Alarm on 130

[Ken]

This post is in response to "Pablo" in San Antonio - he has a Yamaha 130 (V-4 block) that is sounding the alarm when rpm gets over 4000:

The cooling system has basically four parts to it:
1 - the water pump
2 - the water jackets
3 - the thermostats
4 - the pressure control valve (aka pcv, pressure relief valve (prv), poppit valve)

Pablo's motor is sounding the alarm anytime he runs over 4000 rpm - so it sounds to me that the motor is overheating, i.e, one of the thermoswitches is closing.
1 - the water pump could be weak and not providing enough water pressure to cool motor properly - if no pressure gauge and it has been at least three years since last wp repair, then needs to be done.
2 - water jackets could be clogged with mineral deposits/debris. Flush with Salt Away or Salt Terminator. Or may have to remove heads and clean out.
3 - the thermostats could be clogged and not opening properly. Remove and inspect/clean/test per the manual to verify opening to 0.120 inch at approx 135 degrees f.
4 - the pressure control valve could be stuck open and allowing cooling water to pre-maturely dump out the relief holes. Remove and inspect/clean. There should not be but a trickle of water coming out the relief holes under normal operation. The pcv is designed to open at around 20 psi to relieve over-pressure in the water jacket.

If all of the above is working properly and still getting overheat alarm, then pull the thermoswitches and test them per the manual. They should close at around 180 degrees f. and reopen at approx 160 f.
Also, a blown head gasket could cause overheating - check compression on all cylinders.
They should be within 5% of each other.

Pablo, I think I have covered everything here that could lead to your overheat problem - let us know how you come out.
Good luck [img]smile.gif[/img] ,
Ken K

[Pablo]

Thanks Ken, but I have done all that as instructed by you last year, except the head gasket test although I had the engine tuned up 100% last summer and the dealer did not indicate he found a discrepancy with the compression , but I will call him and ask him if he ran a compression test.
thanks again

Pablo

PS: you are very helpful and quick on your responses

[Mike E]

Had problems with my 115 Yamaha (1994) with overheat alarm at RPM's over 5,000. Pulled the heads and found the head gasket's had holes 2" long in them. The compression was still good. **** the heads and check for deposits in the water jackets and replace the head gaskets. Be sure to check the heads for warpege also.

Hope this helps.

[Ken]

Mike,
Thanks for the report - very interesting.
2" long holes in the head gaskets, and no effect on compression ?
How badly clogged up were the head water jackets? How did you remove the deposits from the water jackets?
Also, my shop manual shows sacrificial anodes in each head assy - did you get a chance to look at them? Just curious.
Thanks [img]smile.gif[/img] ,
Ken K

[Dennisg]

Ken
I have twin 2004 F 225s . Do you know if they have sacrificial Zinks "under the hood" ? I know about the rest of them.
Thanks, Dennis

[Ken]

Dennis,
Yes - there are four anodes in the head assy of your motor. Take a look at your motor diagram
in the online catalog above. You can find an exploded view of the head assy under "Cylinder Crankcase 2" - item #15.
It looks like you can replace the head anodes w/o removing the head, as I have to do on my 2-stroke 115.
Look in your owner's manual - there should be some reference in there about the head anodes.
My owner's manual does not say anything about when to replace them, nor does my Yamaha shop manual, but I'm gonna guess they should be replaced about every 600 hours. If I could easily get to mine, I would check them every year - but I'm not gonna pull the heads just as a routine maintenance.
Good luck [img]smile.gif[/img] ,
Ken K

[Mike E]

Ken
The gaskets were sealed around the cylinder's but in the area where water jackets are they were ate through. The worst one had a Swiss Cheese area about 3/8 wide and 2 in. long. I had found trash in the thermostate's a couple of times, pieces of the gasket. The water jackets were clean and the sacrificial anodes looked good. I had 25 lbs. of water pressure at WOT when the horn would go off.
This moter had saw some brackist water before I bought it. I replaced the gaskets, and a few of the head bolts that had some corrosion on them. The last thing I need is a twisted off head bolt. I replaced the gaskets last summer and have had no problems since. Remember to check the head for warpage. If it has gotten hot they might need to shaved.
I had 25 lbs. of water pressure at WOT when the horn would go off.
Mike....

[Ken]

Mike,
Thanks, again.
Sounds like there were hot spots in the head(s) due to uneven cooling caused by those holes in the head gaskets. And I'm just guessing here, because I have not experienced this myself.
I do know that the themo switches (one in each head assy) will close at around 180 degrees f.
and if you get a hot spot in the area where the thermo switch is located, then you are going to get an overheat alarm.
With 25 pounds of water pressure, there is certainly nothing wrong with your water pump.
But you might want to pull the pressure control valve (aka, pressure relief valve, poppit valve), and clean it out, if you haven't already done it.
The PCV is designed to open at around 20 psi, I believe, to relieve over-pressure in the cooling system. It can get clogged with debris and get stuck open or closed. You want the PCV to do it's job when needed - sounds like yours may be stuck closed.
By the way - were your heads warped at all?
Good luck [img]smile.gif[/img] ,
Ken K

[Mike E]

Ken
The heads were warped some, about .008 to .012 I think. I used a file,(draw filed), with a straight edge and feeler gauge to get them back into spec. I work in a machine shop but didn't want to take the chance of milling them on the bridgeport. I put one of them on a milling machine table and was able to bend it back some, before I started working it down by hand. They were bent in a C shape, with the low spot in the middle of the head. I have had the poppit valve out a couple of times along with the thermostat's when I was trying to find the problem. I would say you are correct (Sounds like there were hot spots in the head(s) due to uneven cooling caused by those holes in the head). The alarm never went off if I ran the boat with the right thermostat removed, but the water pressure went to 5psi or less. The thermostat's are needed for some backpressure on the cooling system.

Later Mike..