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# 6 cylinder header bolt oil leak


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Posted (edited)

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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Posted (edited)

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

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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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Posted (edited)
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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Posted (edited)

Not to change the subject but is that a crack in your block (bottom area) near where the tranny bolts to it. Doesn't have anything to do with the leak, just curious. 

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Edited by rcb280z
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no ,I just saw that also in the photo after you said that and I wiped it down with Windex and it is gone I almost crap in my pants going to the garage!!!!!!!!!!!!!!!!!!

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Posted (edited)
53 minutes ago, rcb280z said:

Not to change the subject but is that a crack in your block (bottom area) near where the tranny bolts to it. Doesn't have anything to do with the leak, just curious. 

IMGP0219.JPG

 

11 minutes ago, kully 560 said:

no ,I just saw that also in the photo after you said that and I wiped it down with Windex and it is gone I almost crap in my pants going to the garage!!!!!!!!!!!!!!!!!!

Looks like hair to me. If it was a crack it wouldn’t be so straight.

Edited by Racer X
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1 hour 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

Screenshot_20210317-162050_Samsung Internet.jpg

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41 minutes ago, Racer X said:

 

Looks like hair to me. If it was a crack it wouldn’t be so straight.

Uh my crack is straight up and down. My hair is curly.:bunny:

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Posted (edited)

I'd check the valve cover closely.  There's no oil passage on that side and the engine tilts the other way.  Actually the illustration is poor but I think that only oil passage is on the filter side, for the cam towers or spray bar, and sometimes one up front.  But none back there on that side.

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Edited by Zed Head
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1 hour ago, Racer X said:

I wiped it down with Windex and it is gone

Thank goodness! I even zoomed in on it and had myself convinced it was a crack.

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hey siteunseen thanks for the info, but I am not computer smart like the kids are so I could not fine the fsm on this site for the 1977 n47 cylinder head . so I looked in my haynes and chilton manuals and there are 14 bolts . the 1st setting is 30 ft lbs and the second is 44 ft lbs and the 3rd is 54-61 ft lbs .  you are showing 10 bolts with a max torque of 49 ft lbs? I also would like to thank ever body for the help !!

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22 minutes ago, kully 560 said:

hey siteunseen thanks for the info, but I am not computer smart like the kids are so I could not fine the fsm on this site for the 1977 n47 cylinder head . so I looked in my haynes and chilton manuals and there are 14 bolts . the 1st setting is 30 ft lbs and the second is 44 ft lbs and the 3rd is 54-61 ft lbs .  you are showing 10 bolts with a max torque of 49 ft lbs? I also would like to thank ever body for the help !!

The head Cliff posted isn’t an L series 6 cylinder head, looks like a 4 cylinder head.

Still, the sequence is similar, starting in the middle and working out.

The maximum torque is a range because the head bolts are torque to yield bolts. Since the head has been on the car for so long, you don’t need to go through the stepped sequence of torque values. Also, given that the bolts are tty, it is better to set your torque wrench to the lower end of the maximum range, at 54 ft lbs. Your looking for a loose bolt, not installing a fresh head on a new gasket. I have found broken head bolts this way.

But Zed makes a good point. The oil passages are on the right side of the block and head, and the engine is leaned to the right, about 12 degrees or so.

It would be a good idea to check the cam cover bolts for proper torque before taking it off.

Also, don’t use a cork gasket. They leak before you even put them on. An OEM or equivalent gasket, with no sealer. Torque the bolts, and it should not leak.

 

 

 

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52 minutes ago, kully 560 said:

hey siteunseen thanks for the info, but I am not computer smart like the kids are so I could not fine the fsm on this site for the 1977 n47 cylinder head . so I looked in my haynes and chilton manuals and there are 14 bolts . the 1st setting is 30 ft lbs and the second is 44 ft lbs and the 3rd is 54-61 ft lbs .  you are showing 10 bolts with a max torque of 49 ft lbs? I also would like to thank ever body for the help !!

Sorry. I jumped the gun with a quick google search. My man Jim has the right info it looks like. 

I check in all out through the day with my phone. That's good and bad. I'm thankful these guys cover my arse. LOL

 

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yes I did not think it was a L6 motor . I have the torque sequence from the manuals, and yes it is a good  idea to set my torque wrench at 54 lbs to see if I have a loose bolt . if I do not find any loose bolts should I increase to 60 lbs? I really do not want to change the head gasket if I don't have to ! 60 lbs might be looking for trouble but I already have a oil leak right? I am not low on anti freeze , no oil in the antifreeze and no water in the oil . the motor runs l perfect, and I do remember back in the 80s when I blew a head gasket in the 260 motor what that was like.

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8 minutes ago, kully 560 said:

yes I did not think it was a L6 motor . I have the torque sequence from the manuals, and yes it is a good  idea to set my torque wrench at 54 lbs to see if I have a loose bolt . if I do not find any loose bolts should I increase to 60 lbs? I really do not want to change the head gasket if I don't have to ! 60 lbs might be looking for trouble but I already have a 

9 minutes ago, kully 560 said:

yes I did not think it was a L6 motor . I have the torque sequence from the manuals, and yes it is a good  idea to set my torque wrench at 54 lbs to see if I have a loose bolt . if I do not find any loose bolts should I increase to 60 lbs? I really do not want to change the head gasket if I don't have to ! 60 lbs might be looking for trouble but I already have a oil leak right? 

 

I wouldn’t go any further than checking for loose head bolts. If none move at the low range of the max torque, they aren’t loose.
 

By the way, you can download the FSM here for free, just click the download button and change the save to to your desktop. It is a PDF, so all you need to do after it is downloaded is click it to open.

Easy as opening a book,

Click This Link, Then Click The Download Button

 

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16 minutes ago, kully 560 said:

no worries , I getting old I thought I was having a moment!!

And how old is old?

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