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Head Bolts and Gasket


LTM

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Hi All,

I'm a newbie to this site and it's my first post. I look at this site for advice in repairing my 1983 Nissan King Cab Z24. I blew my head gasket twice between cyl. 3 & 4 and both times I used NAPA (Victor Reinz) head gasket set. I did not replace the head bolts. After the second head gasket blew I started re torquing the head bolts one at a time on tune ups. A bolt on the intake side second to the last bolt, snapped on removal. Now I have a bigger issue. I need recommendation and part # if available,  for head gasket and replacement head bolts. I've owned this truck for 37 yrs. and   I believe it has a lot more life to it.

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I've had zero problems with FelPro for stock applications. Possibly the head is not flat or warped slightly. It'll have to come off to get the head bolt out anyway. Use an industrial straight edge across the length of the head and if a 0.004" feeler gauge will slip under it anywhere it should be planed.

 

Before you do anything know that it is imperative to block the timing chain tensioner from falling out when the cam sprocket is loosened and removed. If not add 4-6 hours to the job.

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You've got me beat, I have had mine 32 years. Sometimes when a bolt snaps they are not as stubborn as you think. Rather than drill and try an easy out try left hand twisting drillbits. Sometimes when drilling as you move closer to the size of the remaining bolt it just backs off with the left handed bit.

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It depends on why the bolt stuck in the first place. If it was corroded by the blowing head gasket, over time it gets rusted into place and can be very hard to drill. I repaired one a long time ago on a L28 that was so bad we had to oversize the hole and glue in a slug then drill and tap that.

 

If there is any remaining bolt sticking out of the block surface, grind it flat before you attempt to drill it. This will help you get the center punch in the center of the bolt.

 

Heat and penetrating oil will be your friend on this repair.

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Thanks for the head gasket lead. I did have the head machined after the second blown gasket. I also need info on head bolts to replace the old ones. By the way, does any one know why only that one bolt threads smelt like burnt oil. The other bolts did not have the same smell

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Thanks NC85ST for the Nissan part No. DatzenMike, I saw your timing chain wedge on another blog and would like to try it. Is it possible to get a PDF so I can make my own. If not I understand. I like the Idea that the wedge holds the tensioner in. I don't need the extra 4-6 hours of work.

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I am getting ready to do the one-bolt-at-a-time retorque on my Z24 with 102k miles.  Getting worried about this very issue - what if I snap a bolt.  Truck is somewhat new to me.  Don't know if anyone ever retorqued before.  Head gasket intact. Better to cross fingers it won't blow than to look for trouble by retorquing?

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If you snap a bolt, you are looking at replacing the bolt, and removal of the broken bolt probably will require the head removed, and the gasket replaced.   If the engine has 102k miles on it, it's performance probably will be improved with a valve job, that you may as well do now that you have to remove the head.

 

A lot can be said for "if it ain't broke, don't fix it" philosophy.

 

Expect about 10% to 20% more torque to break each bolt loose than the maximum torque specification to tighten the head.

When applying torque to loosen the bolts, there is very little stress on the shank of the bolt, until the head of the bolt starts to turn.  Once that happens, the torque applied to the head of the bolt then tries to turn the threaded part of the bolt, and the shank of the bolt twists like a torsion bar.   If the threads of the bolt do not turn, the bolt probably will shear off at the top of the threads on the shank of the bolt.  This usually leaves enough of the bolt above the block surface to grab the bolt with a pair of vice grip locking pliers.  But the head has to be removed to get to it.  Before you try to remove the broken bolt, hitting the top of the broken bolt fairly hard will help to loosen the threads.

 

I have fairly recently retorqued the head bolts on a L-20-B, and a L-18 that have been sitting for an unknown time.  when retorquing the bolts, each bolt turned about a 1/4 turn more that its original position before retorquing.

Edited by DanielC
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I made the timing chain wedge per Mikes drawing and tried to dry fit, but the sprocket bolt is in the way.  Should the sprocket bolt be removed prior to inserting the wedge? This is the first time I'm removing the head without removing the bottom half.

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  • 1 month later...

I've been working on the engine off and on in between honey do projects. I'm about to pull the head off the engine, I've got the crank on TDC and the cam sprocket #2 straight up and the intake  and exhaust rockers are loose, but I noticed the colored link is one link off above the #2 dot  on the outer edge. Do I have to reposition the chain, if not how much would my timing be off if any and in what direction? I hope I don't have to do more work.  

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 The colored links are lined up with the dots stamped into the cam and the crank sprocket when assembled. After the engine is started this relationship is lost and they would align randomly every 10 or 20 or 50??? turns of the engine. Turn the engine forward two turns to the next TDC as you have just done and that colored link will be somewhere else.

 

Once you are ready to remove the cam sprocket mark the chain and the sprocket so it goes back together as it came ap[art.

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  • 4 months later...

Hi all

I just got back to working on my 83 Z24. I bought FEL-PRO head bolts but on the box it had KA24E eng 1989-92 made in japan. Can these bolts replace the original Z24 head bolts? The original head bolts has a number 13 on the head and the FEL-PRO has 12.9 on the head.

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I looked at Z series head bolts for a KA head I have and concluded that they would not work. For one the KA bolts are TTY (torque to yield) another are the lengths and with the Z24 blowing head gaskets it's important to have good fitting bolts and keeping them torqued properly.

 

If they fit properly the box would say '83-'86 Z24 on it.

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Thanks Mike,

Now I need help on finding the correct head bolts for my Z24 and also where I could purchase new exhaust and intake valves since I have the heads off. The valves don't look good and it's the original valves.

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The original head bolts are totally reusable if not damaged. Clean and oil them.

 

Take the valves out and wire wheel the deposits off. Get a tin of valve lapping compound and an electric drill and polish up the face and seat. A clean seat and face is all that really matters. If you replace them you would have to do this anyway and you aren't doing anything for the seats if just replacing the valves.

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This is the tool for the z24 timing chain.

 

Image 1 - Powerbuilt-Nissan-Timing-Chain-Holding-Tool-648832

Z20 Z22 Z24 Timing Chain Tool eBay

 

If the seat is nicked I would take the head in to a machine shop and have them go through the head.  The seat might need replaced.  are any of the seats to deep in the head?  The shop can check the valve guides for wear.  There is a lot to measure when going through a head.  Replacing valves might not fix all the worn/damage parts in your head.  Do you want to pull the head again?

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This sounds weird but the best tool I have ever used to hold the timing chain on napz motors is a wooden coat hanger broken in half, wooden ones are usually two pieces glued in the middle, snap that bastard in half and drill a hole in the fat end. I used to look in my closet when I was in my 20's and think wow, I am so classy with wooden coat hangers, Now in my 40's I look in my closet and see endless timing chain wedges!

HangerOversizeShirtNat10045503_x.jpg

Edited by Logical1
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