VRO. means???

Boatist

Rear Admiral
Joined
Apr 22, 2002
Messages
4,552
Re: VRO. means???

Variable Ratio oil. It means the oil ratio changes. At WOT ratio will be around 50 to one but at idle might to 100 to 1. Put this question in the outboard section and you should get more replys.
 

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: VRO. means???

Variable Ratio Oiling. In theory it went from 150:1 at idle to 50:1 as the rpm went up.
 

dajohnson53

Lieutenant Commander
Joined
Apr 28, 2004
Messages
1,627
Re: VRO. means???

does my 2001 johnson have vro?

Somewhere in the mid-90s (96?) the Johnson/Evinrude system went from VRO to OMS. OMS means Oil Metering System. The pump functions very similarly to the VRO pump, it is just far less variable, essentially constant (I think mixes at 60:1 at low rpms to 50:1 at high rpms).

Actually the VRO itself had two versions - the first was VRO and went from 150:1 to 50:1. In the late 80s, it was changed to VRO2 which went from 100:1 to 50:1. I have a VRO2 pump and it pretty much averages around 60:1 for my useage.

The pumps are generically called "VRO" but really, the more current ones are OMS.
 

hughybabes

Cadet
Joined
Jul 19, 2008
Messages
18
Re: VRO. means???

Thanks. A very informative article. A dealer over here in Melbourne Australia told me to diconnect the fuel line to the motor when boat is pulled from the water as pressure can still draw oil into the carbs. (When the boat was first purchased carbs were full of oil after it had been sitting for some time).
We have following that advice.....Is it necessary?
 

dajohnson53

Lieutenant Commander
Joined
Apr 28, 2004
Messages
1,627
Re: VRO. means???

Thanks. A very informative article. A dealer over here in Melbourne Australia told me to diconnect the fuel line to the motor when boat is pulled from the water as pressure can still draw oil into the carbs. (When the boat was first purchased carbs were full of oil after it had been sitting for some time).
We have following that advice.....Is it necessary?

Do you have quick releases for both the fuel line and the oil line? Mine are both permanently attached to the fuel pump, so disconnecting when not in use is not a viable option. I've never heard of that being done either.

The oil syetem is not pressurized. The tank is actually vented. The oil is primed with a bulb, to purge air out of teh line, but not pressurized. Therefore there is no pressure to force oil into the bowls when the engine is not running. In my thinking, it just can't happen. It couldn't even happen if there was a leak in the diaphragm of the oil side of the pump, again, because there's no residual pressure forcing it in.

Plus, if you read the article, the oil is SUCKED into the fuel pump and then PUMPED into the carbs only when the fuel pump is working - and the fuel pump is driven by pressure from the crankcase, therefore it doesn't work unless the engine is running. It cannot suck oil out of the tank nor pump it into the carbs when the engine is not running!

I've heard of carb bowls being filled with oil IF one attempts to run the engine dry of gasoline - Until the engine actually dies, the pump will continue to pump, but without gasoline, or insufficient gasoline the proportion of oil will be out of wack, maybe even pure oil for a few moments until the engine actually quits from lack of gas.

I'd be interested in hearing if there's any other possible explanation, but I think your mechanic encountered an engine that someone tried to run dry for storage, adn inadvertently pumped pure oil into the carbs. It was not caused by storing it with the fuel/oil lines connected, but because of what happened in the last few seconds when they tried to run it dry for storage.
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: VRO. means???

The original VRO was the thing that killed OMC in the mid 80s, and why there was a VRO2... It had a nasty reputation of killing engines... By now I suspect they have all been removed and the engines returned to pre-mix... Personally I never trust any of the OMC oil mixers...

Chris..........
 

Seon

Petty Officer 1st Class
Joined
Apr 23, 2008
Messages
304
Re: VRO. means???

I just purchased a boat with an 88' Johnson 110 VRO. While getting tune-up parts, the tech recommended that I disconnect and plug the oil line and disconnect alarm wires and go with pre-mix fuel. Said that he's seen several motors burnt due to VRO going bad. So who here have a VRO that's converted to pre-mixing their fuel?
 

kenmyfam

Supreme Mariner
Joined
Aug 10, 2006
Messages
14,385
Re: VRO. means???

I just purchased a boat with an 88' Johnson 110 VRO. While getting tune-up parts, the tech recommended that I disconnect and plug the oil line and disconnect alarm wires and go with pre-mix fuel. Said that he's seen several motors burnt due to VRO going bad. So who here have a VRO that's converted to pre-mixing their fuel?

Now you have opened a huge can of worms !!!!
 

dajohnson53

Lieutenant Commander
Joined
Apr 28, 2004
Messages
1,627
Re: VRO. means???

I just purchased a boat with an 88' Johnson 110 VRO. While getting tune-up parts, the tech recommended that I disconnect and plug the oil line and disconnect alarm wires and go with pre-mix fuel. Said that he's seen several motors burnt due to VRO going bad. So who here have a VRO that's converted to pre-mixing their fuel?

I think it's important to understand what exactly made the tech decide the oil mixing system was to blame. This article puts a lot in perspective:

http://continuouswave.com/whaler/reference/VRO.html

The thing that sways me is that the system has two oil-related alarms, one to tell you the tank needs refilling, and one to tell you the pump isn't getting enough oil for the amount of gas flowing. To me, this is a pretty good warning system. I've never read anything that leads me to believe that the other major outboard oiling systems are better functionally or have better alarms, or that systems that have normal maintenance and inspections aren't very good. On the other hand, I continually watch the level on my oil tank!
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: VRO. means???

... and one to tell you the pump isn't getting enough oil for the amount of gas flowing.

VRO2 has the two alarms. VRO didn't have a monitor on the pump.
And on every single rebuild I have done for a VRO2 failure, this second alarm was also faulty. And this may be why OMC have introduced yet another system....

dajohnson53 said:
To me, this is a pretty good warning system. I've never read anything that leads me to believe that the other major outboard oiling systems are better functionally or have better alarms, or that systems that have normal maintenance and inspections aren't very good. On the other hand, I continually watch the level on my oil tank!

Good idea, but by the time you notice that the oil level isn't falling, you're already under tow back to port....

I have seen more VRO and VRO2 failures resulting in re-builds than all the other systems put together, many times over!

Chris.........
 

kenmyfam

Supreme Mariner
Joined
Aug 10, 2006
Messages
14,385
Re: VRO. means???

Now being a pre-mixer it gives me a warmer and fuzzier feeling that if the fuel is getting through then so is the oil !!!
 

dingbat

Supreme Mariner
Joined
Nov 20, 2001
Messages
15,417
Re: VRO. means???

VRO2 has the two alarms. VRO didn't have a monitor on the pump.
And on every single rebuild I have done for a VRO2 failure, this second alarm was also faulty. And this may be why OMC have introduced yet another system....



Good idea, but by the time you notice that the oil level isn't falling, you're already under tow back to port....

I have seen more VRO and VRO2 failures resulting in re-builds than all the other systems put together, many times over!

Chris.........

How long has VRO2 been out of production?

Any experiance with the OMS "System Check" systems?
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: VRO. means???

Now being a pre-mixer it gives me a warmer and fuzzier feeling that if the fuel is getting through then so is the oil !!!

Give the man a prize!!! You are SO right... And that's why I also like pre-mix....

Chris........
 

kensi

Recruit
Joined
Jul 14, 2007
Messages
5
Re: VRO. means???

some of us older mariners who have been thru it with OMC built outboards thur the years liked to refer to VRO as "Very Rarely Oiling". one of the real screw-ups of the old days. thank god for modern direct injection 2 strokes, like tohatsu/nissan brands and others. ken.

21' carolina skiff
115 hp TLDI tohatsu.
 
Top