check ball and connector question
 

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

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.



https://i.ytimg.com/vi/ILlniRuI7QE/hqdefault.jpg

https://captainyarrr.demand-performa...images/he2.jpg

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

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

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.

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.

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

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

Harden pump, new plates.

https://cimg6.ibsrv.net/gimg/www.off...346571565f.jpg


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.

https://cimg2.ibsrv.net/gimg/www.off...4b3bb463ed.jpg

https://cimg3.ibsrv.net/gimg/www.off...2bb8d980bd.jpg

So on my engine the header kit came with short rubber hoses and stainless plugs so the original hoses, chokepoint and oil cooler get blocked off as the headers dont back drain.

in the first pic you can see the plug on on the chokepoint by the 2 hoses for the coolfuel

the other one that plugs the t inlet on the oil cooler wasnt used since i used a different oil cooler and mounted were the port side airvalve drain thing used to be


you can test if the backdrains failed open by blocking them off

Remove the hoses that go from the backdrains to the choke point and oil cooler, get a foot of hose whatever diameter is on them, 4 hose clamps and a dowel rod, cut the hose into 4 sections stuff a dowel in there and clamp them in place.

that will force the cooling water to follow the circuit around to the heat exchanger same as if the backdrains closed from pressure off the seapump.


mine and every other 496 with cmi headers has the backdrains deleted so it wont hurt the engine.

i would do it only as a test to troubleshoot it and replace if needed since this engine is stock before i paid 140 bucks an hour for soms greasy boot mechanic to walk over and scuff up the boat after it sat in their parking lot uncovered for 2 weeks because "we dont cover and uncover boats" until they get around to dingin you for 700 bucks.

The Perko Tee is the one that has the checkball in it. It's spring loaded. The checkball is not needed, and I recommend removing it. That's the exact issue a friend had with his 30' Baja with 496 Mags. They would run fine up to 45mph or so, but anything over that, they were not getting enough water, and overheated. The checkball was gummed up with seaweed and was not allowing enough water into the engine.

Hey all. This is the fitting that is at the bottom on each manifold. It has no spring or anything inside it, just a check ball.
https://cimg4.ibsrv.net/gimg/www.off...ac9e53c7c.jpeg

Yes that is the part I was referring to originally and you are correct just a ball. What Sydwayz was most recently talking about is a Perko product unrelated to this which allows you to flush the motor without muffs on the outdrive. Its a valve that tees into the incoming raw water supply from the outdrive. It has a one way check valve with a spring.

Jadento

So the perko valve is before the sea water pump which is where the mechanical fuel pressure gauge reads from. I cant see it pegging the gauge past 35 if it was blocking water.

Do mechanical water pressure gauges go bad?

John

We/He has never used the mercury pump out system, so I believe we could eliminate the check valve with no problems. we have a couple things to try still. but may end up trying the delete. Thanks for the info.

John

This thread covers how the system works......

https://www.offshoreonly.com/forums/...ve-496-ho.html

Where should I install a pressure bypass. It already has the fitting to dump it out the side of the boat. on the input side to the water pump or the output?

Did changing these Drain "T" fittings correct the overheating problem? Were they plugged up or bad? I'm having a similar overheating issue and all raw water pumps, impellers, gaskets, and t-stat have been changed.