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11-02-2003, 01:11 PM | #1 |
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Location: mt juliet, tennessee, usa
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What Is Causing This?
My truck is a 69 C10 P/U with a 350/th350.
About 6 months ago I put on a new intake manifold (Holley Street Dominator) and a new carb (Holley 600 cfm 4 bl). Ever since I've had a problem with oil leaking down the side of the carb. I've put thread sealer on the carb hold down studs, but that did not stop the problem. I thought it might be coming out of the line from the PCV valve, but I've tightened that hose clamp as much as I dare. The oil has to be coming from the carb/manifold interface, but I just can't figure out where. Any ideas? jim Mt Juliet Link to My Pix |
11-02-2003, 01:15 PM | #2 |
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If you have oil coming up through the manifold, you have some serious issues. It is most likely coming from the PCV valve. Just buy a new valve and install it. They are cheap and should be replaced every year or so anyway. I hope it is not coming from inside the intake, if it is it means that you are having bad head troubles.
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11-02-2003, 01:22 PM | #3 |
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Naw, the inside of the intake is as clean
as a baby's behind, no oil stains, nothing. The PCV valve is only 6 months old. I got it when I bought the valve covers. Jim Mt Juliet |
11-02-2003, 01:24 PM | #4 |
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There is no oil that travels thru the intake...hence no possible source for the oil. I'm with my new 72...probably coming from the pcv valve. Change it, and hope for the best. Bad rings, and resulting blow by will cause excessive oil to travel thru the pcv valve. I type too slow, just saw your reply. Pull the pcv valve out of the cover while the engine is reved up, and check for blow by.
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11-02-2003, 01:25 PM | #5 |
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Well, the only place it could be getting the oil is from the PCV valve. It doesn't suck vaccum from anywhere else. Evem if it is only six months old I would try a new one. The oil isn't coming from anywhere else I assure you.
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11-02-2003, 01:35 PM | #6 |
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AT fluid being sucked up through the line to the transmission? How is it shifting? Maybe time for a new vacuum modulator valve?
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11-02-2003, 01:42 PM | #7 |
Formerly yellow72custom
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The AT fluid could be the problem....although it is of course red, while oil is brown/black. Pull off the vaccum modulator line and see if it is wet with tranny fluid on the inside.....
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11-02-2003, 01:45 PM | #8 |
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are you sure the oil isn't coming up thru the manifolod bolts it's a very common problem
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11-02-2003, 02:07 PM | #9 |
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He said that the oil is at the base of the carb where it mates to the intake. The intake bolts wouldn't leak oil up there. The trans modulator may be the culprit, but I doubt it.
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11-02-2003, 03:34 PM | #10 |
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Do you live where there is much dust? And are you sure that it is oil? I have a seepage that looks like oil that runs down the side of the carb, but it is just some gas with dust mixed with it and it looks like oil.
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11-02-2003, 04:19 PM | #11 |
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valve cover seals?could they have a leak and spitting oil at high rev.
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11-03-2003, 01:30 AM | #12 |
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I just went through this with my Holley 750. I was positive that I had oil dripping off both the front and back edges of the carb onto my Edelbrock manifold. Felt like oil and looked like oil. Carb is a brand new rebuild by a professional shop. My friend who is a professional mechanic looked and said it was a fuel leak and that gas in small quanities will "varnish" and take on the appearance of oil. I sent the carb back to the shop and he was right. Carb was leaking at the sight glasses in the bowl. He had to double gasket before it was fixed. Check out the fuel leak angle. Good luck.
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11-03-2003, 01:49 AM | #13 |
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most likely its a fuel leak. fuel will look exactly like oil in small quantities. check the bolts holding on the fuel bowls make sure they are snug do not overtighten them use a 1/4 inch ratchet to check em.also the sight plugs can leak as well as the fuel inlets if they dont have the little metal gasket between them and the carb
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11-03-2003, 09:56 AM | #14 |
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Like cdowns said "Check you maniflod bolts" Take them out and put some gasket sealer on them and put them back in. Oil usually leaks out of the center bolts and it does look like it's coming from the Carb.
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11-03-2003, 11:50 AM | #15 |
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wxman1 (I know your pain!)
I've been trying to sort out almost the exact same thing on my 71 350/th350. It is not my intake manifold gasket. It is not my intake bolts. It is not even the top of my valve cover gsakets.
I have this "MYSTERY LINE" that I have yet to see on any other 350. It has what looks like a vacuum fitting coming up from where one of the intake bolts should go on the RHS, rubber hose attached that runs down to the front of the engine block to another similar fitting. Over the weekend I was able to witness this hardened hose (near the carb) leak oil down on to my intake manifold. From there it would pool up, then drip down the back of the engine. It burns once the engine is hot enough...not getting to the ground accept when the engine is running cool. I cut off the hardened section of rubber hose and reclamped it with a more pliable section. Still do not know what this is. One budy thought the line had to be a water line. It looks like a vacuum line. What I saw puddling there is definitely oil. These mysteries SUCK, don't they! |
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