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1999 J50PLEEA Johnson is the engine at question.

I put it in the water for an outing today, the motor started on the first crank as it has always done for me. I am not the original owner.

The motor was pissing water perfect, almost like a hose stream.

I left the doc, and was about to go up on a plane and I get the alarm sound.

It is originally a VRO model which was disconnected before it became my motor.

So I know its not the oil alarm, because that would be sounding continuously.

I pre mix 50:1.

I removed the thermostat housing and the thermostat physcially moved and wiggled, no issues on a tug test, I removed it anyway. Put the cover back on, and ran it, got it up on plane and then the alarm came in, went immediately to idle, and shut the motor off.

Waited a few minutes, and started back up idled over to the dock, shutdown, pulled the thermostat cover, ran the motor without the thermostat cover on.

I got some steam or maybe exhaust fumes coming out from thermostat housing. I don't know if that is normal. Sort of smelled like gas.

I started the motor up, and it shot water right out of thermostat housing. So its getting water up to the thermostat housing.

So that means, the block is getting water up to that point, I don't know the rest of the cooling path, I do believe the upper cylinder, I didn't feel the lower, was warm to the touch, maybe even hot. I didn't let it run for more then 30 seconds while the alarm was on, probably not more then 10 seconds.

So I get water up to the thermostat housing, and still an alarm. Does that mean that there is a block somewhere in the cooling jacket after the thermostat housing?

I will order a head gasket and remove that head cover, because its all i one system, unlike my 1986 Johnson v4 90hp, there was a separate cooling jacket cover I could remove and not access the power head, this seems to be an all in one on the 50hp.

Any other ideas?

Thanks

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Was the engine previously used in salt water? Have you inspected the water pump impeller? I would also recommend descaling the engine.

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Yes , previously salt water, fresh as well.

Water pump housing replaced last minth with new seals, impeller changed, and lower unit oil, an seals.

I get water out the tell tale as well as tstat housing, (i ran motor with it tstat cover an t stat removed, an water blows out) its not the lower unit section. I ruled that out.

Thank you for.respinding and giving.inaigiht. i typed this on cellphone sorry

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Check your wiring to the sending unit, and the temp sending unit itself.

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I am by no means an outboard mechanic, but are you sure it is temp. Adding a temp gauge would help, or at least give you a better idea if the motor was overheating.

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Silentpardner, I will check the wiring, I didn't do that at first because it takes a while for it to alarm, roughly 3 minutes, then I shut it down, and it cools down for 5 minutes or so, then I run it again, and alarm comes in in slightly less time, which I believe to be because it was run and still has residual heat.

To me that's signalling that the temp sensor and wiring is satisfactory.

When it reaches temp, it grounds itself and that actuate a path for current to the buzzer. Then it sounds.

So I can ground the wire, see if it comes in instantly, and do a physical integrity check of the wires.

I also touched the upper cylinder, it was warm/hot to the touch.

jfortson, I do not have a temp guage, however that is a good idea. And the above comment, I touched the upper cylinder, there were as I said, warm/hot to the touch.

I may get an IR gun, borrowed that is, to check for overheating that method, which is better then just touching by hand. Not accurate, sure but all I can do for now.

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Wlagarde, I looked up descaling, never heard of it, till you mentioned it.

I have never done that to previous outboards I have owned.
1996 Mercury 150 offshore V6 2 stroke carbed,
2001 Mercury 40 HP 2 stroke single carb 2 cylinder
And a fail of a motor 1986 90hp v4 johnson, low compression after a month of owning it.

The 2 merc I run on muffs all the time, and I guess that did the part for them, only salt water run since new.

I will check into the descaling, I seen some product from star bright.

Thanks.

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If you flush the outboard with freshwater using rabbit ears after each salt water use it helps with corrosion and calcium deposits build up but it will still happen with time which could possibly be your problem as you don't know what the prior owner did. I used the Bright Bay product (http://www.brightbayproducts.com/prod...marine/hmd) when I descaled mine. Jfortson has a good point to check the exiting water temp as a bad temp sensor (thermal switch) could exhibit the same behavior.

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JW, the IR should give you a good direction. I added a temp gauge to my 2000 70 HP Johnson, and the sending unit is simply bolted to the head using one of the head bolts. Bottom line is that it is measuring the surface temp of the head which is what the IR will do. I have not run the boat is a while, but I believe it runs around 140 (maybe some of you others can on the temp).

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Jfortson that a nice striper you have there.

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What is the temperature of the tell tale stream (test with your hand) when the alarm is sounding.

If it is only warm, it is probably electrical. If wicked hot, it's a cooling issue.

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Hello jw0287, I recently concluded (with final success) a similar situation to yours. Short of pulling the cylinder head off for a thorough de-scaling I cleaned and rebuilt the cooling circuit with a complete water pump assy., thermostat assy., and new temp. sensor.

If possible bench test the temp sensor to see if it is going into close loop and open loop at the appropriate temperatures. I have also added a water temp gauge to my outboard for extra measure of precaution. My original issue was the water impeller beginning to fail but slowly, with less water flow the the block would warm up and trip the sensor but not consistantly. The issue after much testing and inspection by boat shop (and no failure discovered by them) finally revealed itself when only a trickle from the tale-tale was observed by me.

This only happened after a couple of weeks of diagnostics by marine mechanics but solved by me at home one afternoon. Has the motor gone into a "safe mode" operation at any point? The temp sensor may control this operation to protect the outboard.

Best,
Angel M.

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i will check the temp sending unit, just by the name, that sounds to be an expensive part.

and yes it has a tan wire coming out of it, i should be able to test that.

Phil, the temp is cool, and it pumps a lot of water, the stream is wide, and has very nice pressure to it. it flowed better then my previous motors, however when i put a new water pump in and housing, it got even stronger, almost too strong, like when u place your thumb on the end of a hose while its running, to me, there may be a block because of that.

the water like electricity will take the path of least resistance. and if the block is strong big enough or flat out 100% block after the thermostat part of the cooling loop, it would explain why my stream got even better after a new impeller/water pump kit was installed, and it now over heats.

it didn't over heat prior to installing this, as a matter of fact, it pumped good solid stream out the tell tale.

maybe when the new impeller went in, mechanical agitation along with a better stream from a fresh impeller install caused some of the corrosion to break free.

i will be updating you. i am currently busy with my son 30 months (severly autistic), work (US Navy) and other son 14 months, to really tackle this thing, maybe I will have some free time, or drop it off at a mechanic to have them pull the head or diagnose it themselves.

Ill keep you posted.

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dauntless,

i assume new water pump ass., thermo ass., and temp sensor fixed your issues.

did ou run the motor with the termo ass. removed? to see if water got up to that part of your cooling loop?

mine does, but maybe it goes no further, or the temp sensor/switch is bad.

thanks for the reply.

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Hello again jw0287 and you definitly have alot on your plate, the motor can wait a bit.

Regarding checking flow through my thermostat, yes I did but in a bit different manner than how you did it. Late model Yamaha's (2003-present) have a block flush port connection for a garden hose. When I had my thermostat out I checked water flow up to this point and from the therm. cavity I reverse flushed the power head for corrosion and the presence of salt crystals build-up.

My lowerunit was also removed from the motor which allowed me to thoroughly back-flush and to check flow up through the brass water feed tube located within the mid section. Jw my Yamaha is a 2006 2 stroke an I discovered a world of corrosion in the thermostat block cavity since a member described "descaling" early in the thread. I can only imagine what the water passages may look like even after back washing with diluted white vinegar and Simple Green degreaser. I flushed out a significant amount of what I would describe as salt mineral and corrosion flakes which washed out as very small pastey lumps at times.

I don't think the temp. therm switch will be to costly (hopefully less than $40) and thats only if it does not test well. Mine too uses a Tan signal wire. I'm not certain on how early in the water circuit the tale-tale receives it's supply but, I thought if a blockage was present the tale-tale may display a flow drop? If there is loose foreign matter moving around in the block it may be practical to drop the lower unit once again and back-flush the power head thoroughly with a solution be it Salt-Away, White vinegar, and/or a mild degreaser with hopes of dispersing, dissolving, and cleaning the water passages as best as possible.

Best,
Angel M.

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jw: Sounds like you have it covered with all the advice received so far. Based upon your description of taking off the thermostat housing: "I got some steam or maybe exhaust fumes coming out from thermostat housing. I don't know if that is normal. Sort of smelled like gas." This sounds like a compromised head gasket. Since combustion pressure is greater than water pressure, when the engine runs, the water passages can fill with combustion gasses. Not only do these gasses prevent water cooling, but they are hot. You did mention that you have a head gasket on order.

However, this should be the last thing you do because it involves more invasive work. As mentioned, make sure the temp switch is telling the truth by testing it. It is simple to pull it out and put it in a cup of heated water with a thermometer and make sure its contacts close (completing the circuit to ground which sets off the overheat alarm). I trust the waterpump is doing its job based upon your description.

Good luck, let us know what happens.

Al

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JW - Thanks for your service to our country, especially on this 4th weekend.

You have a lot of advice and I am sure somewhere in there, there is a solution. I go back to my 2 cents worth - if you can get/borrow an IR thermometer, shoot the head when running (try several spots) or when the alarm goes off. I think it should be in the 140 to 160 range. Other's comments on the temp would be helpful. If it is in the "safe" range, then I would think the motor is not actually overheating and I would first look at things like the sending unit.

This is not an absolute answer, but just a point to start that may allow not taking things apart.

On second thought, my 2 cents worth is not really worth 2 cents.

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Ayour welcome for the service, its tough, sometimes it seems impossible, i am.stationed on a ssgn submarine and do real missions. You may understand what i mean by real missions if you have a secret clearance and did missions or patrols.

Alan and jfort

Thanks for responses. I will be back on the water with mykids in no time alarm free.

Alan, uhave the revenge i believe, an went around tye us an hawaii with it, awesome, cg took u there?

Mybrother is in the cg. Previously on the pea island now on the northland. Big drug busts in columbia. And a lot of.fishing.

He owns a 13 sport. Whalers run in the family.

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New findings.

Problem solved.

New head gasket installed.

Debris in the cooling jacket.

Removed and flushed.

No more alarm. No over heat.

Thanks for the responses.
Hope this may help someone else in the future.