Poppet valve

[mercurymang]

Can someone explain the function of the poppet valve to me. I been looking at it and don't get it. I thought I got it until I went to install the new baffle plate with the new poppet valve and realized that when you tighten the plate down, the poppet is pushed out as the stem seats into the block. Then the outer side is pushed up against the outer cover. So I don't see where this is any spring action. I just don't get the setup.

 

[Maxz695]

Re: Poppet valve

Can someone explain the function of the poppet valve to me. I been looking at it and don't get it. I thought I got it until I went to install the new baffle plate with the new poppet valve and realized that when you tighten the plate down, the poppet is pushed out as the stem seats into the block. Then the outer side is pushed up against the outer cover. So I don't see where this is any spring action. I just don't get the setup.

Here is the diagram of a 70 HP with T stat and popit. I,m not using either as My motor did not come with the setup for my year 1979. If your not using a t stat then the popit isn,t nessecary. The popit has something to do with the opening of the T stat to relieve pressure. Link to diagram. Mercury Marine 70 HP (3 CYL.) EXHAUST AND MANIFOLD COVERS Parts. Unless your going to be doing early cold morning trips or cold day fishing then the T stat isn,t nessecary. This keeps your engine running at a constant running tempature under all conditions when running. The popit I think goes between the block and the baffle and the T stat goes between the baffle and the outter cover but not sure use the diagram to help you out . Info... I hooked up a Temp switch in my rear water cover (Had to buy a 12mm tap) and bought a dash gage. I at idol speed have about 70 degrees running temp. I have not been out enough to test Wot temp as I have only done a few short runs at WOT. With a T stat depending on the temp T stat be it 120 130 degrees is where your engine temp would be after warm up. When water in the block reches that temp the T stat opens and the popit restricts the pressure from the heated water. The T Stat then opens and closes when temps get higher or lower to let less or more water flow through depending on the water going through the system.

 

[Faztbullet]

Re: Poppet valve

Can someone explain the function of the poppet valve to me.

It is in block to relief water pressure at 2500-and above RPM. The water pumps builds pressure as it runs and the "poppit" is nothing but a spring load pop off valve to relieve this pressure. Make sure you have it (poppit) assembled correctly and you have correct exhaust plate since you replaced it with a new one as there is a 69579 and a 64856 plate.

 

[mercurymang]

Re: Poppet valve

It is in block to relief water pressure at 2500-and above RPM. The water pumps builds pressure as it runs and the "poppit" is nothing but a spring load pop off valve to relieve this pressure. Make sure you have it (poppit) assembled correctly and you have correct exhaust plate since you replaced it with a new one as there is a 69579 and a 64856 plate.

I checked and I have 69579 which matches with my sn.

My new baffle looks just like my old one and am fairly sure it's the correct one. Installed, the spring forces the diaphragm against the baffle. When it's installed, the other end of the poppet sits in the block and is pushed out and is forced against the outer cover. Is this correct. I was pretty careful and am pretty sure I have re-assembled everything as it came off.

 

[Faztbullet]

Re: Poppet valve

If I remember correctly it goes: stem, spring,thru plate,diaphragm,washer and screw...

 

[Maxz695]

Re: Poppet valve

instal as shown in the diagram I posted as seen popit between block and baffle stem out to the cover and the T stat outside the baffle spring facing inwards to the block. http://www.marineengine.com/parts/m...-thru-5579016-usa/exhaust-and-manifold-covers

 

[mercurymang]

Re: Poppet valve

Yep, it's installed right.

Thanks fellas

 

[loreto.z]

If I take out the whole poppet assembly,"my mariner 2cyl. 40 hp has the spring inside a rubber boot" would the high water pressure at 3000 or more rpm damage the engine? It?s just that the water here in the south of Spain is very warm.

 

[mercurymang]

Wow, here's an old thread but I remember it. I think you would be fine at high rpm. I believe it's a bleed off type valve to removing it would just make it always bleed off. The issue would be at low rpm, you may not get sufficient water pressure.