87 elth 90 yamaha alarm .

[Barry wade]

The motor will sound a alarm then go into limp mode . Ive changed the impeller it has plenty on water pressure . can a dirty oil gage sensore in the oil tank make this happen. If so can i take it out and clean it.

[TownsendsFJR1300]

You can have plenty of water pressure and a new water pump, however, if the head / water jackets are gooed up with salt (and not flushed with fresh water), cooling water will NOT get to that area and it WILL over heat. With the age of the engine, unless run in fresh water, is VERY likely.

All the water flow will not get past those built up, clogged pasages and overheat.

Should the passages be clogged, you can weither remove the head(s) and manually clean it or some have used chemicals:

http://www.yamahaoutboardparts.com/f...g-th19434.html


It may be an oiling issue, someone else will chime in on checking that..

[Barry wade]

Thanks scott . the motor is a freash water motor never been to salt water . ill take to head apart and check anyway cant hurt. the motor will plan out fine then run about a half mile and alarm. dosent seem hot . THANKS FOR THE HELP..

[Barry wade]

OK i pulled the head and found a tear in the water jacket. i also took the thermastat loose and started the motor no water was comeing from this. could something be blocking water flow around the head.

[TownsendsFJR1300]

OK i pulled the head and found a tear in the water jacket. i also took the thermastat loose and started the motor no water was comeing from this. could something be blocking water flow around the head.

What is a tear in the water jacket? Do you mean the block (or head) is cracked or is it just a casting line (from the manufacturing process?)

(I probably wouldn't have pulled the head just yet and waitded for others to chime in but your there now..)

Can you snap a picture, post it in "Photobucket" then post it here(its much larger and easier to see).

[Barry wade]

IM talking about the gasket on the head. not the main head gasket.i didnt take the head off i split in half . to check water flow. thermastat looked ok but im new to this . thanks for the info here is the gasket no. 688-11193-a1-00 . if that helps

[TownsendsFJR1300]

you took off part #28, correct then? (the cylinder head cover):

1987 90ETLH Yamaha Outboard CRANKCASE CYLINDER Diagram and Parts

Was there any corroison to speak of under that cover?

And when you say "tear", please elaborate?

[Barry wade]

no corrsion but part# 29 a gasket had a tear in it. . would this restrick water flow through the head.

[TownsendsFJR1300]

no corrsion but part# 29 a gasket had a tear in it. . would this restrick water flow through the head.

Most likely NO. Its pretty much just sealing that top cover to the head and keeping water in. Unless a part of it broke loose and got nto the water passages (not likely).

Just an FYI, a salty corroded engine will have salt built up on both sides of the water jacket in the head, and the cylinder (after the main head is off) usually is caked up (literally with salt, and doesn't alow any water to flow thru).

Are you sure it didn't just tear upon dis-assembly?

Forgot to ask, did you check the thermostat and make sure its working (opening and closing fully)?

[TownsendsFJR1300]

If there was visable corrosion where you are now, it would be much worse deeper in the engine. Especially the cylinder water jacket.

[Barry wade]

no i didnt check the thermastat completley but i will . do you think i need to pull the head to check all water ports . after talking with you about this i dont beleave its a oil issue. when the alarm comes on after i let it set for a bit it starts fine without the alarm . but when i run the motor hard it starts alamring agian .so im on the right track . THANKS AGIAN FOR THE HELP.

[TownsendsFJR1300]

no i didnt check the thermastat completley but i will . do you think i need to pull the head to check all water ports . after talking with you about this i dont beleave its a oil issue. when the alarm comes on after i let it set for a bit it starts fine without the alarm . but when i run the motor hard it starts alamring agian .so im on the right track . THANKS AGIAN FOR THE HELP.

If it was a salt water run engine, it could very well be clogged up with salt,(my neighbor had the same issues in salt water and he rarely flushed his engine making it worse) but YOURS isn't, I would NOT be pulling the head.

I'd check the thermostat first and go from there.


I'm NOT familiar with the oiling system/ alarms, please hold off (besides checking the thermostat) pulling anything else apart...

Please post the thermostat's condition...

[Barry wade]

Its a overheating issue for sure . the gasket on the water pump is leaking so not enuff water pressure to push water through the motor . THANKS AGIAN FOR THE HELP.

[TownsendsFJR1300]

Excellent! The thermostat was operating properly?