1989 Johnson VRO 40 alarm troubles

[numbersguy]

Okay I'm new to this forum but have been reading the posts for the last 2-3 weeks. I bought a 89 Johnson 40 HP VRO with a 20 ft pontoon attatched to it from a guy down the lake from my cottage. It ran for him and with the exception of some flooding issues at warm start-up, that sea foam seemed to help with, it was working decently. I plan to rebuild the carbs this winter as he was not into preventative maint.

Last week while cruising slowly the horn in the controls came on first with a few beeps then as a steady tone. I limped back to my dock and now after trying several things I'm turning to you all. The lake level is low and there are weeds, but I was careful to avoid them and I was getting water out of the tatle tale.

I bought a manual and did some reading and thought it was a VRO problem, but I get plenty of smoke at start up and the plugs seem to be oily when I pull them so I'm not sure that's true.

Now I'm thinking its a thermostat or sensor issue. I get plenty of water out of the tatle tale hose when it runs and when we limped in.

I didn't have all my tools with me so I have not done a compression test, but it was running before this. I plan to test compression this weekend.

Any thoughts? I'm tempted to just buy new thermostat and water pump kit and just replace them, but I really want to know what the problem is and fix that.

Thanks in advance.
numbersguy

 

[d.boat]

Re: 1989 Johnson VRO 40 alarm troubles

Okay I'm new to this forum but have been reading the posts for the last 2-3 weeks. I bought a 89 Johnson 40 HP VRO with a 20 ft pontoon attatched to it from a guy down the lake from my cottage. It ran for him and with the exception of some flooding issues at warm start-up, that sea foam seemed to help with, it was working decently. I plan to rebuild the carbs this winter as he was not into preventative maint.

Last week while cruising slowly the horn in the controls came on first with a few beeps then as a steady tone. I limped back to my dock and now after trying several things I'm turning to you all. The lake level is low and there are weeds, but I was careful to avoid them and I was getting water out of the tatle tale.

I bought a manual and did some reading and thought it was a VRO problem, but I get plenty of smoke at start up and the plugs seem to be oily when I pull them so I'm not sure that's true.

Now I'm thinking its a thermostat or sensor issue. I get plenty of water out of the tatle tale hose when it runs and when we limped in.

I didn't have all my tools with me so I have not done a compression test, but it was running before this. I plan to test compression this weekend.

Any thoughts? I'm tempted to just buy new thermostat and water pump kit and just replace them, but I really want to know what the problem is and fix that.

Thanks in advance.
numbersguy

I don't know how Seafoam could help with a flooding problem. I know it's supposedly a "do everything" elixir but still....

Anyway, which of the following alarms are you hearing:

Steady beep - overheat.
Slow intermittent beep (one beep every 30-40 seconds) - low oil
rapid intermittent beep (one beep every second or so) - no oil

I'm wondering why you thought it might be a VRO alarm? My understanding is that you heard a steady beep which would be overheat.

 

[numbersguy]

Re: 1989 Johnson VRO 40 alarm troubles

Okay I forgot to "say" that the seafoam idea and that the alarm being VRO trouble came from a gentleman down the lake who also owns a Johnson 40. He was adament that the motor should be converted to a pre-mix set up instead of keeping the VRO. I've been reading alot on that topic here.

This was before I bought a manual......

I will say that the seafoam caused lots of smoking while I first started running the engine and I did burn through a tank of gas in the week before the alarm went off. It did seem to run smoother but still had a flooding issue. I'm thinking that rebuilding carbs should take care of that issue as long as I have good compression. Is that correct?

So I was trying to solve the wrong problem if it wasn't an oil issue. I'm picking up a new thermostat today and gaskets and will replace them on Friday when I head up north to my cottage.

Do you think I should replace the temperature sensor too? Is it possible a hot engine can damage that?

The closest marine parts store is about an hour away from my boat so I'm trying to show up with necessary parts.

Thanks
numbersguy

 

[kjdunne]

Re: 1989 Johnson VRO 40 alarm troubles

We need to know which alarm you are hearing, steady on, slow beep, or fast beep.

Steady on is overheating, bad temp switch (sensor), or shorted wire.
You said you have a steady stream from the telltale which does indicate the water pump and t-stat are working.

Simple wiring test is to unplug the tan wire from the switch (upper left of cylinder head), the connector is 4-5 in. from the switch.

With the key on, engine off, there should be no alarm. If the alarm is sounding steady, also disconnect the plug in the wiring from the VRO pump. This is a black rubber connector near the big red connector.

If alarm still sounds with the key on, start hunting for a short to ground in the tan wire to the horn.

If no alarm, short the wiring harness side of the tan wire to a good engine ground, you should get a steady alarm. Reconnect the tan wire to the switch. If you get a steady alarm, the switch is bad. You can verify this with an ohm meter. When cool, the switch should read open to ground, no continuity. It should close at about 165F.

Reconnect the plug from the VRO.

 

[numbersguy]

Re: 1989 Johnson VRO 40 alarm troubles

Thanks for the reply.

It is a solid tone no beeps. When I disconnect the tan wire that leads to the temp sensor the alarm quits with the key on and engine off.

Before this all happened, I would get a quick chirp tone each time I turned the key on at start up. Is that normal behavior?

d.boat gave me this info earlier that i did not know:
Steady beep - overheat.
Slow intermittent beep (one beep every 30-40 seconds) - low oil
Rapid intermittent beep (one beep every second or so) - no oil

I guess that indicates temp sensor....or a short in the system?

About the thermostat, can't water come out of the tattletale hose before the thermostat opens up? I'm worried about cooking this engine. I've read the manual on the cooling system but still would like some guidance from you becasue it is obvious several of you know quite a bit about diagnosis and repairs.

The same guy down the lake that told me it was the VRO alarm advised me to disconnect the wire since I was still getting water out of the tattletale.

Do you know if there is any other system on Johnson motors that causes an alarm to sound other than low oil, no oil, or high temp?

Any help you can suggest would be appreciated.

Thanks
numbersguy

 

[d.boat]

Re: 1989 Johnson VRO 40 alarm troubles

Before this all happened, I would get a quick chirp tone each time I turned the key on at start up. Is that normal behavior?

This is normal and you should make sure it happens every time. It's an alarm self test.

...It is a solid tone no beeps. When I disconnect the tan wire that leads to the temp sensor the alarm quits with the key on and engine off....

d.boat gave me this info earlier that i did not know:
Steady beep - overheat.
Slow intermittent beep (one beep every 30-40 seconds) - low oil
Rapid intermittent beep (one beep every second or so) - no oil

I guess that indicates temp sensor....or a short in the system?...

Exactly. That signal is coming from the sensor that you disconnected. The sensor trips the alarm by causing a ground when it is activated by heat. Therefore the alarm could also happen anytime that tan wire is grounded, for example, if the insulation is cracked or rubbed off and touches a ground. (you can try that - pull the tan wire and ground it).

By shutting off the alarm by pulling the wire, you now know that the sensor itself is causing the alarm, not a short in the wire itself (because if it had a short, the alarm wouldn't stop when you disconnect the sensor). You therefore don't have a wiring/short problem but either the sensor is doing its job and reporting an overheat, or the sensor itself is defective and grounding w/o an actual overheat.

...
About the thermostat, can't water come out of the tattletale hose before the thermostat opens up? I'm worried about cooking this engine. I've read the manual on the cooling system but still would like some guidance from you becasue it is obvious several of you know quite a bit about diagnosis and repairs.

The same guy down the lake that told me it was the VRO alarm advised me to disconnect the wire since I was still getting water out of the tattletale...

I really don't know about the relationship of the tell tale indicator to the thermostats, hopefully someone else will pipe in. I do know that the telltale is not necessarily a fail safe indicator that the cooling is being done properly. My personal opinion is that the guy down the lake is giving you several pieces of bad advice and I wouldn't listen to him.

The correct advice is to figure out why that sensor is tripping the alarm - either a genuine overheat or a defective sensor. You can test the sensor, I don't know the specific steps off hand.

You can also buy a heat sensor gun for as cheap as $25 or so and actually "shoot" the engine when the alarm is sounding and see what the temp. actually is. Be sure to measure both sides and/or several places. Another test is to simply put your hand on the heads while it's alarming. My engines get pretty hot, but I can hold my hand on there for several seconds.

...

Do you know if there is any other system on Johnson motors that causes an alarm to sound other than low oil, no oil, or high temp?...

There are actually four alarms, but the fourth one only exists with V6 and V8 engines, so it does not apply to yours. So the only things causing alarms on your engine are the three mentioned above.

Fourth alarm is a steady beep, similar to overheat, but indicating a fuel restriction. Difference is that in these engines, the overheat also trips the SLOW mode (reduced RPMs) which will only end if the key is turned off. Fuel restriction alarm does not trip the SLOW mode, but is distinguised in that it comes on w/ higher RPMs, and goes away as RPMs are lowered, no need to turn engine off to stop alarm.

 

[Daviet]

Re: 1989 Johnson VRO 40 alarm troubles

The tell-tale is just an indicator that the water pump is pumping water to the engine, it does not mean the cooling system is operating properly. The tell-tale could show a good stream and the thermostat could be stuck or defective and the engine would still overheat, that's the reason for the temp sender and horn.

 

[numbersguy]

Re: 1989 Johnson VRO 40 alarm troubles

Thanks for all that clarification!

Its all starting to make sense. I'm mechanically inclined, just not a mechanic and I have no experience tracing problems on outboards.

I think I'll have to endure listening to the guy down the lake because now that he know we have the same motor, any time I'm out there working on it he shows up. Nice enough guy, but as you said not a great source of correct advice.

I went out and bought a new thermostat and temp sensor and all the gaskets and o rings they require and I'm going to try and replace them this evening when I get up to the cottage. I'm too far away from a marine parts store to run out and get them when I'm up there.

I was going to run a compression test this weekend too, but it is pretty dependent on getting the motor running. Can I do a basic test cold? If so what are acceptable numbers for it. I read about a 10% difference being acceptable, but my manual says everything to a 20 % difference between cylinders is okay. I don't have any idea what the low limit should be though. I was thinkning in the area of 100 to 120 psi is what I should be hoping for. Is that correct?

Thanks again for your help!

numbersguy

 

[Daviet]

Re: 1989 Johnson VRO 40 alarm troubles

Yes, you can do a compression test cold. Remove all spark plugs and ground the plug wires to the block, check compression on both cylinders. They do not publish compression specs, but I would think that if you had at least 100 psi and both cylinders within 10% of each other you are ok. You will probably find your compression is higher than 100 psi.

 

[numbersguy]

Re: 1989 Johnson VRO 40 alarm troubles

Okay so I had some success but now I have new questions too.

I replaced the thermostat and temp sensor. The temp sensor was pretty crudded up and It might have been the original. The thermostat cover was one of the threaded types with a hex head molded on top to help you remove it. The hex head had been broken off which tells me this had been tried before. Luckily I had brought almost every mechanic tool up with me and I just used a really big set of channel locks to grab the cover and it came off after I broke it loose. The thermostat was pretty crudded up too and there was rusty sludge in the spring.


I did a compression test and got 100 psi in top cylinder and 95 in the lower. Lower than I had hoped, but close enough to eachother to be ok. I got the same results dry and after I sprayed fogging oil in the cylinders.

Put it all back together, and got it started up with lots of smoke because of the fogging oil. It took a while to warm up becasue it was 63 out on Saturday but I took it out and ran it around the lake a couple of times. The the alam came back on......I had a steady stream out of the telltale and it actually was warm but not hot water coming out of the engine.

I wiggled the key and the alarm went off. So even though I think both parts needed replacing, there was a short in the system too after all. I have to trace that some otehr time becasue it pretty much rained and was cold the whole weekend. Came home early today becasue of the weather.

Thanks for all the help.

Numbersguy