PCV Tubes route to the flame arrestor in a boat???

[alamantia]

I just picked up my first boat last week. Its a 1987 Wellcraft Elite 222 with a 260/350 and Alpha 1, everything is origional. As you can probably imagine with a 25 year old boat motor, I am guessing that despite how smooth it runs the rings cant be as good as they were in the Reagen administration and the oil on the flame arrestor tells me that I am probably right. How come boats have breather tubes running crankcase crap back thru the carb? This seems stupid to me, which tells there there must be some boat knowladge that I am missing here... What am I missing here? Can I simply route the pcv tubes into the exaust bellows somehow. Would water blow bach thru the tubes into the heads? Did I just answer my own question? Does someone make a bellows with a tube tube to attach the pvc tube to?

 

[Don S]

Re: PCV Tubes route to the flame arrestor in a boat???

I just helps keep the oily/smelly fumes out of the engine compartment and the rest of the boat. Unlike a car that has air circulating over the engine and out the bottom, a boat has an enclosed engine compartment.

You don't want it into the exhaust, with the back pressure you would probably get water and moisture in the engine. Not all those fittings are PCV, most are just open fittings.

 

[scoflaw]

Re: PCV Tubes route to the flame arrestor in a boat???

Does your boat have a PCV valve? If it does, maybe its plugged up. The hose your looking at, with the blowby coming out, is supposed to be drawing in fresh air to work with the valve. If no PCV valve, yeah it's just venting crankcase fumes.

 

[alamantia]

Re: PCV Tubes route to the flame arrestor in a boat???

Na, they are just vent tubes, the "pcv valves" are hollow. These hollow valves are snug in the valve cover grommets and clamped to hoses that are routed up to the flame arrestor.

Its not like a conventional pcv valve that you can shake and it rattles and has a vaccume hose to the manifold.

My drag car has hoses coming from the valve covers that go thru tubes routed to the headder collectors, I figured that would be a better way to go with a boat too.

 

[Don S]

Re: PCV Tubes route to the flame arrestor in a boat???

Your drag car doesn't run water through the exhaust either. No need to re-invent the wheel, boat have worked like this for many years now.

 

[alamantia]

Re: PCV Tubes route to the flame arrestor in a boat???

The engine craves cold clean air, not contaminated hot air. I will have to clean the flame arrestor of oil they way it is set up. The exhaust in my drag car creates a vaccume like a venturi valve which helps pull the crankcase air out thru the collectors, not the other way around. I am not sure that the water would blow back into the heads. Yeah they have been this way for years, but that doesnt explain to me why. I am just saying it doesnt make sence to me, and I think there could be a better way to do it. I could be wrong, I am just saying I dont understand and I am curiouls if anyone else on here has tried routing the tubes through the exhaust or if there is a kit or part to do so. Its not a bidg deal, it seems to run fine, its more me being inquisitive.

 

[Bondo]

Re: PCV Tubes route to the flame arrestor in a boat???

I am curiouls if anyone else on here has tried routing the tubes through the exhaust or if there is a kit or part to do so. Its not a bidg deal, it seems to run fine, its more me being inquisitive.

Naw,... Kits to reinvent the wheel don't sell so good,...











No market for 'em...

 

[ziggy]

Re: PCV Tubes route to the flame arrestor in a boat???

and the oil on the flame arrestor tells me that I am probably right.

probably so. fwiw. i've had my boat safety inspected by the uscg aux. 2 years in a row. both times one of the first things they went after was a dirty flame arrestor. even though mine was clean. i clean it fairly often. anyways. point is, i assume they all get dirty and so does the uscg aux obviously..

i did me a google search. this was one of the many descriptions i came up with.. http://www.britishv8.org/Articles/Positive-Crankcase-Ventilation-PCV.htm
imho, hard to disagree with Don S. why reinvent the wheel.. just keep it cleaned up..

 

[alamantia]

Re: PCV Tubes route to the flame arrestor in a boat???

Bond-o. With all due respesct thats a stupid reply. I just joined the forum to learn. Not be mocked. Making improvements on existing ideas is the foundation of progression. Do you know why i dont route my breather tubes down the carb of my drag car? Its because i dont want it to run worse, i want it to run at its best. Id like my boat to run at its best. I know very little about boats. But i do know an engine wants cold clean air, and this setup could be improved upon and since this all new to me i figured i would ask. Nevermind.

 

[alamantia]

Re: PCV Tubes route to the flame arrestor in a boat???

probably so. fwiw. i've had my boat safety inspected by the uscg aux. 2 years in a row. both times one of the first things they went after was a dirty flame arrestor. even though mine was clean. i clean it fairly often. anyways. point is, i assume they all get dirty and so does the uscg aux obviously..

i did me a google search. this was one of the many descriptions i came up with.. http://www.britishv8.org/Articles/Positive-Crankcase-Ventilation-PCV.htm
imho, hard to disagree with Don S. why reinvent the wheel.. just keep it cleaned up..

Good info, thank you for the reply

 

[Lyle29464]

Re: PCV Tubes route to the flame arrestor in a boat???

Older engines can get pits in the pulleys. This will eat at your belts and of course help plug the flame arrestor.

 

[tpenfield]

Re: PCV Tubes route to the flame arrestor in a boat???

The PCV tube are fine as they are (i.e. leading right up the the spark arrestor) . As you learn more about boat engine set-ups I believe that you will come to agree.

As far as the rings . . . a compression test might be in order, but if the boat has fairly low hours (less than 700) the rings may be fine.

Have you gotten it out on the water for a test run? If so, did it seem to run well?

 

[scoflaw]

Re: PCV Tubes route to the flame arrestor in a boat???

Why would you compare a 25 year old boat to a drag car? At best, it's more compareable to your daily driver. How is the crankcase pressure handled on that? 99% of the cars on the road have a PCV system, with all that hot crap going down its throat.

 

[alamantia]

Re: PCV Tubes route to the flame arrestor in a boat???

Tpenfield

I looked for a boat last summer but whatever I found I couldnt afford, this came along the same week I recieved my christmas bonus and I got a great deal on it. I never did take it on the water, for the money I am willing to take the risk. Its been on the same lake all its life and it starts right up and purrs like a kitten, real clean interior and the hull appears in good condition, no smoke thru the exhaust a little up thru the pcv tubes, as for rings, Im sure they arent optimal, I have 2 small block chevys I could finish off if I need one, getting it in and out of the boat would be more of a concern though.

 

[alamantia]

Re: PCV Tubes route to the flame arrestor in a boat???

Why would you compare a 25 year old boat to a drag car? At best, it's more compareable to your daily driver. How is the crankcase pressure handled on that? 99% of the cars on the road have a PCV system, with all that hot crap going down its throat.

I dont own a car with a PCV system, I have a newer Tahoe. The camaro is carberated and does not require emissions like a boat and I was using tha analogy as a basis for my question.

 

[Don S]

Re: PCV Tubes route to the flame arrestor in a boat???

I know very little about boats. But i do know an engine wants cold clean air, and this setup could be improved upon and since this all new to me i figured i would ask. Nevermind.

Like everything else in life, most things are a compromise. Your engine gets cold clean air through the air vents and leaks around the hatches, engine covers etc. But there need to be a way to get rid of the oil fumes and oil particles developed by your engine. As noted in you ziggies article, all engines have blow by. In boats it can be even more of a problem. Engines ge water in then from many sources, sitting for years being one of them. 100's of posters have had engines that are frozen and won't turn over because of rusty cylinder walls and the rings are rusted to the cylinder. There are also those that do this and get the engine running. Do you really think that those rings, pistons, and cylinder walls are still in perfect shape? I don't but off they go thinking they have an engine that will last for ever.
Marine engines use the exhaust as a way to get the cooling water out of the system, not even close to what a drag car does. Air does not cool these engines in any way shape or form, water does. They normally don't have antifreeze systems either, just raw water cooled. Either way, there is water in the exhaust and you DO NOT want to have your valve covers hooked to a water supply.

Until you understand the cooling and exhaust systems in a boat, you are going to have even more problems understanding what is going on.

Here is a link to the OEM service manual for your engine. Download it, read and understand how your cooling and exhaust system work together, then you will have a better understanding of what we are trying to say. http://www.4shared.com/document/LXsFg1do/Service_Manual_09.html


You also need to stop with the drag care comparison. They have a V8, after that, there is a big difference between automotive and marine.


Here is what your cooling system probably looks like, do you understand what it's saying?

View attachment #9 GM V8 All 85-88 568.pdf

 

[alamantia]

Re: PCV Tubes route to the flame arrestor in a boat???

Like everything else in life, most things are a compromise. Your engine gets cold clean air through the air vents and leaks around the hatches, engine covers etc. But there need to be a way to get rid of the oil fumes and oil particles developed by your engine. As noted in you ziggies article, all engines have blow by. In boats it can be even more of a problem. Engines ge water in then from many sources, sitting for years being one of them. 100's of posters have had engines that are frozen and won't turn over because of rusty cylinder walls and the rings are rusted to the cylinder. There are also those that do this and get the engine running. Do you really think that those rings, pistons, and cylinder walls are still in perfect shape? I don't but off they go thinking they have an engine that will last for ever.
Marine engines use the exhaust as a way to get the cooling water out of the system, not even close to what a drag car does. Air does not cool these engines in any way shape or form, water does. They normally don't have antifreeze systems either, just raw water cooled. Either way, there is water in the exhaust and you DO NOT want to have your valve covers hooked to a water supply.

Until you understand the cooling and exhaust systems in a boat, you are going to have even more problems understanding what is going on.

Here is a link to the OEM service manual for your engine. Download it, read and understand how your cooling and exhaust system work together, then you will have a better understanding of what we are trying to say. http://www.4shared.com/document/LXsFg1do/Service_Manual_09.html


You also need to stop with the drag care comparison. They have a V8, after that, there is a big difference between automotive and marine.


Here is what your cooling system probably looks like, do you understand what it's saying?

View attachment 126303

I apreciate the reply, I fully understand the point of a pcv system. Drag cars (like boats) do not comply to emissions as road cars, drag cars have a carb (like boats) drag cars vent crankcase pressure thru valve covers (like boats) therefore I am using my car as a comparison to my boat. The point I am trying to make is that there are 3 ways to vent crank case pressure here.

1) Tubes that recirculate right back thru the carb, which is what I have on my boat

2) Breathers to the engine compartment, which cars prior to 1974 have.

3) Tubes out the exhaust which is what I have on my drag car.

Of all 3 listed

#1 is less efficent and requires cleaning of the flame arrestor

#2 you cant do in a closed compartment on a boat

#3 draws crankcase pressure out without reburning it and saves cleaning of oil from the flame arrestor

To me #3 sounds like the best option, dont you think?

On my drag car, there are tubes between the valve cover and the exhaust, because the flow of combustion exhaust created by the engine far surpasses the flow of crankcase exhaust creating a vaccume thus assisting pulling out the crankcase pressure. Not backflowing it, so in a boat I dont know how water would get into the head.

In all the ways you should not compair a car to a boat, my origional question about routing crankcase (PCV) tubes has 3 variables,

crankcase pressure

a carburator

exhaust pipes


Since both vehicals have the same 3 varibles this princaple applies equally. So my question is valid. So far the best answer I have gotten is that thats just the way it is, and only theroy that water would go back into the head, which I wouldnt think it would if you look at it like a venturi principal.

Not arguing, just saying it doesnt make sence to me. I apreciate all of the insight. I also apreciate the diagram of the water routing, I kinda suspected thats how it worked, If you route the pcv tubes to the bellows it doesnt interfere with the cooling system.

Thanks.

 

[Don S]

Re: PCV Tubes route to the flame arrestor in a boat???

You shouldn't have to clean a flame arrestor more than once a year during your other yearly maintenance items, and they usually aren't plugged up then. If you do have to clean them more often, then you need to find out why it's getting clogged, and cure the problem.

If you hook your valve covers into the exhaust system, you WILL get water in your engine. This is a boat, not a drag car so stop comparing the two.

 

[alamantia]

Re: PCV Tubes route to the flame arrestor in a boat???

Fine. Not a drag car. Any other vehical where combustion is routed thru the exhaust then. Its better to have clean air go thru a carb than non clean air. Do you know how a venturi valve works? If so. How would water get back into the head?

 

[alamantia]

Re: PCV Tubes route to the flame arrestor in a boat???

Crankcase evacuation system. Thats the name of what i am talking about. I googled it to find out there are kits availabe with check valves. That makes sence now. I wonder if i can find a kit to work with my boat. If its inexpensive i will like to try it. Well see i guess.