Where does this little hose go from the thermostat housing?

[Monterey296Twin5.0Gi]

Where does this little hose go from the thermostat housing? I tried tracing it but I don't have much room to see where it goes. I also tried searching the web and exploded diagrams.

Judging by how rusty my other large hoses were, this one has to be bad since it is so small. I want to replace it. (red arrows in pic below)

Also when changing the impellers the 1 1/4" raw water line kept spilling water, so is that hose very difficult to replace given limited access to back of motor and being in a wet slip?

Thank you.

 

[Fun Times]

That hose goes to the fuel pump assembly to help keep it cooler....Item # 10,

 

[Monterey296Twin5.0Gi]

Thank you, my engines are 1998 5.0GiPBYCCE and the hose goes to the back of the engine. My hose goes to the back of the engine along the valve cover. Thanks to you directing me toward fuel cooling, could it go to a VST (Vapor Separator Tank) at the back of the engine or throttle body? I am just trying to gauge if I can get to the other end easily, to replace it.

 

[Fun Times]

Yes it'd run to the VST system...Item number 29, Volvo Penta Exploded view / schematic Vapor Separator Tank 5.0GiPBYCCE, 5.7GSIPBYCCE - MarinePartsEurope.com

 

[dypcdiver]

Check The VST has a flow that returns to the portside riser. Mine was blocked at both ends and eventually I had to replace the VST, it was blocked and rotted through allowing salt water into the fuel side.

 

[bruceb58]

A lot of people just get a cork and push it into the hose while replacing the water pump. There is very little pressure since its just a few inches below the water line.

 

[Monterey296Twin5.0Gi]

A lot of people just get a cork and push it into the hose while replacing the water pump. There is very little pressure since its just a few inches below the water line.

Thank you, that is what we ended up doing. A cork and a keychain (Ha Ha) worked great, and new impellers cooling well too.

Is it hard to replace that hose at the rear connection? OR would I have to wait for haul-out and outdrive service?

From the throttle body stud back the engines are under our stern area and harder to get to. I have a little more access to the rear of the engines now that we removed our rusty 6gal freshwater heater, but I wouldn't want to blindly pull off a hose that let in water and fumble with a hose clamp.

 

[Monterey296Twin5.0Gi]

I was able to get back and remove the small cooling hose going to the VST on each engine. It didn't look corroded in the hose, but I think the VST on each engine could maybe be clogged.

Could I blow through that cooling hose to see if there is resistance or a clog in the VST? Shouldn't blown air pass through the VST and just bubble in the port-side exhaust elbow?

How hard is it to remove and clean the VST when we can't easily remove our flame arrestor, or access behind the throttle body very easily?

We are still experiencing a bogging down on the raw water cooled port-engine that I mentioned in thread linked below, we try to get on plane and it drops 1000 rpm from 3k to 2k, I am thinking it isn't 'protection mode' and actually fuel related.

1998 VP 5.0Gi looses power, maybe in protection mode

Raw water cooled, and lives in a slip. First thing I want to ask is if you can check or change an impeller in the engine pump with the boat in the water? It is only the Port engine with the problem. It starts/idles great, runs fine in lower rpms, and as you accelerate, it gets all the way up...

forums.iboats.com

 

[Fun Times]

I haven't checked in awhile but you'll want to be as careful as you can be with the VST system as certain "new" parts like these tend to become no longer available and hard to find if still able to track them down.

If clogged, Maybe first try using a vacuum while carefully probing with a pick to unseat any salt water contaminants before blowing things deeper...Maybe try blowing by mouth before using any high air pressure system.

Having little room makes this system a challenge to work on as there's kind of a lot of components to this system.

Here's your fuel system parts catalog...Item number 2 / 18 is where you ought to be able to connect up a fuel pressure gauge to see what you're getting pressure wise...., http://www.volvopentastore.com/Vapo...on_id.470528882--store_id.366--view_id.770806

Take note you also have a low fuel pressure pump too, http://www.volvopentastore.com/Fuel...on_id.470528882--store_id.366--view_id.770803

http://www.volvopentastore.com/Mari...on_id.470528882--store_id.366--view_id.765210

Among many possibilities, There could also be debris in front of the fuel pumps as some pumps have little screens in front of the pump inlet connection.

Hope you can find and easily get this all resolved fairly quickly + hope this helps some, good luck.

 

[dypcdiver]

Your port engine that is giving problems could possibly have a similar problem to the one I had, which turned out to be debris in the inlet gauze of the HP fuel pump that is mounted on top of the VST.
The salt water side of the VST had rotted through to the fuel side (See photo arrow) and the bottom of the fuel side had about 1/16 of an inch of black muck in it. I change my fuel filters every year and have recently cut them open and not found any significant debris. I checked the hose from the Fwd mounted LP fuel pump and found it was PTFE lined so that wasn't the cause.
I replaced the Base of the VST (part number 3854149) from https://imatech.com/ and all problems have now gone.