Yamaha 92 115

[j_jtaylor]

Gday all, I have a 92 115hp yamaha that an audible alam goes off whenever I stay over 4000rpm for any length of time, I dont lose power or anything and no visual alarms appear (Low Oil ect) if I drop back to below 4000rpm for 1 minute or so its fine again. I had a new impella put in in November and there seems to be heaps of pressure. I use the boat in salt and fresh water and flush it every time I use it!!!<br />Thanks for any advice!!!!

 

[mrn714]

Re: Yamaha 92 115

On that engine it is either low oil or running hot. Suggest checking H20 intake for obstructions at your higher speeds draw more h20, then lower, so low intake with cause high temp, running it back will allowing cooling. Also check the oil pickup in tank as it could be clogged as well causing a low draw into the pump giving a warning. <br /><br />

 

[j_jtaylor]

Re: Yamaha 92 115

Thanks for that info, I will have a look and see what I can find!!!

 

[j_jtaylor]

Re: Yamaha 92 115

Some one mentioned that that it could be the pressure relief valve, and that if the valve is shut water will flow out of the "gills" above the cavatation plate??? Is this true?? As I flush the engine out everytime I use it and water has allways flowed through those gills???<br />Thanks again!!!!<br />Sorry about the delay in posts but been up North escaping Perth winter!!!

 

[jim dozier]

Re: Yamaha 92 115

Do a compression test. If everything else in the cooling system such as impeller, thermostat, blockages test out OK, a leaking head gasket will often present as high rpm overheating.

 

[j_jtaylor]

Re: Yamaha 92 115

Gday again, I have changed the Thermos and the impella was done about 15 hours ago, however when I took the boat out on the weekend every thing was fine until I got over 4000rpm for about 5 mins then the alarm went off again. I took the engine cover off and the Port Head was a lot hotter than the starboard one so I assume its the problem. Does this sound like head gasket or blockage? Is there anything I can do to help prevent broken bolts when taking the head off the engine??? It is also idling very rough but is fine at higher Rpm's Thanks for any help!!!!

 

[rodbolt]

Re: Yamaha 92 115

sounds like you have several problems. rough idle with good compression is indicative of dirty carbs. the overheat above 4000 with a good pump and t-stats is indicative of a leaking head gasket. the gasket will allow combustion gas in the cooling system but not nessasarily water into the cyl. or you have built up sand and scale in the cyl passages and water jacket covers. next step is to remove the heads and covers for inspection and cleaning.<br /> good luck and keep posting<br /> ps on breaking bolts, use heat, cursing and prayer.<br />

 

[j_jtaylor]

Re: Yamaha 92 115

Thanks for that Rodbolt, your help is much appreciated, one more thing, is it necessary to both heads or just the one that is overheating?<br />Thanks again!!!!

 

[rodbolt]

Re: Yamaha 92 115

I would do them both. if one side is scaled up or clogged the other side will be right behind it.<br /> good luck and keep posting

 

[j_jtaylor]

Re: Yamaha 92 115

Thanks Rodbolt, will let you know how I go, Im hoping It all goes well!!!!

 

[dcpcccrc]

Re: Yamaha 92 115

thats wierd that the buzzer comes on and doesnt cut your rpms down to 1200 is it a solid buzzer or a intermintet buzzer if its solid then your overheating if not solid then one of the low oil lights should come on do a compression check my 89 yamaha 115 ran all 4 at 116 to 120 all they told me to do to cure the same problem your having is clean the poppit valve. i cleaned it but havent had a chance to go to the lake yet to see if thats going to fix it i will let you know if it does

 

[j_jtaylor]

Re: Yamaha 92 115

It is a solid audible alarm but doesnt drop the RPM at all, I will have a quick look at the poppett valve, and let you know. I think Rodabolt is prbably right as when I changed the thermos there was a fair bit of sand and **** in there!!!

 

[j_jtaylor]

Re: Yamaha 92 115

What is a "good" compression range for these motors to be in, my mechanic has done a compression test and all 4 cylinders are 150psi, sounds good to me???

 

[scottoz]

Re: Yamaha 92 115

A mate had what sounds to be the same problem with his 115 Johno - it was an early 80's motor. He tried all sorts, including new deflector rubbers. Eventually he pulled off the head covers and found an almost complete blockage of black sandy/clayey crap that was obstrucing the galley. Cleaned that out - no problems now.<br /><br />Cheers

 

[dcpcccrc]

Re: Yamaha 92 115

i have a 88 yamaha 115 it runs about 120 on all 4 cylinders now you got me wondering if all mine should have more compression hopefully its just the difference in years the newer the better i hope

 

[j_jtaylor]

Re: Yamaha 92 115

I would guess it would depend on what work the engine had done as well!!! My mechanic is pulling the heads of mine this week, will let you know!!

 

[Ray Neudecker]

Re: Yamaha 92 115

Compression guages do not all read the same. That is why you look for a difference in the cylinders rather than a specific number.