2001 135 Optimax temp. alarm @ low speed

[jeh2337]

I've got a low-hour (approx. 30) 2001 135 Mercury Saltwater Optimax. If I run the engine at about 1500 rpm, approx. 5 knots, for 10 minutes or so I get a constant alarm (which I understand is a temperature warning) and my power drops off. I have to turn the engine off to clear the problem. If I then restart the engine and accelerate up past about 10 knots life is nice. The engine has only been run in fresh water. Any idea why I'm getting temperature problems only at these low speeds?

 

[The Marine Doctor]

Re: 2001 135 Optimax temp. alarm @ low speed

Restriction in the water passages. Possibly sand.<br /><br />Worn Impeller.<br /><br />Sticking poppet valve.<br /><br />TMD

 

[greasemonkeyozi]

Re: 2001 135 Optimax temp. alarm @ low speed

Riding in the ocean is alot more strenious on your cooling system than riding on smooth fresh water. Always keep a closer eye on it whenever in saltwater. Is your motor pissing out a good stream of water from your tail tell?

 

[obxtuna]

Re: 2001 135 Optimax temp. alarm @ low speed

I, too , have this exact same problem. My 2001 135 Opti overheats at low idle speeds. At first, it only happened at idle but it has since started to overheat at 15-1800 RPM while offshore trolling. I have not taken out in a week or so. Looking for a fix without having to tow to the dealer.<br />I am familiar with the impeller and it's location and replacement. Can you enlighten me on the poppet valve?<br /><br />I have a good tell-tale stream all the time. I would also like to check the thermostat. Can anyone give me the "quick and easy" location and procedure for the thremostat and poppet valve?<br /><br />Thank you in advance.<br />Craig Williamson

 

[CU2NITE]

Re: 2001 135 Optimax temp. alarm @ low speed

You really need a manual! You can order one at the top of the page! This site will show you a schematic of your engine www.dougrussell.com. Good luck.<br />CU<br /><br />-------------------<br />RUNNING THE MOTOR WHILE LISTENING TO THE HORN WILL MAKE YOU MORN!!

 

[BRIAN03]

Re: 2001 135 Optimax temp. alarm @ low speed

The alarm you are getting is not tempure but pressure. You are getting a low pressure alarm. If the poppet valve is ok the only way to make it go away is a new water pump. The alarm will go away for about fifty hours. If you kick up the idle with the control it will usally go away. Its a common complant with this engine.

 

[obxtuna]

Re: 2001 135 Optimax temp. alarm @ low speed

Thanks for the input.<br /><br />The alarm that the SmartCraft gauge is giving me is definitely a "high temperature" alarm. The engine temp will steadily rise to about 180-185 before the alarm goes off. The block PSI on the engine that is over heating is just slightly less than the one that does not overheat (about 3.2 as opposed to 3.5 on the 'good' engine at idle). The tell-tale on the overheating engine is not noticeably different than the one on the good engine. They both have excellent flow. It seems that something is not allowing the water flow into the cooling passages within the engine. It seems the water is there, just not properly circulating. The Marine Doc on this site has suggested looking at the water pump (impeller) first. <br /><br />Anyone with a different thought?<br /><br />Thanks for the help. I really appreciate your time...<br /><br />Craig

 

[BRIAN03]

Re: 2001 135 Optimax temp. alarm @ low speed

Its not a flow problem or mechanical issue. Its a sensor issue. Does the alarm go out with rpm increased? A new Impeller will make it go away for awhile. On that engine Mercury Increased the water tube size from the water pump to the block by 50% without increasing the volume of the water pump so there are low water pressure issue at idle once the impeller gets some wear on it. If it bothers you change your impeller every year and only use the factory impeller. If someone put an aftermaket impeller that will cause this problem too. The problem goes a way off idle.

 

[180combo]

Re: 2001 135 Optimax temp. alarm @ low speed

I have another thread on this Forum related to a 2001 Optimax 135 that is overheating at idle only. Increased RPM's cools the engine back down quickly. I have replaced the t'stats, water pump(everything except the bottom section), and poppet valve and spring. Everything that has been suggested so far. While the poppet assy was removed I verified I had water coming from the top of the block that dumps into the poppet assy so it appears the motor is filling with water. I am only able to develope about 1 PSI of water pressure at idle until the t-stats open and then only about .5 PSI. This engine will not overheat while running on a garden hose- possibly due to the lack of any engine exhaust back pressure out of the water.

 

[180combo]

Re: 2001 135 Optimax temp. alarm @ low speed

Anyone have a plumbing diagram for this engine? I would like to see if I can pin down some sort of blockage somewhere.