One Leaky Valve Cover??

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loud41
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One Leaky Valve Cover??

Post by loud41 »

Hey guys!

Been a while! I have a quick question. I've been having a weird issue with one of my valve covers(maybe?). I had the heads off my '63 a while back, reassembled everything and it was all fine. All of a sudden, the driver's side valve cover leaks at the forward end like a sieve. It doesn't drip, it pours. I walked out one day to find a huge puddle underneath and a completely filled heat shroud.

I've tried replacing the old silicone gasket with a new one. Same results... I used a new cork and rubber gasket. Same results. I put a thin coat of sealant on a brand new cork and rubber gasket - both sides.... Same results. I'm starting to feel insane. The valve cover looks fine, and the head looks all shiny and new as usual. The pushrod tubes are dry. What am I missing? Any ideas on where to look?

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bbodie52
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Re: One Leaky Valve Cover??

Post by bbodie52 »

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:think: Here are some ideas and idea sources...

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Advice on Valve cover leak
:link: http://corvaircenter.com/phorum/read.php?1,925117

Oil leak?
:link: viewtopic.php?t=2908
Trip wrote: » Sat Nov 12, 2011 1:49 am

agreed on the Valve covers, if they are 6 bolt you should be fine, if they are cast aluminum they are fine. If they are regular steel valve covers with only 4 bolt holes you NEED the spreaders. They take you from 4 points of focused pressure to 12.. big difference. If you call Clarks you can discuss it with them to get everything you need, they are AWESOME like that. If you are out west at all call Raffee, he could probably hook you up and he is supposed to be a lot of fun to chat with... he oozes personality!
Ray "Trip" Rodriguez III
Gouldsboro, PA

bbodie52 wrote: » Tue Sep 25, 2018 11:48 am

:clap: :not worthy: Your meticulous, showroom — even museum-quality restoration establishes a high standard for many to emulate. :nono: So I humbly wish to point out a very minor error in the installation of the valve cover hold-down clamps. :sad5: You installed them upside-down. :tongue: As installed, they amount to a wide washer to spread the hold-down clamping pressure. But flipping them over allows them to function as-designed, using spring pressure to distribute the clamping load on the valve cover.

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The picture below shows a couple of assembly tips that are helpful on the Corvair engine. The steel retainers mentioned earlier help to spread the pressure applied to the valve cover and gasket along three points, instead of only the bolt head. The outer ends of each strap are curved. Installed as shown, the curved tips act to apply distributed spring pressure on the valve cover in conjunction with each center bolt.

The upper row of head bolts tend to rust and soften with engine heat and exposure to the elements. A new fresh set of flange nuts, properly torqued, and then capped with acorn nuts to protect the exposed threads of each stud will make future removal much easier. The use of a six-point socket instead of a 12-point socket provides a better grip on the nut, which helps to prevent the socket from slipping or rounding-off the corners of the head nut.
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:link: http://www.corvair.com/user-cgi/catalog ... IN&page=13
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Image I even discovered custom versions!
Proform 141-903 Valve Cover Hold-Down Clamp
:link: https://www.amazon.com/Proform-141-903- ... B000CMH2H0

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Hot Rod SB Chevy Chrome Valve Cover Hold Down Spreader Bars SBC 283-400
:link: https://www.amazon.com/gp/product/B00U2 ... i=15726551

Amazon.com Customer wrote:Prevents gasket surface deformation on stamped steel valve covers
June 7, 2016

These items are a must have for stamped steel valve covers. The regular bolts easily deform stamped steel covers when they are tightened. The dimple that creates in the mounting surface almost always causes a leak.

Using these bars spreads out the clamping force on a much larger area of the valve cover so the gasket surface does not get bent or deformed. I always use them with the T bar type valve cover hold-downs because if the T bar hold down screws are mounted in the head first, then these bars drop right over them and stay in place while screwing the T bar down. The bars can be installed with bolts, but it is a little harder to hold the bar and the bolt combination together while initially trying to start the bolt.
The comment about the compression "dimple" also applies to the sheet metal oil pan. Over-tightening those bolts can crush the area directly below the bolt-head into the soft oil pan gasket, pressing the oil pan sheet metal into the crankcase aluminum metal while compressing the gasket. This applies pressure only directly below each bolt head, while leaving reduced pressure to the oil pan surfaces between the adjacent bolts. Since the pan is flat it does not form an oil storage trough to store the oil (like oil pans on V8 engines). Instead, on a Corvair the oil is held above the oil pan gasket, so the gasket must retain several quarts of oil above the seal surface, instead of only forming a barrier from splashing oil (as found on a V8 engine). This makes the Corvair oil seal more difficult to achieve with the flat stamped steel oil pan.

When installing a steel sheet metal oil pan, check to confirm that the mating surface is flat and has not been distorted by over-tightening in previous installations. Correct with a hammer and dolly technique if needed. Use an inch-pound torque wrench to properly tighten the oil pan bolts. NOTE: The specification in the 1961 Corvair Shop Manual is 40-60 in. lbs. for the ¼-20 bolts. In the 1965 Corvair Chassis Shop Manual, the torque specification increased to 85-105 in. lbs., even though the bolt size remained unchanged). :dontknow:

I would suggest the use of a cast aluminum oil pan, which does a better job of distributing an even load between the oil pan casting and the engine crankcase surface.
Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible

loud41
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Re: One Leaky Valve Cover??

Post by loud41 »

Hmmm hold down spreaders. Haha I thought the leak was so strange I didn't even think it was actually a more common issue. I'll give those spreaders a try! The other side seals up so nice, I thought maybe something potentially expensive was broken... I also have an extra set of valve covers. I'll try a different cover out as well just in case my cover is bent on the mating surface or warped. Just while I wait for those spreaders to arrive.

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terribleted
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Re: One Leaky Valve Cover??

Post by terribleted »

I would remove the lower shroud on that side, clean all the oil up there and see for sure where it is leaking if you have not done so already. Could be something other than the valve cover maybe? Valve cover spreaders are essential.
Corvair guy since 1982. I have personally restored at least 20 Vairs, many of them restored ground up.
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loud41
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Re: One Leaky Valve Cover??

Post by loud41 »

Yes I took the shrouds down, degreased everything to clean up all the mess, etc. That way if it would leak again, I could see exactly where it was coming from. It leaks from the same spot on the bottom of the valve cover every time. About 2 inches behind the forward fastener on the bottom. If I really crank down (as much as I dare on aluminum threads) the leak slows up to a steady drip instead of a uh... oilfall. After thinking about it and sleeping on it, I think you guys are certainly right and will wait for those spreader bars to arrive before I do anything else. Thanks so much for the responses. If you don't hear back, you can safely assume it's because I'm too busy driving my leak free corvair.

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Re: One Leaky Valve Cover??

Post by terribleted »

I have had poor luck with the silicone gaskets, particularly if there is any imperfection in the head surface. I recommend using a high quality cork and rubber composite gasket. I have had good luck with Clark's C3018's and C6119's (4 hole/ 6 hole). For a troublesome one I coat the gaskets lightly on both sides with Permatex number 2 non-hardening sealer.
Corvair guy since 1982. I have personally restored at least 20 Vairs, many of them restored ground up.
Currently working full time repairing Corvairs and restoring old cars.
https://www.facebook.com/tedsautorestoration/

Located in Snellville, Georgia

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bbodie52
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Re: One Leaky Valve Cover??

Post by bbodie52 »

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bbodie52 wrote: » Sun Aug 16, 2015 8:25 am

:think: The torque specifications for the oil pan bolts is stated in the 1961 Shop Manual to be 40-60 inch pounds. In the 1965 Corvair Chassis Shop Manual, the specification was increased to 85-105 inch pounds! [The valve rocker cover specs in 1961 were only 30-50 in. lbs., and in 1965 were increased to only 40-60 in. lbs.] The bolt size remained at ¼-20 for all model years, so apparently the GM engineers changed their minds and revised the oil pan torque specifications to reduce oil leaks.

The aluminum casting design [used in aftermarket aluminum cast valve covers and oil pans] should not be subject to the problem with stamped steel pans that can deform and crush into the thick gaskets in the areas directly beneath the bolt holes. When this happens the pressure against the gasket is not distributed evenly, with less pressure against the portions of the gasket between the bolt hole areas. The cast aluminum pan will not crush or deform, so it will tend to distribute pressure more-evenly around the perimeter of the pan to help seal the gasket surfaces. The problem with the Corvair oil pan design is that about four quarts of liquid resides ABOVE the gasket, unlike conventional oil pans that serve as a reservoir with the oil stored below the gasket surfaces. In those oil pans the gasket surface only has to seal against splashing oil, but the Corvair has to seal against continued pressure from a liquid that is constantly trying to find a way to escape — even when the engine is turned off!
:whoa: Over-tightening stamped steel oil pans or valve covers can deform the sheet metal directly under the bolt head, causing the sheet metal to push into the thick gasket material until it bottoms-out against the aluminum cylinder head or engine cases. This crushes the gasket directly under the bolt head, while applying less pressure on the gasket material some distance away from the bolt. Have you examined the valve cover sheet metal around the bolt hole? If it has been deformed that could be the cause of your oil leak.
Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible

joelsplace
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Re: One Leaky Valve Cover??

Post by joelsplace »

loud41 wrote:
Tue Mar 17, 2020 6:52 am
If I really crank down (as much as I dare on aluminum threads) the leak slows up to a steady drip instead of a uh... oilfall.
That is way too tight. The gasket will be collapsed long before you get it that tight. I would guess the valve cover is bent.
The spreaders are good but you want to watch the gap at the bolt and stop tightening just as it touches the valve cover.
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Re: One Leaky Valve Cover??

Post by BeenFreeO2since71 »

joelsplace wrote:
loud41 wrote:
Tue Mar 17, 2020 6:52 am
If I really crank down (as much as I dare on aluminum threads) the leak slows up to a steady drip instead of a uh... oilfall.
That is way too tight. The gasket will be collapsed long before you get it that tight. I would guess the valve cover is bent.
The spreaders are good but you want to watch the gap at the bolt and stop tightening just as it touches the valve cover.
Be sure to take a straight edge to the bottom on the lower edge of your head, it might be warped,


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tcwheels
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Re: One Leaky Valve Cover??

Post by tcwheels »

Very helpful info! I have same issue and PO had them mounted upside down. I’ve ordered new ones as well.


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loud41
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Re: One Leaky Valve Cover??

Post by loud41 »

I'm prepping my other valve covers right now while I wait. I do prefer the cork/rubber gaskets in this case as it is very difficult to gauge the tightness of the fasteners with those pure silicone ones. I really wish Fel-Pro made those awesome premium silicone gaskets for the Corvair. They have a stiff core coated with squishy silicone. The silicone fills the voids while the core prevents the gasket from being crushed. I always get those for my v8's whenever they're available. Very easy to get proper torque on those gaskets. The rubberized cork is the next best thing in my mind. I'll also try setting my covers on a flat surface to see if there's any warping going on, or is that a bad idea? I just can't believe that this car was bone dry before! Making up for lost time now!

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Re: One Leaky Valve Cover??

Post by terribleted »

The key is to tighten the bolts only until the center of the spreaders flatten out against the valve cover surface. Tighten until the centers touch and maybe just a touch snugger...NOT TIGHT.
Corvair guy since 1982. I have personally restored at least 20 Vairs, many of them restored ground up.
Currently working full time repairing Corvairs and restoring old cars.
https://www.facebook.com/tedsautorestoration/

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loud41
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Re: One Leaky Valve Cover??

Post by loud41 »

Alright so I wanted to give a quick update. I pulled my valve covers off, and sure enough, I had (obviously) tightened them down far too much. The bottoms of each gasket had been forced up into each cover, leaving gaping holes for oil to flow through. I had a fresh set of Fel-Pro gaskets (they're a rubberized cork). They're slightly thinner than the other gaskets I've been using, but they fit the valve covers perfectly. I'd also refurbished my spare valve covers, and just decided to go with those since they were all painted up and ready to go. I couldn't resist the urge to use a thin layer of ultra black on each side of the gasket. I did as you guys suggested and only tightened each bolt to the point where the centers of the spreader bars made contact with the cover, and then only a slight bit more. So far, it's looking like I'm finally leak free again. This is such a great community, and I seriously can't thank all of you enough for your help. All of your suggestions contributed in some way to help me get to this point.

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Re: One Leaky Valve Cover??

Post by terribleted »

Great the only possible issue I see is using a silicon based sealant. I have had much better luck with Permatex #2 which is not silly putty. It is ok if they leak you can replace them again using a non silly putty sealant:)
Corvair guy since 1982. I have personally restored at least 20 Vairs, many of them restored ground up.
Currently working full time repairing Corvairs and restoring old cars.
https://www.facebook.com/tedsautorestoration/

Located in Snellville, Georgia

loud41
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Re: One Leaky Valve Cover??

Post by loud41 »

Haha ok I'll look into that!

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Re: One Leaky Valve Cover??

Post by joelsplace »

Silicone used sparingly is great. People that goop it on have given it a bad reputation.
Permatex #2 is good also if used properly and it is actually specified in the factory service manual for some things.
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