1971 SSwirl omc stringer buick v6 fuel vapor coming out valve cover vents

[1971seaswirlOMCstringer]

I have a 1971 seaswirl with an OMC stringer outdrive and a buick v6. From my research I believe it's the 215cu 150hp.
Long and short of it, I've rebuilt the outdrive minus he lower unit which seems to be in perfect running order. I've also solved the overheating issue as it was overheating when I got it, wasn't shifting, intermittent electrically, and running rich and backfiring. Had a water leak at the exhaust manifold, repaired, Yada Yada. A small amount of water is coming out of the gasket seal at the bottom of the carburetor accumulating just underneath it at the top of the motor (just above/behind the water pump. And the bigger issue is that there seems to be a high amount of fuel vapor coming out the valve cover vents. I want to know more certainly what may be causing it so I can zero in on the problem. Anyone have any experience with this?

 

[HT32BSX115]

Re: 1971 SSwirl omc stringer buick v6 fuel vapor coming out valve cover vents

there seems to be a high amount of fuel vapor coming out the valve cover vents. I want to know more certainly what may be causing it so I can zero in on the problem. Anyone have any experience with this?

Howdy,

Welcome Aboard!


If you have a LOT of fuel vapor smell in the oil or breather, you might take a look at the small clear hose that runs (or should run) from the fuel pump to the carb.

That hose is there to port most of the gasoline from the "engine-side" of a mechanical fuel pump to the carburetor when the diaphragm starts leaking. If you do not have the hose, it's possible that someone replaced the pump with an automotive type pump making it an even more dangerous situation!


That's the sign of a fuel pump failure and it should be replaced immediately.


Regards,


Rick

 

[HT32BSX115]

Re: 1971 SSwirl omc stringer buick v6 fuel vapor coming out valve cover vents

As an aside,

I looked at http://epc.brp.com (BRP parts site)

And looked at the parts list for a 71 stringer. I cannot tell if it had a hose for the fuel pump like newer ones have. It's possible that they didn't do that in those days. Either way, if the pump is leaking fuel into the oil, it needs to be replaced.

 

[1971seaswirlOMCstringer]

Re: 1971 SSwirl omc stringer buick v6 fuel vapor coming out valve cover vents

Thanks de Rick. I'm going to start investigating that and will reply again.

 

[Howard Sterndrive]

Re: 1971 SSwirl omc stringer buick v6 fuel vapor coming out valve cover vents

high amount of fuel vapor coming out the valve cover vents.

do you mean oil vapour? or maybe steam?

I can't imagine you would have so much gas in your oil that fuel would be vapourizing in the crankcase. Although you said it was running rich. Change the oil and be careful. People have blown oil pans off engines when they're full of gas instead of oil from a flooding carb or way too much cold cranking.

 

[wrench 3]

Re: 1971 SSwirl omc stringer buick v6 fuel vapor coming out valve cover vents

My first thought on the vapor was blow-by from worn piston wrings. Possibly from the overheating.
The fuel pump on that year probably has what looks like a glass filter bowl attached to the side of it, that is supposed to be checked regularly for fuel that would indicate a leaking diaphragm.

 

[1971seaswirlOMCstringer]

Re: 1971 SSwirl omc stringer buick v6 fuel vapor coming out valve cover vents

I have replaced temporarily the glass filters with cheesy auto part store ones till I get new clean filters. Yes, there's fuel vapor for sure venting from the valve cover gasket. The system was overheating bad when I got it. They had reversed the manifold water supply hoses off the thermostat housing. So, while it was trying to suck cold water in it actually was getting the exhaust ( and sending it the wrong way). In the other hose, where it intended to send out exhaust water, it was just sending more exhaust it's my guess, thus overheating the system immediately and pretty bad. So, rings are definitely being considered. I don't believe there's a mechanical fuel pump. Looks like an old vacuum style. Investigating hose setup right now. If it is running too rich, could that result in excess fuel vapor? Thanks

 

[1971seaswirlOMCstringer]

Re: 1971 SSwirl omc stringer buick v6 fuel vapor coming out valve cover vents

I don't see any hoses aside from the main fuel supply hose going to the carb from the fuel pump. I do see the fuel pump now so, I was wrong about that. I'm going to upload a pic of the existing fuel pump.

 

[1971seaswirlOMCstringer]

Re: 1971 SSwirl omc stringer buick v6 fuel vapor coming out valve cover vents

I don't see any hoses aside from the main fuel supply hose going to the carb from the fuel pump. I do see the fuel pump now so, I was wrong about that. I'm going to upload a pic of the existing fuel pump.

Pics of carb and fuel pump

 

[Silvertip]

Re: 1971 SSwirl omc stringer buick v6 fuel vapor coming out valve cover vents

I have a 1971 seaswirl with an OMC stringer outdrive and a buick v6. From my research I believe it's the 215cu 150hp.
Long and short of it, I've rebuilt the outdrive minus he lower unit which seems to be in perfect running order. I've also solved the overheating issue as it was overheating when I got it, wasn't shifting, intermittent electrically, and running rich and backfiring. Had a water leak at the exhaust manifold, repaired, Yada Yada. A small amount of water is coming out of the gasket seal at the bottom of the carburetor accumulating just underneath it at the top of the motor (just above/behind the water pump. And the bigger issue is that there seems to be a high amount of fuel vapor coming out the valve cover vents. I want to know more certainly what may be causing it so I can zero in on the problem. Anyone have any experience with this?

There is no 215 Buick V6. That engine started life as a 198 CI, went to 225, 231 and and in its later auto applications 251 CI. There was a 215 CI aluminum V8 in small Buicks and Oldsmobiles of the day but it didn't appear as a marine engine (at least that I'm aware of).

 

[Howard Sterndrive]

Re: 1971 SSwirl omc stringer buick v6 fuel vapor coming out valve cover vents

how is this vapour being identified as fuel? by smell? you are capturing it on a paper towel and lighting it?

If you run an engine for long with that much gas in the crankcase, you will damage the engine bearings. Explosion hazard too.

 

[wrench 3]

Re: 1971 SSwirl omc stringer buick v6 fuel vapor coming out valve cover vents

That is an automotive fuel pump. GET IT OFF OF THERE! If the diaphram leakes on it, it will fill your engine compartment with fuel. Verry verry bad!

 

[bigdirty]

Re: 1971 SSwirl omc stringer buick v6 fuel vapor coming out valve cover vents

uh, ya.. that looks automotive to me as well... DANGER! DANGER! My 81 chris (omc powered) had a similar 'looking' pump, but with a small glass bowl sticking off the side of it... i would think thats what is supposed to be on there...

 

[Boomyal]

Re: 1971 SSwirl omc stringer buick v6 fuel vapor coming out valve cover vents

uh, ya.. that looks automotive to me as well... DANGER! DANGER! My 81 chris (omc powered) had a similar 'looking' pump, but with a small glass bowl sticking off the side of it... i would think thats what is supposed to be on there...

Marine fuel pumps, with the glass bowl have a double diaphragm. That bowl accesses the space between the diaphragms. If one ruptures, the bowl fills with gasoline. Auto pumps do not have the dual diaphragm and a rupture can send gasoline flowing into the crankcase. Ka.....Boom!

 

[xjdriver]

Re: 1971 SSwirl omc stringer buick v6 fuel vapor coming out valve cover vents

is there gas in the oil???

 

[Silvertip]

Re: 1971 SSwirl omc stringer buick v6 fuel vapor coming out valve cover vents

The picture showing the carb and the flame arrestor definitely shows the barb fitting at about the 5 o-clock position for the fuel pump hose. Obviously nothing is connected to it so the current fuel pump is not a marine pump and should not be installed on this engine. The question is asked, "is there fuel in the oil" and it is not being answered. You are sitting on a potential bomb so check the oil, or better yet drain it start from scratch (after you replace the fuel pump and connect the hose to the flame arrestor).

 

[wrench 3]

Re: 1971 SSwirl omc stringer buick v6 fuel vapor coming out valve cover vents

The automotive fuel pump has an oil seal between the diaphragm and the crankcase, and vent holes in the pump housing. I don't say that gas couldn't get into the crankcase but it would definitely be spraying all over the bilge.

 

[1971seaswirlOMCstringer]

Re: 1971 SSwirl omc stringer buick v6 fuel vapor coming out valve cover vents

No gas in the oil, no fuel spraying/leaking into bilge. Yes, there was a 215 and a 225 buick v6 in 1971. This is the 215 based on the sn on the motor and through my conversations with various suppliers. I took apart the carb, found the gaskets backwards, etc... Explains ALOT but I haven't been able to do any real testing till I get it to the bay again on Saturday. I found a rebreather system diagram as you all have advised and from what these boat mechanics are saying out here, it's not necessary. It's just a smog redesign for emission control as of 1972 - burns off the excess exhaust and gums up the carb - makes system less efficient but probably negligible. Working right now, will update again later

 

[xjdriver]

Re: 1971 SSwirl omc stringer buick v6 fuel vapor coming out valve cover vents

Prolly just blow- buy

 

[1971seaswirlOMCstringer]

Re: 1971 SSwirl omc stringer buick v6 fuel vapor coming out valve cover vents

Blow-by, I agree. Doing rebreather setup. you're all prolly right about it being the best move. Going to replace the fuel pump as well. Thanks everyone, definitely making progress.