'89 Johnson 60HP overheating

Dumbass

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Hello all. Its been a while since I posted here. I have a weird problem with my motor. It is randomly going into SLOW mode due to overheating. Using an IR temp sensor the upper cylinders measure 150+/-, the lower cylinders measure 180+/-. I have "thrown" the following parts at the problem:
Cooling system: new impeller, thermostat
Fuel system: new in-line filer, new cartridge filter, replace VRO pump with non-VRO pump (I have been pre-mixing since I bought the boat, 10+ years ago).
Electrical: new power pack, new coils, new plugs, new thermal sensor.
If the thermal sensor wire is disconnected from the power pack, the problem goes away. Other VRO alarm wires have been disconnected (low oil,etc_).

During this process I have "fixed" the problem a number of time only for the problem to return. Sometimes SLOW occurs within 2-3 minutes of running on plane. Sometimes it doesn't occur at all with the motor running flawlessly for over an hour.

This motor runs great, idles great. I am at a loss as to the next step. Any ideas on what to throw at it next?
 

racerone

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Is this the 56 cubic inch block ?----Model # is ?-----Does the tell tale hose come off the side of the block or the top ?-----Did you install the latest water pump kit that comes with cooling system modifications ?
 

Sea Rider

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Fresh or salt water usage, how old is the motor ? Which was the thermo condition when removed ?

Happy Boating
 

Dumbass

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Is this the 56 cubic inch block ?----Model # is ?-----Does the tell tale hose come off the side of the block or the top ?-----Did you install the latest water pump kit that comes with cooling system modifications ?
I dont know. Model # is either J60ELCE or J60TLCE (cant read the info plate. Working from memory. Motor has trim/tilt)). Tell tale comes from top of block. The kit was from Johnson/Bombardier but I do not remember anything different in it from earlier kits I have installed.
 

Sea Rider

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Salt water for the last 10+ years. 1989. Old thermo looked clean when removed.
Assume it's not the original thermo the motor came with as to look clean specially if running on salt water for the last 10 + years or has been cleaned ?

Happy Boating
 

Dumbass

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Assume it's not the original thermo the motor came with as to look clean specially if running on salt water for the last 10 + years or has been cleaned ?

Happy Boating
Yes, I have changes the thermostat and impeller a couple of times in the past.
 

Sea Rider

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Dumbass

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If the motor has not been internally desalted from new, that's the problem. It's not cooling as it should, too much crude, salt formation on the entire water passages and the overheat sensor triggering prematurely. With more use will get worse....check same issue : https://forums.iboats.com/threads/why-is-the-ob-overheating.740657/

Happy Boating
Sea Rider, The motor has been flushed consistently throughout its life. Earlier years (not owned by me) was in fresh water. Based on your response, I assume the exhaust chamber cover needs to be remove and internal passages cleaned. Would the head need to be removed as well? I also wonder how many of the bolts will cooperate and come out. They have been in place since new.
 

Sea Rider

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Dumbass,

When you clean all the water passages need to tear the cylinder head, exhaust cover, thermo housing and powerhead from it's base. Will need to manually scrape with a wooden sushi stick all the filth found in all those mentioned water passages. The issue is that any bolt highly salted can break when removing, you've got only 2 alternatives, take the risk and go that way or keep overheating eternally and missing the boating fun at speed.

I'm the only one here recommending this cleaning procedure which been doing for years now with different HP motors. Pics 1-3-4-8 corresponds to a motor with 500 clocked worked hours in salt water and near daily use, was flushed on muffs for at least 10 minutes after returning home from new. Pics speaks for themselves. Now cleaned to perfection as a preventive internal maintenance running as an Olympic champ...

None of the parts that you have thrown into your motor were needed after all the water passages were cleaned to mint clean condition (Pics 5-7)

Happy Boating
 

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Dumbass

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Dumbass,

When you clean all the water passages need to tear the cylinder head, exhaust cover, thermo housing and powerhead from it's base. Will need to manually scrape with a wooden sushi stick all the filth found in all those mentioned water passages. The issue is that any bolt highly salted can break when removing, you've got only 2 alternatives, take the risk and go that way or keep overheating eternally and missing the boating fun at speed.

I'm the only one here recommending this cleaning procedure which been doing for years now with different HP motors. Pics 1-3-4-8 corresponds to a motor with 500 clocked worked hours in salt water and near daily use, was flushed on muffs for at least 10 minutes after returning home from new. Pics speaks for themselves. Now cleaned to perfection as a preventive internal maintenance running as an Olympic champ...

None of the parts that you have thrown into your motor were needed after all the water passages were cleaned to mint clean condition (Pics 5-7)

Happy Boating
Thank you, Sea Rider. It may be above my skill level. But like you said, not much good as is. I appreciate the information.
 

Sea Rider

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Thank you, Sea Rider. It may be above my skill level. But like you said, not much good as is. I appreciate the information.
To tear such parts it's not rocket science, try to find someone experienced that can remove those parts for you at your home, will need to manually clean/scrape off all the water passages filth to immaculate clean cond. A gasket set only costs $ 74.00, torque all gaskets to specs, put powerhead back on pan and that's it.

Take advantage to decarbon the exhaust cover, piston heads and cylinder head as well as seen in pic 5. Will have a motor cooling and running properly as when out of the box for years to come.

Happy Boating


 

Fed

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Apr 1, 2010
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Sometimes it doesn't occur at all with the motor running flawlessly for over an hour.

I suspect you're being led down the garden path regarding corrosion being the problem.

I'd be revisiting the temp sensor (2 wires or 1?) and the whole alarm setup including power pack before stripping it down looking for excess corrosion.
Also revisit poppit valve & thermostat.
I recall I think people "adjusting" the spring on the poppit valve, I believe it's called a vernotherm?

There shouldn't be SLOW mode on that motor as far as I know but maybe it's been retro fitted, there is also a diode that forms part of the system.
Do you have a working alarm horn?
Are the water intakes clear?
Did you fit a complete water pump kit, racerone mentioned an upgrade kit?
Lots of questions before stripping.
 

racerone

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Well----1990 might have been the first year for slow on them.----Trouble shoot the cooling system first.
 

Crosbyman

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did not read all the post but...did you ever inspect the water intake cavity below the water pump ???
 

Sea Rider

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The OP has already changed new : Impeller, thermostat, power pack, coils, plugs, thermal sensor with no avail.

The thermostat assy is composed of the following : thermostat assy, spring, vernatherm, if the OP has changed a complete thermo kit, comes already with said parts, there's also a relief valve spring which should be the poppet valve with a different name. Did the rrvp was removed from the cylinder head housing ? if so, which was the condition found regarding the housing and spring, were both clean, salted ?

You should never ever finger any spring, comes factory adjusted with a given resielency to work as intended. The vernatherm is an internal part of the thermo assy, the poppet valve is part of the cylinder head, 2 different springs that has nothing to do with each other.

BTW, being led down the garden path has nothing to do with corrosion, has lots to do with extremely salted water passages and probably bit of corrosion under them which is normal due to the motor worked on salt water for + 10 years.

Happy Boating
 

Crosbyman

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but did he inspect the water intake cavity below the impeller plate ? . Any accumulated silt would impeded incoming water flow into the pump impeller cavity of the pump....


just asking... my old Merc 50 had a loose grommet floating around in that cavity ....??? drove me nuts when it plugged the pump when it felt like it !
 

Faztbullet

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Mar 2, 2008
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That's a real simply cooling system...if it doesn't overheat at idle as stated and only intermittently at WOT check the seat in head that the T-stat housing which also is the poppet valve, sets in. These do degrade and will swell restricting flow thru head at WOT. Also pull head and check upper passage as any floating scale could restrict passage. Only thing that will put it in SLOW is head overheating..
 

Sea Rider

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If the OP installed a new thermo, probably have checked both mentioned Cup and Valve Set Cond ? have seen those gone bad on motors not counting with thermo switches while running wot and hidden kelp covering both lower leg's water intakes.

If planing removing the powerhead from the pan, might as well take advantage to remove the exhaust cover and the cylinder head to scrape all the internal water passages on a flat surface, just don't do it on the wife's kitchen table. If scale, salt layers is found under the lower powerhead expect to find same on all the water passages without any doubt....

Happy Boating

 

Dumbass

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Apr 16, 2007
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Thank you for all of the replies. I have replaced the electrical components, cooling components and the thermal sensor. This motor did have SLOW originally. The only alarm left is the thermal sensor as VRO has been disabled and old fuel pump replaced with a non-VRO model. The only alarm wire connected to the power pack is the thermal sensor. Alarm siren stopped working a few years ago. Fatzbullet mentioned the thermostat seat. I did notice it seemed more oval than round, maybe due to corrosion. I will replace this part and inspect the area behind it in the process. Crosby man mentioned cleaning the intake below the impeller. I did this as well.
Sometimes it doesn't occur at all with the motor running flawlessly for over an hour.

I suspect you're being led down the garden path regarding corrosion being the problem.

I'd be revisiting the temp sensor (2 wires or 1?) and the whole alarm setup including power pack before stripping it down looking for excess corrosion.
Also revisit poppit valve & thermostat.
I recall I think people "adjusting" the spring on the poppit valve, I believe it's called a vernotherm?

There shouldn't be SLOW mode on that motor as far as I know but maybe it's been retro fitted, there is also a diode that forms part of the system.
Do you have a working alarm horn?
Are the water intakes clear?
Did you fit a complete water pump kit, racerone mentioned an upgrade kit?
Lots of questions before stripping.
 
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