AR190 with overheat issues.

[redthumper9]

So a friend of mine bought a used AR190 at the end of last season. We were only able to take it out once before he deployed. It ran fine for about 10-15 mins and then threw the overheat warning. It had a good stream from the pee hole, but the water was hot coming out. I didn't notice any cavitaton and the impeller seemed clear of any foreign objects. We let it cool about 30 mins, then returned to the dock. He comes home in a couple of months and I know is looking forward to using the boat this summer so I want to have some ideas to help him out when he get back. I had some really nasty thermostats on my old SX210 that ended up being the root of a cooling issue, but I've had no issues with my 1.8's in my AR240. Any cooling guru's want to chime in?

 

[CrankyGypsy]

thermosensor: i used the YDS to watch the sensor reading. it was rusted and would suddenly jump to 266*+ (tripping the dash light) once it got around 230-240*. i also used a non-contact thermometer to compare both engines.

my engines also seem to have quite a bit of insulating scale. i've done some acidic flushes - not 100% cured, but it's an improvement.

 

[Matt Phillips]

How's the intake screen look?

 

[Higgy]

Well I hope you figure it out. I had the same issue last time I had my SX192 on the water. It would throw the overheat alarm after about 15-20mins of WOT. So far all I've done is pull the intake screen and check out the impellor. Then ran it on the hose for an extended flush... I'm hoping some fresh gas might cure my issue but I realize that may be a long shot. Keep us posted! Pullin for ya!

 

[Higgy]

I found something interesting on the other site and I am wondering if some of our newer boats might be suffering from a similar issue with the plastic fittings in the cooling system. This is something I've been meaning to check out on my boat but haven't found much time to tinker with it lately. Go to the site which shall not be named and do a search for "Overheat" here is a couple screenshots so you know what I'm referring to.



You see the plastic in those fittings was not molded correctly or was not properly finished before the factory installed it. He knocked those thin pieces out to remove the obstruction and it cured his overheat. I know he's workin on an MR1 but it's possible we have a similar issue.

 

[ruztew]

I had a thermostat freeze shut, pee stream was fine but water was not hot (because it wasn't cycling through engine to cool it). Threw overheat alarm after running a bit... Replaced the termostat and ran fine again.....that was on the mr1 engine

 

[Cobra Jet Steering LLC]

I had a thermo sensor issue engine was NOT hot but alarm kept triggering, Yamaha fixed it under warranty

 

[OperationROL]

I found something interesting on the other site and I am wondering if some of our newer boats might be suffering from a similar issue with the plastic fittings in the cooling system. This is something I've been meaning to check out on my boat but haven't found much time to tinker with it lately. Go to the site which shall not be named and do a search for "Overheat" here is a couple screenshots so you know what I'm referring to.
View attachment 35290
View attachment 35291

You see the plastic in those fittings was not molded correctly or was not properly finished before the factory installed it. He knocked those thin pieces out to remove the obstruction and it cured his overheat. I know he's workin on an MR1 but it's possible we have a similar issue.

That's from @buckbuck . He ended up pulling the engine and going through the entire cooling system to find that the "y" was obstructed by those knockouts that were not removed. I mentioned him so he can chime in. He is the master of the cooling system.

 

[redthumper9]

Thanks for the replies. The first thing I was going to check was the intake screen, then the thermostat and then the y-fitting (I think I glanced over someone who had an issue with it a while back). I've also heard of a few thermo sensor issues and that would be next on the list after the others are checked.

 

[Higgy]

Thanks @OperationROL for tagging @buckbuck on this thread. The man deserves proper credit for his work, and I failed to give credit accordingly. I apologize for that.

 

[Scottintexas]

You can find Buckbuck's video of the how the cooling systems works in our FAQ under "general maintenance", how the cooling system works

 

[redthumper9]

So finally an update. My friend returned from deployment and promptly put the boat back in the water. Once again, overheat after some hard running. I told him to bring it over and I'd check what I could. Removed and cleaned thermostat, but it really wasn't very dirty, cleaned intake screen.....once again, no blockages there either. Removed the y fitting and checked for blockages......nothing. So I told him to order some plugs and an oil change kit. I read on here that new plugs corrected some temp issues, but that was older engines but I figured it couldn't hurt. He came back over last week and we changed the plugs. Then as I was removing the oil, it just kept flowing and flowing and flowing. Took a total of about 5.5 quarts out. Strange since typically you only get 3/3.5 out of the 1.8's. I put about 3.5 back into the engine and it read full. Could the over filling of oil have caused an overheat? He ran the boat over an hour yesterday with no issues. Fingers crossed.......we think we've got it. BTW......checked the air filter and there was no visible oil.

 

[tdonoughue]

Is it still running ok?

Can't for the life of me figure out why too much oil would cause overheating, but I guess that anything is possible.

 

[redthumper9]

@tdonoughue ......Im not sure of he has taken it back out since then. You get some interesting info if you google overheating due to to much oil. Not saying that is what it was......that's still to be determined.

 

[blacksapphirez]

mine did that on the first day i bought it. same symptoms....thermostat and temp sensor replaced under warranty and all is good