Engine problem: over-heat alarm/engine won't start

Tim M · 08 August 2004, 19:49

I was having one of the worst outings ever this afternoon (after the car had got stuck in the mud, and one of my "crew" had slipped getting into the boat taking three others with them, and breaking my hand held VHF dropping it on the floor) when, things got much worse!

Having stopped for lunch, I was for a quick spin, before returning to the beech to collect my passengers. After about 10/15 minutes we were all back in the boat, with me pushing it out a bit to get some depth (it slops very gradually were I was). Eventually got in, trimmed the engine down so that the cavitation plate was just under the water to get it going (it was still quite shallow). Engine started, but so did an alarm. Now, my understanding of the Mariner 40hp 2stroke 2cliyder I have is that there are two alarms; one for the oil, and one for it over heating. Having topped the oil up the day before, I knew and it was fairly full, and double-checked - loads of oil.

So, I narrowed it to over heating. This seemed quite logical since it had hit a quite lumps of mud here are there getting off the beach. However, the telltale was squirting quite happily, and the water didn't feel hot - just warm.

Anyway, since I was stuck about 10 minutes from the slip I thought I would continue slowly. Did this, but after a few minutes the engine cut out. I assumed this was the over-heat cut out thing coming into play. But, the engine seemed cold!

Fortunately there was a boat nearby that gave us a tow back to the slipway.

Anyway, got home, stuck the flush-muffs on, and water was coming out of all the usual holes. But, when I turned the key, the alarm still came on, and I could not get it started. The power trim didn't seem to work either at this point - all I could here was the solenoid clicking. So, I undid the battery cables, cleaned them, and put them back on. The power trim worked, until I moved the boat. Now it doesn't...

So, can anyone give me any clues? I was thinking that perhaps there might be something wrong with the thermostat on the engine. Where do I find this?

TIM

Turbodiesel · 09 August 2004, 07:24

I would suggest you have a look at both the overheat switch and the oil level switch. The overheat switch is on the cylinder block on the left hand side of the spark plugs as you look at the back of the engine. Short it out and see if it beeps at you. Do the same for the oil level swich which is a small probe in the bottom of the oil tank. The thermostat should be ok if you getting a tell tale but if you want to have a look at it, it is on the port side of the engine at the top of the exhaust plate. Its got i think from memory four bolts that hold it in place. The thermostat should open at 130 Degress F.
Part number F970682. As to it not starting you need to check if it has a spark then start from there!. If the solenoid is just clicking it could be faulty or you could have a flat battery. You can check the solenoid by bridging the two terminals (slitghtly dodgy way to do it!) it will spark a bit but it will prove a point. If the engine turns over when you bridge the solenoid then then solenoid will need replacing. Hope this helps.

Tim M · 09 August 2004, 11:36

Tired to start it again this morning. I'm not getting an alarm any more. However, it still fails to start. In fact nothing works. All I get is clicking - from the powertrim, and the starter motor (one click) and the choke when I press the key in. I tested the battery, and it's fully charged. I checked the battery cables, and there is power getting to the engine. Re-checked the terminals but they're fine.
This must surly be an electrical problem somewhere.....

Tim M · 09 August 2004, 11:40

Just re-did the battery terminals (again). This time I got the powertrim working. However, when I tried to start the engine I got the usual click, then nothing. Now when I try the powertrim, all I get is clicking again!!!

PS. The alarm is back....

Andy Cox · 09 August 2004, 12:34

It sounds as though you have 2 seperate problems.
1. Some where in the battery cabling I think you have a poor connection. Do you have a battery isolator switch, if so eliminate it by ( for testing purposes) removing the cable from the switched side and bolt it on top of the cable coming from the battery and try cranking it again. If this sorts it replace the isolatoer switch. Are both cables attached at the engine OK? Is there any sign of corrosion in the cables? Is your battery really fully charged - you should have an off load voltage of 12.8v (fully charged). Beleive it or not, a voltage of 12.2v is only 50% charged.
2. The alarm problem sounds like one of 2 or 3 things. As has allready been said, check the temerature switch and the oil switch, also depending on the age and model there may also be a seperate alarm module. Follow the cables from both switches and if they go into a small black box with only 2 other wires (purple and black) then you have an alarm module. I have come accross problems with these before.
I hope this helps a bit.

Andy

Tim M · 12 August 2004, 16:53

Engine still not working.

Tested the battery and it's 12.48v. Is that likely to be a problem?

Next thing to check is the battery cables....

Erin · 12 August 2004, 18:03

The voltage of the battery when it's sitting idle is not a good way of testing its charge level. I've had a similar problem on a ride-on mower. Clicking from the solenoid but not enough power in the battery to turn the engine over. Put it on charge if you can for a few hours then try again, this will show if it's a battery problem.

I have also heard of some engines that will not start if trimmed up. I've no idea if your engine has this but maybe worth checking that the trim sensor isn't faulty and somehow tricking the engine into thinking it's trimmed up.

Tim M · 12 August 2004, 18:52

The engine doesn't have that protection.

I'll barrow a battery charger and charge it up. If that doesn't work I think I'll leave it to the profesionals to fix!

Tim M · 18 August 2004, 12:18

My outboard saga continues.....

Charged the battery up last night, and tried the engine again this morning. Everything works now (so I assume it didn't before because the bat was flat).

Anyway, it still doesn't start. The start motor keeps turning it over, but it just won't come to life - it's like the kill cord it out (which it isn't!).

Found the thermostat and shorted it; this made the alarm much louder. I therefore assume that that's a sperate alarm which has nothing to do with the one that is already on. I'm therfore pretty sure it ain't the thermostat which is at fault.

As for the oil level switch, I drained all the oil out of the tank, and poked the float with a scewdriver. This didn't seem to do anything.
In conclusion, (IMHO) it's either the oil level alarm which has a fault, or the control box is past it's best.

Does anyone have any other ideas?

Tim

Mosser · 18 August 2004, 13:47

I've had a problem before on a 2-stroke Mariner 50hp where the alarm was going off but the engine appeared healthy (though I didn't have any of the starting problems you describe). As the engine was "newly" installed (it was a second hand engine mind), I brought it back and the service document stated that the alarm unit was faulty and was replaced. Didn't make much sense at the time, but I accepted it.

Just letting you know that this can happen. As for your starting problem, it certainly appears to be electrical based on what you say. Could moisture be interfering with the control electronics? All electrical contacts should be checked and scrubbed clean. Start at the battery and take it all the way through to the plugs.

Not much help...

Tim M · 18 August 2004, 13:51

Just spent the last hour taking the control box apart. What a job that was - there's hundreds of wires and loads of greese. Anyway, all apearded to be well. Checked all the connections and they were sound.
I've decided to take it to a Mariner service place to get it checked over; it's been two weeks now and I still havn't fixed it!

Thanks all for the help!

Tim

Daniel TD5 · 18 August 2004, 18:03

sorry to hear you are having problems with your engine

ive had two alarms sound on my one when we went up the thames the oil alarm
came on as it was low

the next one may be what happen to yours i came in to very shallow water
then trimed the engine up when it got to about the top fin as i forgot it was running the alarm came on i turned it off and took the boat home got the
wash kit out started it up the alarm came one trimed it down reved it and it stopped

may be some thing is stuck on

dan

Hightower · 18 August 2004, 19:30

When I was running low on oil I tilted my outboard so that I prop flipped to shore and the low oil buzzer sounded and the engine cut out. Mines not a Mariner but a Yam 80 but what I'm trying to say is that if you have a oil sender/control fault that the control thinks you out of oil then it stands to reson that the engine would cut out to protect it's self.

I guess the other fault was a dead battery with you trying to start you engine repeatedly.

Hope you solve your problems,

Andy

Tim M · 25 August 2004, 11:58

Just an update on my engine:

Took it to a Mariner service place. They have got it working again. The bloke told me that he spent five hours on it, and finally found the problem; a wire had become unplugged somewhere. He charged me £147 for the privalige, but to be fair, he did plug it in again for me!

Louise · 25 August 2004, 12:09

Glad it's fixed but

rather a lot of money for plugging in a wire! I hope he showed you which wire, in case it comes adrift again!!!

Nick Hearne · 25 August 2004, 12:18

Thats £19.40 per hour, not bad I would say!
But it dose heart when it is for something so simple!
Nick