Manifold leak??

[jtraf]

Just wondering if others have experienced the same issue.

Just finished rebuilding the head on my 85 SWB SD33T Patrol due to a previous blown head gasket. I had the head machined, cracked tested and pressure tested all fine. I replaced valve guide seals and had just previously replaced water pump and most of the hoses under the bonnet.

After I had put it together and fired it up I noticed that there was an exhaust leak that I could not track down. Mind you this was after the death rattle from the reco injectors, very scary I have to say.

I took it down to the local mechanic and had the valve clearance checked and he found that the exhaust manifold was leaking in a couple places.

I have since taken it all off and cleaned it and replaced it to find it leaking again. I then took it off again and replaced the previous new gasket with another new gasket but it is still leaking. I noticed that there was some marking on the mating surface of the manifold and added some Loctite Heat proof silicon but it has blown out again. I rang Nissan for a price on the manifold and was shocked at the cost and wreckers only sell them complete with turbo.

Have others had this problem. Is a new manifold the only way? I can't have it machines as the bolts also hold in the intake manifold.

Or do I just ignore the leak for now??

I am almost ready to throw a match to it.

[Woop]

When i had the cyl head overhauled on my TD42, when it came back from the shop, i used an oilstone and carefully made sure that the mating surface of the exhaust manifold was completely straight and free from burrs and high spots. I then removed all the manifold studs and did the same thing on the manifold mating surface of the cyl head. Then bolted to 2 together, and checked with a feeler guage that there were no gaps between the 2.

Nick

[totto]

I had the same problem on mine. It seemed that the leak was on the lower side of the manifold-to-cylinder head surface. After a bit of thinking and checking, i took the complete manifold assembly out of the car, and used a straight metal file to deburr the surface of the manifold - it had serious groves from rust.
IMPORTANT! I also, when reinstalling it in the car, loosened the support mounted on the turbo outlet to the engine block to make sure this didn't restrict tightening of the manifold to the block. I suspect that support to have been wrongfully adjusted earlier, thus preventing the manifold to be tightened completely to the cylinder head.
I also, just to be sure, applied a thin coat of exhaust mounting compound on both sides of the gasket, the kind of compound that expands and hardens .
After tightening the manifold bolts i then retightened the bolts on the turbo outlet-to-block support. After running the engine warm, i then retightened the manifold bolts again (especially the two lower ones - very hard to reach without burning oneself on the manifold! )
After this, the manifold has had no leaks at all.

If you have to have the manifold machined, let them machine the intake manifold too, taking equally much off both - that way you'll have no problems with the bolts holding both manifolds....

[V8Patrol]

The cause .......

when reinstalling it in the car, loosened the support mounted on the turbo outlet to the engine block to make sure this didn't restrict tightening of the manifold to the block. I suspect that support to have been wrongfully adjusted earlier, thus preventing the manifold to be tightened completely to the cylinder head.

The cure .......

If you have to have the manifold machined, let them machine the intake manifold too, taking equally much off both - that way you'll have no problems with the bolts holding both manifolds....

Good call mate

Kingy