Overheated using muffs. Telltale weak. Common with muffs?

I took the advice of several posters and ran fresh water through the engine using "muffs". Only problem was that it took a minute or so to see the telltale pee. When the telltale finally showed, it was weaker than it normally is while in the water. Then, the overheat buzzer went off. It was only at idle during this whole process so I assume it didnt get too hot(I shut it down immediatly). Is this common? I ran the engine at WOT on the ocean yesterday just before I hauled it for the winter, and it ran fine with a strong telltale. Is it common for this to occur withmuffs? Its a 2000 130hp Yamaha.

Re: Overheated using muffs. Telltale weak. Common with muffs?

It is easy to set the water supply to the muffs for too little water, PC. That might be the problem.<br /><br />Good luck.

Re: Overheated using muffs. Telltale weak. Common with muffs?

Hey JB, since it was you that responded, I just want to take this time to say THANK YOU! Not just for this response, but for all the other bits of advice you have given to me over the year and a half I've been a member of this board. Quite often you answer questions for other people and I get an education on just reading through them. You are indeed a fine person for taking your time to answer questions of complete strangers like me. So a sincere and warm thanks. Pat

Re: Overheated using muffs. Telltale weak. Common with muffs?

Try running the hose at full pressure. My 60 4-stroke Yam produces a strong tell tale at idle within a couple of seconds - which I direct into a bucket as well as doing the flush run with a big container under the motor. I use the captured water to wash down the boat. Must admit we have fairly good water pressure here, just not enough of the stuff itself. IMHO if you don't get a good straight tell tale of water either you have low hose pressure or your water pump needs checking.

Re: Overheated using muffs. Telltale weak. Common with muffs?

Thank you very much for the feedback, Pat.<br /><br />Many guys are on here daily, offering simple or expert help. The times the helped offer thanks are too few.<br /><br />Thanks again for the feedback. You have made my day.

Re: Overheated using muffs. Telltale weak. Common with muffs?

hello<br />yep use full water pressure and if it persists its the first sign you pressure valve is failing

Re: Overheated using muffs. Telltale weak. Common with muffs?

Hi Patrolcarr,<br /><br />I had a similar problem with my 250 sw2. Couple of times this summer alarm went off while flushing at idle. If I bumped rpm's up slightly alarm shut off. Always had a telltale stream plus alarm would turn off and never had a problem while in the water or at higher rpm's so a little perplexed about why this was happening. When winterizing I pulled lower unit for typical maintenance and when I pulled water pump apart found that the gasket between housing and lower unit had slipped out of the groove on one of the bends approx. 1 inch and created a space for water to leak by. Had to have happened at last impeller replacement as housing was tightened down securely. I'm installing temperature and more importantly water pressure guages this winter for additional security. Being a long time boater with many years involved with I/O's on the offshore performance end we relied upon these to head off problems. Most important thing is to keep an eye on these guages while underway which can be a pain in the butt but necesary.<br />Hope you find the problem and maybe this will help.

Re: Overheated using muffs. Telltale weak. Common with muffs?

AS rodbolt said, this can be the first sign of a poppet valve sealing problem or also a water pump not properly sealed or not enough pressure on the hose. If the water pump has not been off, It mighht be a good time to clean the poppit valve assembly. A fairly easy process.

Re: Overheated using muffs. Telltale weak. Common with muffs?

Is the "poppet valve" actually listed in the shop manual using that term? I have the Clymer manual. Is it easily accessible?

Re: Overheated using muffs. Telltale weak. Common with muffs?

My poppet valve on my Yamaha C115 (250 hours) became sticky with corrosion/deposits and stuck open, and I rinse the salt out with fresh water religiously! My water pressure gauge was reading low and I thought my water pump was bad...changed pump...still low pressure, because the poppet valve was stuck open and dumping out the majority of the cooling water= low pressure and elevated temperature. Be sure to really clean the rubber seat well..vinegar and a toothpick or some other device that can scrape off the crud but not damage the rubber. Put anti seize on the mounting bolts. Oh yeah, I meant to mention that I run my motor in an old salvaged deep bath tub and I get FULL pressure (18 - 20 lbs.) from about 1200rpm's up...it even reads a few pounds at idle. It's a great way to be able to bench run the motor with NO fear of overheating. Keep a hose running into the tub to compensate for the water lost out of the pee hole. I installed a water pressure and temperature gauge...wouldn't own a boat without them. You can really keep an eye of what's going on and actually diagnose problems by using them. One more thing, when a poppet valve gets stuck open, the pee stream is still coming out but at a really reduced level...at high rpm that could mean trouble. There's water pressure but not near enough. The pee hole is a device only slightly more evolved than an idiot light.

Re: Overheated using muffs. Telltale weak. Common with muffs?

Ooops, I forgot what you asked. The poppet valve in my manual is I believe called a pressure control valve. Be sure to pay attention to the disassembly, it's simple but the plastic valve has a long end and a short end..mine has the long end towards the block, it actually inserts into the spring. It's at the back of the motor below the heads and kind of out of sight...two 10mm bolts and out it comes under spring pressure.

Re: Overheated using muffs. Telltale weak. Common with muffs?

In the Clymer manuel, the first step when servicing the water pressure valve is to remove the ECU and ignition coils. I have never done this, is it complicated? I'm a little intimidated. Can I take it off as a unit, without having to disconnect too many wires? Uncle Daddy, what was your experience with this? As usual, any feedback is greatly appreciated. PC

Re: Overheated using muffs. Telltale weak. Common with muffs?

i dont usually remove any of that. i have a long 1/4 drive extension with a wobble end. it does give you better access when the ecu is removed. just remove the grounds and pull the plug leads off the plugs then remove the 4 bolts holding the assembly on. leave the ecu plugs connected and just swing it out of the way. maybe remove the plug that runs off to the port side?

Re: Overheated using muffs. Telltale weak. Common with muffs?

I brought this up before (ECU removal) - the "pros" (Rodbolt et al) don't remove it. But while removing and reinstalling the poppet valve cover doesn't look like a problem with the right extension ratchet, I am a little leery of an amateur's ability to do the cleaning properly when it's all buried so far back. <br /><br />Also the last cover I removed on my engine was the thermostat cover and I had to scrape old gasket off of both the cover as well as the mating cylinder head surface. If that has to be done with the poppet valve cover gasket and it's back there half-covered by the ECU, it looks pretty hit-or-miss.<br /><br />Is removing the ECU a big deal? Isn't is worth the tradeoff for us weekend mechanics?

Re: Overheated using muffs. Telltale weak. Common with muffs?

Thanks for all the excellent feedback. I was just wondering, are there any sites anybody could recommend here online where I'd be able to purchse Genuine Yamaha replacement parts? Or at least high quality copy's? When I go to the Yamaha site, it only points out where the dealers are located which are quite a hike from where I live. If not, I'll just have to make that hike. PC