2000 Yamaha 150 VMax Heating Alarm Problem...

[flawebmaster]

I am having a problem with my Skeeter bass boat that is driving me nuts. The boat is a 2000 Skeeter 185ZX with a 150 Yamaha VMax fuel injected engine. I have owned this boat since new and it has been great with no problems until recently. About a year ago, my overheating alarm started going off for no apparent reason. It only happens when you cruise at the same RPM (4,500-5,000) for an extended length of time (15 minutes or so). The motor starts, idles, runs great and does everything it should except for this annoying problem. I took the boat into my local Yamaha dealer and they changed the water pump impeller, water pump plate, pop off valve, intake screens and thermostat. The engine pumps at least 20 pounds on the water pressure gauge when running. When the alarm goes off, I can see that the P-hole is squirting water in a strong stream and water is coming out of the back of the lower unit vent. There is no steam or any obvious signs of overheating. When I stop the boat and let it idle, the alarm goes away in about 1-2 minutes. Any ideas? I would hate to buy a new engine just to fix this problem, but I'm thinking about it.

 

[yamamarinetech40]

Re: 2000 Yamaha 150 VMax Heating Alarm Problem...

The water stream out the back only tells you the pump is working...it doesn't tell you water is circulating well enough throughout the engine....run the engine until alarm sounds, stop boat and quickly(so stays hot), pull cowling and put two fingers on head near temp sensor....if you can leave your fingers on head for a few seconds, not hot...this is the method you can trust more than pee stream or gauge....did anyone check the thermosensor?

 

[flawebmaster]

Re: 2000 Yamaha 150 VMax Heating Alarm Problem...

Thanks for the reply. Can you please tell my where I can find the temp sensor on my engine? How about a manual temp gauge? I am going to take the engine back to the dealer next week to have it checked out. I don't recall them mentioning the thermosensor, but I will ask.

 

[yamamarinetech40]

Re: 2000 Yamaha 150 VMax Heating Alarm Problem...

I believe it's on port side and under(behind) the elect. stuff mounted in plastic there(relays, ect.) If they didn't check that the first time with above symptoms...I would balk at the bill, but find out first and play it cool.

 

[flawebmaster]

Re: 2000 Yamaha 150 VMax Heating Alarm Problem...

I spoke to my dealer and here is what I'm going to do. I purchased a laser thermometer that I can point at the power head. I'm going to run the boat and take a base reading from the power head with the engine up to operating temperature but without the alarm. I will then cruise around and see if I can duplicate the alarm problem. With the laser temp gauge I will check the power head and see if it's running hot or if something else is causing the problem. What do you think?

 

[solaman]

Re: 2000 Yamaha 150 VMax Heating Alarm Problem...

I have a 115HP Yamaha, I had a simular problem as you, I could run all day at 4000 - 4200rpm no problem, if I pushed it to pass 4300 rpm my high temp alarm would go off, idle it down and it the alarm would stop buzzing. I had about 10psi water pressure. I changed the water pump to no avail. brought it to a shop, they changed the thermostats, water pressure started staying around 15psi at 4200rpm but the alarm still would sound after a few min when running above 4300rpm, he then changed the popet valve, got the water psi up to 21psi at 4200rpm, the alarm then started going off once it got above 4600rpm. The Mech. checked it with a heat gun and the heads ran about 169deg. surface temp at 4600rpm. He changed the sensors thinking they were bad. Still the alarm would sound, next he pulled the cylinder head covers and found the water passages partially clogged with build-up, he pulled the heads to get to the rest of the passages in the head, I then bead blasted the passages in the heads and head covers, put it all back together, i ran it for 3 miles at 5300rpm and all is well.

Sorry for the long story

 

[flawebmaster]

Re: 2000 Yamaha 150 VMax Heating Alarm Problem...

I thought about that, but my boat has always been run in freshwater. Can't see how anything can build up in the block, but that's sure possible. Is your engine used in salt water? What was the build up? I lowered the engine a knotch on the jack plate and am going to give it a try with the laser temp gauge. Thanks for your help!

 

[flawebmaster]

Re: 2000 Yamaha 150 VMax Heating Alarm Problem...

Lowered the engine 1" and ran the lake this morning to test it out. After running 3-4 miles at 4,800 RPM the overheat alarm went off. Used the laser temp gauge to check the top of the block and got 155 degrees. Let the engine idle for a minute and the alarm went away. Took the boat up to 4,800 a second time and after another 3-4 miles the alarm went off again. Now we are getting somewhere! At least I can duplicate the problem. Ran around the rest of the morning at 3,500 RPM and the alarm never went off. I am thinking I must have a blockage in my water jacket. Called the dealer and they are going to pull it apart next week and see if I have any blockage. I'll keep you posted...

 

[solaman]

Re: 2000 Yamaha 150 VMax Heating Alarm Problem...

I run my engine in fresh, brackish, and saltwater. I will admit I never would flush it when I got home, but from now on I will everytime I get home. The way yours acts is exactly the way mine would. I could run all day at 4200rpm and below.
Good luck with yours.

 

[flawebmaster]

Re: 2000 Yamaha 150 VMax Heating Alarm Problem Fixed!

Re: 2000 Yamaha 150 VMax Heating Alarm Problem Fixed!

The mechanic took the heads off and sure enough there was a bunch of gunk blocking the water flow. Got the boat back and it runs great. Before it was fixed when I ran 4,500 hardly any water came out of the exhaust port. Now, tons of water is coming out. Flushing sounds like a good idea even for a freshwater motor. Thanks for all your help!!

 

[JUSTINTIME]

Re: 2000 Yamaha 150 VMax Heating Alarm Problem Fixed!

Re: 2000 Yamaha 150 VMax Heating Alarm Problem Fixed!

yes flush evry time of use
i use salt away with mine