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Discussion Starter #1
Ok, my 86 el co has been leaking oil for some time now. I have checked a lot of things out and it still drops oil on headers and smokes from time to time, not out exhaust pipe.
I have about decided it is the valve covers which are aftermarket cast aluminum and probably Chinese anyway,I'm looking for a set of factory valve covers as I got rid of mine to see if that fixes the problem, hopefully it will. It smokes a lot more when the engine is under a strain or high revving. I guess my question is that I suspect it is leaking enough to loose vacuum and my transmission has begun shifting differently and causes the car to seem to run rough. Does it sound plausible that it could be loosing enough vacuum to cause shifting problems?????

thanks
 

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My original covers, the driver side back leaked oil for years, not enough to worry about. Either change gaskets, and tighten correctly, or get a pair of stock ones and see if those don't leak. Loose bolt, or bad gasket is my guess; a oil leak should not make it run as you stated. How much oil are you losing in a week's time ??
 

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I would think the originals would be more prone to leaking than the aluminum replacements. That's been my experience, anyway. The factory originals have a pretty weak rail and are very easy to bend by overtightening. Using the long "washers" can help, but they still leak pretty easily.

I use a set of rubber/steel reusable gaskets and aluminum valve covers. Some people swear by putting some silicone on the mating surfaces, but I haven't had much luck with that.
 

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Discussion Starter #5
The problem started when the new covers bumped against the bracket for the cruise control, drivers side, back, bottom corner. I had to file that corner down to get it to seat and clear the cruise bracket. Anyway, may have had to file too much or still just an awkward place to fit the covers back on without scraping off all the silicone sealer off in the process, I have used the rubber gaskets with steel and some rtv sealant but still getting the leak at that corner. I'm probably going to take the cruise brackets and all that stuff off as I don't use it anyway????
 

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I had problems with oil leaking all over my exhaust manifolds and when i put headers on, i decided to end that problem by getting a set of chrome edelbrock valve covers, and Mr. Gasket rubber gaskets, using the long valve cover hold-downs. I put a thin layer of silicone on both sides of the gasket, but only on the bottom, front and back sides of the valve cover, the top isnt necessary thanks to gravity. Also around the bolt holes. But, yeah, get rid of that cruise control bracketry as it might be keeping the valve cover from tightening down properly if its hitting it. My dad swears by the original cork valve cover gaskets as he sais the cork squeezes and molds into the riples in the covers better than hard rubber, wich i understand his theory, but i already put my rubber ones on as i just described, and no oil leaks at all. and i look everyday i drive it for leaks of all sorts....hey its 47 years old, right? Be sure to wipe off all the leaked oil off the block, manifolds etc when you are fixing it so you can see if there's fresh leaks. Good luck
 

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Discussion Starter #7
I've not seen the long hold downs how long are they and can you get them at the parts store?
 

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IF you have four hold-down screws on the outside going thru the gaskets, you can get the long bolts with a hand-turned tightner on each at most any parts place.
 

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the long style hold downs are about 4" long, use one per bolt, and just spread the tension across the valve cover a bit better. If you are going to re-use your old valve covers, you can use a body hammer or bal-pin and flatten the gasket seat on your bench vice. I got my brackets at O'reilley auto parts, i'm sure you can get them at any auto parts place, napa will have them too, but i'm in california, so i dont know if you have those parts chains where you are at. I even used my original valve covers successfully for a while, leak free by straightening them like i described, and using new gaskets with the silicone on both sides of the gasket, and also using the long style valve cover tie downs before i decided to get all chrome-ey on my motor and get new chrome valve covers. Just make sure you resist the temptation to tighten your valve cover bolts down too much as you will re-warp them quite easily and the leaks will be right back. those bolts don't have to be very tight at all. i used just a socket on an extension with no wratchet, and tightened them by hand. the silicone will hold very well
 

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as stated above, the main thing is that the rails are straight and DON'T overtighten them, however i don't think your vacuum problem is related to the valve covers, with the engine running at idle take a spray bottle (the kind like windex comes in) full of soapy water and mist it around the sides of the intake/carb, ect. when the rpms change you have found a leak you didn't mention if you have a pcv valve or are running breathers on your valve covers but that could come into your vacuum leak as well GL hope you cure the problem
 

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The vacuum problem which may affect the trans, may be the modulator line/hoses running from the manifold, down to the modulator on the transmission. And maybe even the smoking is a modulator problem, letting oil get sucked into the intake.

Get under there & pull the hose off of the modulator, & see if there is any oil in the hose. If there is, 12 bucks for a new modulator will fix that part of the problem. And the short hoses on the modulator line may need replacing.

Just something for you to check out......
 

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Discussion Starter #12
Ok, think i got it stopped. Removed the brackets, cleaned it good and put a thick bead of RTV silicone, let it sit for about 4 hours, and drove it and no leaks so far............... thanks for the help and right it did not effect the shifting problem but somehow you know like when you just wash it, it just drove better, sweet! Also found a Vac leak at the PVC valve and got that fixed now. Next I need to figure out that tranny problem
 
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