1989 120HP johnson VRO overheat warning

[ajahman]

Hi folks
I,m new to this board.Found it on a Google search.Great site!I hope someone will be able to help a little with a couple of problems that I have with my outboard.I have a 1989 4 cyl.120 HP VRO equiped outboard that may be running hot.I say MAY be because the overheat alarm sounds but the temp. gage say its OK.In the green zone.Does anyone know if this motor has a low fuel delivery alarm.Also,the boat dosnt seem to have the power it had just a few months ago.Kinda sluggish.Any info. or advise would be greatly appreciated.
Thanks
Ajahman

 

[yamamarinetech40]

Re: 1989 120HP johnson VRO overheat warning

I don't understand why everyone has alarms, but won't FEEL the heads on motor to see if hot....if I have an alarm and the gauge says it's not hot, I'm gonna feel the motor to see which is telling a lie....as far as engine loosing power, with no information could guess alllll day...checked the plugs? know how? Fuel filter(s)?
Ok, if motor is hot, then you have to think about new impeller/water pump(1st), didn't say if in saltwater but restrictions in cooling system passages(2nd), and it gets bad from there...
If NOT hot, then is the alarm for temp or oil, is it a steady beep? If it's not hot could also be bad temp sensor....

 

[ezeke]

Re: 1989 120HP johnson VRO overheat warning

The constant alarm is an overheat. The 120HP and 140HP did not come with the fuel vacuum/obstruction warning switch which would also give a constant alarm.

Your engine has S.L.O.W. which will limit the engine speed to 2500 RPM whenever the temperature of either bank of cylinders reaches 203? F.

S.L.O.W. is controlled by the same temperature switch that sounds the horn.

It is likely that your temperature gauge is only connected to the port bank of cylinders.

 

[Joe Reeves]

Re: 1989 120HP johnson VRO overheat warning

Ajahman..... The warning alarms are as follows:

(VRO Horn Warnings)
(J. Reeves)

1 - A steady constant beep = Overheating - The V/6 engines, possibly some others, have a fuel restriction warning which is also a steady constant beep.
2 - A beep every 20 or 40 seconds = oil level has dropped to 1/4 tank. (Late model engine = Every 40 seconds)
3 - A beep every other second = VRO failure, air leak in oil line, oil restriction, (anything that would result in a lack of oil being supplied to the engine).

NOTE - If the warning horn is the black plastic (overpriced) three wire type horn, the warning horn should beep once when the ignition key is turned to the ON position. If it does not, it is either faulty or someone has disconnected it (a stupid move!). At any rate, if it does not beep which indicates that the horn is non functional, find out why and do not run the engine until the problem is corrected.

If overheating..... the engine has two thermostats located at the top area of the cylinder heads. Perhaps one thermostat has failed, stuck shut, but is not on the bank that the heat gauge sender is located.

The sluggish no power mention...... First thing to do is to check the compression and spark. What is the compression on all numbered cylinders? Spark should jump a 7/16" gap with a strong blue lightning like flame... a real SNAP! Doe it?

To avoid a lack of communication, exactly which type horn warning are you experiencing?

 

[ajahman]

Re: 1989 120HP johnson VRO overheat warning

Thanks for the replies fellas.Keep em comming.
To be more specific about the engine. I did check the spark and compression.Good spark on all cylinders.Compression on cylinders 1,2,3,4 were as follows 100,105,95.100.The 95 is a little worrying.I did feel the cylinders when the warning horn(steady continuous horn)sounded and the engine did not feel overly hot neither did the pee stream.As soon as I throttled down, the horn stopped and the temp.gage dropped low into the green zone.The previous owner told me that he took out the thermostats because one of them got stuck closed by a piece of trash once sooooo he removed them and I have left them that way.The engine has always ran near the top of the green zone near the red on the temp.gage when I run at cruise RPM (4000-4500 rpm).Could this be becauce the Tstats are out?The VRO seems to be working as I have marked the oil resoviour and oil is being pumped out of it,at what rate I dont know.Several months ago I did notice the warning horn would occasionally "chirp" but not sound continuous or with any cadence such as every1/2 sec. or 30 sec.The boat is a Henry O 17ft challenger,a great boat for coastal Georgia.How could I test the S.L.O.W system on this engine?Once again Thanks!

 

[ajahman]

Re: 1989 120HP johnson VRO overheat warning

Just got in from running the boat.Temp gage ran into the red zone after 5-8 min. running time at 4500-5000rpm...no overheat alarm or S.L.O.W.Felt the cyl. heads, top two very warm but not hot,lower two warm.Pee stream cool.Top speed 23.5 mph!Any ideas?
Thanks

 

[johnson1989]

Re: 1989 120HP johnson VRO overheat warning

You are looking at a water pump issue, Thermostat issue or Water Defelctor issue. Same problem with my 89 110HP . Its cheap enough to replace all if you can. Do a search and you will find Joe reeves fixes for all of the issues. Good Luck

 

[ezeke]

Re: 1989 120HP johnson VRO overheat warning

I think we can eliminate the water deflectors; 90 degree loopers don't have them.

The temperature gauge is a good way to keep an eye on the cooling system but will not tell you anything about the adequacy of the water pump, which needs to be serviced periodically. A pressure gauge would be more helpful in that regard.

You may find that cleaning the thermostat housing will help with the problem.

I believe that you may find that while the vernatherm may be removed, everything else is still in there.

BTW,You should not run your big bore looper without thermostats.​

 

[Joe Reeves]

Re: 1989 120HP johnson VRO overheat warning

As Zeke states, there are no water deflectors on that model.

The clue lies with the fact that the previous owner removed the thermostats when the engine obviousy overheated.... I say overheated as otherwise, why remove them? That mickey mouse type procedure is something that really gets to me.

The water pump was obviously failing previously so he removed the thermostats to avoid the price of installing a new water pump assy.

Now, install a new complete water pump assembly. Not doing so may very well lead into a engine overhaul scenario. Now, about the thermostats....

(Thermostat Purpose)
(J. Reeves)

Many engines are considered high performance engines and demand a thermostat(s), and many smaller hp engines also require a thermostat for the following reason. The pistons actually distort/twist off round when running. The thermostat is required to keep the outer wall surrounding the steel cylinder, and the cylinder wall itself at a temperture to compensate for the distortion.

With the thermostat removed, the difference in temperture between the inside the cylinder and the water jacket quickly reaches a point whereas (in effect) you have a oblong piston running up and down a round cylinder, or vice versa. Bottom line is without the thermostat, the piston and cylinder wall could be damaged in a short period of time.

The thermostat in your car isn't there simply to have the heater function properly..... think about it.

 

[ajahman]

Re: 1989 120HP johnson VRO overheat warning

Thanks guys for all of the info. I knew that I would find good folks that knew more about this engine than I do.It really is a good motor it just needs some attention.looks like a trip to the mechanic is in my future.I currently have the boat on a dock and have to run about 10 miles to get it to a boat ramp.Do you guys feel that it would be safe to do so if I ran at low RPMs and kept the temp. in the green?Once again,thanks!

 

[Joe Reeves]

Re: 1989 120HP johnson VRO overheat warning

I don't think 10 miles is going to do any damage running the way you state.

 

[ajahman]

Re: 1989 120HP johnson VRO overheat warning

Thank you Mr. Reeves and everyone else for your help.Just wanted to get an expert opinion before I did any serious damage to the engine.I suppose I,ll have a lesiurely cruise to the boat ramp this week.Thanks again!