Exhaust Gunk

[Fazz90]

Is is normal to have this much gunk built up in the exhaust?
Engine is a 2 stroke Johnson116597


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[ericcs]

what size motor, looks like over oiling!

[Fazz90]

what size motor, looks like over oiling!

2003, 115hp, Oil Injected


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[scottar]

A bit is normal but that does look excessive. Looks like a combination of oil and exhaust carbon. Make sure she is reaching the recommended wide open throttle RPM. Have you been doing a lot of low speed work or running for extended amounts of time on the ears at home?

The early VRO units were also prone to check valve failure in the oiling system. With the one I owned, this lead to hard starting due to one of the two carbies being choked with oil if the engine sat for any more than a few days. At the advice of a long term OMC mechanic I disconnected it and went back to 50:1 pre-mix - motor never ran so well. It also allowed for the fuel to be idled out of the carbs at the end of the day which meant a lot easier starting next time round. Also had the added advantage of not killing the engine in the event of a fuel/oil pump failure.

Also, never use the primer bulb to keep a VRO engine running in the event of a fuel pump failure - doing so will mean the engine is not being lubricated and will fail as one of my uncles found out the hard way. If the engine is on premix, using the primer bulb as a fuel pump to keep an engine running isn't an issue.

[Darren J]

Re pre mix. I had an early 90's 140 ecu ride 140. Always pre mixed st 50:1. On the advice of s very reputable mechanic (+20 years knowledge)from one of brisbanes well known marine outlets advised too rich and run 75:1. I did from then on, never had any issues, ran a little cleaner at idle etc.

Oh. And never had an exhaust look like that.

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[ericcs]

if it's a FICHTengine, maybe it can't be converted to premix?

[scottar]

if it's a FICHTengine, maybe it can't be converted to premix?

True Eric. There weren't many ficht johno's but there were a few. If it is a ficht with an exhaust like that though it's not a healthy critter.

[Noelm]

No 2003 Johnson FICHTs made, still kind of puzzles me why people disconnect the oil system, far better to just look after it and go boating.

[ericcs]

was there ever a fix for the VRO pump, other than disconnecting it?

[Fazz90]

Havent done much low speed work of late, in fact lately when it is running on low revs or idle, the overheat alarm has been coming on. Which is how i came to see this issue as i was running it on ear muffs at home, i wanted to check water flow in thermostats.
Now i have 2 problems.......
That i know if anyway


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[Noelm]

was there ever a fix for the VRO pump, other than disconnecting it?
What do you want to "fix"? the later model OMS is very reliable, the early system was OK, but didn't have an alarm, but was still reliable, most were disconnected on bad advice, especially from mechanics who used to just remove it "because"

[Fazz90]

Any suggestions on how to remedy this, apart from disconnecting the oil line?

[Fed]

Prolonged running on the muffs will cause the gunk because the combination of tap water pressure & the water pump is enough to lift the thermostat (it doubles as a poppet valve) and over cool the motor.

It's the same effect as in the water at higher speeds but then you want it to lift the valve because the motor needs extra cooling at higher rpm.

Idling in the water the motor relies completely on the water pump for cooling but at speed it also gets a boost from the ram effect of the water pushing into the water pickup vents.

My first guess would be you need a water pump service to cure the in water low speed overheating then take it for a good run and it should come back gunkless (dry).

[myusernam]

Looks to me like it's overoiling. I'd be getting the oil mixing circuit checked. Or top up, and see what rate you are using it at as a ratio to fuel. Also you should run some omc engine tuner decarboniser through it and leave overnight.

[Fazz90]

This motor is driving me nuts
March this year i had overheating issues, replaced water pump and thermostats, then around July/August, noticed motor sounded like it was choking, then it wouldn't turn on, changed batteries, spark plugs, ended up changing power pack.
Ran like a dream over 3 trips, then overheat alarm started to sound again when in low rev range/idle.
All of this only after being rebuilt 3 years ago (previous owner promise)
The joys of owning a 2nd hand boat...

[Fed]

Are you plowing the bottom or power loading, sand & silt can destroy an impeller in less than a minute. Trust me I've done it.

I honestly believe power loading & unloading is the reason many people replace their impellers every year due to the sand it kicks up.

FWIW you could run that motor on double oil & still come back with a dry hub.

[Fazz90]

Hi Fed,

What do you mean by Plowing the bottom and power loading/unloading?

[Noelm]

Plowing simply refers to driving through sand/mud banks with the prop chewing up the bottom, driving the boat on and off the trailer is power loading/unloading.

[Fazz90]

Haven't done any driving through mud or sand banks. But i do drive the boat on and off the trailer

I never knew that it would have that much of an impact on the impeller.

In saying that though, when i changed the impeller earlier this year, it was in pretty good shape, no sand found inside the housing

[Fed]

Is it possible you picked up a plastic bag while idling around or is the overheat happening all the time?

Those bags are very sneaky, as soon as you stop they release & sink so you don't see them unless you're quick.

I wouldn't worry about the gunk just yet, concentrate on the overheat.