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Valve cover leak

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JimF
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Valve cover leak

Post by JimF » Tue Apr 08, 2014 9:15 am

IMG_0709.jpg
I have a 283 (flywheel forward) that leaks oil from the rear (lowest) corner only after running at medium RPMs for a while. It does not leak when sitting or idling. It appears that it is not only leaking but that it is actually blowing small amounts of oil under pressure as there is oil on the side of the motorbox. Obviously I need to remove and re-gasket the cover but do these engines normally build up pressure in the valve cover? There is no vent in the top of the valve cover like my 350. The 350 has a hose to the carb air intake to suck up fumes I suppose.
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1930 Chris-Craft Model 100 20' "MOXIE"
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Re: Valve cover leak

Post by mfine » Tue Apr 08, 2014 10:12 am

I believe these had a crank case breather line coming off the front of the engine to the flame arrestor rather than off one of the valve covers. I can't see that in your photo, but I also don't see a bunch of other critical parts that would normally need to be there for you to be running the engine.
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Re: Valve cover leak

Post by JimF » Tue Apr 08, 2014 2:38 pm

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OK. I cheated slightly and used a picture of the engine before it morphed from a 283 to a 327. There appears to be no breather but there is a small brass in front of the carb. Would this be for the breather? So am I right that pressure is building up in the valve cover? Do you see other places that might be missing parts?
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1930 Chris-Craft Model 100 20' "MOXIE"
1940 Chris-Craft Red and White 25' "Old Paint"
1946 Chris-Craft Sportsman 25' "CinCity"

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Re: Valve cover leak

Post by mfine » Tue Apr 08, 2014 3:45 pm

If we are looking at the same brass plug that is a vacuum port which you don't want to open.

The parts I noticed missing in the first photo were major items such as a carb, drive shaft, exhaust hoses etc. and on first blush the new photos look more complete. You don't seem to have any type of venting so, yes, I would assume there is going to be pressure and it is going to escape at the weakest point which it seems is your valve cover gasket (luckily cheap and easy to replace).

I see you have aftermarket exhaust logs and I assume you are not looking for a showboat 100% original install so you can get a set of cheap valve covers with vents and either let it vent into the carb or setup a PCV system with an air input and a positive suction.
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Re: Valve cover leak

Post by mfine » Tue Apr 08, 2014 3:50 pm

I am having a hard time posting photos, so I will try in a separate post, but my setup has a PCV valve on one cover going to the vacuum port (smaller line on near side) and the other cover has air intake and a convenient oil fill location (big chrome pieces).

Edit: Never mind, the pic finally showed up above.

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Re: Valve cover leak

Post by JimF » Tue Apr 08, 2014 4:28 pm

283.jpg
I found this on the internet and it looks like what I have. Could that be a PCV valve screwed into the intake manifold and then a rubber hose to the flame arrestor?
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1930 Chris-Craft Model 100 20' "MOXIE"
1940 Chris-Craft Red and White 25' "Old Paint"
1946 Chris-Craft Sportsman 25' "CinCity"

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Re: Valve cover leak

Post by JimF » Tue Apr 08, 2014 4:32 pm

get-attachment.aspx.jpeg
I took a picture of my other engine and the piece looks identical to my internet picture.
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1930 Chris-Craft Model 100 20' "MOXIE"
1940 Chris-Craft Red and White 25' "Old Paint"
1946 Chris-Craft Sportsman 25' "CinCity"

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Re: Valve cover leak

Post by 68 cavalier » Tue Apr 08, 2014 5:45 pm

Hi jim. I have a 1968 283. From the pic's it look's like you dont have a pvc valve. On my engine a copper tube goe's from the front of the block, (where on a car engine,, the distributor would go.) to a pvc valve that is screwed into the intake in front of the carb. I would also make sure the oil filler cap isnt plugged. is that the original intake manifold? I have some pic's,,not pretty if i can figure out how to send them i will. mike
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Re: Valve cover leak

Post by mfine » Tue Apr 08, 2014 5:54 pm

Jim, Your manifold and that internet one look different than the one in my first picture which is from a 1959 ski boat and I believe to be fairly original. Yours looks like the low profile manifold and the internet picture seems to be the same manifold and it sure looks like they are using that port as a vent but I am not sure that is how CC did it. FWIW, If it vents into the carb intake it is just a CV since the P in PCV means there is positive ventilation from actively sucking clean air into it.

Check out the 10th page of this PDF that is labeled 24...

http://www.sea-way.com/283ccweb.pdf

That looks like your manifold and CC shows a 3/4" pipe plug there. I see no provision for venting in that diagram so it had to be venting somewhere else. Unfortunately the index indicates that is shown on page 36 which is not included in the scan. I would guess CC pulled it off the front cover like they did with the other 283's like in the first pic I posted and Mike's above, but I don't know. There are a ton of ways to vent, and the important part is that you have one and it is working.

I would talk to whomever did the engine work and ask them how they intended it to be venting. They should know. Both of your engines show the port capped off (like the CC PDF) and you do not have the hose port bracket on the flame arrestor so it must be somewhere else not showing in your pics or the builder left it unvented which would be really odd.

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Re: Valve cover leak

Post by JimF » Tue Apr 08, 2014 6:35 pm

Thank you for all the input. For a number of reasons, the guy that assembled the engines is not available. All the internal work was done by a reputable machine shop. I guess my question is this: If I install a PCV valve or even just a brass barbed fitting and a rubber hose to the flame arrestor from that hole in the intake manifold as shown in the internet photo, will that reduce the pressure in the valve covers? If not, could I not find some after market valve covers with openings for tubes to the flame arrester or use those chrome round things (thats a technical term) that fit in the hole of the valve cover? Either way my bilge would look a lot better.
1930 Chris-Craft Model 100 20' "MOXIE"
1940 Chris-Craft Red and White 25' "Old Paint"
1946 Chris-Craft Sportsman 25' "CinCity"

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Re: Valve cover leak

Post by farupp » Tue Apr 08, 2014 7:15 pm

Here is a picture of the 1961 283 engine that is installed in my Sea Skiff. It has a PCV valve located on the starboard valve cover. The PCV Valve hose goes to the base of the carburetor mounting.


283 Engine Forward.jpg
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283 Flywheel Forward engine

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Re: Valve cover leak

Post by jim g » Tue Apr 08, 2014 7:33 pm

JimF wrote:Thank you for all the input. For a number of reasons, the guy that assembled the engines is not available. All the internal work was done by a reputable machine shop. I guess my question is this: If I install a PCV valve or even just a brass barbed fitting and a rubber hose to the flame arrestor from that hole in the intake manifold as shown in the internet photo, will that reduce the pressure in the valve covers? If not, could I not find some after market valve covers with openings for tubes to the flame arrester or use those chrome round things (thats a technical term) that fit in the hole of the valve cover? Either way my bilge would look a lot better.
Ok. Before you do anything. Let me explain what the port does. The hole in front of the carb that you have plugged. That hole is for the PCV valve to go in. Its a round black cylinder about 2 inches long. This regulates the amount of air going into the intake. Its connected to the vent that came off the block by the tach drive. If you hook a hose to the hole you have plug and run it to the flame arrester you will have a MASSIVE intake leak.

Now the more horsepower your engine makes the more positive crankcase pressure your engine will have. After the 283 chevy moved the vent up to the oil filler neck. You can see it on a picture of a chris craft 327F engine. A little later they moved it to the valve covers.

So on your engine you can do one of several things. 1. Is you can live with it as it is. or 2. You can put in crankcase vents. There are 2 ways to go about doing it. You can get a new set of valve covers that have the holes in them for the vents or you can drill and install a special rubber grommet in your old covers. I've attached a link for the type grommet you need. You need to make sure you get the correct one for the thickness of your valve covers.

If you choose to have vents in your valve covers. You can either run the vent hose to the top of the flame arrester or you can run them to the plug hole on the intake. If you choose to run them to the flame arrester. You want the vent that you put into the grommet to be open. ie no valve inside of it. If you choose to run it to the hole thats plug in the intake you have to use the round valve that is shown in the first picture you posted.

Running it to the top of the flame arrester is the easiest because your only dealing with unmetered air. Doing it the other way your dealing with metered air and it can effect the idling of your motor.

Also attached a picture of how I vent the 350 conversions of the chris craft 283's that I do.

Oh also the oil leak you have is not caused by crankcase pressure. Pressure will find easier ways out. Its probably leaking because of one or two things. First one is the flange on the cover has probably been bent upwards from the over tighten the valve covers over there life time. If you keep your old covers you need to make sure the flanges are flat so they push on the gasket enough to seal it. I usually spend about an hour straighten the flanges on each engine I do. The other thing to do is to use a good sealant on both sides of the gasket. Any of the permatex ultra sealants work very good. You only need to put a thin coat on the gasket not half the tube on each gasket.

If you have any questions feel free to contact me.


http://www.summitracing.com/parts/sum-g3413/overview/
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Re: Valve cover leak

Post by 68 cavalier » Tue Apr 08, 2014 7:43 pm

Hi jim. mike here. If you use the barbed fitting idea your engine will not run. ( to spare a long story ! ) A pvc valve is a spring loaded device that restrict's air flow from the crank case depending on how many rpm's the motor is turning. It has to due with intake manifold pressure. Low rpm's the valve is mostly closed. Wide open throttle it go"s mostly open. Working this way it help's with maintaining intake manifold pressure in an rpm range so the air fuel mixture supply to the cylinder's stay's optimized.
If you go with different valve cover's with those "chrome round thing's" you will find your boat smelling like your engine's crank case. Also a pvc valve help's reduce pollution. If it isnt raining tomorrow ill try to get a brand or part number off mine and send it.

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Re: Valve cover leak

Post by mfine » Tue Apr 08, 2014 8:39 pm

If you are going to redo things in a non-original fashion, I would use the PCV valve and not just run a hose or hoses to the intake. The suction on the intake will get most of the fumes, but not all of it like a direct PCV setup. I have both and it is noticeable.

Also, if you go with a PCV I would put the PCV on one side and a breather on the other. The breather is the "round chrome things." Generally speaking the best system has clean air coming in on one side and dirty air going out the other through a PCV valve. See the picture in my second post. On the near side there is a PCV going to the intake manifold. The far side has two "chrome things," one a push in breather and the other is actually an oil fill cap that matches the breather. So, the intake manifold sucks dirty air in through the PCV on the port side and fresh air gets sucked in on the starboard side. This setup has no fume smell or mess like the prior install or my other boat which has passive venting to the air intake. My valve covers were $25, $2 for a PCV valve, and the breather and oil cap were $6 each so a pretty cheap upgrade. You will probably want to add a can of CC blue paint though, unless you are OK with chrome valve covers.

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Re: Valve cover leak

Post by 68 cavalier » Thu Apr 10, 2014 6:32 pm

Jim mike again. I had pulled the pvc valve and other part's to paint today. It was hard to read but i did get some info off it. On the valve it 's printed AC spark plug,,,Type cv-99c. It was hard to read. mike
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Re: Valve cover leak

Post by evansjw44 » Thu Apr 10, 2014 8:01 pm

The original CC PCV system used the CV-99 to control the air flow. If you remove it you have to plug the entry port to the carb or you will have a massive vacuum leak. But note that the original PCV plumbing has an oil mist separator in the lifter gallery so that the PCV doesn't suck up oil mist. If you use a valve cover PCV scheme as the picture shows you need to use valve covers with an oil mist separator or you will be sucking the oil mist under the valve covers. You will have a massive oil consumption problem. Most after market valve covers don.e have the oil mist separator.
Jim Evans

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Re: Valve cover leak

Post by JimF » Sat Apr 12, 2014 1:31 pm

I am traveling this weekend and just got a chance to catch up. Before Ieft I installed new valve covers with one opening in each one. These covers have some sort of baffle under the opening. Mist dispersal? I hope I hope I bought a plain breather (round thing) for one side of the engine. The other breather has a short fitting to connect a 5/&" hose to run to the flame arrester. I could probably fit the PC valve there. How am I doing?
1930 Chris-Craft Model 100 20' "MOXIE"
1940 Chris-Craft Red and White 25' "Old Paint"
1946 Chris-Craft Sportsman 25' "CinCity"

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Re: Valve cover leak

Post by jim g » Sat Apr 12, 2014 3:38 pm

JimF wrote:I am traveling this weekend and just got a chance to catch up. Before Ieft I installed new valve covers with one opening in each one. These covers have some sort of baffle under the opening. Mist dispersal? I hope I hope I bought a plain breather (round thing) for one side of the engine. The other breather has a short fitting to connect a 5/&" hose to run to the flame arrester. I could probably fit the PC valve there. How am I doing?

You only need a PCV valve if you are running the hose into a port on the carb that is below the butterflies. Thats usually at the base of the carb. Also if you were going to run it to the plug off hole in the intake you would need to use a PCV valve. If your running it to the top of the flame arrester do not use a PCV valve.

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Re: Valve cover leak

Post by JimF » Sat Apr 12, 2014 4:09 pm

Sounds like I am there. Still concerned about the oil mist separators.
1930 Chris-Craft Model 100 20' "MOXIE"
1940 Chris-Craft Red and White 25' "Old Paint"
1946 Chris-Craft Sportsman 25' "CinCity"

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Re: Valve cover leak

Post by jim g » Sat Apr 12, 2014 4:14 pm

JimF wrote:Sounds like I am there. Still concerned about the oil mist separators.

The baffle in the valve cover is all you need to keep the oil out of the vent tubes.

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Re: Valve cover leak

Post by mfine » Sun Apr 13, 2014 7:26 am

If you are losing noticeable amounts of oil out of a SBC valve cover vent something else is wrong.

Now the good and the bad of what you have. On the good side, you are vented now so there will be no pressure to pop a gasket or spray oil out of an opening that already popped. On the down side, without the PCV hooked up to a vacuum source, the breather may breath in or out, so you may get fumes in the engine box now. The PCV valve is only a couple of bucks so if you notice an odor issues it is a cheap and easy fix. The other option is to replace the breather with a second hose to the flame arrestor.

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Re: Valve cover leak

Post by JimF » Sun Apr 13, 2014 1:40 pm

This looks good. I think I will try it with one hose from the breather on one side to the flame arrestor and the other side just a plain breather. If it stinks, it is easy to add another hose to the other side. This is a big open utility so there should be plenty of fresh air circulating around. Thank you all for the help!
1930 Chris-Craft Model 100 20' "MOXIE"
1940 Chris-Craft Red and White 25' "Old Paint"
1946 Chris-Craft Sportsman 25' "CinCity"

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Re: Valve cover leak

Post by JimF » Fri Apr 18, 2014 5:11 pm

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To finish the discussion, I have added new valve covers (chrome!!) I know but even if I painted them they would not be original, and who can resist a little bling? Fired the engines today and could not see any leaks. Life is good!! Thanks
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1930 Chris-Craft Model 100 20' "MOXIE"
1940 Chris-Craft Red and White 25' "Old Paint"
1946 Chris-Craft Sportsman 25' "CinCity"

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