Adding VRO to non VRO 1978 Evinrude

[bcomer]

A friend of my has a new VRO system for a newer engine than mine. Can I add this to my older '78 85HP Evinrude and expect it to work? I would love to get away from having to mix the oil and gas.<br /><br />The part number on the system is OMC part #176995<br /><br />Thanks for your help.

 

[seahorse5]

Re: Adding VRO to non VRO 1978 Evinrude

It won't work on a '78 motor because the engine was never designed for oil injection. You would need to drill the crankcase for oil passageways to the main bearings. The intake manifold would have to be machined. Brackets would need to be fabricated, plumbing redone, fittings drilled and tapped, etc. Not worth the cost or effort.<br /><br />VRO motors did not come out until 1984.<br /><br />The new "VRO's", actually called Oil Metering Systems, OMS pumps, have a part number starting with 5000...

 

[bcomer]

Re: Adding VRO to non VRO 1978 Evinrude

Thanks for the quick response. Looks like I will still be mixing unless there is another solution. Is there any automatic way (aside from buying a new motor) to mix oil and gas?

 

[R.Johnson]

Re: Adding VRO to non VRO 1978 Evinrude

Seahorse: 50-1 oil is fed to the carb, or carbs' by the VRO, which should be renamed constant ratio. I have never seen a technical explanation of what changes were made to the block , or manifold, either in a manual, or at several service schools. My thinking is that 50-1 leaving the carb is 50-1 no matter how it got to the carb. Why would a 50-1 mixture from a VRO need special oil passages to the main bearings. I know there have been numerus changes to the recirc. system on these engines. Just curious where you got the information on changes to oil passages, and why?

 

[bcomer]

Re: Adding VRO to non VRO 1978 Evinrude

I was thinking the same thing. I was an auto mechanic years ago and am new to the outboard world but I was thinking the same thing. If the gas mixture is going to the same place whether it is mixed manually or automatically, wouldn't it work the same way.<br /><br />As I understand it the fuel pump would have to be replaced by a combination oil / fuel pump--maybe that is the issue--the pumps will not interchange?<br /><br />I was also wondering on the VRO system what drove the mixture ratio--is it vacuum--if so is that easy to get a connection for on an outboard like mine?<br /><br />Would love it if this would work!

 

[seahorse5]

Re: Adding VRO to non VRO 1978 Evinrude

At the service schools back in those early VRO days, everyone wanted to swap out the old fuel pumps and retrofit VRO's. The schools showed the internal changes to the motors back then. They don't teach that stuff anymore since we are talking 20 year old motors, and it's not economically feasable to try to change things that old. With enough time, money, and skill, you can do anything, though.<br /><br />The new OMS pumps are not 50:1 at idle, they are closer to 75:1 and at speed, close to 50:1. Most boaters average 60:1 depending on their use. They operate on both crankcase vacuum and pressure pulses.

 

[DJ]

Re: Adding VRO to non VRO 1978 Evinrude

I've never seen an OMC oil injection system (VRO) that fed the crank bearings. All they ever did was mix fuel with the oil, before the carbs.<br /><br />I do recal asking the question regarding adding it to my old '83' model. I recall I was told it could be done.<br /><br />Perhaps Joe Reeves will comment on this.

 

[seahorse5]

Re: Adding VRO to non VRO 1978 Evinrude

The VRO doesn't feed the crank bearings directly. The '84 and later crankcases, intake manifolds, gaskets, etc. had different passageways than the '83 and earlier motors. One thing that used to mess up the '84 and later motors was the use of a '83 or earlier intake manifold gasket that looked almost identical, but did not have the holes for the main bearing feed passages. After a few hours of running, you would hear the whine of the center mains on a V6 from lack of enough lube. They would get just a little lubrication from dripping down from the cylinder above them. When removed, the center main bearing races would look like washboards.

 

[DJ]

Re: Adding VRO to non VRO 1978 Evinrude

That still doesn't make sense. Why can one run 50:1 pre mix, with no trouble?