Pan evac systems are notorious for not working on a motor with mufflers on it.
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| A few years ago Lou, Kesteb and Dr. Dodge opined on evac kit https://www.slantsix.org/forum/viewtopic.php?t=19253 |
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| Author: | rock [ Sat Aug 19, 2006 12:05 pm ] |
| Post subject: | A few years ago Lou, Kesteb and Dr. Dodge opined on evac kit |
Hi folks, A few years ago Lou, Kesteb and Dr. Dodge offered good thoughts on an evac system. Well, they application wasn't exactly mine as I am not racing. But I do have the continuing oil leak that steams me. I bought a Evac kit the other day...basically two breather caps with 5/89 hose outlet and two pipe nipples. I am wanting to reduce pressure in the crankase in my new engine in hopes of stopping the leak at pan and rear main seal. Since I am enjoying my Dutras and have a pair of 2" pipes from them to the collecter, how far from the exhaust pipe to manifold junctions should the pipe nipples go? I assume these are just brazed into a hole drilled into the two exhaust pipes? I will likely use braided stainless hose for the connections, but is an evac as simple as this...just connect each end of the valve cover to a new breather, remove the PCV valve and block its carb port, and away you go? Think it will help a pan leak in a below 3500 rpm engine? Thanks, rock 64 d100 |
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| Author: | zedpapa [ Sat Aug 19, 2006 12:09 pm ] |
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for the most part, yes, it is that simple. although you have to install a check valve in the hose to keep the flow going one way. i think the check valves from an air injection system will work. zedpapa |
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| Author: | Pierre [ Sat Aug 19, 2006 3:38 pm ] |
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How bad is the leak, and does it happen just leaving the car sitting overnight w/o running? A pcv system should be enough venting under that low a rpm assuming engine is in good health. |
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| Author: | slantzilla [ Sat Aug 19, 2006 3:50 pm ] |
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Pan evac systems are notorious for not working on a motor with mufflers on it.
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| Author: | sandy in BC [ Sat Aug 19, 2006 5:48 pm ] |
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I just installed an evac system on our mudbogger(not slant) 3 weeks ago. I used a breather on one valve cover and ran the evac from the other. I used a check valve from an AIR system that had a 1 5/8 hose fitting on one side and pipe nipple on the other. I just welded a nipple on the header collector It seems to work OK.... It changes the carb settings when you plug the PCV off. You get quite a bit richer cuz you dont have the extra "air" from the PCV. I went with the evac system to get around detonation caused by crankcase fumes "diluting" the mix and reducing apparent octane rating. It seems to work..... we won our class and had the fastest pass ever (5.28 in a 180ft pit 3 ft deep) I dont think I would run one on a street vehicle....I think PCV is better |
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| Author: | rock [ Sun Aug 20, 2006 6:03 am ] |
| Post subject: | Well, seems evac is no solution? |
Thanks guys! Pierre, the leak is verywhat I consider small, a drop every 15 seconds, but blows all over everywhere at road speed. Drips while sitting and hot, but not cold. It comes from between the oil pan and the rubber timing chain cover gasket .... under the rubber gasket and in the area near the corner bolt. I have now pulled the oil pan and timing chain cover and am fixing to apply the mopar sealant y'all recommended, but think to put it on both sides of the gasket . Unfortunately it may be that the rear main seal leaked too because there is oil on the clutch disc, but it may have come from a leaking gasket too...just haven't got into that yet. Having this on an engine with less than 100 miles on it made me determined to do all possible to stop it. SO, I got a new PCV valve and a new oil breather cap in and have got another oil pan and timing chain cover. I had the flats of the new iming chain cover milled flat and am ready to put it on. After putting on the PCV valve and the breather cap, but before disassembly for regasketing, at idle and at 2000 rpm the PCV valve was sucking hard from carb but the suction at rear valve cover hole for the PCV valve wasn't strong (to my hand's palm) and the suction at the oil breather cap hole wouldn't hardly pull in a piece of writing paper...So in the old line of "in for a dime, in for a dollar, I am preparing a global repair and got to looking into the evac too. But, I think what Sandy and Slantzilla seem to be saying is not to add in the evac? The guys at my machine shop who suggested the evac are mopar racers and may have thought it was a racing machine. It is a street vehicle ('64 dodge truck) with a muffler, albeit not your grandma's slant six. I think what Sandy is saying is he used a PCV valve AND hooked one line of an evac to a breather cap...thereby using both devices? I could try this but Slantzilla's caution makes me wonder if this would be at all worth doing. If it is well known that muffled systems and evac's don't go together, then I won't do ANY evac and will glue up gaskets instead and maybe even change valve covers. I was also told by the racers to use copper RTV on BOTH sides of the pan and timing chain cover gaskets instead of using the mopar sealant I got after suggestion from the forum. ...I have never doped up both sides of a gasket and it smacks of a desperation technique, but I am willing to try. SO, is it no evac, new valve cover too, or dope thorough on both gasket sides, and copper RTV instead of mopar black? Thanks! rock '64d100 |
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| Author: | CStryker [ Sun Aug 20, 2006 7:20 am ] |
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Doping both side of the gasket just makes sense to me. I mean, sealing one side has no effect on the other, and either side leaking has the same results. I have also had bad experiences in general with copper RTV compared to black, except in very high heat situations. You may, however, want to take my opinions with a grain of salt, as I routinely commit the cardinal sin: The only gasket on my truck that /isn't/ RTV'd on both sides is the valve cover. (Now that I think about it though, I may RTV the gasket to the valve cover side only next time just to keep it fro falling off when I take it off to re-lash the valves.) Most people think that is the epitome of ignorance, but it sure doesn't leak, and I have yet to see any negative effects. |
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| Author: | argentina-slantsixer [ Sun Aug 20, 2006 10:31 am ] |
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Quote: You may, however, want to take my opinions with a grain of salt, as I routinely commit the cardinal sin: The only gasket on my truck that /isn't/ RTV'd on both sides is the valve cover. (Now that I think about it though, I may RTV the gasket to the valve cover side only next time just to keep it fro falling off when I take it off to re-lash the valves.) Most people think that is the epitome of ignorance, but it sure doesn't leak, and I have yet to see any negative effects.
I'm doing that too. Hate to see crappy gaskets leak and unfortunately, most of the time you get crappy gaskets. It's not a matter of budget with me it's that just when I pull and replace something is sunday and no car parts business in the world is open (no on this country or timezone, hehehe) and I have to shut eyes and brains off for a moment and reach in my "garbage gaskets" cabinet. 
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| Author: | Pierre [ Sun Aug 20, 2006 10:56 am ] |
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There are two different gaskets we are dealing with here - the paper/cork one between pan rail and block, you can use either the spray copper stuffs or rtv (for rtv, my preference is the light grey mopar high temp 4x4 differential sealant). On the rubber timing cover > pan gasket, you really don't need anything there, they have two or three sealing ribs as it is and once it squishes thats it - I always like to add a smidge of rtv on both sides of it anyway. This makes the rubber slip around so make sure you have it situated properly before assembly, including pulling those little rubber nubs all the way through. When you say you had the flats of the timing chain cover milled - you aren't talking about the rubber gasket sealing surface are you? If you did take some material off there, the rubber gasket may not get squished enough. When I remove my pcv valve with car running and put it to my palm, it has enough suction to cause mild pain and make a temporary red indent on my skin. I feel no suction at the breather or oil fill hole. While your crankcase vent system may have issues, I still don't think its the cause of your oil leaks though judging by how much you say is leaking. I don't recall off hand but when you put a vacuum gauge on the dipstick tube there is a spec as to how much your supposed to read... 1-2" I want to say but double check fsm. |
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| Author: | sandy in BC [ Sun Aug 20, 2006 11:37 am ] |
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A couple of points: I used the EVAC only on the race car....PCV was eliminated. I was more interested in crankcase breathing at WOT than idle. A new motor till it breaks in has more blowby than a broken in motor. I think your blowby/crankcase breathing situation will settle down soon enough. I wonder if a larger PCV (mebbe 440) would help. Make sure your breather breathes(on my race car I violated the breather to flow more to help the EVAC pull more outta the motor....) I just buy good gaskets and goo nothing.....RTV is for when you use no gasket (IMHO) |
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