oil leak

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v8junkie
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Joined: Wed Aug 19, 2015 2:28 pm

oil leak

Post by v8junkie »

Trying to trace oil leak pooling on the rear of the block(302) have changed valve cover gasket thinking this would do,but oil is still evident. Looks to be coming from Cylinder head gasket, engine run,s great no usual symptom,s of head gasket failure,can they leak externally? Intake gasket feels dry.
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Roger King
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Location: St Ives, Cambs

Re: oil leak

Post by Roger King »

It'll be the rear intake seal, always is. Not a head gasket unless you've done something very wrong.

How to install a SBF intake manifold:

http://www.mustangsteve.com/intake.html

I have made taller alignment studs than Steve uses - I'd suggest getting some 5/16" UNC bolts that are longer than his, say 4-5", from somewhere like Namrick. Cut the heads off and grind the cut end to a smooth round finish to help guide the head into place.

Also, I would NOT use Felpro gaskets with built-in silicone beads. If you do, make sure you check their torque setting regularly (monthly, to be safe) and change at the first signs of water leakage at the front. These are a competition gasket, and the golden rule is 'Racing' stuff should not be used on road engines, unless you are going to tear the engine down every 4-500 miles. Like you would a race engine. I favour the Victor Reinz black plain gaskets which Real Steel carry.

Did you use the cork end gaskets when you assembled the engine? If yes, that's your leak, right there. When you get the new intake gasket set, chuck those end pieces away and buy a good quality RTV. Würth is good and will keep a long time once opened.

Roger
Paul Blore
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Re: oil leak

Post by Paul Blore »

It's a very similar situation with the big blocks as well, although you can't use guide stubs because all of the bolts go into the heads, which are at 45 degrees.

Felpro make a gasket with a steel core, which I've found works well. The core prevents the gasket from creeping, which is what tends to happen with the standard ones.

With regard to the front and rear valley seals, I've built mine both with and without the cork seals and my personal preference is with them, but you must ensure that the block surface is spotless and free from any oil or grease to get good adhesion and still use a good quality RTV goo. I've used grey Hermatite with good results, available from Halfords.

I don't know if the same applies to small blocks, but it is advisable to drop the distributor in place on big blocks before tightening any of the manifold bolts to ensure correct alignment.

Paul
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Roger King
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Re: oil leak

Post by Roger King »

For the 302: all bolts go into heads, vertically. With siliconised gaskets, over time the coolant dissolves the silicone element producing the leakage. If you're lucky, they leak out of the front of the engine. If you're not, they leak into the lifter valley. If you're very unlucky, they leak into the intake port into the cylinder.

Image

I wouldn't fit the 302 distributor until the next day, to ensure that you can easily re-torque the intake bolts the following morning as they settle. It is not affected at all by the intake.
If you do choose to use the cork gaskets, you should really adjust thickness if the block has been decked or the heads skimmed. Remember, you will have two thin silicone sealing surfaces, one above and one below the cork, as opposed to just the one thick one between block and intake. I can't speak for big blocks but they're really not recommended on SBFs.
Last edited by Roger King on Fri Feb 17, 2017 12:38 pm, edited 1 time in total.
Paul Blore
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Re: oil leak

Post by Paul Blore »

Ah, I see from that picture that, unlike on the FE, the distributor doesn't go through the inlet manifold.

On the FE, the inlet manifold bolts go into the heads perpendicular to the mating face.

The steel core Felpro manifold gaskets (for FE's) don't move and dissolve like that one has. Presumably, they're made of a different material.

Paul
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