Yamaha warning problem

[mdhux]

I have a 22ft boat with a 175HP Yamaha. Both are early 90's models. The problem I have is when I after I launch the boat the overheat warning goes off. It goes for about 10-20 seconds and then stops and the motor runs without a problem after for the rest of the day.

I make sure I warm the motor up before I reverse off the trailer. The tell tale will always start and continue to put out water. I then idle around whilst the car is parked. Usually about 1 minute later the warning will go start buzzing. The tell tail is still normally putting out water (a couple of times it has stopped for about 5 seconds). As mentioned previously the warning buzzer will go for 10-20 seconds and then stop, and not a problem with the motor after that.

I have taken it to the shop and they have been unable to recreate the fault. Yet it happened the next time I took it out. Any ideas?

[A_DIFF_PERSPECTIVE]

a stab in the dark??????????? thermostat sticking???
johnny M

[mdhux]

The shop replaced that. It does not do it in the fresh water bucket. Thanks anyway.

[ahoj]

tell tale could be having blockage it can happen when you run through weeds... Give it a poke with a soft wire while its running. There must be some restriction in water going out at full capacity--- next is water pump... try the soft wire first... 1990 model.. when was the water pump replaced last?

[ahoj]

I make sure I warm the motor up before I reverse off the trailer.

Ha---- you are running the water pump dry- do you know what a water pump impellor looks like? its relatively soft rubber nylon composition and if run dry at say 2000 rpm for one min the impellor and casing will heat up and can burn the rotor your impellor may need replacing and I hope it is all...

Ahoj

[johnnytheone]

Does it tend to do it more after reversing? -I know the water flow going in to the pickup in reverse can get a bit "dirty", and thus there is a bit of an interruption to the volume passing the temp sender. That happened on our 130 E'rude. The impeller was fine but the housing was a wee bit worn, we replaced it, no more problems. Have you also checked to see if it's an indication fault on the warning circuit, 'cause they can do funny things as well when nothing is actually wrong. Give me a set of decent gauges anytime as you can tend to see problems in their early stages rather than a buzzer that just tells you your'e buggered. John.

[mdhux]

I give the engine a really good warm-up on the trailer (sometimes up to 5-10 minutes). I reverse off slowly. It only happens when I then go forward and after about a minute or so.

I thought it was a blockage as well or something to do with water flow. The shop said they looked at these and could not find a problem. I have taken the family out for the day and had the motor up for a few hours while we had lunch, swimming, etc on one of the islands. Not a problem when we got going again. Been fishing in the one spot for a few hours, again not a problem.

The engine actually runs really well after this happens. I have actually run around a little faster after it has been launched just to make sure it had nothing to do with the fact that I idle around after it has been launched; buzzer still went off.

When I reverse later during the day there is not a problem.

Thought it may have been a false indication, but it happens only once at the start of the day. I would have to totally agree about the gauges, it gives me the creeps that there is only lights and buzzers. On that note the oil light is always green after start (and there is always a tank full of oil)

Even gone to the operators manual to make sure it was not a 'standard' feature.

The only thing I could think of is I use the auto-choke at the start of the day, but could not see how this could be doing it. The biggest problem is the shop say they could not recreate the fault, but it has happened everytime I have gone out (only brought the boat 3 months ago).

I might take it back to the shop to check the impellor and casing.

Thanks for you suggestions

[troy]

I know a bloke just down from me and he has a yamaha and the alarm goes off everytime he takes it out.
The mechanic has checked it over on a lot of occasions and cannot find anything.
Yet the motor still runs fine.
Troy

[Grand_Marlin]

Mdhux,

The only other thing I could think of, do you have the motor deep enough in the water as you are warming it up on the trailer?

Have you tried warming it for only (say) 30 seconds on the trailer, then reversing off to see if it still does it?

Cheers

Pete

[razorline]

I have had the same problem once with our 250 yamie, and it turned out to be the "popit valve" sticking. apparently this $2 part empties the water out of the head when it's coming down from high engine speed,( eg warming up engine) and stops the water in the head from boiling hence sending the alarm off.
Something else to check out :-/
Cheers Razorline

[razorline]

Sorry guys I meant to the block, not , the head ;)
cheers Razorline

[mdhux]

Thanks,

The motor is definitely in enough water when I warm it up. This morning when I took it out, after I gave it a good warm up on the trailor, rather than idle around in fwd until the trailer was parked I drove around at 1500-2000 r.p.m. NO BUZZER!

However, I think I will get the popit valve checked out.

Once again thanks for your input. I will keep you posted on how I go

Matt

[madmix]

had a similar problem with a 90hp yamaha.
alarm would go off after short periods of idling.
Tell tale looked and felt fine, open up throttle
and alarm would stop. Had impeller replaced and no more
problem.

cheers Mick

[HarryO]

G'day MDHUX.

It could be a sticking poppet valve, you'll find this at the back of the engine near the bottom in the middle.
There will be a hose coming off it,
and 2 or 3 bolts holding the valve housing to the block.

Before you remove it, determine if there is any water running out of
the HORIZONTAL vents above the cav plate above the prop
during flushing.

This is where the poppet drains.

After warming, if no water is present, then it is not operational.

If the pressure out of the telltale is strong, then the poppet
is sticking, and if the pressure is weak, it may be the impellor is
not creating enuf pressure to open the poppet valve.

Good luck.

Harry.

[madmix]

forgot to mention that when I was having alarm problems
due to impeller, I could let it idle for ages with muffs, without
setting off alarm.
Living on property all my water is tank water pumped through
pressure pump, and obviously the lower water temperature and
hose pressure was enough to keep motor cool enough.
As your service mob have been unable to recreate problem in
fresh water flush tank, it may be that the change in water temp
is just enough to stop alarm. would imagine a sticking poppet
valve would be recreated by test run.

[Skipsta]

My Yamaha 90hp's alarm often goes off when I first turn the ignition on when the motors tilted up at the boat ramp. prob with mine is a Low oil warning. Thought I'd throw this in because none of the other advice seems to fit the bill :-/