Yamaha 200 overheating

[gr8rg8r]

Hi,<br /><br />One of the two 1997 Yamaha 2-stroke 200 HP Saltwater Series engines on my 25' Grady White Sailfish overheats and powers down. My marine mechanic has replaced the water pumps, removed the thermostats, and removed the heads and check for water passage restriction (there was none).<br /><br />He said he put a laser on the engine and knew that it was hot, and therefore not a sensor.<br /><br />He seems lost for an answer and I am getting concerned. He suggested taking off the powerhead and inspecting it for a leak in the water tube(?). Is this the direction to go?<br /><br />By the way, Rodbolt - you are a legend on the Continuouswave.com (for Whaler enthusiasts) forum.<br /><br />Thanks

 

[rodbolt]

Re: Yamaha 200 overheating

hello<br /> there are many reasons for overheat. the discharge side of the block can be clogged. its rare to have a pressure valve problem at high speeds but the grommet pocket and grommet need to be cleaned and replaced at least every other year. the t-stats are part of the water pressure controls and must be in place. the relief valve and grommet must be there and the correct pump and assy procedures must be used. nwhat RPM does this occur and can you make it repeat?<br /> good luck and keep posting<br /> PS lots of things I have never seen but I have never seen the water tube corrode away on one of these engines. if it has a simple test run with a water pressure gauge will tell.

 

[gr8rg8r]

Re: Yamaha 200 overheating

Rod,<br /><br />It overheats at 3000 rpm within 10 minutes - with or without t'stats. It overheats every time.<br /><br />I assume the marine mech. installed the water pump correctly.<br /><br />Would it be likely that the discharge side of the block was clogged if the water passages visible under the heads looked clean?<br /><br />Would a marine mech replace the grommets when he replaced the thermostats?<br /><br />Thanks, Rod

 

[rodbolt]

Re: Yamaha 200 overheating

hello<br /> mmm will the marine tech replace anything? would depend on the techs level of expertise and reliability. some cant trouble shoot a splinter if it were in their butts.<br />it sounds like a cses of exhaust gas intrusion in the cooling system or the pump is not sealed. sometimes the small rubber dam at the rear of the pump can get pushed up with corrosion and cause the pump to suck air. normally this will show up as low water pressure on the flusher. in the water it may not suck air until the exhaust gas pressure and hull speed uncover the dam area.<br /> its a tough call but if the water covers and heads have been apart and your sure the pump is installed correctly and the water pressure is good and both heads are overheating about equal I would suspect the discharge area is restricted. I dont think you can see the water tube just by removing the power head. the exhaust housing must be disssasembled for that. are you positive its an overheat and not a low oil alarm? does the temp indicator blink or do the oil bars blink? a restricted oil filter in the remote tank will give the same symtoms but a different visual indicate.its odd that both heads are getting hot the same at the same time. before I pulled the power head I would remove the head covers and exhasut covers and have a look. did this problem start after any maint. what temp did his laser show ? I would do more trouble shooting before I removed a power head. was anything added to the hull that would alter waterflow to the gearcase? post back with any more info but especially with the visual indicators and the head temps

 

[gr8rg8r]

Re: Yamaha 200 overheating

Rod,<br /><br />Update on the overheat problem:<br /><br />Yes, the first time the marine mech took out the boat, he measured the temperature with a laser and it was overheating. After replacing the water pump and thermostats and inspecting the block for constriction (there was none), the mech took the boat out again and it idled down again. Then, he tested temp again and it was not overheating. He took the boat out a third time with a fuel tank with premixed gas and it ran fine for over an hour.<br /><br />Soooo, it seems that there were two problems: an initial overheat with a problem with an oil delivery problem. He thinks the problem is with the oil pump.<br /><br />I have several questions:<br /><br />1. How does the engine know that there is an oil delivery problem? I imagine there is a sensor for this?<br /><br />2. If oil is pre-mixed, why does the computer allow the engine to run? In other words, how would it know that there was oil in the fuel?<br /><br />3. Have I done damage to this engine, even though it has idled down?<br /><br />Thanks for any input.<br /><br />Richard

 

[vinney]

Re: Yamaha 200 overheating

There is no way the ECM knows about oil delivery after the oil tank on the engine. Here is the REAL deal Your guy doesnt know what he is doing. Yamaha's dont have over-heating problems. Here is what you need to have done by someone who knowns this engine. You NEED to use Yamaha factory parts only. No sierra or any other so call oem parts. Put a complete Yamaha Water pump kit in the lower unit, Change the thermo's and clean the bypass valve. You have a texted book problem that your guy has made into a cluster. I hope your not paying for his lack of knowledge. Flat rate on the water pump 2 hours .5 on the thermo's and .5 on the bypass valve. 3.0 hours total with a wash.

 

[rodbolt]

Re: Yamaha 200 overheating

hello<br /> if the bolts come loose, the water pump on your v6 yammi is a 45 min operation. unless I am in a hurry.<br /> the tstats are a 10 min ordeal. some relief grommets take 20 min or so. the HPDI takes me about 3 hours.<br /> like vinney says the yammi does not monitor oil flow. it monitors oil level in the remote tank and the engine tank. its a very common problem to have a clogged filter in the remote tank and the engine at higher speeds can use oil faster than the transfer pump transfers it.<br /> as for damage, I hope not. those are good engines. if they idle fine now and power up ok I would imagine they are fine.<br /> post us back if you find a problem <br /> good luck and keep posting

 

[gr8rg8r]

Re: Yamaha 200 overheating

Vinnie, Rod,<br /><br />I had lengthy discussion with the mechanic today and here is what happened: Two of the tubes from the oil pump to the cylinders were clogged (one completely, the other partially). Because these cylinders were getting little or no oil, friction was building up and that caused the engine to idle down and eventually stop. The mechanic had thought the problem was with the water pump, which had never been replaced on a 1997 engine (with only 100+ hours), but after replacing the water pump, the engine still would idle down and eventually stop. However, after adding oil to the gas, the engine ran fine because it was getting oil and was not overheating!<br /><br />The mechanic checked the compression and it was high and consistent among the cylinders so I think the problem is solved with no permanent damage. As a precaution, he is going to check the other engine.<br /><br />I am going to replace the oil and clean and check the tanks and hoses and run 60:1 in the tank to be on the safe side.<br /><br />Thanks for your input.<br /><br />Richard<br /><br />I am excited to take this boat out this weekend.

 

[vinney]

Re: Yamaha 200 overheating

If this STORY is true. Your engine will not live without oil. Its going to blow up. You can take it down now and save it or wait till it takes the crank and a rod or rods out and if your real lucky it will take the block with it. If that engine slowed down from the pistons grabbing the cylinders the damage is done. Its a matter of time. I Can't say I've seen oil line clogged befor on a yamaha. There is a filter on the oil tank in the boat. I would find someone else Who known this product. A compression test will not show skuffed pistons.

 

[rodbolt]

Re: Yamaha 200 overheating

hello<br /> I tend to agree with vinney. I have never seen a clog in the late style. if its carbed each cyl has a check valve in the line. if its EFI ox66 it has a manifold that feeds all six lines to the VST. if it had no oil it will destroy a rod beaing rapidly. it will also destroy a piston skirt. the slow down was the physical mechanical interference of the piston growing to large for the bore.<br /> if the story is true. take it apart now or it will take itself apart.<br /> your choice.<br /> good luck and keep posting.<br /> PS how and what kind of test was used to check for clogs? there is a specific test to use. what method was used here?

 

[gr8rg8r]

Re: Yamaha 200 overheating

Vinney, Rodbolt:<br /><br />An update: The engines weren't overheating, the first mechanic was incompetent.<br /><br />The second mechanic quickly found the problem to be fuel problems; bad gas and dirty carbs.<br /><br />All is fine now.<br /><br />BTW: Rodbolt, would you happen to know the parts needed to convert a 1996 Yamaha 40 tiller to remote steering (other than the control itself). I specifically need the parts to connect the steering , throttle, and shift cables to the engine.<br /><br />Thanks

 

[Ray Neudecker]

Re: Yamaha 200 overheating

I have seen cases where the oil valves in the lines have been clogged due to poor quality oil and long periods of non use. There will usually also be a gallon of Wally World labeled oil in the boat when this happens. People can find a way to screw up the best engineered products. Yamaha did offer a kit to convert the 40 from tiller to remote operation. The kit and labor to install are quite expensive. (To my limited pocket book anyway) It will require an experienced tech to install and adjust correctly. Don't hang around while it is happening unless you need to learn some new curses.

 

[rodbolt]

Re: Yamaha 200 overheating

hahahaah yep<br /> I agree with ray.<br /> the only thing worse than converting to remote is converting to tiller <br /> agggggggg at the words we learn <br />glad to see you found someone to assist with your problem. this motor gig is not voodoo. they suck squeeze bang and blow. all the other doodads just help make it happen faster.<br /> good luck and keep posting

 

[gr8rg8r]

Re: Yamaha 200 overheating

Thanks Rod,<br /><br />Thanks Ray,<br /><br />Richard