkogs]

You need a marine alternator for the added shielding.

Sparks and bilges tend to boom into big red flowers :target:

 

[Lou C]

The OEM gasket for the Q-Jet was a thick one about 3/16ths not a thin paper one. Which one are you using?

 

[Chris5280]

Thanks, Lou. I wondered about the thickness of the carb gasket on the quadrajet, but I asked the company that rebuilt it and they claimed it wouldn't make a difference. Took your hint, put the old thick rubber gasket back in and she purrs like a kitten now.

I probably should start a new thread for this, but now my only problem is a hard start. Even if I only let the boat sit overnight, and pump the throttle 20 times, it takes 5-6 cycles of this to fire up. (Or, I spray some starter fluid in the carb and it fires right up.) When it does finally fire, it idles nice and smooth and quiet. I don't want to have to spray starter fluid in every time I put the boat in the water, though. This doesn't seem normal, and it never happened before until I put in this rebuilt carb. What gives?!

 

[Lou C]

Some Quadrajets are known for leaking well plugs that can be fixed by epoxying them or using JB weld. The custom rebuilders replace them with a threaded plug and o ring. I have not had this issue with mine but I have heard of it......the leaking plugs allow gas to drain out of the float bowl over time.