popett valves how are to change?? 1999 150

How hard are the popet valves to change on a 1999, 150hp blue water series?? The reason why i am changing them is because, the motor seems to run hot durring idle and the water out of the tell tail is not that force full & hot. I replaced the water pump and tstats. I noticed durring idle that there is water coming from where the two anodes on the lower unit are, looking at my good old manual that is where the popet valves dumps off at. I am not sure if that is normal durring idle is it?? Also when i did a search about my problem lots of people said that if it was wide open the motor would over heat, but how come my manual says that the motor will run cool and never make it to operation temperature?? Is it because of year?? <br />Well i just want to make sure that the valve is the problem before I messing with something where i can brake a bolt!! I know what salt water does to motors. any help would be great!!

Re: popett valves how are to change?? 1999 150

the poppet or pressure relief valve controls water pressure , the t-stats control water temp/flow through the cyl heads.<br /> the control valve will dump excess pressure into the exhaust stream, the discharge of the t-stats is also directed to the exhaust stream, both can discharge through the tell tale hose.<br /> thats why the merc carbed and EFI v6 motors have 140* plus water from the tell tale occasionally.<br /> without going to my manual and refreshing my muddy all I can say is do the poppit maint now or wait until the diaphram ruptures and water is injested into the intake air stream and destroys a crank or a piston.<br /> what I am trying to say is break them now or break them later, the only difference is in the amount of secondary damage.

Re: popett valves how are to change?? 1999 150

Rodbolt,<br /><br />"or wait until the diaphram ruptures and water is injested into the intake air stream and destroys a crank or a piston."<br /><br />I don't think that is possible!!!<br /><br />If the poppet is open, below 2500 rpms, the water is dumped out of the water jackets/block prematurely so there is not enough water to cool the block. It will be dumped into the exhaust. The same will happen with a ruptured diaphram as the poppet will be opened at that point. Some water might exit the poppet cover in that case, and if so is that what you are refering to as possibly getting into the intake?<br /><br />His symptoms do suggest a poppet problem however...

Re: popett valves how are to change?? 1999 150

KCLost<br /> your actually way lost<br /> the cover has an airvent hole. when the diaphram ruptures,not if, the water sprays out of the vent hole into the cowl where its picked up as a water mist in the air box intake, if it does not take out a piston it usually rusts a bearing.<br /> its just how it is.<br /> I have replaced to many cranks and pistons cause of a ruptured diaphram. its even worse if mud and debris have the cowl drains clogged.

Re: popett valves how are to change?? 1999 150

That's what I thought you meant... Makes sense...

Re: popett valves how are to change?? 1999 150

some of the two,3 and 4cyl mercs will do the same thing.<br /> in fresh water they dont fail as fast, here sometimes it will fail in 2 years or less as the corrosion around the edge of the diaphram will cut the rubber up and allow water pressure to blow through the air vent in the diaphram cover. but all fail sooner or later unless periodic replacement is done.

Re: popett valves how are to change?? 1999 150

I've noticed that corrosion a lot also... I really wish they would make those covers out of something that is much more corrosion resistant...I've been known to add a "little" bit of sealant just for assurance around the groves only...