Logo
FULL SITE MENU

305 Mercruiiser mystery

fastjeff

fastjeff

Gold Medal Contributor
I'm embarrassed to admit this, but I can't find out where the second hose from the flame arrester goes. One hose goes to the PCV valve in the port valve cover, but the other?

It's a 1986 305 Mercruiser Alpha One.

Jeff
 
No pvc..

pvc only on auto or possibly efi and/or emission newer product
the "pvc" is empty/hollow if not it is not for that boat.
There should be two, ond on each valve cover.
Typically a simple rubber grommet in valve cover and one each hollow pvc looking part connected to hose (what ever type "hose" is used)

Also if there is a vacuum port at base of carb, its not marine!
 
Last edited:
Also if there is a vacuum port at base of carb, its not marine!
Jack , some mercruiser do use an actual pvc to the base of the carb

An engine serial number is helpful, but if you do have an actual PVC under suction it goes in 1 valve cover , the other goes to the flame arrestor.
If you have no actual pvc, both hoses got to the valve cover and to flame arrestor
 
Not A 1986 V8....

I know there were some but i believe those were older models....possibly some of the rochester 2 bbls like on the inline 6.
i dont remember seeing any on "modern" lets say MR/Alpha product
 
fastjeff said:
I'm embarrassed to admit this, but I can't find out where the second hose from the flame arrester goes. One hose goes to the PCV valve in the port valve cover, but the other?

It's a 1986 305 Mercruiser Alpha One.

Jeff
Click to expand...

the hoses should be symmetric - left to right.....and, as noted, there shouldn't be any PCV valve in the rocker box grommet, only a 'connector' and some are 'straight' where others have a '90'....

I've seen a few Crusader q-jets that actually had vacuum ports in the throttle plate.....but they were sealed by a piece of closed end heat shrink....
 
Found where that hose went--hiding under the exhaust manifold. Was a bear to plug it back in, but...

Thanks all!

Jeff
 
Marine engines don't have PCV valves just vents that are routed to the intake air. Sometimes you find PCV valves but they aren't necessary as these are a really for EPA emissions on road-going vehicles. The vent hoses are perfectly adequate for venting crankcase gasses back into the engine. The valve isn't really needed cz you aren't stopping starting decelerating coasting like you do in a car so the chances of backflow are pretty minimal.
 
Back
Top