Volvo 300-B (5.7L) mystery hose

KetchiMan

Seaman
Joined
Jun 28, 2011
Messages
73
This might be the dumbest question ever, but I'm about to install this a Volvo 300-B (closed cooling system) in my boat and there's a mystery hose, and I've got 2 mechanics who can't figure out what it is.

It's a small diameter hose that goes from the fuel pump/fuel cooling unit (on the front starboard side of the engine) over to the port side of intake manifold, right behind the alternator (pic below). The other hose going into the fuel cooling unit comes from the port side exhaust manifold, so I'm assuming it's cycling seawater. Does this thing cycle seawater through the intake manifold? Cuz that seems crazy... Did someone hook this thing up wrong?

Again, I feel like I'm going to feel like an idiot whan I get the answer, but I gotta ask...
So okay, go ahead... make me feel dumb... :)

You can see where it goes ito the intake manifold in the pic here. It's the small hose with the hose clamp right behind/under the sticker on the alternator.

1609006451274.png
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,120
It looks like ti goes into the water jacket on the intake so if your raw water cooled it circs raw water to cool the pumps or A/F thru the hoses to the pumps
 
Last edited:

KetchiMan

Seaman
Joined
Jun 28, 2011
Messages
73
Top