any clues as to why I am over heating..

[bob johnson]

1995 115 johnson looper.

motor seems to be running very good...

runs all the way to 5800 rpm no problem..

after the motor warms up...it appears one head is running up to 180-190 degrees at low rpm.

water pressure at idle is about 8-10

at wot the water pressure is 30 psi!

at wot the temperature will fall back to about 140-150



so It gets kinda warm...putzing around at low rpm

I have two temp sendors and one gauge...I have a switch to go back and forth from reading one head orthe other..

I think the guage is actin gup...because when ever I get high readings, on one head I get no reading on the other..

dont know if its the switch or the sender..

but the temps can easily be seen falling at I cruise about 4000 rpm!!!

if in fact one head is getting hotter than the other..

what can I do, to fix it, so it doesnt run hot at low rpm??

is the head water passages clogged maybe??

will I be able to fix it with the head off??

mechanic tells me its a real pain to reinstall the head with these big o-rings and no gaskets...

he says if the head warped I may never get a seal..

I am getting a little leakage into the cyliner on the non hot side

thanks


bob

 

[jonesg]

Re: any clues as to why I am over heating..

A cheap infra red thermometer will show you whats really going on.

If its over-heating for sure and if the water pump is good ... I'd start with the thermostats, compression test to see the extent of the head leak and pull both heads. Re-do the water deflectors and test the heads for warps.

 

[tashasdaddy]

Re: any clues as to why I am over heating..

fresh or salt water running? could be weak, wearing impeller, has it been changed in the last 2 years?? if salt water, have the tstats been changed in last 2 years????

 

[bob johnson]

Re: any clues as to why I am over heating..

I replaced the T-stats about a month ago.....

one seat looked fine the other was kinda suspect..

what is the water pressure number for a brand new , or excellent operating impeller?

I am getting about 10 at idle and up to 30 at WOT

should I have more pressure??

I am running mostly salt water and I suspect the previous owner as well, because i found some barnacles on the extra trim holes in the mount base.

the compression is great....just am pretty sure I have a water leak because the buildup I found on one spark plus was all salt. the mechanic I go to for parts told me is was probably a bad O-ring on under the head...

when i replaces the t-stats, I didnt see any residue in the passages in and around the t-stat openings..

the high temp side is not the side with the suspect water leak.

I almost picked up a few temp sticks they sell ...still might give that a try...

bob

 

[Chris1956]

Re: any clues as to why I am over heating..

Bob, I get 30+ PSI at high speed on my '98 Johnny 150HPV6. I do not know what the idle water pressure is, however. I would therefore think your pump is good.

 

[bob johnson]

Re: any clues as to why I am over heating..

well the motor really like the 30 PSI.....it just doesnt like anything under 20



the head gets too hot..

so really trying to figure out two things

WHY is it getting so hot?
how do i solved it?

bob

 

[jonesg]

Re: any clues as to why I am over heating..

aha ..salt on sparkplug, you gotta pull the head.
Compression leaks can cause overheating due to lean running.

 

[tashasdaddy]

Re: any clues as to why I am over heating..

if you have salt on the spark plug, you have water in the motor. get those heads off NOW!! before more damage is done. slight head gasket leak into the cooling system will make the motor run hot, as the hot compression gases are getting into the cooling system, heating the water immediately. also could be exhaust gasket or pin hole in exhaust cooling plate.

 

[bob johnson]

Re: any clues as to why I am over heating..

well i am pretty sure (90%) the head with the leak( ie salt on the plug) was on the head that wasnt running hot.

but ill pop the head...

is it difficult to reinstall those big O-rings?

should I take a cut on the heads to make sure they are flat??????
before i reintall them?

anything to look for, or look out for?

maybe ill run it again to verify the head that is getting hot and if it is the head with the water deposits build up on the plug..


the water pressure feed is coming off the cool head( 90%) sure..

maybe i dont have the pressure i think in the other head...

I guesss i could also put a water feed in over there to check as well..

bob

 

[Faztbullet]

Re: any clues as to why I am over heating..

If its the starboard side thats warmer, that is normal due to engine design.

 

[bob johnson]

Re: any clues as to why I am over heating..

again, I am pretty sure it is the starboard side...

I know the plug that is getting the salt deposits in the lower port cylinder.

I have switched the wires from one sending unit to the other a few times, because they seldom seem to both work!!!

(might be my switch, that divers the signals to a single temp guage.)

any tips on the O-ring reinstall you guys can give me.

the old codge mechainc i get parts from says...whooo ooo you are gonna hate doing that!!!!!!!

dont do it!!

he loves to say DONT DO IT!! ha ha

bob

 

[jonesg]

Re: any clues as to why I am over heating..

The danger is getting salt on the crank bearing surfaces, it will etch them and ruin the crank....
You really need to get in there and find out whats goin on.
I would speculate after I stop the damage.
Could just be water deflectors dislodged, who knows.

 

[bob johnson]

Re: any clues as to why I am over heating..

The danger is getting salt on the crank bearing surfaces, it will etch them and ruin the crank....
You really need to get in there and find out whats goin on.
I would speculate after I stop the damage.
Could just be water deflectors dislodged, who knows.

if I do this job,what parts will i need to replace with new?

thanks

bob

 

[bob johnson]

Re: any clues as to why I am over heating..

can anyone point out the Water DEFLECTOR?

bob

 

[bob johnson]

Re: any clues as to why I am over heating..

after surfing the net for several hours, I have come to the conclusion this motor does not even have water defelectors!!!

maybe they are a crossflow item, but they dont appear to be used on this 60 degree motor

bob

 

[bob johnson]

Re: any clues as to why I am over heating..

an update, if anyone was interested.

took the boat out today to watch the temps closely and maybe nail down exactly what is going on, and maybe switch sending wires.

both temp senders send good signals and I was switching back and forth from one head sender to the other, as to which sender was feeding my temp guage( I have two senders connected to and on -on siwtch whcih feeds my tempo guage.

the temperatures went up evenly to about 160, then one fell to about 120,


at that point , the one side slowly climbed and the other side, which had fallen suddenly which the t-stat opened, eventually went to ZERO..

crazy huh...the one that was till reading ran all the way to 210!!

I didnt trust them so i pulled into the shallows and pulled the cover and felt the heads...they felt the same.

I idled in the shallows and pulled the sender wires and started switching them..

with one on at a time, i was getting 140 in both heads...

I had thought the swithc was doing something funky...

I am kinda sure of it now..
water pressure at idle is 10 lbs!!

the guage and switch seem to work until my rpms get up....then the signals go in opposite directions...one runs up to over 180, even 200 and the other drops to nothing...

when they both give a reading they were always 140-160

after i tested both senders and verified each head was the same temps, i hooked them both back up and ran the motor, up to 3000 rpms


once one went above 160, the other fell to nothing...

I dont know why one is affecting the other!!!

had to be in the switch...other wise the wires have nothing to do with each other.

anyway, thanks for listening..

I feel i dont have an over heat issue at all. and will remove the trim guage that doesnt work and install another temp guage and run a sender to its own gauge..

bob

 

[Chris1956]

Re: any clues as to why I am over heating..

Tricky problem. Is there any insulation damage on the wires? That motor has the Quickstart feature right? That would mean that one sensor was a dual sensor for the quickstart. Did you test it for quickstart and overheat function? Maybe that is defective?

 

[jonesg]

Re: any clues as to why I am over heating..

Let me guess, you used a 2 pole switch?
You need a 3 pole so the wires don't cross feed each other.
Either that or an isolation diode/s to isolate the signals from each other.

 

[bob johnson]

Re: any clues as to why I am over heating..

havent tested for the quickstart...dont even know what that is..

one issue is the controls came with the 97 90 hp I had, but that motor had a knock, and I left the controls on and got an adapter to run the red plugged 95 motor.

dont know if that means anything...

i got the systems check and it goes through the motions when i start...but the over heat lights stays on all the time..

and the over heat alarm goes off exactly 2 minutes after I turn the key on( even if i dont start the motor!!) and it goes off in exactly 10 seconds, every time!

so i just let that stuff... go..because after that the motor runs fine..

I added the temp guage and senders to be pro active, and try and prevent major engine damage.

I think the motor has the SLOW system, but it has never engaged.

the motor apparently has never gotten hot...a few times i have touched the motor and both heads feel the same... i can hold my finger on the head no problem for 3 or 4 seconds, before it gets kinda to hot to stay.

the water pressure has always been good( vie guage)

so

I THINK all my issues are funneling down to the guage/switch/sender problem.

I do have an ON-ON... I am not sure if that is called a 2 pole or not..

I can add a switch that is on-off-on..

will that potentially help?

funny thing is the guage isnt getting hot, the switch isnt getting hot...

so why the change?? how can a bad sender( when it gets hotter maybe) cause an issue with the guage when the wire is not passing through the switch.

unless of course it is the handoff from ON to ON because of the switch design

thanks for the input guys.

nut and bolts are kinda easy to figure out..black magic, electrical type stuff, is poisonous to me!!!!!

bob

 

[bob johnson]

Re: any clues as to why I am over heating..

Let me guess, you used a 2 pole switch?
You need a 3 pole so the wires don't cross feed each other.
Either that or an isolation diode/s to isolate the signals from each other.

I will bypass the switch and hook one wire up to the guage this week, and after the motor warms up, ill just un do the wire lead from that sender and put it on the sender in the other head....

and see what it reads..

the only way it could get more direct would be use the same sender in both heads one at a time while hot..

of course that would be just for diagnostic use..

Ill would try the new style siwtch, before i went to two seperate temp guages though.

bob