VRO/OMS Over Oiling Johnson 98 150

[Riley C]

Hi Guys,


I have got a over oiling issue in my 98 150. 730hours on gauge but can’t confirm as the boat was barely used by previous owner.

When in storage couple days after use. I find Clean Oil leaks around the midsection while in garage. Carbs don’t leak fuel, all been just serviced.

I find oil is charging through the fuel line somehow and going back into carbs. Can be harder to start when in storage for a month.

I found the VRO tank cap was super tight, pressurising? It’s an old cap without check valve, I have put a small hole in the top of it. I can now draw air through it. Could inability to vent cause the issue?

The carb bowls are fine not warped or leaking.

Replaced the worm clips on hoses with snap locks.

I pulled the pulse limiter an primed the line, no fuel came out so maybe not the pump?

Tested the lines for leaks, The fuel lines are fine and do not loose pressure until it connects to the fuel housing of the motor. Perhaps the green oil furl connector and the lower cowl?

Just wanted ask if you guys know other places this may cause the issue.

Can fuel separator or the fuel housing be places to check, that cause over oiling? Cant see weeping there but haven't checked internally.

I will vacuum test tomorrow to test lines.

 

[jimmbo]

What makes you think the it is being 'Over Oiled'? Normal consumption is 16 oz of Oil for every 6 gal of Gas at WOT, Lower speeds consume less, Your engine has the OMS Pump which doesn't lean out as much as the VRO did, ao about 8 oz per 6 gals of gas would be about the lowest and that is at Idle.
Oil has to go to the carbs as it is mixed with the fuel.
Are you unhooking the Fuel Line and running the motor till it stalls when you are Storing it?
When the Engine is tilted up, some fuel will spill from the carbs. The gas will evaporate, but the Oil mixed in will not. Eventually it will seap out of the cowl

 

[Faztbullet]

I found the VRO tank cap was super tight, pressurising? It’s an old cap without check valve, I have put a small hole in the top of it. I can now draw air through it. Could inability to vent cause the issue?​

All the signs of a bad 710 cap oops..oil cap

 

[Riley C]

All the signs of a bad 710 cap oops..oil cap

Fazt,

I started her up after putting the hole through it and testing all the lines. I don't loose prime until the connection to the fuel housing.

I can't for the life me find the air/fuel leak. Or where the clean oil came from.

With the hole in the cap though I believe this has helped a lot. Hell of lot less smoke at start up.

 

[Riley C]

What makes you think the it is being 'Over Oiled'? Normal consumption is 16 oz of Oil for every 6 gal of Gas at WOT, Lower speeds consume less, Your engine has the OMS Pump which doesn't lean out as much as the VRO did, ao about 8 oz per 6 gals of gas would be about the lowest and that is at Idle.
Oil has to go to the carbs as it is mixed with the fuel.
Are you unhooking the Fuel Line and running the motor till it stalls when you are Storing it?
When the Engine is tilted up, some fuel will spill from the carbs. The gas will evaporate, but the Oil mixed in will not. Eventually it will seap out of the cowl

Hi Jimbo,

Thanks,

I know 50:1 idle mix, the way this thing idle killed birds in my street there was that much smoke. I don't unhook anything, no need too, I just turn the key switch off.

I think we have sorted it with the oil cap vent for now, seems to run way better now I put a little hole at the top.

Cheers.

 

[Chris1956]

Over oiling on that motor can be caused by an air leak into the gasoline supply. A prime culprit is the main strainer under the air box. It should have 2 rubber seals.

Air leaks on the water separator (if you have one), or at the fuel line connections could also cause over oiling.

 

[Fed]

Prolonged flushing on the muffs will cause oil to come out because they don't get hot enough to burn it all.

Having said that if the oil is clean then my money would be on the air box leaking.

 

[Riley C]

I have it sorted now guys.

After replacing a lot of zip ties and reselling o'rings. The primer has held most pressure of the night other than 2 pumps. So definitely no air leaks.

After testing a few times in the test tank it was half the smoke after venting the cap. Along with completing the above.

Super stoked now I don't flood the street with smoke when I start her. Also not fowling plugs either.

 

[jimmbo]

I always considered the Smoke an Effective Mosquito Control

 

[Mikey N.C.]

Premix can't over oil . rite ?

 

[Mikey N.C.]

Have u looked on port side (phillips head screw) where gas and oil lines connect to. Motor side oil and gas lines ?

 

[Riley C]

Have u looked on port side (phillips head screw) where gas and oil lines connect to. Motor side oil and gas lines ?

Sure did Mikey. I pressure tested with vice grip and it held pressure from bulb to fuel filter housing.

i think I have it now. Fingers crossed.

 

[boobie]

You probably cured the problem when you drilled the hole in the oil cap. They did have bad caps that weren't venting and causing your problem.

 

[Riley C]

You probably cured the problem when you drilled the hole in the oil cap. They did have bad caps that weren't venting and causing your problem.

Thanks Boobie!

Also.

I think I have slightly warped bowls on the port side. So I have slightly sanded them down on glass with sand paper, as per some guys on this forum. If it stops the slight weeping great! If not I’ll buy some new bowls.

 

[dingbat]

I always considered the Smoke an Effective Mosquito Control

and...when combined with the “motion of the Ocean”, a proven producer of projectile vomiting...lol

 

[Riley C]

Hey guys I know there is no way to tell hours other than meter.

I have also got some poor pics inside the bores. All the cross hatching is there, not much scoring at all.

Would this mean it hasn't done 700 hours? The hatching is still profound. The rest of the engine is like it's brand new, maybe it the gauge of the previous engine also. Last owner didn't have it long so couldn't tell me what the first owner did.

Is there a way to see by hatching if the engine has done an approximate?

 

[Faztbullet]

Cross hatching is not a good indicator of anything...bore can be worn and still have crosshatch. Luckily a 60° block will hold it shape pretty dang good.Only thing to worry about is the block becoming a leaker.

 

[Riley C]

Cross hatching is not a good indicator of anything...bore can be worn and still have crosshatch. Luckily a 60° block will hold it shape pretty dang good.Only thing to worry about is the block becoming a leaker.

Thanks Fazt,

when you say leaker you mean from power head seals?

The compression is good on this, 100-105psi warm test on all six. I haven’t done a leak down test before.

I believe OMC deliberately had the blocks at lower compression on purpose?

none the less the fuel system holds well now. No more air or VRO cap leaks and warped bowls fixed.

 

[flyingscott]

He means the casting flaw that about 25% of those blocks have. Watch for.water intrusion on the #1 cylinder.

 

[Riley C]

He means the casting flaw that about 25% of those blocks have. Watch for.water intrusion on the #1 cylinder.

flyingscott,

Thanks for that, I will keep an out for it.

Is there anything else to watch out for on the 60degree?

i don’t run with ethanol but previous owner may have. Does this affect the fuel diaphragm or were the 1998 models ok with running it?