Oil in exhaust manifold bolt holes 427

ABC123 · Uber Guru

Oil in exhaust manifold bolt holes 427

4SPEED427 · A Poncho Legend!

Don't use manifold gaskets on a big block. If they leak, it means the manifold isn't flat. A gasket will work for a while, then burn out and warp the manifold even more. Find someone with a good straight edge and check the manifold. A machine shop can plane them for you if they are warped.

The bolt holes are blind, I'm 99% certain so if you have oil in there it's from an external source.

I've just never had issues with leaky manifolds on big blocks and I've never used a gasket. Never. They had no gasket from the factory and should never need one.

ABC123 · Uber Guru

I do agree with not using gaskets but I was looking for a quick fix until I could get a chance to pull everything apart.

I am really worried about a cracked head with the oil.

The exhaust manifold leak is on cylinder #one and those studs are soaked with oil.

seventy2plus2 · Canadian Poncho Superstar!

1. The manifold bolts DO NOT go into the oil chamber of the head - 100% sure.
2. I suppose it's possible for the valve cover gaskets to leak down into the manifold bolt holes. Oil seems to find its way into odd places.

Early in your post you say you're working on the "front right of this 427". Later you mention you're working around the power steering pump, then you say you're working on "#one"
Sounds like you're working on the front left of the engine, #1 cylinder.

For what it's worth, remove the manifold bolts, spray brake clean into the holes to clean them out, clean the bolts and put them back in. See what that does.

FYI - if you have a cracked manifold, I'm sure I have a replacement. I'd just have to double check casting dates.

ABC123 · Uber Guru

seventy2plus2 wrote:
1. The manifold bolts DO NOT go into the oil chamber of the head - 100% sure.
2. I suppose it's possible for the valve cover gaskets to leak down into the manifold bolt holes. Oil seems to find its way into odd places.

Early in your post you say you're working on the "front right of this 427". Later you mention you're working around the power steering pump, then you say you're working on "#one"
Sounds like you're working on the front left of the engine, #1 cylinder.

For what it's worth, remove the manifold bolts, spray brake clean into the holes to clean them out, clean the bolts and put them back in. See what that does.

FYI - if you have a cracked manifold, I'm sure I have a replacement. I'd just have to double check casting dates.

Sorry, Front left biggrin

All good points.

The studs on the ends of the manifolds, where the midpipes attach, scare me.

The idea was to try the gasket to see if the leak would go away.

The valve cover gaskets will be changed now that the AC compressor has been moved out of the way.

4SPEED427 · A Poncho Legend!

ABC123 wrote:
The studs on the ends of the manifolds, where the midpipes attach, scare me.

You're worried they will break? Someone in your area must have a torch to heat them? Even if you break them they always can be removed later with a torch and a welder.

seventy2plus2 · Canadian Poncho Superstar!

Randy, you say "the exhaust manifold leak is on cylinder #one and those studs are soaked with oil."
Are they bolts or studs? Mine are bolts, but I don't have a/c.

65 SD L79 · Canadian Poncho Superstar!

one of the engine builders this way has a large belt sander. I take all my manifolds to him. nice flat surface

ABC123 · Uber Guru

seventy2plus2 wrote:
Randy, you say "the exhaust manifold leak is on cylinder #one and those studs are soaked with oil."
Are they bolts or studs? Mine are bolts, but I don't have a/c.

Yes, they are all bolts.

Some were very loose but number 1 was tight.

ABC123 · Uber Guru

65 SD L79 wrote:
one of the engine builders this way has a large belt sander. I take all my manifolds to him. nice flat surface

I'm heading your way this weekend but I don't think I will have the manifold off by then.

Long work hours are coming up.

65 SD L79 · Canadian Poncho Superstar!

ABC123 wrote:
65 SD L79 wrote:
one of the engine builders this way has a large belt sander. I take all my manifolds to him. nice flat surface
I'm heading your way this weekend but I don't think I will have the manifold off by then.
Long work hours are coming up.

If you can get them off I will take them in

LT1Caddy · Poncho Master!

I have a BB. When the valve cover gaskets leak, the oil runs down the block and into any indention it can find. Then driving down the road, the wind helps blow the oil where it ends up.
I would start with the vc gaskets first because I had a similar problem. I changed some fittings for the oil pressure gauge at the back of the block and thought it was leaking at one of the joints, changed the vc gasket and the oil fitting dried up....

HTH

cdnpont · Canadian Poncho Superstar!

Sure, the factory could put a manifold on a head without a gasket. But I cannot see how it could work trouble free later unless everything gets re trued. It's a crap shoot isn't it?

There is a industrial thin foil backed graphite sheet available that will 100% cure any exhaust leak...permanently. You just have to cut it yourself to fit.

I made them for my 496. Never a sound in all the years. The bolts never loosened at all either. The stuff is absolutely amazing, I'll look for the name of it if you want.

LT1Caddy · Poncho Master!

Mark... those older parts, in the 60"s, were cast with REAL metal. Not the watered down cast iron like that was used in the mid 70's. The 60's castings will stay straight and not warp for years if they don't get overheated. ( the main reason they warp). The fasteners were also better quality, and steel or iron. Every part was quality steel, not watered down recycled off shore steel...