#1
IP: 130.36.62.223
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Oil Filler Cap Question
What is the purpose of the ventilation holes in the oil filler cap?
What would happen if the cap were completely sealed? The reason I ask is that I notice most of my excess engine smoke seems to come out of the filler cap gap and holes, and not much is going out the PCV tube. Any thoughts? -Rick |
#2
IP: 64.252.192.206
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Rick,
Best you'll do is to force the smoke to exit around the flywheel end of the crankshaft, which has no seal. Short of a ring job, give the Indigo PCV kit a try. If your smoke isn't too bad, the PCV kit will give you some more time until you need rings. |
#3
IP: 173.166.26.241
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I have the Indigo pcv kit and it works perfectly. I plugged up the oil filler tube by threading it for npt and then using an npt plug.
Last edited by hanleyclifford; 07-13-2016 at 08:35 PM. |
#4
IP: 130.36.62.185
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Pcv
Thanks Hanley,
It would seem that a new PCV set-up is in my future...I like the plug idea, too. What size tap was that? No blow-by smoke would be a real treat! -Rick |
#5
IP: 99.65.136.114
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Rick,
Before switching to a PVC system, you might try "tuning up" your existing setup. Since the filler cap and the flame arrestor are subjected to oily blowby, they tend to become plugged, over time, and loose their airflow efficiency. Using spray carb cleaner or soaking in carb cleaner, is probably the easiest way to clean them. Finally, and this is the most important thing, make sure that the curved rubber hose is cut at the correct angle and is actually touching the flame arrestor element (see the Moyer photo). My "high mileage" A4 displays almost no blowby after performing this "tuneup" Tom |
#6
IP: 24.136.67.99
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Cap
Rick the vents are so the engine can breath on the inside. Actuall it is mostly to expell the nasty gasses that get by the rings. My A-4 is going on it's 41st year and is a bit tired to say the least. I replaced my cap with an automotive type when I bought the boat. The type I bought has a hose bib connection instead of the vents underneath. I attached a long hose and ran it up through my exhaust fan pick up hose. That vents most of the gasses out of the cabin and out of the cowl on the transom, I use my exhaust fan WHENEVER THE ENGINE IS RUNNING. Since then I have installed the PCV kit as soon as I saw one available and it made a huge differance in the amount of blowby venting out the fill tube. I did leave my hose and automotive cap in place and I have no fumes or smell in the cabin. Note~ my engine is in the middle of the boat on top of the keel.
Everyone should have a PCV setup as they keep the inside of the engine much cleaner! Dave Neptune |
#7
IP: 99.65.136.114
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Dave,
You forgot to add, be prepared to do a carb adjustment because of lost manifold vaccum, after the addition of the PVC kit. Tom |
#8
IP: 173.166.26.241
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One of the reasons why I blocked off the breather was for exactly the reason of preserving vacuum. The pcv system when allowed to pull freely thru a breather cap does two things. It robs the manifold of vacuum by drawing air in from the outside. The breather cap also reduces the effectiveness of the pcv by reducing th amount of crankcase air being drawn. I believe there are sufficient air leaks in the engine to preclude a dangerous pressure environment.
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#9
IP: 99.65.136.114
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Hanley,
I certainly agree that if adding a PVC kit, plugging the breather cap hole or using a "non breather" type of cap will add to the effectiveness of the system. The amount of air drawn through the PVC system should be governed by the PVC valve and hopefully will flow all of the blowby gasses. As a side note, it is not uncommon in race engines to use vaccum pumps to pull as much air out of the crankcase as possible which has proven to add measurable horsepower. Tom |
#10
IP: 71.134.240.155
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Pcv
I found this nice cap (see photo) at the hardware store. When tightened the rubber gasket (I trimmed it) expands out and seals.
I tried it out today, and it seemed to work great, with just a bit of blow-by from the black tube missing the flame arrestor (has been cleaned). I'm still going to install a PCV kit to capture all gases. What carb adjustment is necessary? -Rick Last edited by rpowers; 03-05-2011 at 06:53 PM. |
#11
IP: 24.136.67.99
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Adjustments
Rick the carb adjustment directions come with the kit. What it amounts to is because of the additional air through the PCV valve need a bit more fuel~~about a 1/4~1/2 turn in on the adjustment.
Dave Neptune |
#12
IP: 24.136.67.99
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Breathing
I think that with the pcv kit you need the breathers to work. They are calculated for the engine with the breather. Without it gasses will still collect in the crankcase because there is no incoming air to displace the gasses other than what blows by the rings. You need the flow of clean air through the breather for the pcv to function as designed.
Dave Neptune |
#13
IP: 71.134.240.155
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Breather
Dave,
Ah, yes, good thought. I can try it both ways. Hanley has a persuasive argument and so do you. Thanks for the carb adjust tip. I'm presuming that is with the idle mixture screw on the back side of the carb facing up. I'll report back on Wednesday after I get it installed. -Rick Last edited by rpowers; 03-06-2011 at 11:25 PM. |
#14
IP: 24.136.67.99
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Adjustment
Rick, yes it is just a bit of a tweak on the idle mixture screw.
Dave |
#15
IP: 99.96.67.36
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"Automotive style"
Although I don't seem to need a PCV system yet, I have been following those threads closely. Input from Hanley and Dave sparked an idea that might just be the ideal PCV system, so here goes. If the original rubber hose system was left in place and the pcv valve was plumbed from the intake manifold or a carburator adaptor plate, to a non vented filler cap with a hose bib, this would very closely "mimic" most automotive systems. In essence, any excess fumes that were not removed by the pcv valve would be pulled into the carb air stream.
Tom |
#16
IP: 216.115.121.253
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Thatch,
That is pretty much what I did. I have not finished it yet, I have to install the plate at the carb. I would encourage you to think about a pcv even for an engine in good condition. There is always some blowby, even in new engines. The reasons for the development of pcvs were varied, but one benefit is that it helps remove the oil mist that seems to coat every thing in the engine room. I have been in an engine room that was just slimy, and the owner could not keep it clean. He said it was always smokey and foggy down there after running the engine (a diesel in good working order). I asked him about crankcase ventilation. We could not find any method for controling it, just a breather on the oil filler. I think the blower helps, but the mist drifts around the engine bay before it gets blown out and generally slimes the place.
__________________
Whiskeyjack a '68 Columbia 36 rebuilt A-4 with 2:1 "Since when is napping doing nothing?" |
#17
IP: 69.225.228.95
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The blow by smell would generally not appear in my boat until I had motored for several hours. After that I could see a haziness inside the boat and you could smell it as well. I recently installed the Indigo PCV kit and it works excellent. I have not noticed whether I need to do anything about the oil filler cap yet. Probably won't know until we get into hot weather and I motor for long periods. I did need to make a slight carb adjustment.
I would recommend this upgrade to all A-4 owners. Even if your engine is new, it is essentially being operated for long periods of time inside a small enclosed space. Under these condition any motor will create unwanted fumes and smells. DVD |
#18
IP: 206.125.176.3
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Hanley, where is that picture of your capped off oil filler?
I spent a significant portion of the winter scraping/wiping/breaking down & removing the pretty thick layer of slime Russ was referring to. I'd like to keep it away! Rick..wasn't it you that was asking about the year of your engine? The serial # is clear as day right under your oil filler!
__________________
-Shawn "Holiday" - '89 Alura 35 #109 "Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!) Last edited by sastanley; 03-07-2011 at 03:07 PM. |
#19
IP: 173.166.26.241
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Shawn - Check post #3 on this thread.
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#20
IP: 63.239.65.11
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Quote:
You tapped your Hot Spot© for your temperature gauge. What kind of readings are you getting from there? |
#21
IP: 99.96.67.36
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Russ,
If I do decide to add a PCV system, one of the reasons will be to lean out the mixture a little. I would like to hear how your plug readings (or anyone else's for that matter) change after the addition of the kit. Tom |
#22
IP: 71.118.13.238
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PCV changes
Tom I check my plugs after each cruise and before and after any changes I make. I noticed no differance that I could see on the plugs although I did need to fatten up the idle about a 1/4 turn.
Perhaps Hanley with his O2 sensor could measure a bit oif change I could not "see". Russ, FYI my engine and I did notice one differance that may affect you a bit in the cold. The engine acts colder until it has run a minute or two and takes an extra turn or two on the starter to get lit~~no biggie. Dave Neptune |
#23
IP: 138.88.81.142
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Oops...sorry Hanley...I didn't realize it was already posted in this thread.
__________________
-Shawn "Holiday" - '89 Alura 35 #109 "Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!) |
#24
IP: 206.230.48.34
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I think he added a spark plug making it the world's only Atomic Five®.
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#25
IP: 216.115.121.253
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Thatch, if you need to lean your carb, that should be doable without modification of the intake. if it's running rich, get that fixed independently of the pcv mod.
Re. plug readings: Sorry, I just don't run my engine enough to get any trends yet. I only have about ten hours on my engine. I'm still in the fixin' it-findin' time-ernin' money stage of boat life. I work on the theoretical side of Atomic power for now.
__________________
Whiskeyjack a '68 Columbia 36 rebuilt A-4 with 2:1 "Since when is napping doing nothing?" |
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