Poppet Valve/Relief Valve?

[KCLOST]

I've been trying to find out what may cause what I feel is too high of a temp at full throttle. 1986 Merc. 175 hp....<br /> The water pump is fine (new), the stats are new, the spark plugs are wet, and the compression is good at all cylinders... At full throttle the temp gauge reads almost if not right at "H".<br />It receeds to mid range quickly at lower/Mid rpms.<br />I have not had a high temp alarm, but it still concerns me...<br /><br />My question is, could a faulty Poppet Valve be a cause for my problem? What does this valve do and if bad what do I look for?<br />Thanks in advance. I've decided not be become a full time marine mechanic..............................

 

[jjroebuck]

Re: Poppet Valve/Relief Valve?

got the same problem on my suzuki dt 85... replaced the same parts as u...but im trying to find my poppet valve location...

 

[jjroebuck]

Re: Poppet Valve/Relief Valve?

i found this info on a post... im going to try a poppet valve, if i can find the location

Someone may want to elaborate on this:The poppet valve regulates water pressure in the block. At idle your water pump barely pushes water through the block, especially through the top cylinders. When you increase rpm's the water is forced through the motor by a combination of the water pump and the force of the water pushing into your water pump from forward motion in the boat. The poppet valve will open when the water pressure in the block becomes too high and it relieves the motor of this extra water pressure by redirecting the water out the exhaust ports. If the valve is too weak or has a leak it let's water pass that is needed in the upper parts of the block. Hope this helps.

 

[SkipperC]

Re: Poppet Valve/Relief Valve?

i have a 86 175 mariner. My temp alarm goes off at high speeds and my motor is hot. i also have a new impeller, thermostats, and i put a poppet valve kit in. it still gets hot but im not sure the poppet valve is working correctly. i have a good stream of water out the tell tale until high rpms. i could have installed the valve wrong not sure how though. if u figure anything out please let me know.

 

[gss036]

Re: Poppet Valve/Relief Valve?

The poppet does as stated below, but normally opens around 2500 rpm+-. If it stays open it will cause low speed over heating. If you have a water pressure gauge, which I think is as or more important than a temp gauge, then you can see the valve opening. There is no kit available for the Mercury, just have to buy individual parts. I think the most troublesome cause of overheating is the grommet is pushed inside the block and causes water flow problems and the carrier not seating. Also if the diaphragm has a hole in it, it may not build up enough pressure to open up and allow excess water to flow through the exhaust.