1984 185HP Evinrude Won't rev past 2000 rpms

[nebuhcanezzar]

I have a new to me 1984 Evinrude 185HP outboard on my 19 foot Grady White boat. I have struggled with getting any reliable performance out of this motor this whole season. I am hoping someone can help answer a few questions with some issues that I suspect may be putting my motor into SLOW mode. I apologize in advance if I use the wrong terminology, I am still learning. To assist in clarity I will add pictures when I get home tonight.

1. On the starboard side of my outboard at the top of the water cover on the cylinder there is a small port where I believe the thermostat would be located behind. This port has an opening in it by design. When I turn my motor on in short order a very steady stream of water shoots out of there. The water gets hot enough that I can't keep my hand under it. I am suspecting that either my thermostat is stuck in either a fully open or fully closed state. Or perhaps the bypass valve? behind it may be stuck. So my simple question to start would be is this normal for water to spraying out of there? Follow up question is it normal that this water be very hot but my telltale which also has a very steady stream seems to be the same temperature of the water that the boat motor is sitting in?

2. It appears that my VRO was bypassed. I suspect that it wasn't done correctly. I noticed one of the ports on the VRO was open not plugged at all so I have recently plugged that and the engine seems to sound a little less rough. On all the videos I have watched on how to bypass it shows disconnecting a half-moon electrical plug. On my motor I can't seem to locate that at all. It appears on my VRO there is no electrical plug coming from it at all. Is this just due to the age of my motor?

Thank you for anyone willing to respond with suggestions.

 

[racerone]

Well----Nice try but I do not believe that 1984 models had the S.L.O.W. system.----The early VRO units did not have a warning module.---Therefor no wires.----There should be no water coming out of that ----VENT ----hole on the thermostat / poppit valve cover.----Most important to post the compression numbers on this motor.

 

[nebuhcanezzar]

Hi racerone. Thanks for such a quick reply. I will post compression numbers when I get home. I can say that when I first got the boat home I checked compression and the middle cylinder on the port side was very low, around 30 psi. I believe the other 5 cylinders were around 110 or 120, just working from memory. I have ran Seafoam through it to decarb but that didn't seem to improve the middle cylinder. I have confirmed with a spark tester that spark is getting to all 6 cylinders.
I know a lot of this falls on my shoulders and I should've done more research before buying but I was sold the boat as a solid-runner. My first two times out I was satisfied but ever since then it has been not able to exceed 2000 rpms. My first two outings I was up around 4000 to 4500 rpm going about 30mph according to the GPS. The motor has also been very rough to start. I know going through the carbs would be a definite good thing to do but given that it was performing and then stopped I had hoped that maybe the S.L.O.W system I have heard others speak of could be the cause of my problems.
This winter I planned to pull the heads and check the low cylinder, replace the gaskets, rebuild the carbs and replace the impeller. The season is nearly over so I was hoping that I might be able to get it back to the 30mph state for the last run of the season before I really roll up my sleeves and dive deep.
I have also replaced all the spark plugs, plug wires, fuel lines, and added two fuel filters. I also changed the prop from a 17 pitch to a 21 pitch.

 

[Bosunsmate]

You need to sort out that heating issue before anything else, sounds like you may need to pull the head and check that other cylinder, i suspect you will need to dive in deep but you will come back out of it with a well built motor (parts a relatively cheap) and a whole lot of knowledge

 

[racerone]

Well----Changing from 17" to 21" pitch will not help RPM..----Hurry----Find a shop with a dynamometer or a test prop.----Those can be used to determine actual power output.----The cylinder with 30 PSI has a blown head gasket or it is broken piston rings and REBUILD time.---STOP running this motor.

 

[nebuhcanezzar]

Thanks to you both for responding to my questions. I guess deep down I knew this would be the answer. I did another compression check and results are the same as I quoted from memory above.

It sounds like I have two immediate problems to tackle: the potential overheat issue and why water is coming out of the thermostat/bypass valve and then get to the bottom of the issues with the cylinder with the low compression. I hope for the latter it is just a bad gasket causing a vacuum leak and not broken piston rings scoring the cylinder wall.

Looks like my first season ends really before it ever really started. I guess on the brightside now I have a project to keep me focused during the cold winter months.

Open to any other suggestions on things I should look at or troubleshoot with this motor. Hopefully next season it is ready to rock.