3 problems: Fuel mist from oil line, overheating, and fuel leak re: 1989 v6 150 2.0L

[pjbrownva]

I say I'm close, because I think the only work left is to replace the gaskets under the power head and by the exhaust plates, and then drill, tap and repair the stripped bolt holes using helicoils, at which point I hope to be 100%

More updates later this spring!

It's alive!!!! I pulled the power head, and replaced all of the gaskets... this time with the correct one's in the correct places.
I drilled and tapped the stripped threads, and diligently installed helicoils where needed. For some holes, I put in two helicoils, so that that the bolt
would have a longer surface to grip.

When all was said and done, IT WORKS!!!! -- and quite well at that!

Easy to start, runs well, good power!

I've been out 3 times now, and no issues!

Thank's Scream & Fly... It was a lot of work, but I'm soooo happy to have it done...

And thank you everyone for the good advice, insights and parts.... I really appreciate it!

-Phil

[sizzler]

It's alive!!!! I pulled the power head, and replaced all of the gaskets... this time with the correct one's in the correct places.
I drilled and tapped the stripped threads, and diligently installed helicoils where needed. For some holes, I put in two helicoils, so that that the bolt
would have a longer surface to grip.

When all was said and done, IT WORKS!!!! -- and quite well at that!

Easy to start, runs well, good power!

I've been out 3 times now, and no issues!

Thank's Scream & Fly... It was a lot of work, but I'm soooo happy to have it done...

And thank you everyone for the good advice, insights and parts.... I really appreciate it!

-Phil

Hi Phil,

I finally found a thread discussing my exact problem - gas mist coming from the check valve/oil pressure fitting on the lower starboard side of the block. This is my second with the oil injection removed, and both had no cap/seal placed over the valve end, so I've assumed it needed to be allowed to breath. Some gas mist escaped from the prior block, but not as much as the current one, which sounds just like what you described. It seems your problem went away, but I can't seem to identify what fixed it, or what ultimately came to be your final understanding of what should be with this.

What's up with this?

Thanks,
MG

[Merc 2.5]

They r bleed lines and should b hooked up , it recirculates unused fuel and also oils upper and lower bearing

[pjbrownva]

Hi Phil,

I finally found a thread discussing my exact problem - gas mist coming from the check valve/oil pressure fitting on the lower starboard side of the block. This is my second with the oil injection removed, and both had no cap/seal placed over the valve end, so I've assumed it needed to be allowed to breath. Some gas mist escaped from the prior block, but not as much as the current one, which sounds just like what you described. It seems your problem went away, but I can't seem to identify what fixed it, or what ultimately came to be your final understanding of what should be with this.

What's up with this?

Thanks,
MG

Can you post a photo with an arrow (or your finger) pointing to the valve where the mist is coming out?

That way I can be sure I know what you're referring to.
@Merc 2.5 is spot on about the bleed lines needing to be hooked up. We can likely post a diagram for your motor if you don't have a factory service manual, but let's start by confirming with a photo exactly what you're referring to.

-Phil

[pjbrownva]

If you're talking about the large tube on the starboard side, that is supposed to pressurize your oil injection system.
I'm not sure what you do if you delete the oil injection... meaning leave it open, put a hose on it and plug it, or put some type of
valve on it. You'll have to read up on that.

Regarding the spray coming out of that port, you are correct. That's exactly one of several problems I had when rebuilding my motor.
Although I repaired and replaced MANY PARTS during my rebuild, here are my top three guesses of which repairs most likely fixed the fuel
mist problem you speak of.

1) Replacing worn out needle valves and needle valve seats in the carbs, and properly adjusting the float valves to ensure that the needle valves are fully closing.

-- With a worn needle valve or valve seat, or a float that's mis-adjusted so that the fuel flow isn't shut off properly within the carb, you'll have excess fuel and oil coming out of some of the carbs. That excess fuel and oil has to go somewhere, and it could be the cause of the mist you're seeing. This problem would also give you poor fuel economy because you're pumping extra fuel that's not needed. I don't know how much of this extra fuel would get recycled through the bleeder lines, but that's a possibility... although I also don't know if the fuel is somehow burned once it flows through the bleeder lines, or what happens to it. I suppose you could say ignorance is bliss?

2) Bad, Clogged or stuck open One-way valves for the bleed lines

There are multiple (more than 6, I THINK) bleed lines. Their purpose is to remove excess oil from the fuel and air intake area, and pump that oil to other parts of the engine where they can lubricate parts such as your engine bearings.

Each bleeder line has a one-way valve screwed into the motor at one of the two connections. The one-way valve opens to allow the oil to be pushed a little bit through the bleeder line when there's pressure, and closes when there's suction so that the same oil won't be sucked back in.

If the valves are worn out, clogged, or stuck open, then this won't work, and the oil will just slosh back-and forth through the line without being removed. This could cause excess oil to show up as a mist through that port. It also would prevent certain parts from receiving the lubrication that they were designed to receive. I guess bad bleeder tubes themselves, or cracked ones could also be a problem, but I don't know that could cause your symptom. Certainly a clogged line or clogged port would cause the same problem.

3) Cleaned out the exhaust chest behind the exhaust divider plate, and the inside of the exhaust divider plate itself, replacing the round "spaghetti" seal in the middle, and the exhaust divider plate gasket while I was at it.

My motor never ran properly until after I had done this. When I removed the exhaust divider plate (it's in the back of the motor. The plate between the two piston head covers) there were thick amounts of caked-up soot all over the place, and I suspect it had built up to the point where it was impacting the exhaust flow. Maybe the extra oil floating around didn't help, and caused extra build up. I don't know, so may this part is spot on, or maybe it's BS. :-) ... but cleaning out the exhaust chest, installing the rubber seals *correctly* on the two thermostats, and properly rebuilding the poppet valve with new parts and a new gasket were the last three steps I took (out of many, many steps) before my motor finally ran correctly.

i don't think that the thermostat and poppet valve contribute to the fuel and oil spray issue, but I suspect that excessive soot buildup in the exhaust divider plate can be or contribute to the problem. If the engine can't get it's exhaust out properly, it can't take in air properly, and so it's possible that you might end up with excess fuel and thus excess oil hanging around near the intake area.

Hopefully this advice helps. I don't have advice on how to diagnose these problems... maybe the factory service manual can help... because often it's best to diagnose the cause of your problem, so that then you can concentrate on fixing what's wrong.

In my case, I was rebuilding a old motor that sat for about a decade and had known problems, so my motto was, when-in-doubt, replace, repair or rebuild... but I was focused on doing a rebuild and ending up with a (hopefully) reliable motor, so I didn't mind cleaning, adjusting, repairing and replacing parts that *might* be causing a problem, because then I would feel comfortable that these parts were then less likely to be a future problem, even if they weren't causing problems right then -- I guess that's the difference in mindset in doing a repair vs trying to refurbish an old motor that's not working right.s.

Good luck, and feel free to use this thread to update us (if the mods are oK with that). I eventually corrected all of the issues I posted about in this thread, and am a happy boater now, so i'm fine if you post here, unless the SnF gods frown on that and would prefer that you open a new thread.

-Philip

[sizzler]

Thanks very much, Philip! All three suggestions are intriguing. I wonder, though, did you replace THIS check valve, the one all the gas is misting out of? It seems from it's availability that it must need replacing/must get replaced fairly often. I don't recall you mentioning replacement of it, but since you have been quick to replace parts... Maybe I just need to replace this thingamajig?

I've come across a couple of oil-injection removal instructions that say to cap or plug this check valve, so I'm almost comfortable doing it. What concerns me is that maybe the misting is a symptom of another problem that I needs to be addressed. But maybe its totally normal. I guess that is another question I would appreciate chiming in from any who know.

My engine's story is very similar to yours, by the way. I found a replacement block that had been sitting for 9 years, though very well cared for in a spotless garage. It runs great, but the fuel mist, aside from it being disconcerting for the reasons mentioned, causes a very unwelcome slick on the water at the dock.

Thanks again.
MG

[Merc 2.5]

Post a pic of the issue

[sizzler]

Hey sorry haven't posted a photo - 55 miles away from it all until Friday....

[pjbrownva]

Thanks very much, Philip! All three suggestions are intriguing. I wonder, though, did you replace THIS check valve, the one all the gas is misting out of? It seems from it's availability that it must need replacing/must get replaced fairly often. I don't recall you mentioning replacement of it, but since you have been quick to replace parts... Maybe I just need to replace this thingamajig?

I've come across a couple of oil-injection removal instructions that say to cap or plug this check valve, so I'm almost comfortable doing it. What concerns me is that maybe the misting is a symptom of another problem that I needs to be addressed. But maybe its totally normal. I guess that is another question I would appreciate chiming in from any who know.

My engine's story is very similar to yours, by the way. I found a replacement block that had been sitting for 9 years, though very well cared for in a spotless garage. It runs great, but the fuel mist, aside from it being disconcerting for the reasons mentioned, causes a very unwelcome slick on the water at the dock.

Thanks again.
MG

If it's the port that I'm thinking of, then that port doesn't have a vacuum valve at that location. There are two vacuum relief valves that are part of the external oil tank system, but that port is open, and a hose goes from the mota to the external oil tank. The port produces the the pressure that pressurizes that oil injection system. Then there is once valve that will let air out if the pressure is too high (I think 2 PSI), and another valve nearer to the oil pump that will let air in if there's a vacuum, so that the oil can continue to flow.

[sizzler]

[pjbrownva]

Thank you @sizzler. I stand corrected on my statement (so I was wrong), but only partially corrected on the likely impact.

So, the short answer is that I'm unsure... but I'll try my best to help. Anyone who knows more, or who can help test on a known-good engine, please jump in or help out where you can.

Here's what I can contribute...


Start by checking that one-way valve, to confirm it's working. I'd probably remove it, put a hose on it, and try blowing and sucking, or use a pump or something else to help test. Be careful not to use too much pressure. If it can hold 3 or 4 PSI, then I'm sure it's good, since a different valve (#2 mentioned above) vents the pressurized system at 2 PSI.

If the valve is bad, replace it and see what happens.
If the valve is good, then it's not the cause of the mist.

Anyone with more knowledge please chime in!

As the attached oil injection system diagram shows:



(The diagram shows 3 pressure valves...

1) the one you pictured lets air flow out of the engine block allowing that value to pressurize the remote oil tank, but doesn't let the air flow back into the engine, ensuring that the oil tank stays pressurized.

2) the one in the top left of the diagram, vents if the pressure is more than 2 PSI, so it keeps the pressure at or below 2 PSI (more or less). I don't know if it acts as a regulator to regulate the pressure, or whether it acts as a safety valve to prevent over-pressurization if there is a problem... I guess that detail doesn't really matter, as long as you don't have oil dripping out of the vent line it's attached to.

3)the one by the middle of the picture where the oil flows to be mixed with the fuel is a backflow preventer. It's there to make sure that oil can flow to mix with the fuel, but fuel won't flow the other way and start to travel up the oil line or mix with the oil in the oil supply line and possibly the oil reservoir too.)

So the purpose of the port we're focused on is to pressurize the remote oil tank system. It *does* have a one-way valve whose purpose is to see that the port only only produces air flow to pressurize the remote oil tank and doesn't provide suction that would remove the pressure.


:-)

Phil

[pjbrownva]

Did I replace this valve?
I know I bought a replacement,
I don't recall if I ever installed it,
but I do know that something other than replacing that valve fixed the fuel mist problem I was having.


Here's some new info:

Bleed line diagram for carbed engines:



From the diagram, it appears most likely that the piston side of the bleed line is providing suction to "pull" excess oil and fuel from the crankcase through the bleed lines and into the cylinders to be burned.

So... remove and test the valve that you posted an image of. If it's bad, then it is letting air into the crankcase at the same time as at least some of the cylinders are providing suction to the crankcase through the bleed lines, and *maybe* this causes the excess oil and fuel to remain, instead of being sucked into a cylinder to be burned.

So first, check the valve, and replace it if it's bad.

Once you know the valve is good, then if fuel still sprays out of the valve with the valve open to the air, then your problem has a different causes... my first guess would be a needle valve not fully closing in one of the carbs, but that's only guess, and there could be other causes, but the one-way valves on the bleeder hoses are probably easier and less time consuming to check.

[pjbrownva]

More info:

Another way to check the valve, is by putting a hose on it, and seeing if it produces at least 2 PSI of pressure when the engine is running... assuming you have a way of checking that.

(See last line of trouble shooting chart below)

Attachment 440773

Also, here's clarification on the other check valves and their purpose.
I was wrong about one of them.

The one listed as #7 (see attachment below)



is a 4 PSI check valve, that opens to let air into the system
to prevent the oil injection pump from creating suction if the oil supply hose from the remote
oil tank becomes blocked and won't let oil flow.


-Phil