mark10187 Posted February 12, 2013 Share Posted February 12, 2013 Hi guys, Just wondering if anyone has had this issue before I've had issues with the water pump have changed the housing impeller cleaned the pipe thats comes out of the water pump have had a marine mechanic look at it and spent over a grand changing side plate gaskets and checking water pipes with still no fix the boat starts and pumps water out fine when I rev the motor with no load its fine water pumps out and it's Luke warm once on the water idling water pumps out fine as soon as the speed gets over 6 knots the motor gets hot and the motor kicks back into neutral if the speed is over 15 knots steam comes out of the engine and It kicks back into neutral I am thinking possibly a blockage in the head but other than that no idea Link to comment Share on other sites More sharing options...
njsconst Posted February 12, 2013 Share Posted February 12, 2013 Mate sounds like a salt build up in the top of the head. I had the same problem in one of my motors years ago and the symptoms were identical. Unfortunately to fix mine they had to pull the whole head apart and send it away to be sand blasted. Was very costly....and that was 8yrs ago. I used to flush my engine thoroughly after every use to. Now I use 'Saltaway' when flushing as a preventative measure in my new engine. The other way to fix it is next time your on the water....there are four nuts that hold the engine on the boat. Just unscrew the bolts and problem fixed! Good luck. Link to comment Share on other sites More sharing options...
mark10187 Posted February 12, 2013 Author Share Posted February 12, 2013 If that would be the problem would using saltaway to flush it clear the problem at all or is the only way to clear it out by taking the head off? Link to comment Share on other sites More sharing options...
njsconst Posted February 12, 2013 Share Posted February 12, 2013 From the symptoms you have described I would imagine it is well and truely blocked. No product will clear the build up and I would assume it needs to be pulled down and overhauled unfortunately. Saltaway and the other similar products are preventative measure to stop this occuring in the first place. Link to comment Share on other sites More sharing options...
Geoff Posted February 12, 2013 Share Posted February 12, 2013 From what you describe , it is OK when the motor is cold but after it warms up then the problem arises. Have you removed & checked the thermostat both for salt build up & actual opperation. It's not uncommon for these to develop a fault Geoff Link to comment Share on other sites More sharing options...
mark10187 Posted February 12, 2013 Author Share Posted February 12, 2013 There's no thermostat on this model 4 cylinder two stroke Mariner that was the first thing I thought it could have been the thermostat but found out they don't have one Link to comment Share on other sites More sharing options...
Guest Aussie007 Posted February 12, 2013 Share Posted February 12, 2013 since u spent $1000 on getting the exhaust gaskets replaced im thinking the mechanic removed the power head and inspected the exhaust and water pump pipe i think your problem might be your water pump impeller have u removed this? it could be the wrong type it could even be worn and slipping on the shaft Link to comment Share on other sites More sharing options...
Day's Fishin Posted February 12, 2013 Share Posted February 12, 2013 There's no thermostat on this model 4 cylinder two stroke Mariner that was the first thing I thought it could have been the thermostat but found out they don't have one Strange they don't have a thermostat! How does the motor warm up to operating temperature with water pumping straight through? I had problems a number of years ago with a Mariner overheating when trolling and it was the thermostat's. There was 2 in my motor? I am running a Mariner on my tinny now and I think their a great motor. Regards Jeff Link to comment Share on other sites More sharing options...
Day's Fishin Posted February 12, 2013 Share Posted February 12, 2013 Mate sounds like a salt build up in the top of the head. I had the same problem in one of my motors years ago and the symptoms were identical. Unfortunately to fix mine they had to pull the whole head apart and send it away to be sand blasted. Was very costly....and that was 8yrs ago. I used to flush my engine thoroughly after every use to. Now I use 'Saltaway' when flushing as a preventative measure in my new engine. The other way to fix it is next time your on the water....there are four nuts that hold the engine on the boat. Just unscrew the bolts and problem fixed! Good luck. Good alternative to fixing it. Regards Jeff Link to comment Share on other sites More sharing options...
mark10187 Posted February 13, 2013 Author Share Posted February 13, 2013 since u spent $1000 on getting the exhaust gaskets replaced im thinking the mechanic removed the power head and inspected the exhaust and water pump pipe i think your problem might be your water pump impeller have u removed this? it could be the wrong type it could even be worn and slipping on the shaft Yeah have changed the key way impellar and the water pump housing and all the gaskets on the pump and still have the issue Link to comment Share on other sites More sharing options...
Geoff Posted February 13, 2013 Share Posted February 13, 2013 Bustoff . As Day's Fishin say's , How does the motor warm up to operating temperature with water pumping straight through? I had problems a number of years ago with a Mariner overheating when trolling and it was the thermostat's. There was 2 in my motor? There is something in the motor sensing the heat & causing it to " kick back into nutral if over 15 knots" . Normally this is connected to the thermostat. Geoff Link to comment Share on other sites More sharing options...
mark10187 Posted February 13, 2013 Author Share Posted February 13, 2013 Strange they don't have a thermostat! How does the motor warm up to operating temperature with water pumping straight through? I had problems a number of years ago with a Mariner overheating when trolling and it was the thermostat's. There was 2 in my motor? I am running a Mariner on my tinny now and I think their a great motor. Regards Jeff Not too sure but it definitely doesn't have A thermostat Checked and double checked the manual to make sure Link to comment Share on other sites More sharing options...
mark10187 Posted February 13, 2013 Author Share Posted February 13, 2013 Bustoff . As Day's Fishin say's , How does the motor warm up to operating temperature with water pumping straight through? I had problems a number of years ago with a Mariner overheating when trolling and it was the thermostat's. There was 2 in my motor? There is something in the motor sensing the heat & causing it to " kick back into nutral if over 15 knots" . Normally this is connected to the thermostat. Geoff Could be a temp sensor in the power head that does that Theres definitely no thermostat in it Link to comment Share on other sites More sharing options...
Guest Aussie007 Posted February 13, 2013 Share Posted February 13, 2013 Could be a temp sensor in the power head that does that Theres definitely no thermostat in it whats your model number? Link to comment Share on other sites More sharing options...
mark10187 Posted February 13, 2013 Author Share Posted February 13, 2013 93 Mariner Magnum 40hp I believe there a detuned 50hp Link to comment Share on other sites More sharing options...
Guest Aussie007 Posted February 13, 2013 Share Posted February 13, 2013 i just posted a microfiche of your engine but i noticed its got the USA shops name stamped on the picture so deleted my post your engine will have a thermostat maybe someone has removed it look on the cylinder head at the top there will be 2-3 bolts bolting a small plate onto the cylinder head Link to comment Share on other sites More sharing options...
Guest Aussie007 Posted February 13, 2013 Share Posted February 13, 2013 dam hopefully this works unbolt the cover ive circled if u still cant find the problem take it to huey Link to comment Share on other sites More sharing options...
dunc333 Posted February 13, 2013 Share Posted February 13, 2013 on very rare ocassions i have only seen on a tohatsu where the water pump tube connects to the power head sometimes the pipe gets to hot and closes in on its self thus restricting the flow to the powerhead and when under load she will over heat and the only fix is to pull powerhead and replace waterpump tube,and if not your thermo or salt buildup in your head or waterpump my money is on the tube ,let us know what you find.cheers dunc333. Link to comment Share on other sites More sharing options...
a boat Posted February 13, 2013 Share Posted February 13, 2013 Hi Guys, alot of good advise as usual but the picture is not a picture of a 40HP Mariner like the OP has. This engines and its cooling system is pretty straight forward and best thing to do is make sure someone that knows what they are doing and from the sounds on it the person who has worked on it does not, then get them to fit a genuine complete water pump kit and make sure the water passages are clean-which again is very easy , if you know what you are doing. Your engine has a temp sender that sets off a horn but will not restrict RPM and no it does not have a thermo and as I said is a very simple cooling system and knowing how there are many useless tech in this indusrty it does not surpise me you had to spedn over $1K and stll not fixed-it is a shame to say that but it is facts in this industry. If you want bring it in and I will get to the bottom of it. To unbolt the engine and let it drop to the oceanfloor is pretty extreme and for its age and techniology that old girl are a pretty nice 40HP carby engine. Cheers, Huey. Link to comment Share on other sites More sharing options...
mark10187 Posted February 13, 2013 Author Share Posted February 13, 2013 Found the problem!!!!! Stripped the top cover off cleaned the gasket off found sand and pieces off and old water pump took the leg off and attached the hose and flushed it with the hose on the water pipe and rubber pieces and sand came out hopefully that's problem solved time will tell I guess from now on I'm only going to take it to reputable marine mechanics what a waste of money....... Link to comment Share on other sites More sharing options...
mark10187 Posted February 13, 2013 Author Share Posted February 13, 2013 Only problem now some of the bolts were coroded and snapped off so drown them in inox and try to get the off with visegrips or easy outs Link to comment Share on other sites More sharing options...
Guest Aussie007 Posted February 13, 2013 Share Posted February 13, 2013 Only problem now some of the bolts were coroded and snapped off so drown them in inox and try to get the off with visegrips or easy outs snapped bolts are a massive pain in the ass best not to touch them your self leave whats there and drop it into huey i once bought a engine to rebuild and like over 10 exhaust bolts snapped so ive been down that track Link to comment Share on other sites More sharing options...
Day's Fishin Posted February 14, 2013 Share Posted February 14, 2013 Good to hear you may have found the problem. You can't beat Huey for advice. One of my sons mates took an old merc to him after the local merc dealer told him it was too old and wouldn't touch it, ( just wanted to sell him another one,) and Huey fixed it. That was 3years ago and it's still running. AAA for Huett Marine from me. Regards Jeff Link to comment Share on other sites More sharing options...
mrsswordfisherman Posted February 14, 2013 Share Posted February 14, 2013 Good to hear you may have found the problem. You can't beat Huey for advice. One of my sons mates took an old merc to him after the local merc dealer told him it was too old and wouldn't touch it, ( just wanted to sell him another one,) and Huey fixed it. That was 3years ago and it's still running. AAA for Huett Marine from me. Regards Jeff Great stuff and Huey is held in high esteem by most raiders. We only have the best sponsors here at fr:) Mrsswordie Link to comment Share on other sites More sharing options...
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