1995 115 ocean runner, stumper

motor shakes and breakes up above 2600 rpms..purrs like a kitten up to 2500 rpms...2500 or less all vitals are good water pressure 20 psi, water temps 120 in both heads...

what happend...is two scenarios

was running all day great , i was running down river at 4500 rms for about 2 miles...watching for debris in the river and for birds on the water..also watching a huge barge i was passing...so i wasnt watching my guages...

when i came upon a large area of logs i slowed, but it was too late to avoid them, and i went over a long log. I felt it hit the boat, then the lower unit, then the prop..

I was only doing about 2000 rpms at the time.. then I throttled back up wondering if I did any damage..so after about 30 seconds i glanced down at the guages and I was 220 degrees in one head and 200 in the other!!!!

I quickly idled down..and in about 30 seconds the temps dropped back into the 120's.

so i throttled back up and the motor started shaking badly....I idles down...

temps were good...it ran great under 2500 rpms..but If i tried to go 2600 rpms or more ...motor shook and bucked...

I ran all the 2 more miles back to the ramp at 2000-2500 rpm...purred great...

checks i did this morning...after i got home..

spark is great in all four cylinders.

compression is 120 125 130 130

the prop spins perfectly true...no wobble at all...

thats where I am.... wondering...what can cause this shudder and shake violently above 2500 when all vitals seem ok...

dont know what caused it...the log or the high temps...

STRONG water pressure!!!

any ideas where to start looking??

thanks

again 1995 johnson 60 degree lopper V4 ocean runner... spark plugs are dark oily.....stained..brown...but no build up...

I always run extra oil



bob

Re: 1995 115 ocean runner, stumper

I will add that the water temps fluctuate, as if the thermostat has a mind of its own...I can run for an hour and then all of the sudden the temps start to rise...slow her down for 3 minutes or so, the temps drop and then you are good to go...for another half hour or hour. same thing with idleing...all the sudden the temps start to rise.... push her a little faster and the temps fall... and then you are back to doing what ever you want...


its like just CHANGE the rpm and the temps correct.....

so the high temps is not TOTALLY UNUSUAL....but i usually catch it before it gets that high..

and when it changes, the temps fall down to 100-120!!!!!!!!!

normally it wil run up to 160 and stay there...


hope that helps some


bob

Re: 1995 115 ocean runner, stumper

just a guess, it picked up some junk, ran hot, damaged thermos or poppets.

Re: 1995 115 ocean runner, stumper

Do you think the motor thinks it is overheating and therefore it goes into S.L.O.W. mode?

Re: 1995 115 ocean runner, stumper

Don't know about your temp problem but if I were yu I'd have that prop checked out at a prop shop you may have one blade bent slightly and that will cause your motor to shake; been there ,done that when I hit a log. Could'nt tell anything wrong with prop until I had it checked.

Re: 1995 115 ocean runner, stumper

thanks for helping out.

dont know exactly why the temps spike...and are so easy to cool and get back to running...


the temp alarm did not go off...

the guage seemed pegged but i think it only goes to 220...the book says the alarm should go off when the temps hit 240 degree.

any way, aparently the SLOW did in fact engage with no alarm

and the 2500 rpms was the threshold it maintains...

I have learned that the vibration is the system shutting down cylinders which is like misses...thus the vibration..

the s SLOW system stays engaged until two things happen.

one the temps come down below 207 degree ..AND the ignition is turned OFF

I never turned the ignition off...thus the whole way back my SLOW was engaged

the motor runs perfect again...

i just need to watch the temps for that ODD spike in heat.. just back off the throttle for a minute and then throttle back to my cruise speed and i am good for a long time....the temp spike can happen while ideling as well!!!!

there MAY be something inside the motor and cooling system that catches and block water flow...

I have 25+ psi at 5000 rpms of water pressure....but the temp will spike anyway.

I did suck up a ton of mud in sept and the water Pizzer stop completely....

I may run the motor without T-stats for a while to see if i can purge the syatem


bob

Re: 1995 115 ocean runner, stumper

Just for the heck of it, have you checked your warning horn to make sure it's working ? Key on, ground out tan wire on block.

Re: 1995 115 ocean runner, stumper

Will the motor run above 2600 rpm or does it just run rough and won't go any faster?

Have you checked the prop shaft for being bent, even just a little?

Re: 1995 115 ocean runner, stumper

bob johnson said:

thanks for helping out.

dont know exactly why the temps spike...and are so easy to cool and get back to running...


the temp alarm did not go off...

bob

Click to expand...

I'd test that temp alarm and check the poppet valves.

Re: 1995 115 ocean runner, stumper

seahorse5 said:

Will the motor run above 2600 rpm or does it just run rough and won't go any faster?

Have you checked the prop shaft for being bent, even just a little?

Click to expand...

100% it was the SLOW system engaged....doing its job...

which limits the rpms to 2500 BY making the motor run rough...dont know exactly how it does it, but i think it is killing spark to various cylinders randomly) which makes the motor vibrate and shake
prop shaft is perfect..motor runs great again( because the SLOW system was reset.
)

I have the syatems check in this motor. when i turn the motor on , it beeks for a while as the light all go off one by one.

the HOT light has always stayed on...for the last 2 years..no matter what temp the motor is..

after exactly 2 minutes the alarm sounds continuous and after exactly 10 seconds it shuts off...

no matter what temperature the motor is.

I checked the sensors in oil on the stove and they both checked out good..


if i ground the brown wire from the temp sensor...the alarm should sound???

is that correct?

this is exactly why i have guages... and dont rely just on water pressure...

the water pressure is great and the motor can still over heat....

just got to pay attention to them

bob

Re: 1995 115 ocean runner, stumper

jonesg said:

I'd test that temp alarm and check the poppet valves.

Click to expand...

pretty sure this motor doesnt use poppet valves...has thermostats which are enclosed in plastic... I think the flow is small, but thats the way all these motors are.... so i figure they know what they are doing..


bob

Re: 1995 115 ocean runner, stumper

OK, It sounds like the wiring from the System Check Tach to the temp sensors is grounding, causing the Hot light to come on. I cofirm with an ohmmeter, and then visually check the wire end-to-end to see what the issue is.

If you have good water pressure, and the motor is overheating, you must have some restriction issues. Remove the thermostats and see if that helps. If not, you need to start checking the water jacket for clogs.

Re: 1995 115 ocean runner, stumper

The t-stat is a combo poppet and t-stat in one,the spring holds it shut alowing t-stat to pass water thru it and when block pressure is high it unseats and reliefs pressure.

Re: 1995 115 ocean runner, stumper

ok the t-stat housing is under light spring pressue into a rubber seat!!!

and yes removing the t-stats changes a lot!!

for one the water pressure never gets above 5 psi!!!

and the tmeps never even move off 120 degree( lowest number)

I wonder what the spring pressure is behind the t-stat housing!!!!

if it is under 20 lbs, then it must beopening when i am running over 4500 rpms..


but i also suspect somethign else is floating around inside the motor getting caught once in a while...because of the incinsistancy of the temp run ups

sometimes high rpms, other times very low rpms....

and just changing the rpms..usually starts the temps to falling again!!


bob