LittleChief Posted August 13, 2017 Report Share Posted August 13, 2017 I have a 2000 Yamaha 130hp V4 on my MA. I am having a small issue with the overheat alarm going on intermittently. I have replaced the impeller and t-stats and it seems that every other trip after running for about 30 mins the overheat alarm goes off. For instance, I ran all Thursday afternoon and no alarm. Come Friday the alarm came on after about 20 mins. I am able to run WOT as well without an alarm most of the time. The motor is peeing just fine, but I am wondering if it is the water jackets that are clogged or some other small issue. I am thinking not enough water is flowing to the area where the sensor is that triggers the alarm (not sure where this is), but I know it is not an oil issue as the small tank under the cowling is at the appropriate level is oil is flowing properly. Is there anything else I should consider or replace? Thanks in advance for your help. Link to comment Share on other sites More sharing options...
Wanaflatsfish Posted August 13, 2017 Report Share Posted August 13, 2017 13 minutes ago, LittleChief said: I have a 2000 Yamaha 130hp V4 on my MA. I am having a small issue with the overheat alarm going on intermittently. I have replaced the impeller and t-stats and it seems that every other trip after running for about 30 mins the overheat alarm goes off. For instance, I ran all Thursday afternoon and no alarm. Come Friday the alarm came on after about 20 mins. I am able to run WOT as well without an alarm most of the time. The motor is peeing just fine, but I am wondering if it is the water jackets that are clogged or some other small issue. I am thinking not enough water is flowing to the area where the sensor is that triggers the alarm (not sure where this is), but I know it is not an oil issue as the small tank under the cowling is at the appropriate level is oil is flowing properly. Is there anything else I should consider or replace? Thanks in advance for your help. yes, water jackets can be an issue..... There is a post somehwere on here on how to clean....the heads are 17 years old...if you have not cleaned them...it could be an issue.....it's pretty simple to do, just need a good dremel and about 3-4 hours. dc Link to comment Share on other sites More sharing options...
DonV Posted August 13, 2017 Report Share Posted August 13, 2017 One more thing. Check the compression and see if you have any water in the cylinders. The Yamahas are known to have corrosion issues and sometimes the top of the cylinder will corrode just enough to let in water under pressure. I really hope that's NOT the problem because it happened to me and the only repair is a new block or rebuilt engine. Good luck. Link to comment Share on other sites More sharing options...
LittleChief Posted August 13, 2017 Author Report Share Posted August 13, 2017 I checked the compression last week and I am 130-140psi across the board. I tried looking up the post on how to clean the heads, but I am not able to find it. Hopefully somebody knows where it is. Thanks! Link to comment Share on other sites More sharing options...
hurricane Posted August 13, 2017 Report Share Posted August 13, 2017 Don't think I would rule out low oil just cause the tank is full. If the impeller is good and new Tstat, I would lean towards oil. Many engines run years and tons of hours and never have problems with the water passages, that would be that very very last thing I would go after. The float in the tank could be damaged, or a wiring issue. Also the main tank pump could be intermittent or filter clogged, and the engine tank gets low on occasion. Just thoughts, but I would double verify oil system before going down the water passage path. Link to comment Share on other sites More sharing options...
whichwaysup Posted August 13, 2017 Report Share Posted August 13, 2017 Does that engine have a poppit valve? Would explain why at low rpm you are getting the alarm but not at high rpm. My vmax does that if I get silt in it, poppit gets stuck closed and I have to run it over 1000 rpm to clear it. Link to comment Share on other sites More sharing options...
LittleChief Posted August 13, 2017 Author Report Share Posted August 13, 2017 Yes, it has a poppit valve- I might as well replace that too. I am going to take a closer look at the oil pump and filters as well. Thanks guys. Link to comment Share on other sites More sharing options...
Lap it Up Posted August 14, 2017 Report Share Posted August 14, 2017 Replace the poppet but more than likely it is build up/scale in the water passages. Pull water jacket covers on the heads, spray on/off acid to melt it away then spray heavily with water to dilute and wash away acid. Buy two new gaskets and give it a try. If the build up is really bad you will have to pull the heads but the passages on the cylinder walls are larger and don't clog as easily. I normally see the most build up in the passages under the water jacket covers. Careful with the bolts. They are soft and can/will snap. Work them back and forth, light heat if needed and knocker loose to help. Link to comment Share on other sites More sharing options...
LittleChief Posted August 14, 2017 Author Report Share Posted August 14, 2017 Where can I buy the on/off acid? A quick Google search is only bringing up on/off hull cleaner. Link to comment Share on other sites More sharing options...
JEM Posted August 14, 2017 Report Share Posted August 14, 2017 On/Off hull cleaner is an acid. Link to comment Share on other sites More sharing options...
MuddyBottomBluz Posted August 14, 2017 Report Share Posted August 14, 2017 If the heads are removed you can soak them in a solution of water and Sodium Bisulfate. What is it, known as PH Down for pools and is a dry acid purchased at your neighborhood home store. The stuff will eat the salt away without affecting the metal or the paint, and I do mean eat all the salt away, nothing left without you breaking a sweat. http://www.jones-hamilton.com/spd/technical/applications.html The stuff is cheap, will remove rust from steel and cleaned salt off my heads overnight. Got tired of the old school way and thought there had to be a better way and used it without even knowing the actual benefits and was amazed. Just don't get it on concrete, turns it rusty color, does not affect your bare skin, just would not leave it on long without rinsing it off. Tip of the Day! Link to comment Share on other sites More sharing options...
justfish Posted August 15, 2017 Report Share Posted August 15, 2017 Had it done by a "mechanic" buddy on my 90 when I was chasing the same thing. Cleaning the water jackets isn't difficult, it's the bolts that will give you fits. If I remember right there are ALOT of em and he and or I broke a few. And my motor was well taken are of and garage kept....my power head bolts came out like butter, but not the water jacket ones. Then there wasn't even much build up,,,, I once saw a thread on hull truth about some sort of vinegar flush that looked like it got a lot of salt out. Maybe search for that I personally would test a couple water jacket bolts and see what you up against then make a game plan... Btw - My problem ended up being the water pump housing was not tightened completely when the impeller was changed - that friend "mechanic" musta lost one of my bolts when he changed it so used one he had laying around and it bottomed out just before it was tight enough to make a seal. He is no longer my mechanic or friend Link to comment Share on other sites More sharing options...
James Grissom Posted August 16, 2017 Report Share Posted August 16, 2017 If you haven't pulled the heads off yet . I would check the 2 thurmstats to see if they are gummed up , easy 30 min check. also sparkplugs electrodes condition Link to comment Share on other sites More sharing options...
Fishtails Posted August 17, 2017 Report Share Posted August 17, 2017 I was questioning a mechanic about the same issue. He suggested that I get an infrared thermometer ($12 @Walmart) run the motor until the alarm goes at which time you can check all around each part of the head with it. You should be able to discover where the hotspots are then you can focus your attention there. If you fail to find any hotspots your problem could be something else besides salt. Link to comment Share on other sites More sharing options...
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