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HBCALIAKID

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I have a 2006 mercury/Yamaha 225 CXXL4Scounter rotating , can’t find the location on the poppet valve. Any help would really appreciate it.
 
I have no idea. Now that I have offered my credentials, I have a few "comments". On smaller Mercury engines, like their 4 cylinder 2000ish year engines it accompanies the thermostat under a common cover on the upper left back of the engine block water jacket encircling the spark plugs.

Some smaller engines have it on top of the engine near the rear cover.

Some Mercury V engines have the pop-off valve cover attached to a hose that exits the top of the block (at a Y connection.....separate banks of 3 cylinders and a common hose for water exiting the block, and goes down to where the engine block meets the rest of the engine proper. The thermostats are in the top of the 3 cylinder banks.

My conception of the device is to wait until the block is full of water....protecting the top of the top piston(s) like is the case with thermostats, and that is where, when water pressure reaches a certain value....on Mercs it's 2500 RPM, it opens and allows increased flow through the block at the higher RPMs where more heat is generated.

I would assume the valve would be the diameter of a Quarter coin or larger and may be under the cover with the thermostats. Since the engine mentioned is obviously a V type, I would assume that the cooling loop would be similar to Mercury's. Obviously my comments don't cover all applications, but the intent is to give you an idea as to what you are looking for.....if you have no other reference. Good luck.
 
HBCALIAKID said:
I have a 2006 mercury/Yamaha 225 CXXL4Scounter rotating , can’t find the location on the poppet valve. Any help would really appreciate it.
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Is it sticking? Use low pressure compressed air to free it by placing the nozzle of a blow gun at the fitting for the water stream below the powerhead that shows the water pump is working. Just a short burst.
 
jimn said:
Is it sticking? Use low pressure compressed air to free it by placing the nozzle of a blow gun at the fitting for the water stream below the powerhead that shows the water pump is working. Just a short burst.
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That's a neat idea. If it cleared the problem, I'd go ahead and replace the valve (anyway) as the root causes (corrosion I'd guess) is still at the site of the reluctance to open.
 
Texasmark said:
That's a neat idea. If it cleared the problem, I'd go ahead and replace the valve (anyway) as the root causes (corrosion I'd guess) is still at the site of the reluctance to open.
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I was summerizing an outboard and at the time, I didn't know about the poppit valve, so after replacing the impeller, etc and reassembly, I basically freaked out when I saw nothing coming out. Apparently, someone heard what I had said (not something nice people say), so he came out and I told him that no water came out- he told me about the compressed air and it worked. The ball sticks after sitting over the Winter. I don't know how it was winterized, so I can't comment about the possibility that it may not have been run before being put away or if any maintenance had been done.

I don't think it would be a good idea to make that assembly out of a metal that can corrode- that would be asking for trouble.
 
jimn said:
I was summerizing an outboard and at the time, I didn't know about the poppit valve, so after replacing the impeller, etc and reassembly, I basically freaked out when I saw nothing coming out. Apparently, someone heard what I had said (not something nice people say), so he came out and I told him that no water came out- he told me about the compressed air and it worked. The ball sticks after sitting over the Winter. I don't know how it was winterized, so I can't comment about the possibility that it may not have been run before being put away or if any maintenance had been done.

I don't think it would be a good idea to make that assembly out of a metal that can corrode- that would be asking for trouble.
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Spring tension is necessary to keep it shut during low water pressure operation where the Tstat's in charge....RPMs below 2500. Doubt that one could provide that function without something that has spring sensitivity without it not being metal. Having a (resilient) rubber plug against the aluminum engine is a necessity, but it's the functionality of the device that's the problem. IMHO.
 
Texasmark said:
Spring tension is necessary to keep it shut during low water pressure operation where the Tstat's in charge....RPMs below 2500. Doubt that one could provide that function without something that has spring sensitivity without it not being metal. Having a (resilient) rubber plug against the aluminum engine is a necessity, but it's the functionality of the device that's the problem. IMHO.
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A stainless spring would work, but the rest can be plastic. Sitting for an extended period causes this- who knows what kind of poi is in the water?
 
jimn said:
A stainless spring would work, but the rest can be plastic. Sitting for an extended period causes this- who knows what kind of poi is in the water?
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Fine except the sealing surface. Surely that interface has to have a "contourable" device and rubber is such, plastic isn't!
 
Texasmark said:
Fine except the sealing surface. Surely that interface has to have a "contourable" device and rubber is such, plastic isn't!
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I would hope they use some kind of Silicone rubber since it can be heat-tolerant and stuff doesn't really like to stick to it but as I posed, I haven't needed to remove or replace one of these.
 
Yamaha refers to the valve as a pressure control valve. Purpose is to open and prevent water pressure from becoming too high when the motor is running at high RPM's. It does not act as some Mercury valves do.

It is located on the exhaust guide. Rear of the motor. A panel has to be removed to gain access.



 
boscoe said:
Yamaha refers to the valve as a pressure control valve. Purpose is to open and prevent water pressure from becoming too high when the motor is running at high RPM's. It does not act as some Mercury valves do.

It is located on the exhaust guide. Rear of the motor. A panel has to be removed to gain access.



Click to expand...
Nice comprehensive response. That should make the poster's job very easy especially with the diagrams!
 
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