poppet valve?

[caspari]

what does this thing do? How do I check it? Does the water come straight from the foot to the t- state and then flow to the rest of the engine and back through the poppet to cool the exhaust and foot at higher rpm's? The manual I purchased doesn't explain these things. 135 91 merc. I see exhaust coming back through the tale-tell, no water. How much compression should the motor have, once again the book doesn't say(shop manual purchased at west marine). Can anyone help?

 

[FranksMerc]

Re: poppet valve?

The poppet valve opens when additional cooling is needed and when the engine is being throttled. When idled the poppet valve will be closed. If the poppet tears water will weep from the little hole in the cover. Its very cheap and easy to replace. The poppet can be a cause for overheating if poppet is stuck. <br />If no water is coming out of the tell tale the water pump would be the first thing to check.

 

[vinney]

Re: poppet valve?

The bypass valve is so that too much water pressure doesnt build up in the water passages. The bypass valve comes off its seat with pressure. If the bypass valve doesnt seat it will over heat at idle. If it tears it will leak water into the engine pan. It has been known to put water in the bottom cylinders and hydro the engine. They need to be changed every 200 hours.

 

[rodbolt]

Re: poppet valve?

hello<br /> yep what vinney says. the poppet really only serves to regulate water pressure in the block. excess water is dumped back overboard. the poppet is a valve term. it is a poppet type pressure vavle. the spring and the diaphram determine when it opens. if the diapram tears it sprays water into the cowl. lots of good engines get junked due to lack of maint.the vale is under a cover located under the switch boxes. depending on design will have 2 or 4 1/2" head bolts holding it to the motor.<br /> good luck and keep posting.<br /> ps the t-stats are the last thing the water sees before exiting the block. the hose connects the t-stat housing to the tell tale and the overboad part of the powerhead adapter. that is why mercs have such hot tell tale temps. almost all other manufactures use tell tale water from the motor before it circulates.

 

[caspari]

Re: poppet valve?

Where is the t state located. The book seems to suggest under the poppet housing on other models. I did remove the poppet and it looked ok but I didn't see a thermostate. I intend on doing as much prevenative maintenance as possible and hope for the best results in the long run. thanks for posting. you guys are great.

 

[rodbolt]

Re: poppet valve?

the thermostats are at the top of the heads. two 1/2" headed bolts on each housing.<br /> good luck and keep posting

 

[caspari]

Re: poppet valve?

Found the t states, thanks. had to take it to the shop and see if they can get the foot off.

 

[caspari]

Re: poppet valve?

Are there any more t-states in the motor other than the 2 in the heads. We removed the t-states from the heads after a test run the other day. The thing stopped pumping water after it idled for about 30 minuites and over heated. Strange problem. After it cooled down and with the t-states removed we cranked it up at the house, after it warmed up alittle it began to pump water like it is supposed to, as if the t-states opened and let water flow but we removed the t-states? This doesn't make sense unless theres a hidden t-state somewhere. Is there?

 

[KCLOST]

Re: poppet valve?

Hmmmmm,,,,<br /><br />Forget about the t-stats for a minute... (by the way, you only have two of them. there isn't a hidden one anywhere).Buy some new ones just to be sure though.<br /><br />I think you have an impeller/pump problem... After running for a while the impeller may get warm/soft and loose it's grip on the pump housing, hence you loose water pressure.<br /><br />When was the last time it was replaced? Did you ever get the lower unit off, If it was seized on, it's probably been a while since it was serviced...

 

[chumbucket]

Re: poppet valve?

While we are on poppet valve, What kind of sealant,to hold the grommet in the block ??? The one the plastic valve,spring go's in-out of.

 

[Mettaree]

Re: poppet valve?

No sealant. The grommet is grooved to fit on a shoulder on the plastic carrier that is in the block then the poppet valve will slide into the grommet opening.<br /><br />

 

[chumbucket]

Re: poppet valve?

Thank's JKW, Retired and tired myself, Couple boat's and pickup's keep me besy.