jadento

496HO on both sides of engine under the exhaust manifold there is a check ball with a housing. I have called it a poppet valve but am not sure that is the correct nomenclature. Anyway, I am trying to figure out how the raw water side of the cooling system uses this part and its purpose. Seems it would be some kind of high pressure bypass. I have a friend having overheating issue and we have been thru the whole raw water system and not found anything wrong. Were trying to understand the purpose of this thing.

John

Sydwayz

iTrader: (1)

I think you are referring to the water drain system. Fore port, and starboard aft is where they are located. You pressurize the schraeder valve up on top of the motor, behind the heat exchanger, and those two actuators open, and allow water to drain out.

Chances are the issue is in the heat exchanger. Remove it completely, and clean out the tubes. And you need to order new end cap gaskets, as they go bad, and get sucked into the end cavity restricting water raw water flow. This is common, and the gaskets cannot be reused. There are posts here on OSO about such in the past.

PA.WOODCHUCK

Is it closed cooling system? If so PM your email address and can send cooling flow diagram. Does engine have cats?

jadento

Thanks Brian. I know about the water drain system. I had not thought about how this might incorporate. The heat exchanger has been removed and looked straight thru from end to end. The gaskets were replaced even though there were all there and looked nothing like what are show above. The Oil cooler and power steering cooler were also checked. Sea water pump impeller replaced, bravo water hose replace, "Bravo itise" hose replaced. Coolant thermostat replaced. Exhaust manifolds backflushed. Were kinda at a loss.

John

jadento

Yes closed cooling 2001 496 ho. no cats. We have found a few diagrams. They dont really show the water pump out system thought. I can PM you.

Sydwayz

iTrader: (1)

Does it have a fresh water flush system installed from the factory? I have seen where the factory systems have a check-ball "tee" installed and the tee can get gummed up with debris, restricting water flow.

underpsi68

Factory sea water pump? If so is the housing scored/grooved?

jadento

Yes fresh water flush, not sure its factory. But has the perko valves in it. But with the cap in the flush fitting i cant see how that could affect flow. plus one symptom is high pressure as read from the at the sea water pump which is after the flush valve. Which is a mechanical gauge....pegs 35 Psi gauge.

John

jadento

Harden pump, new plates.

outonsafari

iTrader: (4)

https://www.hardin-marine.com/p-5180...865828a02.aspx


https://www.perfprotech.com/blog/boa...m-flow-diagram


i think your talking about part #3, what they do and how they are connected is from memory, but i think they backdrain the water in the manifolds into the raw water side of the cooling as they are both connected to the 1 1/4 hose from seapump to heat exchanger.

port side, it drains into the oil cooler which has a t inlet

starboard side, it drains into the plastic choke point which sends water to the cool fuel

( thats what it did on mine, but its an 04)


when the engine is started water pressure closes them and routes the water around the engine thru the coolers then the exhaust.

maybe they failed partially open and some of the water is getting out of the cooling circuit before it can get to the heat exchanger causing the overheat.


time your water exit, hook up the hose start the engine and if water comes out right away, those valves prob failed open.

it takes 10 seconds or more to get water out of my exhaust, every time i start it i wanna shut it off because it takes so long to fill it up and come out the pipes.

mine are removed they were not connected directly to the drain valves/airpump system, indirectly yes since they back drain into the hose that the airpump system drains from, which by the way is also completely removed from my engine.