Author Topic: Merc 150/V6 outboards oil injection (Read 6786 times)

Rosscoe · « **on:** February 25, 2016, 07:51:04 PM »

It was my understanding that the Merc oil injection was not prone to malfunctioning like the OMC set up, because it runs off the/a cam?
Why is it I see most Merc V6's seem to die due to oil injection failure? I've seen folks disconnect it. Is it different than an inline 4 which I think are reliable?
Is there a flaw in the design or maybe people just beat these motors more?

Hyperacme · « **Reply #1 on:** February 26, 2016, 07:48:43 AM »

I've heard the Mercury V6 oil pump drive gear is plastic on some models, and prone to failure.
Not sure of years used.
Try a Google search for "disconnecting Mercury 2 & 2.4 liter V6's".
Steve might have more info.

Are you looking at one for your fleet ?

74 Carlson the II · « **Reply #2 on:** February 26, 2016, 12:37:59 PM »

Oil injection is awsome and great untill it fails. Wrong oil will cause problems, running a oil tank dry then filling back up will cause problems and design problems like plastic gears. Pre mix is a pain in the arss but it is a guarantee that your motor WILL get oil if you mix it RIGHT. I will NEVER run oil injection on any 2-stroke outboard. Just don't trust it. I would much rather pre-mix than rebuild.

Rich_V174SS · « **Reply #3 on:** February 26, 2016, 01:25:40 PM »

On a Merc the oil pump failures are usually due to the drive gear inside the block on the crank shaft breaking because they were plastic resulting in less or no oil being pumped. Some models had a shaft rotation sensor feeding a signal into the warning module to warn if the pump shaft wasn't spinning.

I have seen one case of an oil pump failure because someone connected the pump regulation linkage arm incorrectly and instead of opening with more throttle it worked opposite and closed off oil as throttle was increased. The engine suffered two scored pistons and needed replacement.

As for OMC oil pump failures I've never seen one that failed to pump oil. It was often more the case they didn't pump enough fuel or they pumped too much oil. Many people blame the infamous VRO pump for a scored piston when most of the time it's got nothing to do with problem. VRO pumps inject the oil directly into the fuel line before being distributed to each carburetor so they all get fuel/oil mix simultaneously. If a piston scores or burns up it's more because of a carburetor or intake problem causing less fuel to enter that cylinder.

74 Carlson the II · « **Reply #4 on:** February 26, 2016, 01:49:19 PM »

Like Rich said and I was about to say myself, It's not just the oil pump it's self that cause's a burn down. The oil pump it's self works fine, it's just all the other stuff that goes with it to make it work that fails. I like pre-mix, easy to do once you have done it a few times. I never worry when Im out boating if my oil injection system is going to fail.

Rich_V174SS · « **Reply #5 on:** February 26, 2016, 02:00:54 PM »

I like pre-mix myself, it's a sure way to know the lubrication is there. However, a stuck float valve, clogged jet or broken reed valve will still cause a cylinder to run lean and burn a piston or score a cylinder no matter what oil system is used. Unless it's got direct oil injection where the oil is squirted right into the cylinder walls like on an Evinrude E-Tec. But I've seen failures there too.

74 Carlson the II · « **Reply #6 on:** February 26, 2016, 02:25:48 PM »

One of the culprits for a 2-stroke motor burn down is OLD gas. Gas looses its octane as it ages (aka. sitting during the winter months) octane is important to a 2-stoke motor. loss of octane will cause detonation. I always run the best gas I can get, BP sells 93 but I perfer nonoxygenated 92.

Jason · « **Reply #7 on:** February 26, 2016, 03:11:01 PM »

ehhhh, nothing lasts forever. Run her till she pops!

I do like how the newer systems adjust the amount of oil injected based on RPMs. Saves money on oil, helps keep the water cleaner, and the engine should run better as well.

Or just get one of these. No oil in the fuel!

Rich_V174SS · « **Reply #8 on:** February 26, 2016, 04:47:59 PM »

Yamaha has a problem with their big block 4 strokes, I think the 250hp engines and up. The adapter plate that the power head/block sits on was made with inferior-grade aluminum and is prone to rotting out, especially in salt water. When that happens you get water in the engine oil and the engine blows up. We had one come into the shop like that back in the fall. It was only a year and a half old. Yamaha wouldn't warranty it so we removed the engine from the boat and re-rigged it for a new Evinrude E-Tec.

CVX Fever · « **Reply #9 on:** February 26, 2016, 05:16:43 PM »

Ross my answer to your question is to get that CV23 w/350 Mag on the water!

84carlson · « **Reply #10 on:** February 26, 2016, 09:24:18 PM »

I've run 2 vro motors for 30 years never an issue, I would never go back to mixing again. Just my 2 cents...

Hyperacme · « **Reply #11 on:** February 26, 2016, 10:55:29 PM »

I've owned dirt bikes from the early 70's thru the mid 80"s, snowmobiles from the mid 80's thru the 90's. all with motor driven oil injection pumps.
Never had a problem with them, never really gave them a second thought.
Would check the cable adjustment from time to time, always ran a good quality oil.

Dirty carb's and bad gas would be the biggest cause of motor problems with two strokes.
A little fuel system service go's a long way ...

1983glastronss16 · « **Reply #12 on:** February 28, 2016, 10:22:33 AM »

The oil injection it's crap delete it and remove the oil tank of the motor that's what I done and have a good luck mixing my own oil

Rosscoe · « **Reply #13 on:** February 29, 2016, 09:34:07 AM »

Not too much news in favor of Oil injection. I had thought the Merc system was supposed to be reliable, but only seem to hear of problems on the V6's so I figured it must be a different system.
Personally, I like the convenience of oil injection and it really became more obvious to me with an on board tank in the 17, getting the ratio correct etc. Portable tanks are easier in that respect.
I would like to re power the CVX 17 with more power.

Kip, I need to start making plans for the attack on the 23. I should get it all torn down so when it gets warm, I'll be ready to glass. I had hoped to sell some things to free up some space but so far, that hasn't been the case. I have to move it back and forth from the barn to the shop to get the interior and motor out. Kind of a pain.

CVX Fever · « **Reply #14 on:** February 29, 2016, 10:42:18 AM »

Ross you got so many boats I couldn't remember what it is that the CV23 needed. At least you got that nice big building to keep everything in and plenty of room/land to park stuff!

Rosscoe · « **Reply #15 on:** February 29, 2016, 10:47:15 AM »

Quote from: CVX Fever on February 29, 2016, 10:42:18 AM

Ross you got so many boats I couldn't remember what it is that the CV23 needed. At least you got that nice big building to keep everything in and plenty of room/land to park stuff!

Yeah I have the same problem. The 23 needs a transom.

My plan (as of today) would be to put a 140-150 on the CVX17 and put the tired 115 on a stand until I can get it rebuilt. By that time, I could be working on the Viper and that is where the 115 would end up. For me, I think that would be plenty on that boat.

Hyperacme · « **Reply #16 on:** February 29, 2016, 10:57:07 AM »

" I like the convenience of oil injection "

Same here ...
Not much history of our 1989 Mercury/Marnier's 115 HP motors going bad because of oil injection problems.
Keep tank topped off, make sure line are new and not leaking oil.

Rosscoe · « **Reply #17 on:** February 29, 2016, 10:59:18 AM »

Quote from: Hyperacme on February 29, 2016, 10:57:07 AM

" I like the convenience of oil injection "

Same here ...
Not much history of our 1989 Mercury/Marnier's 115 HP motors going bad because of oil injection problems.
Keep tank topped off, make sure line are new and not leaking oil.

That is what was making me think the oil injection system was different on the inline 4's to the V6's

Hyperacme · « **Reply #18 on:** February 29, 2016, 11:08:09 AM »

I think they were ... But 150's used the plastic drive gear.
The 2.0 liter V6's came out a few years before of our inline 4 cyl.
Must have changed gear by the time our motors were released.

Also make sure your control box "BEEP'S" when you turn on the key.

Rosscoe · « **Reply #19 on:** February 29, 2016, 11:11:01 AM »

I wonder if they learned a lesson and changed the gear to metal on the V6's at some point?