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# 6 cylinder header bolt oil leak

kully 560

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I now have a oil leak from the # 6 cylinder header bolt dripping down by the bell housing , it looks like the second bolt in on a n47 head is this just a bad gasket ? all spark plugs look great , when I assembled the motor 25 years ago I used the old hardware I did not know at the time about changing out the hardware . so I  now see msa auto sells the new hardware kit and gasket . I sprayed carb cleaner around the intake and have no rise in rpms . is it just a bad gasket and old hardware ? thanks for the help

Edited by kully 560
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maybe its a valve cover gasket fail, oil dripping down to around the exhaust manifold. I don't see how oil could leak out of a exhaust bolt hole. Maybe some UV dye in the oil an then look with a UV light.

Edited by Dave WM
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no it is oil that is running down the side of the motor at the # 6 cylinder no a lot . when I wipe my finger under the header it is wet with oil . I sprayed carb cleaner all around the intake manifold with no change in rpms either . the cylinder head is not leaking as far as I can see and the motor runs and idles perfect . I drove it yesterday and at a stop light I thought I had auto start stop it was so smooth .  could it  be the bottom of the intake ? maybe bolts? I did use all the old hardware back in 1997, and at that time I had no idea that I was supposed to use all new hardware I guess for stretching ?  does any of these bolts go into any oil passages? I also did not use any bolt / threat sealer back then either. 

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26 minutes ago, kully 560 said:

I will check again on the valve cover but it looked dry , I will get a picture posted also thanks






Have you checked the tightness of the intake and exhaust manifold fasteners?

Still, even if they were loose, engine oil wouldn’t be leaking from there.

I would say the head gasket is leaking some. Take the cam cover off and check the torque on the cylinder head bolts.


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3 minutes ago, kully 560 said:

I was afraid of that, does anybody know what the torque pattern is and the torque specs for n47 cylinder head? thanks

Look in the factory service manual, available for download on this forum.

I had a head gasket leak on an older L series engine in my 280ZX and tightening the head bolts to spec stopped it. I drove that old beater around for ten years after that without a bit of trouble.


Edited by Racer X
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